Campbell CR7 Instruction manual

Campbell CR7 Instruction manual
CR7 MEASUREMENT AND CONTROL SYSTEM
INSTRUCTION MANUAL
REVISION: 7/97
COPYRIGHT (c) 1991-1997 CAMPBELL SCIENTIFIC, INC.
This is a blank page.
WARRANTY AND ASSISTANCE
The CR7 MEASUREMENT AND CONTROL SYSTEM is warranted by CAMPBELL SCIENTIFIC, INC. to
be free from defects in materials and workmanship under normal use and service for thirty-six (36)
months from date of shipment unless specified otherwise. Batteries have no warranty. CAMPBELL
SCIENTIFIC, INC.'s obligation under this warranty is limited to repairing or replacing (at CAMPBELL
SCIENTIFIC, INC.'s option) defective products. The customer shall assume all costs of removing,
reinstalling, and shipping defective products to CAMPBELL SCIENTIFIC, INC. CAMPBELL SCIENTIFIC,
INC. will return such products by surface carrier prepaid. This warranty shall not apply to any CAMPBELL
SCIENTIFIC, INC. products which have been subjected to modification, misuse, neglect, accidents of
nature, or shipping damage. This warranty is in lieu of all other warranties, expressed or implied, including
warranties of merchantability or fitness for a particular purpose. CAMPBELL SCIENTIFIC, INC. is not
liable for special, indirect, incidental, or consequential damages.
Products may not be returned without prior authorization. To obtain a Returned Materials Authorization
(RMA), contact CAMPBELL SCIENTIFIC, INC., phone (435) 753-2342. After an applications engineer
determines the nature of the problem, an RMA number will be issued. Please write this number clearly on
the outside of the shipping container. CAMPBELL SCIENTIFIC's shipping address is:
CAMPBELL SCIENTIFIC, INC.
RMA#_____
815 West 1800 North
Logan, Utah 84321-1784
CAMPBELL SCIENTIFIC, INC. does not accept collect calls.
Non-warranty products returned for repair should be accompanied by a purchase order to cover the repair.
815 W. 1800 N.
Logan, UT 84321-1784
USA
Phone (435) 753-2342
FAX (435) 750-9540
www.campbellsci.com
Campbell Scientific Canada Corp.
11564 -149th Street
Edmonton, Alberta T5M 1W7
CANADA
Phone (780) 454-2505
FAX (780) 454-2655
Campbell Scientific Ltd.
Campbell Park
80 Hathern Road
Shepshed, Loughborough
LE12 9GX, U.K.
Phone +44 (0) 1509 601141
FAX +44 (0) 1509 601091
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CR7 OPERATOR'S MANUAL
TABLE OF CONTENTS
PAGE
WARRANTY AND ASSISTANCE
SELECTED OPERATING DETAILS .............................................................................................. v
CAUTIONARY NOTES ...................................................................................................................... vi
OVERVIEW
OV1.
PHYSICAL DESCRIPTION
OV1.1
OV1.2
OV1.3
700X Control Module .......................................................................................................... OV-1
720 I/O Module.................................................................................................................... OV-2
Enclosures and Connector Options .................................................................................... OV-2
OV2.
MEMORY AND PROGRAMMING CONCEPTS
OV2.1
OV2.2
OV2.3
Internal Memory .................................................................................................................. OV-3
CR7 Instruction Types......................................................................................................... OV-6
Program Tables and the Execution and Output Intervals ................................................... OV-6
OV3.
PROGRAMMING THE CR7
OV3.1
OV3.2
OV3.3
OV3.4
OV3.5
Functional Modes ................................................................................................................ OV-8
Key Definition ...................................................................................................................... OV-8
Programming Sequence ..................................................................................................... OV-8
Instruction Format ............................................................................................................... OV-9
Entering a Program ............................................................................................................. OV-9
OV4.
PROGRAMMING EXAMPLE
OV4.1
OV4.2
OV4.3
OV4.4
Measurement .................................................................................................................... OV-10
Output ............................................................................................................................... OV-12
Editing an Existing Program .............................................................................................. OV-14
EDLOG Program Listing ................................................................................................... OV-14
OV5.
DATA RETRIEVAL OPTIONS ................................................................................ OV-15
OV6.
SPECIFICATIONS ...................................................................................................... OV-17
i
TABLE OF CONTENTS
PROGRAMMING
1.
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
2.
2.1
2.2
2.3
3.
3.1
3.2
3.3
3.4
3.5
3.6
3.7
3.8
3.9
3.10
FUNCTIONAL MODES
Program Tables - *1, *2, and *3 Modes ................................................................................. 1-1
Setting and Displaying the Clock - *5 Mode ........................................................................... 1-2
Displaying and Altering Input Memory or Flags - *6 Mode ..................................................... 1-2
Compiling and Logging Data - *0 Mode ................................................................................. 1-3
Memory Allocation - *A........................................................................................................... 1-4
Memory Testing and System Status - *B Mode ..................................................................... 1-5
*C Mode - Security ................................................................................................................. 1-6
*D Mode - Save or Load Program .......................................................................................... 1-7
INTERNAL DATA STORAGE
Final Storage Areas, Output Arrays, and Memory Pointers ................................................... 2-1
Data Output Format and Range Limits .................................................................................. 2-2
Displaying Stored Data on Keyboard/Display - *7 Mode ........................................................ 2-3
INSTRUCTION SET BASICS
Parameter Data Types ........................................................................................................... 3-1
Repetitions/Card Number....................................................................................................... 3-1
Entering Negative Numbers ................................................................................................... 3-1
Indexing Input Locations ........................................................................................................ 3-2
Voltage Range and Overrange Detection .............................................................................. 3-2
Output Processing.................................................................................................................. 3-2
Use of Flags: Output and Program Control........................................................................... 3-3
Program Control Logical Constructions ................................................................................. 3-4
Instruction Memory and Execution Time................................................................................ 3-6
Error Codes ............................................................................................................................ 3-9
DATA RETRIEVAL/COMMUNICATION
4.
4.1
4.2
4.3
4.4
5.
5.1
5.2
6.
6.1
6.2
6.3
6.4
6.5
EXTERNAL STORAGE PERIPHERALS
On-Line Data Transfer - Instruction 96, *4 Mode ................................................................... 4-1
Manually Initiated Data Output - *9 Modes............................................................................. 4-2
Storage Module ...................................................................................................................... 4-3
Printer Output Formats........................................................................................................... 4-4
TELECOMMUNICATIONS
Telecommunications Commands .......................................................................................... 5-1
Remote Programming of the CR7.......................................................................................... 5-3
9 PIN SERIAL INPUT/OUTPUT
Pin Description ....................................................................................................................... 6-1
Enabling Peripherals .............................................................................................................. 6-2
Interrupting Data Transfer to Storage Peripherals ................................................................. 6-2
Telecommunications - Modem Peripherals............................................................................ 6-2
Interfacing with Computers, Terminals, and Printers ............................................................. 6-2
ii
TABLE OF CONTENTS
PROGRAMMING EXAMPLES
7.
7.1
7.2
7.3
7.4
7.5
7.6
7.7
7.8
7.9
7.10
7.11
7.12
7.13
7.14
7.15
7.16
7.17
8.
8.1
8.2
8.3
8.4
8.5
8.6
MEASUREMENT PROGRAMMING EXAMPLES
Single Ended Voltage-LI200S Silicon Pyranometer ................................................................7-1
Differential Voltage Measurement...........................................................................................7-1
Thermocouple Temperatures Using 723-T Reference ...........................................................7-2
Thermocouple Temperatures Using an External Reference Junction ....................................7-2
Thermocouples for Differential Temperature Measurement...................................................7-3
Temperature with Calibrated Thermocouples.........................................................................7-4
107 Temperature Probe ..........................................................................................................7-5
207 Temperature and RH Probe.............................................................................................7-5
Anemometer with Photochopper Output .................................................................................7-6
Tipping Bucket Raingage with Long Leads.............................................................................7-6
100 ohm PRT in 4 Wire Half-Bridge........................................................................................7-7
100 ohm PRT in 3 Wire Half-Bridge........................................................................................7-8
100 ohm PRT in 4 Wire Full-Bridge ........................................................................................7-9
Pressure Transducer-4 Wire Full-Bridge ..............................................................................7-10
Lysimeter-6 Wire Load Cell...................................................................................................7-11
227 Gypsum Soil Moisture Block ..........................................................................................7-13
Nonlinear Thermistor in Half Bridge (CSI Model 101)...........................................................7-14
PROCESSING AND PROGRAM CONTROL EXAMPLES
Computation of Running Average ...........................................................................................8-1
Rainfall Intensity ......................................................................................................................8-2
SUB 1 Minute Output Interval Synched to Real Time .............................................................8-3
Analog Output to Strip Chart ...................................................................................................8-4
Converting 0-360 Wind Direction Output to 0-540 for Strip Chart...........................................8-5
Covariance Correlation Programming Example......................................................................8-6
INSTRUCTIONS
9.
INPUT/OUTPUT INSTRUCTIONS .....................................................................................9-1
10. PROCESSING INSTRUCTIONS ......................................................................................10-1
11. OUTPUT PROCESSING INSTRUCTIONS ...................................................................11-1
12. PROGRAM CONTROL INSTRUCTIONS ......................................................................12-1
MEASUREMENTS
13. CR7 MEASUREMENTS
13.1
13.2
13.3
13.4
13.5
13.6
13.7
Fast and Slow Measurement Sequence ...............................................................................13-1
Single-Ended and Differential Voltage Measurements .........................................................13-1
The Effect of Sensor Lead Length on the Signal Settling Time ............................................13-3
Thermocouple Measurements ............................................................................................13-11
Bridge Resistance Measurements ......................................................................................13-15
Resistance Measurements Requiring AC Excitation ..........................................................13-19
Pulse Count Measurements................................................................................................13-20
iii
TABLE OF CONTENTS
INSTALLATION
14. INSTALLATION
14.1
14.2
14.3
14.4
14.5
Environmental Enclosure, Connectors and Junction Boxes ................................................ 14-1
System Power Requirements and Options .......................................................................... 14-2
Humidity Effects and Control................................................................................................ 14-5
Recommended Grounding Practices ................................................................................... 14-5
Use of Digital Control Ports for Switching Relays ................................................................ 14-6
15. I/O CARD ADDRESSING AND MULTIPLE I/0 MODULES
15.1
15.2
I/O Card Identification Number Decoding ............................................................................ 15-1
Use of Multiple I/O Modules ................................................................................................. 15-4
APPENDICES
A.
GLOSSARY.............................................................................................................................. A-1
B.
CR7 PROM SIGNATURES FOR SYSTEMS EQUIPPED WITH
STANDARD SOFTWARE .................................................................................................... B-1
C.
BINARY TELECOMMUNICATIONS
C.1
C.2
C.3
D.
D.1
D.2
Telecommunications Command With Binary Responses......................................................C-1
Final Storage Format .............................................................................................................C-3
Generation of Signature .........................................................................................................C-4
CALIBRATION PROCEDURES
Voltage Reference Calibration Procedure..............................................................................D-1
Clock Calibration Procedure ..................................................................................................D-2
LIST OF TABLES .......................................................................................................................... LT-1
LIST OF FIGURES ........................................................................................................................ LF-1
INDEX ................................................................................................................................................... I-1
iv
SELECTED OPERATING DETAILS
The channel numbering on the Analog Input
Card refers to differential measurements. Single
ended measurements assume the HI and LO
side of each differential channel are two
independent single ended channels, e.g., the HI
and LO side of differential channel 2 are single
ended channels 3 and 4 respectively.
Floating Point Format - The computations
performed in the CR7 use floating point
arithmetic. CSI's 4 byte floating point numbers
contain a 23 bit binary mantissa and a 6 bit
binary exponent. The largest and smallest
numbers that can be stored and processed are
9 x 1018 and 1 x 10-19, respectively.
When multiple measurements are specified in
one measurement instruction (through use of
the "Repetitions Parameter") the CR7 I/O
Module is capable of sequencing through 500
fast, single-ended measurements per second.
This specification is the MEASUREMENT
SPEED and should not be confused with
throughput which is the rate at which
measurements are made, converted to
engineering units and stored in Final memory.
With the 700X Control Module (6303 CPU
board), the maximum throughput rate for fast,
single-ended measurements is approximately
310 measurements per second (1 second
execution: Instruction 1 entered 4 times, 3 times
with 99 repetitions, once with 11 repetitions).
The computations performed in the CR7 are
done in floating point arithmetic. Internally, the
number is stored and processed as a binary
number with a 23 bit binary mantissa and a 6 bit
binary exponent. The largest and smallest
numbers that can be stored and processed are
9 x 1018 and 1 x 10-19 respectively. The size
of the mantissa limits the resolution of the
arithmetic to 1 part in 223 binary (1.3 x 109
decimal).
Time is stored with data in Final Memory only if
specifically requested through use of the Real
Time Instruction 77.
Data in Final Storage can be erased without
altering the program by using the *A Mode to
repartition memory. The simplest method is to
re-enter the current allocation for Input Storage
(32 locations is the default allocation). All
memory can be erased and the CR7 completely
reset by entering 1744 for the number of bytes
left in Program Memory.
Data is stored in Final Memory only by Output
Processing Instructions and only when the
Output Flag is set.
The default case for data stored in Final
Memory is low resolution (4 characters). High
resolution values (5 characters) must be
specified through use of Instruction 78. All data
contained in Input Memory is displayed (*6) as
HIGH RESOLUTION (5 characters) but the
default case for all data stored in Final Memory
is LOW RESOLUTION unless high resolution is
specified through use of Instruction 78.
On-line (as opposed to a manually initiated
dump) data transfer to peripherals (printer,
storage module, etc.) occurs only if enabled
through use of the *4 Mode or Instruction 96.
Data transfer to cassette tape is no longer
supported.
v
CAUTIONARY NOTES
The typical current drain for the CR7 is
approximately 100 mA while executing and 8-10
mA quiescent. Do not allow the lead-acid
batteries (2.5 Ahr) to drop below 11.76 V as
irreversible battery damage may result.
Damage will occur to the analog input channel
circuitry if voltages in excess of +16V are
applied for a sustained period.
A POTENTIALLY DANGEROUS situation can
result due to hydrogen gas build up if the CR7 is
housed in a gas tight enclosure and the internal
lead acid batteries are shorted or overcharged.
Hydrogen concentration levels may occur which
are capable of causing injury or equipment
damage if ignited.
An external battery connected to the I/O Module
+12V and ground terminals continues to power
the CR7 system even though the CR7 power
switch is off. Reverse polarity protection is NOT
provided on this connection so exercise
extreme care if connecting external power
supplies.
vi
CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW
The CR7 Measurement and Control System combines precision measurement with processing and
control capability in a battery operated system.
Campbell Scientific, Inc. provides three documents to aid in understanding and operating the CR7:
1. This Overview
2. The CR7 Operator's Manual
3. The CR7 Prompt Sheet
This Overview introduces the concepts required to take advantage of the CR7's capabilities. Hands-on
programming examples start in Section OV4. Working with a CR7 will help the learning process, so
don't just read the examples, turn on the CR7 and do them. If you want to start this minute, go ahead
and try the examples, then come back and read the rest of the Overview.
The sections of the Operator's Manual which should be read to complete a basic understanding of the
CR7 operation are the Programming Sections 1-3, the portions of the data retrieval Sections 4 and 5
appropriate to the method(s) you are using (see OV5), and Section 14 which covers installation and
maintenance.
Section 6 covers the details of serial communications. Sections 7 and 8 contain programming examples.
Sections 9-12 have detailed descriptions of the programming instructions, and Section 13 goes into
detail on the CR7 measurement procedures.
The Prompt Sheet is an abbreviated description of the programming instructions. Once familiar with the
CR7, it is possible to program it using only the Prompt Sheet as a reference, consulting the manual if
further detail is needed.
Read the Selected Operating Details and Cautionary Notes at the front of the Manual before using the
CR7.
OV1. PHYSICAL DESCRIPTION
The CR7 features a modular, multiple
processor design that provides precision
measurement and control capability in a rugged,
battery operated system. Control Module
functions include real-time task initiation,
measurement processing, data storage,
telecommunications, and keyboard/display
interaction. The I/O Module performs all analog
and pulse signal measurement functions as well
as the analog and digital control output
functions. The I/O Module contains its own
processor card, a precision analog interface
card, and seven card slots which can
accommodate any combination of I/O Cards.
Sensor leads are connected to the I/O cards via
screw terminals.
A maximum of four I/O modules, separated by
up to 1,000 feet, may be connected to a single
Control Module in applications that require
distributed measurement capability.
OV1.1 700X CONTROL MODULE
Contains the CPU card, with 24K of system
PROM and 40K of RAM; the serial interface
card for peripheral communication and
connection of up to four I/O Modules; and the
keyboard display card. Two slots are present
for optional RAM expansion. The system's 2.5
Ahr lead-acid batteries and AC charging
circuitry are also contained in this module.
The CS I/O 9-pin port provides connection to
data storage peripherals, such as the
SM192/716 Storage Module, and provides
serial communication to computer or modem
devices for data transfer or remote
programming (Section 6). This 9 pin port does
NOT have the same pin configuration as the
OV-1
CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW
RS232 9 pin serial ports used on many
computers.
The SDM terminals adjacent to the serial port
allow connection to Synchronous Device for
Measurement (SDM) peripherals. These
peripherals include the SDM-INT8 Interval
Timer, the SDM-SW8A Switch Closure Module,
the SDM-CD16AC AC/DC Controller, and the
SDM-OBDII Engine Controller Interface.
709
512K MEMORY CARD: This card
provides RAM storage for an additional 262,126
Final Data values. Only one 709 card may be
installed.
voltage with respect to the CR7 ground. Singleended channels are numbered sequentially,
e.g., the HI and LOW sides of differential
channels 2 are single-ended channels 3 and 4,
respectively (Section 13.2).
724
PULSE COUNTER CARD: Provides 4
pulse counting channels for switch closures, low
level AC cycles, or high frequency pulse signals.
725
EXCITATION CARD: There are 8
switched analog excitation channels. These
supply programmable excitation voltages for
resistive bridge measurements. The excitation
channels are only switched on during the
measurement. Only one is on at a time.
OV1.2 720 I/O MODULE
The processor card provides regulated power
for analog and digital functions from the
unregulated 12 volt supply. The analog
interface card contains a 16-bit A/D-D/A
converter, and a precision voltage reference.
The standard I/O Module contains slots for 7 I/O
Cards; the expanded Model 720XL contains 14
slots. All input and output connections to the
I/O module are transient protected with spark
gaps.
The +12 volt and ground terminals provide a
direct connection to the CR7 power supply.
723
ANALOG INPUT CARD: Contains 14
differential or 28 single ended inputs. Input
ground terminals connect to a heavy copper
bar, which reduces single ended measurement
offsets to less than 5µV.
723-T ANALOG INPUT CARD WITH RTD:
Identical to the 723 Card except that a platinum
resistance thermometer is mounted in the
center of the terminal strip. The PRT provides a
reference junction temperature for
thermocouple measurement. The PRT
measurement is accurate to ±0.1oC over a
range of -40oC to +60oC.
The numbering on the terminals refers to the
differential channels; i.e., the voltage on the HI
input is measured with respect to the voltage on
the Low input. When making single-ended
measurements either the HI or the Low channel
may be used independently to measure the
OV-2
The two Continuous Analog Output (CAO)
channels supply continuous output voltages,
under program control, for use with strip charts,
X-Y plotters, or proportional controllers.
The 8 Digital Control Ports (0 or 5 volt states)
allow on-off control of external devices. These
control ports have a very limited current output
(5mA) and are used to switch solid state
devices which in turn provide power to relay
coils (Section 14.4).
726
50 VOLT ANALOG INPUT CARD:
Provides 8 differential or 16 single ended inputs
for full scale DC ranges of ±50 V and ±15V.
Resolution is 1.66 millivolts on the ±50 V and
0.5 millivolts on the ±15 V range. The common
mode range is ±50 volts.
OV1.3 ENCLOSURES AND CONNECTOR
OPTIONS
ENC-7L
ALUMINUM FRAME FOR
LABORATORY ENVIRONMENTS: 17" x 12" x
6"; provides a housing for benchtop use or a
frame for attachment to a wall or a NEMA type
enclosure.
ENC-7F
ENVIRONMENTALLY SEALED
FIBERGLASS ENCLOSURE: 20" x 13" x 10";
housing for harsh environments. Sensor leads
enter via two ports fitted with 0.75" conduit
bushings, and plugged with removable
stoppers. The 1.040" hole size accommodates
#14 shell size circular connectors.
CR
7
CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW
E
LV
F
LIE
RE
VA
ES
PR
N
IO
UT
CA
ON
TT
S BU
RE
SE
FO
CA
G
IN
BE
LO
CK
UN
FIGURE OV1-1. CR7 Measurement and Control System
OV2. MEMORY AND PROGRAMMING
CONCEPTS
The CR7 must be programmed before it will
make any measurements. A program consists
of a group of instructions entered into a program
table. The program table is given an execution
interval which determines how frequently that
table is executed. When the table is executed,
the instructions are executed in sequence from
beginning to end. After executing the table, the
CR7 waits the remainder of the execution
interval and then executes the table again
starting at the beginning.
The interval at which the table is executed will
generally determine the interval at which the
sensors are measured. The interval at which
data are stored is separate and may range from
samples every execution interval to processed
summaries output hourly, daily, or on longer or
irregular intervals.
Figure OV2-1 represents the measurement,
processing, and data storage sequence in the
CR7 and shows the types of instructions used
to accomplish these tasks.
OV2.1 INTERNAL MEMORY
The CR7 has 40,960 bytes of Random Access
Memory (RAM), divided into five areas. The
five areas of RAM are:
1. Input Storage - Input Storage holds the
results of measurements or calculations.
The *6 Mode is used to view Input Storage
locations to check current sensor readings
or calculated values. Input Storage defaults
to 28 locations. Additional locations can be
assigned using the *A Mode.
2. Intermediate Storage - Certain Processing
Instructions and most of the Output
Processing Instructions maintain
intermediate results in Intermediate
Storage. Intermediate storage is
automatically accessed by the Instructions
and cannot be accessed by the user. The
default allocation is 64 locations. The
number of locations can be changed using
the *A Mode.
OV-3
CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW
ANALOG IPUTS
SDM PORTS
Input/Output Instructions
1. Volt (SE)
2. Volt (DIFF)
4. Ex-Del-Se
5. AC Half Br
6. Full Br
7. 3W Half Br
9. Full Br-Mex
11. Temp (107)
12. RH-(07)
13. Temp-TC SE
14. Temp-TC DIFF
17. Temp-Panel
101
102
103
104
113
115
118
CS I/O PORT
SDM-INT8
SDM-SW8
SDM-AO4
SDM-CD16
SDM-SIO4
Set SDM Clock
SDM-OBDII
Telecommunications
Program Control Instructions
96 (Storage Module, Printer)
97 Initiate Telecommunications
98 Print Character
C1
700X CONTROL MODULE
C3
I/O MODULE
+12
720
C2
+12
MADE IN USA
SDM
CAMPBELL
SCIENTIFIC
INC. LOGAN, UTAH
SERIAL I/O
ANALOG INTERFACE
726
50 VOLT INPUT
1
H
2
H
3
H
1
2
3
4
5
6
7
8
H L
H L
H L
H L
H L
H L
H L
H L
1
CR7
4
MEASUREMENT & CONTROL SYSTEM
2
H
724
PULSE
COUNTER
I. D.
RTD
1
H L
1
2
H L
2
3
H L
4
H L
5
H L
SWITCHED ANALOG OUT
3
4
5
6
7
6
H L
8
1
7
H L
8
H L
9
H L
10
H L
CONTINUOUS ANALOG OUT
2
11
H L
12
H L
13
H L
14
H L
DIGITAL CONTROL OUT
1 2 3 4
5 6 7 8
725
EXCITATION
DATA
3
4
ON
1
2
3
A
4
5
6
B
7
8
9
C
*
0
#
D
AUX.
POWER
OFF
MADE IN USA
CONTROL PORTS
PULSE INPUTS
EXCITATION OUTPUTS
CAO
Input/Output Instructions
3. Pulse
Input/Output Instructions
4. Ex-Del-Se
5. AC Half Br
6. Full Br
7. 3W Half Br
9. Full Br-Mex
11. Temp (107)
12. RH (207)
22. Excit-Del
21ANALOG OUT
Input/Output Instructions
20 Set Port
Program Control Instructions
83 If Case < F
86 Do
88 If x < = > y
89 If x < = > f
91 If flag, port
92 If Time
Command Codes:
4x Set port x high
5x Set port x low
6x Toggle port x
7x Pulse port x
FIGURE OV1-2. CR7 Wiring Panel and Associated Programming Instructions
OV-4
CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW
INPUT/OUTPUT
INSTRUCTIONS
Specify the conversion of a sensor signal
to a data value and store it in Input
Storage. Programmable entries specify:
(1) the measurement type
(2) the number of channels to measure
(3) the input voltage range
(4) the Input Storage Location
(5) the sensor calibration constants
used to convert the sensor output to
engineering units
I/O Instructions also control analog
outputs and digital control ports.
INPUT STORAGE
PROCESSING INSTRUCTIONS
Holds the results of measurements or
calculations in user specified locations.
The value in a location is written over
each time a new measurement or
calculation stores data to the locations.
Perform calculations with values in Input
Storage. Results are returned to Input
Storage. Arithmetic, transcendental and
polynomial functions are included.
OUTPUT PROCESSING
INSTRUCTIONS
INTERMEDIATE STORAGE
Perform calculations over time on the
values updated in Input Storage.
Summaries for Final Storage are
generated when a Program Control
Instruction sets the Output Flag in
response to time or events. Results
may be redirected to Input Storage for
further processing. Examples include
sums, averages, max/min, standard
deviation, histograms, etc.
Provides temporary storage for
intermediate calculations required by the
OUTPUT PROCESSING INSTRUCTIONS;
for example, sums, cross products,
comparative values, etc.
Output Flag set high
FINAL STORAGE
Final results from OUTPUT
PROCESSING INSTRUCTIONS are
stored here for on-line or interrogated
transfer to external devices (Figure
OV5.1-1). When memory is full, new
data overwrites the oldest data.
FIGURE OV2-1. Instruction Types and Storage Areas
OV-5
CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW
3. Final Storage - Final, processed values are
stored here for transfer to printer, solid state
Storage Module or for retrieval via
telecommunication links. Values are stored
in Final Storage only by the Output
Processing Instructions and only when the
Output Flag is set in the users program.
The 18,336 locations allocated to Final
Storage at power up is reduced if Input or
Intermediate Storage is increased.
4. System Memory - used for overhead tasks
such as compiling programs, transferring
data, etc. The user cannot access this
memory.
5. Program Memory - available for user
programs entered in Program Tables 1 and
2, and Subroutine Table 3. (Sections OV3,
1.1)
The use of the Input, Intermediate, and Final
Storage in the measurement and data
processing sequence is shown in Figure OV2-1.
While the total size of these three areas
remains constant, memory may be reallocated
between the areas to accommodate different
measurement and processing needs (*A Mode,
Section 1.5). The size of system and program
memory are fixed.
OV2.2 CR7 INSTRUCTION TYPES
Figure OV2.1 illustrates the use of the three
different instruction types which act on data.
The fourth type, Program Control, is used to
control output times and vary program
execution. Instructions are identified by
numbers.
1. INPUT/OUTPUT INSTRUCTIONS (126,101-104, Section 9) control the terminal
strip inputs and outputs (the sensor is the
source, Figure OV1-2), storing the results in
Input Storage (destination). Multiplier and
offset parameters allow conversion of linear
signals into engineering units. The Control
Ports and Continuous Analog Outputs are
also addressed with I/O Instructions.
2. PROCESSING INSTRUCTIONS (30-66,
Section 10) perform numerical operations
on values located in Input Storage (source)
and store the results back in Input Storage
(destination). These instructions can be
used to develop high level algorithms to
process measurements prior to Output
Processing (Section 10).
OV-6
3. OUTPUT PROCESSING INSTRUCTIONS
(69-82, Section 11) are the only
instructions which store data in Final
Storage (destination). Input Storage
(source) values are processed over time to
obtain averages, maxima, minima, etc.
There are two types of processing done by
Output Instructions: Intermediate and Final.
Intermediate processing normally takes
place each time the instruction is executed.
For example, when the Average Instruction
is executed, it adds the values from the
input locations being averaged to running
totals in Intermediate Storage. It also keeps
track of the number of samples.
Final processing occurs only when the
Output Flag is high. The Output Processing
Instructions check the Output Flag. If the
flag is high, final values are calculated and
output. With the Average, accumulated
totals are divided by the number of samples
and the resulting averages sent to Final
Storage. Intermediate locations are zeroed
and the process starts over. The Output
Flag, Flag 0, is set high by a Program
Control Instruction which must precede the
Output Processing Instructions in the user
entered program.
4. PROGRAM CONTROL INSTRUCTIONS
(85-98, Section 12) are used for logic
decisions and conditional statements. They
can set flags, compare values or times,
execute loops, call subroutines,
conditionally execute portions of the
program, etc.
OV2.3 PROGRAM TABLES AND THE
EXECUTION AND OUTPUT INTERVALS
Programs are entered in Tables 1 and 2.
Subroutines, called from Tables 1 and 2, are
entered in Subroutine Table 3. The size of each
table is flexible, limited only by the total amount
of program memory. If Table 1 is the only table
programmed, the entire program memory is
available for Table 1.
Table 1 and Table 2 have independent
execution intervals, entered in units of seconds
with an allowable range of 0.0125 to 6553
seconds. Intervals shorter than 0.1 seconds are
allowed only in Table 1. Subroutine Table 3 has
no execution interval; subroutines are only
executed when called from Table 1 or 2.
CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW
Table 1.
Execute every x sec.
0.0125 < x < 6553
Table 2.
Execute every y sec.
0.1 < y < 6553
Table 3.
Subroutines
Instructions are executed
sequentially in the order they
are entered in the table. One
complete pass through the table
is made each execution interval
unless program control
instructions are used to loop or
branch execution.
Table 2 is used if there is a
need to measure and process
data on a separate interval from
that in Table 1.
A subroutine is executed only
when called from Table 1 or 2.
Normal Order:
MEASURE
PROCESS
CHECK OUTPUT COND.
OUTPUT PROCESSING
Subroutine Label
Instructions
End
Subroutine Label
Instructions
End
Subroutine Label
Instructions
End
FIGURE OV2-2. Program and Subroutine Tables
OV2.3.1 THE EXECUTION INTERVAL
OV2.3.2 THE OUTPUT INTERVAL
The execution interval specifies how often the
program in the table is executed, which is
usually determined by how often the sensors
are to be measured. Unless two different
measurement rates are needed, use only one
table. A program table is executed sequentially
starting with the first instruction in the table and
proceeding to the end of the table.
The interval at which output occurs is
independent from the execution interval, other
than the fact that it must occur when the table is
executed (i.e., a table cannot have a 10 minute
execution interval and output every 15 minutes).
Each instruction in the table requires a finite
time to execute. If the execution interval is less
than the time required to process the table, the
CR7 overruns the execution interval, finishes
processing the table and waits for the next
execution interval before initiating the table.
When an overrun occurs, decimal points are
shown on either side of the G on the display in
the LOG mode (*0). Overruns and table priority
are discussed in Section 1.1.
A single program table can have many different
output intervals and conditions, each with a unique
data set (output array). Program Control
Instructions are used to set the Output Flag which
determines when output occurs. The Output
Processing Instructions which follow the instruction
setting the Output Flag determine the data output
and its sequence. Each additional output array is
created by another Program Control Instruction
setting the Output Flag high in response to an
output condition, followed by Output Processing
Instructions defining the data set to output.
OV3. PROGRAMMING THE CR7
A program is created by keying it directly into
the datalogger or on a PC using the PC208 or
PC208W Datalogger Support Software program
EDLOG. This manual describes direct
interaction with the CR7. Work through the
direct programming examples in this overview
before using EDLOG and you will have the
basics of CR7 operation as well as an
appreciation for the help provided by the
software. Section OV3.5 describes options for
loading the program into the CR7.
OV-7
CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW
OV3.1 FUNCTIONAL MODES
User interaction with the CR7 is broken into
different functional MODES, (e.g., programming
the measurements and output, setting time,
manually initiating a block data transfer to
Storage Module, etc.). The modes are referred
to as Star (*) Modes since they are accessed by
first keying *, then the mode number or letter.
Table OV3.1 lists the CR7 Modes.
TABLE OV3-1. * Mode Summary
Key
Mode
*0
*1
*2
*3
*4
*5
*6
LOG data and indicate active Tables
Program Table 1
Program Table 2
Program Table 3, subroutines only
Enable/disable printer output
Display/set real time clock
Display/alter Input Storage data, toggle
flags
Display Final Storage data
Final Storage data transfer to cassette
tape
Final Storage data transfer to printer
Memory allocation/reset
Signature test/PROM version
Security
Save/load Program
TABLE OV3-2. Key Description/Editing
Functions
Key
Action
0-9
*
A
B
C
Key numeric entries into display
Enter Mode (followed by Mode Number)
Enter/Advance
Back up
Change the sign of a number or index
an input location to loop counter
Enter the decimal point
Clear the rightmost digit keyed into the
display
Advance to next instruction in program
table (*1, *2, *3) or to next output array
in Final Storage (*7)
Back up to previous instruction in
program table or to previous output
array in Final Storage
Delete entire instruction
D
#
#A
*7
*8
*9
*A
*B
*C
*D
OV3.2 KEY DEFINITION
Keys and key sequences have specific
functions when using the CR7 keyboard or a
terminal/computer in the remote keyboard state
(Section 5). Table OV3.2 lists these functions.
In some cases, the exact action of a key
depends on the mode the CR7 is in and is
described with the mode in the manual.
#B
#D
OV3.3 PROGRAMMING SEQUENCE
In routine applications, sensor signals are
measured, processed over some time interval,
and the results are stored in Final Storage. A
generalized programming sequence is:
1. Enter the execution interval, determined by
the desired sensor scan rate.
2. Enter the Input/Output Instructions required
to measure the sensors.
3. Enter any Processing Instructions required
to get the data ready for Output Processing.
4. Enter a Program Control Instruction to test
the output condition and Set the Output
Flag when the condition is met. For
example, use Instruction 92 to output based
on time, 86 to output each time the table is
executed, and 88 or 89 to compare input
values. This instruction must precede the
Output Processing Instructions.
5. Enter the Output Processing Instructions to
store processed data in Final Storage. The
order in which the data are stored is
determined by the order of the Output
Processing Instructions in the table.
6. Repeat steps 4 and 5 for output on different
intervals or conditions.
OV-8
CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW
OV3.4 INSTRUCTION FORMAT
Instructions are identified by an instruction
number. Each instruction has a number of
parameters that give the CR7 the information it
needs to execute the instruction.
The CR7 Prompt Sheet has the instruction
numbers in red, with the parameters briefly
listed in columns following the description.
Some parameters are footnoted with further
description under the "Instruction Option Codes"
heading.
For example, Instruction 73 stores the
maximum value that occurred in an Input
Storage Location over the output interval. The
instruction has three parameters (1)
REPetitionS, the number of sequential Input
Storage locations on which to find maxima, (2)
TIME, an option of storing the time of
occurrence with the maximum value, and (3)
LOC the first Input Storage Location operated
on by the Maximum Instruction. The codes for
the TIME parameter are listed in the "Instruction
Option Codes".
The repetitions parameter specifies how many
times an instruction's function is to be repeated.
For example, four 107 thermistor probes, wired
to single-ended channels 1 through 4, are
measured using a single Instruction 11, Temp107, with four repetitions. Parameter 2
specifies the input channel of the first thermistor
(channel 1) and parameter 4 specifies the Input
Storage Location in which to store
measurements from the first thermistor. If
Location 5 were used, the temperature of the
thermistor on channel 1 would be stored in Input
Location 5, the temperature from channel 2 in
Input Location 6, etc.
Detailed descriptions of the instructions are
given in Sections 9-12.
OV3.5 ENTERING A PROGRAM
Programs are entered into the CR7 in one of
four ways:
b. Stored/loaded from SM192/716 Storage
Module
3. Loaded from Storage Module or internal
PROM (special software) upon power-up.
A program is created by keying it directly into
the datalogger as described in the following
Section, or on a PC using the PC208
Datalogger Support Software.
PC208 Software programs are used to develop
and send programs to the CR7. Program files
developed can be downloaded directly to the
CR7 via direct wire, telephone, or Radio
Frequency (RF).
Programs on disk can be copied to a Storage
Module. Using the *D Mode to save or load a
program from a Storage Module is described in
Section 1.8.
If the SM192/716 Storage Module is connected
when the CR7 is powered-up, the CR7 will
automatically load program number 8, provided
that a program 8 is loaded in the Storage
Module (Section 1.8).
It is also possible (with special software) to
create a PROM (Programmable Read Only
Memory) that contains a datalogger program.
With this PROM installed in the datalogger, the
program will automatically be loaded and run
when the datalogger is powered-up, requiring
only that the clock be set.
OV4. PROGRAMMING EXAMPLE
The best way to become acquainted with the
CR7 is to program it and make some
measurements. If your CR7 contains either a
723 or 723-T Analog Input card, a short
copper-constantan thermocouple (TC) should
be connected to channel 5. In this example, you
will program the CR7 to sample the
thermocouple temperature. If you have not
purchased the 723-T with a Resistive
Temperature Device (RTD) to measure the TC
reference junction temperature, a "dummy"
reference temperature will be used.
1. Keyed in using the CR7 keyboard.
2. Loaded from a pre-recorded listing using
the *D Mode. There are two types of
storage/input:
a. Stored on disk/sent from computer
(PC208 software).
OV-9
CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW
Tables OV3-1 and OV3-2 summarize the
Keyboard Commands and Control Modes used
to program the CR7, monitor Input and Final
Storage and control data output to peripherals.
The instructions, and their associated
parameters, are the CR7's programming steps
and are used to build the CR7's program. It is
not necessary to understand all the commands
to proceed with this programming exercise. It is
helpful to find the example's instructions on the
CR7 Prompt Sheet provided with this manual.
As you become familiar with programming the
CR7, you will find that the Prompt Sheet or the
PC208 program EDLOG has all the information
you need to write your program. By following
along on the Prompt Sheet as you proceed with
this exercise, you will learn how to use it to write
your own programs.
OV4.1 MEASUREMENT
To make a thermocouple temperature
measurement, the CR7 must know the
temperature of the reference junction. The CR7
takes the reference temperature, converts it to
the equivalent TC voltage, adds the measured
TC voltage and converts the sum to
temperature through a polynomial fit to the TC
output curve. In this example, the reference
junction is at the Analog Input Card. Its
temperature is measured with Instruction 17,
Panel Temperature. If you have an Analog
Input Card with RTD, check to see which
number is assigned to it. A tag labeled RTD is
on the left hand side and the card number is on
the right hand side of the Analog Input Card. If
the RTD card is not card 1, you must enter the
correct card number as Parameter 1 of
Instruction 17. If you do not have an Analog
Input Card with RTD, you will omit Instruction 17
from the Program and enter a "dummy"
reference temperature after the Program is
compiled.
The thermocouple temperature measurement is
made using Instruction 14 (differential voltage
measurement of TC) on differential channel 5.
When using a copper-constantan
thermocouple, the copper lead is connected to
the high input of a differential channel and the
constantan lead is connected to the low side.
The channel numbering printed on the Analog
Input Cards refers only to differential channels.
OV-10
Either the high or low side of a differential
channel may be used for single ended
measurements. (Each side is counted when
assigning single ended channel numbers; e.g.,
the high side of differential channel 8 is single
ended channel 15 and the low side is single
ended channel 16).
The first parameter in Instruction 14 is the
number of times to repeat the measurement: 1
is entered because only one thermocouple is
measured. If more thermocouple
measurements were desired, the copper leads
would be connected to the high sides of
consecutive differential channels, the
constantan leads to the low sides and the
number of repetitions entered in Parameter 1
would equal the number of thermocouples.
Parameter 2 is the voltage range to use when
making the measurement. The output of a
copper-constantan thermocouple is
approximately 40 microvolts per oC difference
in temperature between the two junctions. The
+5000 uV scale will provide a range of +5000/40
= +125 oC (i.e., this scale will not overrange as
long as the measuring junction is within 125 oC
of the panel temperature). The resolution of the
+5000 uV range is 166 nV or 0.004 oC.
Parameter 3 is the Input Card number and
Parameter 4 is the channel on which to make
the first measurement. If more than one
thermocouple is measured, the CR7 will
automatically advance through the channels
and on to the next card if necessary. Similarly,
Parameter 7 is the Input Storage Location in
which to store the first measurement; e.g., if
there are five repetitions and the first
measurement is stored in location 3, the final
measurement will be stored in location 7.
Parameter 6 is the Input Storage location in
which the reference temperature is stored, and
Parameters 8 and 9 are the multiplier and offset
to apply to the temperature value. A multiplier of
1 and an offset of 0 give the result in oC, a
multiplier of 1.8 and an offset of 32 give the
result in oF.
Now that you have some idea of what you are
telling the CR7 by entering the parameters, we
will proceed with programming the CR7.
CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW
TABLE OV4-1. Thermocouple Measurement Programming Example
TURN ON THE POWER SWITCH AND PROCEED AS FOLLOWS:
Display
ID:Data
Key
HELLO 01
Display
ID:Data
Key
:0064
*
00:00
1
01:00
A
01:0.0000
2
01:2
A
Description
The number after "HELLO" will count up as memory
is checked. If you have a 512K Memory Card, this
can take a long time; key # to abort the test. The
result of the CPU board memory check is then
displayed (Sect. 1.5)
Enter Program Table 1, advance to Execution
Interval
Enter 2 second Execution Interval advance to first
instruction
-------Users without RTD omit next Instruction-----01:P00
01:00
17
1
02:0000
1
01:P17
01:1
A
A
02:1
A
Measure Panel Temp., advance to first Parameter
RTD in input card #1, if RTD card other than #1,
enter correct card #
Store temp in location 1
-------Users without RTD continue here------Instruction Location Number will be 1 less (i.e., 01:P00)
02:P00
01:00
02:00
03:00
04:00
05:00
06:0000
07:0000
08: 0.0000
09: 0.0000
14
1
2
1
5
1
1
2
1
02:P14
01:1
02:2
03:1
04:5
05:1
06:1
07:2
08:1
09:0.0000
03:P00
00:00
A
A
A
A
A
A
A
A
A
A
*
0
:LOG 1
TC temp., differential meas.
1 repetition
Range code (5000uV, slow)
Input card #1
Input channel of 1st TC
TC type (copper-constantan)
Reference temp. is in location 1
Store TC temp. in location 2
Multiplier of 1
No offset entered (offset=0), advance to next
instruction
Exit Table 1
Enter *0 Mode, compile table
The CR7 is now programmed to measure the thermocouple temperature and to store the result in Input
Storage Location 2. The colon between the ID and Data fields blinks each time Table 1 is executed,
every 2 seconds in this example. If you do not have an RTD, the "reference temperature" is 0.0 and the
value stored in Location 2 is the difference in temperature between the panel and the thermocouple. The
*6 Mode can be used to monitor the values in the Input Storage and to change the value of the dummy
reference temperature.
OV-11
CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW
TABLE OV4-2. Using *6 Mode to Observe Example TC Measurements
(User with Model 723-T RTD Card)
Display
ID:Data
Key
:LOG 1
*6
00:00
0
Display
ID:Data
06:0000
01:21.234
02:22.433
01:21.199
:LOG 1
Key
A
A
B
*
Description
Enter *6 Mode, advance to first location
Panel temp is 21.234 oC, advance to location 2
TC temp is 22.433 oC, backup to location 1
Panel temp is now 21.199 oC
Return to *0 Mode
TABLE OV4-3. Using *6 Mode to Observe Example TC Measurements
(User with Model 723 Card, No RTD)
Display
ID:Data
Key
:LOG 1
*6
:0.0000
20
00:00
0
Display
ID:Data
06:0000
01:0.0000
02:2.9533
01:0.0000
:20
01:20.000
02:22.866
Key
A
A
B
C
A
A
*
:LOG 1
You can advance through Input Storage by
keying in the advance command, A, or backup
by keying in the backup command, B. The Input
Location you are observing is shown on the left
in the display ID field. The temperature data
stored in the Input locations are updated every 2
seconds, each time Table 1 is executed. Verify
this by changing the temperature of the
thermocouple (hold it in your fingers) while
monitoring the proper Input Location.
OV-12
Description
Enter *6 Mode, advance to first location
Reference temp is 0.0oC, advance to location 2
TC "temp" is 2.9533 C, backup to location 1
Setup to change stored value
Store 20 in location 1
Advance to location 2
The TC temp in location 2 using a reference
temperature of 20o
Return to *0 Mode
It is possible to go directly to a specific Input
Storage location by entering the *6 Mode and
keying in the desired location before keying A.
A similar utility is available in other Modes.
OV4.2 OUTPUT
In the following example instructions are
appended to Table 1 to output the time and the
average temperatures to Final Storage every 5
minutes.
CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW
TABLE OV4-4. Example Programming to Obtain Five Minute Averages
Display
ID:Data
Key
Display
ID:Data
1
3
: LOG 1
01:00
01:3
A
03:P00
01:0000
02:0000
03:00
92
0
5
10
03:P92
01:0
02:5
03:10
A
A
A
A
Enter If Time Instruction
Enter 0 minutes into interval
Enter 5 minute time interval
Set output Flag 0
04:P00
01:0000
05:P00
01:00
02:0000
77
10
71
2
1
04:P77
:10
05:P71
01:2
02:1
A
A
A
A
A
Enter Output Time Instruction
Code for HR:MIN
Enter Average Instruction
2 repetitions
Location of 1st input data to be averaged
*
Exit Table 1
Enter *5 Mode to set clock (the clock will be running)
Enter Year
Enter Julian day (January 11 assumed in this
example)
Enter Hours:Minutes (24 hour time, 1:24 PM
assumed in this example)
Exit *5 Mode, compile Table 1, commence logging
data
00:00
01:00
06:P00
Key
*
00:00
05:00
05:0000
5
85
11
:00:21:32
05:85
05:11
A
A
A
05:00:21
1324
05:13:24
A
13:24:01
Description
*0
Program Table 1
Advance to 3rd Instruction location (Key in 2 if
Instruction 17 was not entered, Instruction Location
Number will be 1 less than shown in table)
: LOG 1
The CR7 is now programmed to sample the panel and thermocouple temperatures every 2 seconds and
to output the time and the average temperatures to Final Storage every 5 minutes. Each Output Array
sent to Final Storage will consist of 4 data values. The first value will be an output identifier which gives
the number of the Table which caused the output, and the instruction location number of the instruction
which set the output flag. The second value will be the time, and the third and fourth values will be the
average temperatures of the I/O Module and the thermocouple. Values stored in Final Storage can be
viewed using the *7 Mode. Table 1.2-5 shows an example of the use of the *7 Mode, it is assumed that
the CR7 has been logging data for 8 minutes since the time was set in the previous example.
OV-13
CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW
TABLE OV4-5. Using *7 Mode to View Values in Final Storage
Display
ID:Data
Key
Display
ID:Data
:LOG 1
00:00
Key
Description
*
7
07:9.0000
A
01:0103.
A
02:1325.
03:22.57
04:23.43
01:0103.
02:1330.
03:22.61
00:00
A
A
A
A
A
*
0
:LOG 1
Enter *7 Mode. The DSP is at Final Storage location 9,
advance to first data value
Output identifier: users who did not enter Instruction 17 will
see 01: 0102 because the output flag is set by the second
instruction in Table 1
Time
Average panel temp for readings between 1:24 and 1:25 P.M.
Average thermocouple temp.
Output identifier
Time
Average panel temp for readings between 1:25 and 1:30 P.M.
Enter *0 Mode
OV4.3 EDITING AN EXISTING PROGRAM
When editing an existing program in the CR7,
entering a new instruction inserts the
instruction; entering a new value for an
instruction parameter replaces the previous
value.
To insert an instruction, enter the program table
and advance to the position where the
instruction is to be inserted (i.e., P in the data
portion of the display), key in the instruction
number, and then key A. The new instruction
will be inserted at that point in the table,
advance through and enter the parameters.
The Instruction that was at that point and all
instructions following it will be pushed down to
follow the inserted instruction.
An instruction is deleted by advancing to the
instruction number (P in display) and keying #D
(Table OV3-2).
To change the value entered for a parameter,
advance to parameter and key in the correct
value then key A. Note that the new value is not
entered until A is keyed.
TABLE OV4-6. EDLOG Listing of Example
Program
*
01:
1
2
Table 1 Programs
Sec. Execution Interval
01:
01:
02:
P17
1
1
Panel Temperature
IN Card
Loc :
02:
01:
02:
03:
04:
05:
06:
07:
08:
09:
P14
1
2
1
5
1
1
2
1
0
Thermocouple Temp (DIFF)
Rep
5000 uV slow Range
IN Card
IN Chan
Type T (Copper-Constantan)
Ref Temp Loc
Loc [:TC Temp ]
Mult
Offset
03:
01:
02:
03:
P92
0
5
10
If time is
minutes into a
minute interval
Set high Flag 0 (output)
04:
01:
P77
10
Real Time
Hour-Minute
05:
01:
02:
P71
2
1
Average
Reps
Loc
OV4.4 EDLOG PROGRAM LISTING
The examples in the rest of this manual use
program listings generated by EDLOG, the
datalogger Program Editor for the PC
(PC208(W) Software). The EDLOG listing does
not show the CR7 display or the "A" keystrokes
used to enter data. The EDLOG listing for the
previous example is given in Table OV4-6.
OV-14
CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW
OV5. DATA RETRIEVAL OPTIONS
There are several options for data storage and
retrieval. These options are covered in detail in
Sections 2, 4, and 5. Figure OV5-1
summarizes the various possible methods.
Regardless of the method used, there are three
general approaches to retrieving data from a
datalogger.
1. On-line output of Final Storage data to a
peripheral storage device. On a regular
schedule, that storage device is brought
back to the office/lab where the data is
transferred to the computer. Another
storage device is usually taken into the field
and exchanged for the one which is
retrieved so that data collection can
continue uninterrupted.
2. Bring a storage device to the datalogger
and transfer all the data that has
accumulated in Final Storage since the last
visit.
3. Retrieve the data over some form of
telecommunications link, that is, Radio
Frequency (RF), telephone, short haul
modem, multi-drop interface, or satellite.
The PC208 software automates this
process.
Regardless of which method is used, the
retrieval of data from the datalogger does NOT
erase those data from Final Storage. The data
remain in the ring memory until:
•
they are written over by new data
(Section 2.1)
•
memory is reallocated (Section 1.5)
•
the power to the datalogger is turned
off.
Table OV5-1 lists the instructions used with the
various methods of data retrieval.
TABLE OV5-1. Data Retrieval Methods and Related Instructions
Storage
Module
Printer, other
Serial Device
Telecommunications
(RF, Phone, Short Haul, SC32A)
Inst. 96,
*4
*9
*D
Inst. 96, 98
*4
*9
*D
Inst. 97
(Telecommunications Commands)
TABLE OV5-2. Data Retrieval Sections in Manual
Topic
Instr. 96
Instr. 97
*4
*8
*9
*D
Storage Module
Telecommunications
Section in Manual
4.1, 12
12
4.1
4.2
4.2
1.8
4.3
5
OV-15
CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW
+12
720
I/O MODULE
700X CONTROL MODULE
MADE IN USA
CAMPBELL
SCIENTIFIC
INC. LOGAN, UTAH
SERIAL I/O
ANALOG INTERFACE
6
H L
7
H L
8
H L
1
2
3
4
5
6
7
8
9
H L
H L
H L
H L
H L
H L
H L
H L
H L
10
H L
11
H L
726
50 VOLT INPUT
1
H
2
H
3
H
1
H L
2
H L
3
H L
4
H L
5
H L
1
CR7
4
MEASUREMENT & CONTROL SYSTEM
2
H
724
PULSE
COUNTER
I. D.
RTD
1
2
SWITCHED ANALOG OUT
3
4
5
6
7
13
H L
14
H L
4
725
EXCITATION
ON
OFF
Display
Storage
Module
Card Storage
Module
DATA
3
DIGITAL CONTROL OUT
1 2 3 4
5 6 7 8
CONTINUOUS ANALOG OUT
1
2
8
12
H L
Multidrop
Modem
1
2
4
5
7
8
9
C
*
0
#
3
D
6
A
B
AUX.
POWER
MADE IN USA
Shorthaul
Modem
RF Modem
Phone
Modem
Satellite
Interface
Phone
Modem
Satellite
Ground
Station
Transceiver
Storage
Module
Card Storage
Module
RS-232
Interface
RS-232
Interface
Direct
RS-232
Interface
Multidrop
Modem
Shorthaul
Modem
RS-232
Interface
Logger Time 00:03:54
Flags
Ports
H=Help
Transceiver
RF Base
Station
V = View save to file
F1. . F8 = Toggle flags
P1. . P6 = Toggle ports
C = Collect data
G = Graph enter/exit
R = Re-scale
+ = Incr. auto exponent
- = Decr. auto exponent
1: SOLAR
2: TEMP C
3: RH %
2300
2200
2100
2000
1900
1800
900
800
700
1700
1600
600
500
400
1500
1400
1300
300
200
1200
1100
1000
100
Scale = Auto
FIGURE OV5-1. Data Retrieval Hardware Options
OV-16
CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW
OV6. SPECIFICATIONS
Electrical specifications are valid for over a -25° to +50°C range unless otherwise specified.
Analog Inputs
(723T or 723 Card specifications below;
726 ±50 V Card specifications discussed in
System Description)
Voltage Measurement Types: Single-ended or
differential.
Range and Resolution: Ranges are software
selectable on any input channel.
Full Scale
Resolution
Input Range (mV)
Differential Single-ended
±5000
166
µV
333
µV
±1500
50
µV
100
µV
±500
16.6 µV
33.3 µV
±150
5
µV
10
µV
±50
1.66 µV
3.33 µV
±15
500
nV 1000
nV
±5
166
nV
333
nV
±1.5
50
nV
100
nV
Accuracy of Voltage Measurements:
Differential: ±0.02% FSR (±0.01%, 0-40°C)
(e.g. ±0.02% FSR = ±2.0 mV for ±5 V range)
Positive single-ended: ±0.02% FSR
(±0.01%, 0-40°C) ±5 µV
Negative single-ended: ±0.03% FSR
(±0.015%, 0-40°C) ±5 µV
High Frequency Pulse Mode
Minimum Pulse Width: 2 µs
Maximum Input Frequency: 250 kHz
Voltage Thresholds: The count is incremented
when the input voltage changes from below
1.5 V to above 3.5 V.
Maximum Input Voltage: ±20 V
Low Level AC Mode
This mode is used for counting the frequency
of low voltage, sine wave signals.
Input Hysteresis: 11 mV
Maximum AC Input Voltage (RMS): 20 V
Frequency Range:
Minimum AC Input Voltage
(mV RMS)
15
25
50
160
Range (Hz)
1
1
1
1
to
to
to
to
100
1,000
3,000
10,000
Digital Control Outputs
(725 Card)
Each card includes 8 digital control outputs.
Transient Protection
All input and output connections to the I/O
Module are protected using spark gaps that
are rated to 10,000 A. The spark gaps are
connected directly to a heavy copper bar on
each input card with no more than 2 inches of
20 AWG copper wire.
Control Module
Processor: Hitachi 6303
Memory: 24K ROM; 40K RAM, 709 Card
provides an additional 512K RAM.
Data Storage: 18.8K values, standard; 280K
values, expanded.
Display: 8 digit LCD (0.5” digits).
Peripheral Interface: 9-pin, D-type connector
on the Control Module panel for connection to
storage module, card storage module,
multidrop interface, modem, printer, or RS-232
adapter. Baud rates selectable at 300, 1200,
9600, and 76,800.
Output Voltages (no load):
High: 5.0 V ±0.1 V
Low: < 0.1 V
I/O Module Interface: Optically isolated current
loops allow connection of up to 4 I/O Modules.
I/O Modules can be separated from the Control
Module by up to 1,000 feet.
Output Resistance: 400 Ω
Clock Accuracy: ±1 minute per month.
Analog Outputs
(725 Card)
Maximum Program Execution Rate: System
tasks can be initiated in sync with real-time up
to 80 Hz.
Each card contains 8 switched and 2 continuous
analog outputs.
System Power Requirements
Switched: Provides a precision voltage for
resistance measurement, then switches off
(high impedance). Only one switched output
can be active at a time.
Voltage: 9.6 to 15 VDC
Internal Batteries: Sealed rechargeable with
2.5 Ahr capacity per charge.
Common Mode Range: ±5 V
Continuous: A preset voltage is held until
updated. Voltage degrades 0.17 mV every 7
seconds. All continuous analog outputs (and
digital control ports) can be active simultaneously.
Common Mode Rejection: > 140 dB (DC to 100 Hz)
Range: ±5 V
Normal Mode Rejection: 70 dB (60 Hz with
slow differential measurement)
Accuracy: Same as voltage measurements.
Input Current: 100 pA max
Output Current: 25 mA at ±5 V, 50 mA at ±2 V
Input Sample Rates: Fast A/D conversions are
integrated over 250 µs. Slow A/D conversions
are integrated over 16.67 ms for 60 Hz AC
rejection or optionally, 20.0 ms for 50 Hz AC
rejection. Differential measurements include
two conversions, one with reversed input polarity, to reduce thermal offset and common mode
errors. The following intervals do not include
the self-calibration measurement which occurs
once per instruction.
Input sample Typical input
rates
noise
ms/channel
nV/RMS
Fast Single-ended
2.9
350
Fast Differential
4.7
250
Slow Single-ended
22.0
43
Slow Differential
43.0
30
Fast Differential (TC) 7.9
250
Input Current Noise: 9 pA RMS (slow differential)
Input Resistance: 2.5 GΩ typical
Sustained Input Voltage without Damage:
≤ ±16 VDC
Pulse Counters
(724 Card)
Pulse Counters per Card: 4
Maximum Counts per Interval: 32,767 (with
overrange detection)
Modes: Programmable modes are switch
closure, high frequency pulse, and low level AC.
Switch Closure Mode
Minimum Switch Closed Time: 1 ms
Minimum Switch Open Time: 4 ms
Maximum Bounce Time: 1.4 ms open without
being counted.
Resolution: 166 µV
Resistance and Conductivity
Measurements
(Combination of 723 and 725 Cards)
Accuracy: ±0.01% of full scale bridge output
provided the matching bridge resistors are not
the limiting factor.
Measurement Types: 6-wire and 4-wire full
bridge, 4-wire, 3-wire, and 2-wire half bridges.
High accuracy, low impedance bridge
measurements are made ratiometrically with
dual polarity measurements of excitation and
output to eliminate thermal emfs. AC resistance and conductivity measurements use a
750 µs excitation pulse with the signal integration occurring over the last 250 µs. An equal
duration pulse of opposite polarity is applied
for ionic depolarization.
Typical Current Drain: 3.5 - 6 mA (minimum
system) quiescent, 16 mA during processing,
100 mA during analog measurement.
Charging Circuit: Requires DC or rectified AC
voltage from 15 to 25 V. Thermal compensation is included to optimize charging voltage
according to ambient temperature.
External Batteries: Any 12 V external battery
can be a primary power source; internal batteries provide a backup while the external
batteries are changed.
Operation from AC Sources: An AC operated
battery charger is included with the enclosure
to maintain full charge on the batteries where
AC power is available. In the event of power
failure, the internal batteries will keep the
system operational for up to 5 days in most
applications.
Physical Specifications
Size:
ENC 7L
ENC 7F
ENC 7XL
17” x 12” x 6”
20” x 13” x 10”
19” x 19” x 10”
Weight:
~40 lbs (ENC 7F with 700X, 720, &
seven I/O cards).
Warranty
Three years against defects in materials and
workmanship.
OV-17
CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW
This is a blank page.
OV-18
SECTION 1. FUNCTIONAL MODES
1.1 PROGRAM TABLES - *1, *2, AND *3
MODES
Data acquisition and processing functions are
controlled by instructions contained in program
tables. Programming can be separated into two
tables, each having its own programmable
execution interval. A third table is available for
programming subroutines which may be called
by instructions in Tables 1 or 2 or by a special
interrupt. The *1 and *2 Modes are used to
access Tables 1 and 2. The *3 Mode is used to
access Subroutine Table 3.
When a program table is first entered, the
display shows the table number in the ID Field
and 00 in the Data Field. Press A and the CR7
will advance to the execution interval. If there is
an existing program in the table, enter an
instruction location number prior to A and the
CR7 will advance directly to the instruction (e.g.,
5 will advance to the fifth instruction in the
table).
1.1.1 EXECUTION INTERVAL
The execution interval is entered in units of
seconds as follows:
0.0125 .... 0.1 seconds, in multiples of 0.0125
0.1 .....6553 seconds, in multiples of 0.1 second
Intervals less than 0.1 second are allowed in
Table 1 only. Execution of the table is repeated
at the rate determined by this entry. The table
will not be executed if 0 is entered. Values less
than 0.1 are rounded to the nearest even
multiple of 0.0125. If the Interval is 0.1 or
greater, the CR7 will not allow entry of digits
beyond 0.1.
The rate at which the CR7 can execute a given
table must not be confused with the sample
rates for the measurements contained within
the table. When a table is executed and a
measurement is made, the Control Module
instructs the I/O Module which measurement to
make and how many times to repeat it on
successive channels. The I/O module then
repeats the measurement as fast as possible
and stores the data until the Control Module is
ready for it. The Control Module takes the raw
data and scales it as required by the instruction
initiating the measurement. The next instruction
in the table is not executed until the scaling is
completed. The maximum sample rate for a
measurement is the rate at which the I/O
Module can make a number of measurements
specified by a single input instruction. Because
the sample rate does not include the processing
time required to scale the measurements into
engineer units, the execution time of an
instruction will be greater than the sample rate
for the measurement specified by the
instruction. The execution times for the
instructions are given in Section 3.9.
The throughput rate is the rate at which a
measurement can be made and the resulting
value stored in Final Storage. The maximum
throughput rate for fast single ended
measurements is approximately 310
measurements per second.
If the specified execution interval for a table is
less than the time required to process that
table, the CR7 overruns the execution interval,
finishes processing the table and waits for the
next occurrence of the execution interval before
again initiating the table (i.e., when the
execution interval is up and the table is still
executing, that execution is skipped). Since no
advantage is gained in the rate of execution
with this situation, it should be avoided by
specifying an execution interval adequate for
the table processing time.
NOTE: Whenever an overrun occurs,
decimal points are displayed on both sides
of the sixth digit of the CR7 display (e.g., L
O.G. in the *0 Mode).
When the Output Flag is set high, extra time is
consumed by final output processing. It may
be acceptable if the execution interval is
exceeded at this time. For example, suppose it
is desired to measure every 0.1 seconds and
output processed data every ten minutes. The
table requires less than 0.1 seconds to process
except when output occurs (every 10 minutes).
With final output processing the time required is
one second. With the execution interval set at
0.1 seconds, and a one second lag between
samples once every 10 minutes, 10
measurements out of 6000 (.17%) are missed:
an acceptable statistical error for most
populations.
1-1
SECTION 1. FUNCTIONAL MODES
1.1.2 SUBROUTINES
Table 3 is used to enter subroutines which may
be called with Program Control Instructions in
Tables 1 and 2 or other subroutines. The group
of instructions which form a subroutine starts
with Instruction 85, Label Subroutine, and ends
with Instruction 95, End. (Section 12)
1.1.3 TABLE PRIORITY/INTERRUPTS
Table 1 execution has priority over Table 2. If
Table 2 is being executed when it is time to
execute Table 1, Table 2 will be interrupted.
After Table 1 is completed, Table 2 resumes at
the point of interruption. If the execution interval
of Table 2 coincides with Table 1, Table 1 will
be executed first, followed by Table 2.
Interrupts by Table 1 are not allowed in the
middle of a measurement or while output to
Final Storage is in process (the Output Flag,
flag 0, is set high). The interrupt occurs as
soon as the measurement is completed or flag
0 is set low.
1.1.4 COMPILING A PROGRAM
When a program is entered, or any changes are
made in the *1, *2, *3, *4, *A, or *C Modes, the
program must be compiled before it starts
running. The compile function checks for
programming errors and optimizes program
information for execution. If errors are
detected, the appropriate error codes are
indicated on the Display (Section 3.10).
Compiling occurs when the *0 , *6, or *B Modes
are entered and prior to saving a program listing
in the *D Mode. Compiling only occurs after a
program change has been made; subsequent
use of any of these Modes does not cause
compiling.
Compiling with the *0, *B, or *D Mode sets
all output ports and flags low and resets the
timer (Instruction 26) and all data in Input
and Intermediate Storage to ZERO.
When the *6 Mode is used to compile data
in Input Storage, the state of flags, control
ports, and the timer are UNALTERED.
Compiling always zeros Intermediate
Storage.
1-2
1.2 SETTING AND DISPLAYING THE
CLOCK - *5 MODE
The *5 Mode is used to display time or change
the year, day of year, or time. When *5 is
pressed, the current time is displayed. The time
parameters displayed in the *5 Mode are given
in Table 1.2-1.
The CR7 powers-up with hours and minutes set
to 0 and the day and year set for the date that
the PROMs were first released by Campbell
Scientific. To set the year, day, or time, enter
the *5 Mode and advance to display the
appropriate value. Key in the desired number
and enter the value by pressing A. When a new
value for hours and minutes is entered, the
seconds are set to zero and current time is
again displayed. To exit the *5 Mode, press *.
When the time is changed, a partial recompile
is done automatically to resynchronize program
execution with real time. The resynchronization
process can change the interval of a pulse rate
measurements for one execution interval as
explained in the PULSE COUNT Instruction 3 in
Section 9.
TABLE 1.2-1. Sequence of Time Parameters
in *5 Mode
Key
Display
ID:DATA
*5
A
A
A
:HH:MM:SS
05:XX
05:XXXX
05:HH:MM:
Description
Display current time
Display/enter year
Display/enter day of year
Display/enter
hours:minutes
1.3 DISPLAYING AND ALTERING INPUT
MEMORY OR FLAGS - *6 MODE
The *6 Mode is used to display or change Input
Storage values and to toggle and display user
flags. If the *6 Mode is entered immediately
following any changes in program tables or the
*4 Mode, the programs will be compiled and
execution will begin.
When the *6 Mode is used to compile data
values contained in Input Storage, the state of
flags, control ports, and the timer are
UNALTERED. Compiling always zeros
Intermediate Storage.
SECTION 1. FUNCTIONAL MODES
TABLE 1.3-1. *6 Mode Commands
Key
Action
A
Advance to next location or enter new
value
Back-up to previous location
Change value in displayed location(Key
C, then value, then A)
Display/alter user flags
Display current location and allow a
location no. to be keyed in, followed by
A to jump to that location
Exit *6 Mode
B
C
D
#
*
1.3.1 DISPLAYING AND ALTERING INPUT
STORAGE
When *6 is keyed, the display will read
"06:0000". One can advance to view the value
stored in Input Storage location 1 by pressing A.
To go directly to a specific location, key in the
location number before keying A. For example,
to view the value contained in Input Storage
location 20, key in *6 20 A. The ID portion of
the display shows the last two digits of the
location number. If the value stored in the
location being monitored is the result of a
program instruction, the value will be updated
each time the instruction is executed.
Values may be entered into input locations
using the change command, C. While viewing
the contents of the input location in which the
value is to be entered, key C; the location
number in the ID field will disappear. Key in the
desired value and then enter it by pressing A.
If an algorithm requires parameters to be
manually modified during execution of the
program WITHOUT INTERRUPTION of the
Table execution process, the parameters can
be loaded in Input Storage locations and the *6
Mode can be used to change the values. If
values must be in place before program
execution commences, use Instruction 91 at the
beginning of the program table to prevent
execution until a flag is set high (see next
section). The initial values can be entered into
input locations using the *6 Mode after
compiling the table. The flag can then be set
high to enable the table(s).
If any program tables *1, *2, *3, or *4 output
options are altered and complied in the *0
Mode, values in Input Storage will be set to 0.
To preserve values entered in Input Storage,
compile with *6.
1.3.2 DISPLAYING AND TOGGLING USER
FLAGS
If D is keyed while the CR7 is displaying a
location value, the current status of the user flags
will be displayed in the following format:
"00:01:00:10". The characters represent the
flags, the left-most digit represents Flag 1 and
right most Flag 8. A "0" indicates the flag is low
and a "1" indicates the flag is high. In the above
example, Flags 4 and 7 are set high. To toggle a
flag, simply key the corresponding number. To
return to displaying the input location, press A.
Entering appropriate flag tests into the program
allows manual control of program execution.
For example: It is desired to be able to
manually start the execution of Table 2.
Instruction 91 is the first instruction entered in
Table 2:
01:
01:
02:
P91
25
0
If Flag
5 is set low
Go to end of program table
If Flag 5 is low, all subsequent instructions in
Table 2 will be skipped. Flag 5 can be toggled
from the *6 Mode, effectively starting and
stopping the execution of Table 2.
1.3.3 DISPLAYING AND TOGGLING PORTS
The current status of the Digital Control ports on
the active 725 excitation card can be displayed
by hitting "0" while looking at an input location
(e.g., *6A0). Ports are displayed left to right as
C8, C7, ..., C1 (exactly opposite to the flags). A
port can be toggled by pressing its number on
the keypad while in the port display mode.
The active excitation card defaults to address 1.
The active card may only be changed with
Instruction 20 in the CR7 Program (Section 9).
1.4 COMPILING AND LOGGING DATA *0 MODE
When the *0 Mode is entered after
programming the CR7, the program is compiled
(Section 1.1.4) and the display shows "LOG"
and the numbers of the program tables that
were enabled at compilation. The display is not
updated after entering *0.
1-3
SECTION 1. FUNCTIONAL MODES
When the *0, *B, or *D Mode is used to compile,
all output ports and flags are set low, the timer
(Instruction 26) is reset, and data in Input and
Intermediate Storage are RESET TO ZERO.
There are 1744 bytes allotted to program
memory. This memory may be used for one
program table or shared among all program
tables. Tables 3.9-1 to 3.9-4 list the amount of
memory used by each program instruction.
The CR7 should normally be left in the *0 Mode
when logging data. This Mode requires slightly
less power than Modes which frequently update
the display.
Input Storage is used to store the results of
Input/Output and Processing Instructions. The
values stored in input locations may be
displayed using the *6 Mode (Section 1.3).
1.5 MEMORY ALLOCATION - *A
Intermediate Storage is used by Output
Processing Instructions to store the results of
intermediate calculations necessary for
averages, standard deviations, histograms, etc.
1.5.1 INTERNAL MEMORY
There are eight sockets on the CR7 CPU board
which are used for Read Only Memory (ROM)
or Random Access Memory (RAM). The basic
CR7 is provided with 64K of memory: three 8K
Programmable Read Only Memory (PROM)
chips for a total of 24K ROM and five 8K RAM
chips. Appendix E describes how to change
RAM and ROM chips.
Final Storage holds output data, the results of
Output Processing Instructions which are stored
when the Output Flag is set high (Section 3.7).
The data in Final Storage can be displayed
using the *7 Mode (Section 2.3).
Figure OV2-1 illustrates the use of Input,
Intermediate, and Final Storage.
When powered up, the CR7 displays HELLO
while performing a memory check. As the
check is performed, a number on the right of
the display is incremented as each 8 K block of
memory is checked. With standard memory the
count will stop at 8. If additional memory
card(s) are present, the count will proceed
accordingly. The Power-up memory check is
quite extensive and can take considerable time
if the 709 512K Memory Card is installed. To
abort the extensive test (a shorter version is still
performed), press the # key. When the memory
test is completed, the number of K bytes of
RAM plus ROM is displayed.
Each Input or Intermediate Storage location
requires four bytes of memory. Each Final
Storage location requires 2 bytes of memory.
Low resolution data points require 1 Final
Storage location and high resolution data points
require 2. Section 2 describes Final Storage
and data retrieval in detail.
Table 1.5-1 lists the basic memory areas and
the amount of memory allotted to them in the
standard CR7.
The size of RAM, including any additional
memory cards which may be present, can be
determined with the *A Mode (Section 2.4.2)
TABLE 1.5-1. Memory Allocation in Standard CR7
PROM
Memory
Program
Memory
System
Storage*
Input
Storage*
Intermediate
Final Storage*
Storage*
Standard w/709
Memory Card
Avail. bytes
24K
1744
2160
128
256
36,672
590,960
Avail. Loc.
-
-
-
32
64
18,336
280,480
*Default allocation on power-up
1-4
SECTION 1. FUNCTIONAL MODES
TABLE 1.5-2. Description of *A Mode Data
Key
Entry
Display
ID: Data
*A
01: XXXX
The number of memory locations currently allocated to Input Storage. This
value can be changed by keying in the desired number (minimum of 32,
maximum limited by available memory).
A
02: XXXX
The number of memory locations currently allocated to Intermediate Storage.
This value can be changed by keying in the desired number (limited by available
memory).
A
03: XXXXX
The number of memory locations currently allocated to Final Storage. This
number is automatically altered when the number of memory locations in Input
and/or Intermediate Storage is changed. A minimum of 768 locations are
always retained in Final Storage.
A
04:XXXX
The number of bytes remaining in Program memory (1744 bytes total).
Entering 1744 will ERASE ALL MEMORY and put the CR7 through the initial
power-up routine.
Description of Data
1.5.2 *A MODE
The *A Mode is used to 1) determine the
number of locations allocated to Input,
Intermediate, and Final Storage; 2) repartition
this memory; 3) check the number of bytes
remaining in program memory; 4) erase Final
Storage; and 5) to completely reset the
datalogger. When *A is keyed, the first value
displayed is the number of memory locations
allocated to Input Storage. Press A to advance
through the memory values. Table 1.5-2
describes what the values seen in the *A Mode
represent.
The numbers of memory locations allocated to
Input, Intermediate and Final Storage default at
power-up to the values in Table 1.5-1.
The sizes of Input and Intermediate Storage
may be altered by keying in the desired value
and entering it by keying A. The size of Final
Storage will be adjusted automatically.
One input or Intermediate Storage location can
be exchanged for two Final Storage locations
and vice-versa. Input and Intermediate Storage
must reside in the CPU board RAM. If
additional memory boards are present, it is
possible to use all of the CPU board RAM for
Input and Intermediate Storage. A minimum 32
Input and 768 Final Storage locations will
ALWAYS be retained. If no Intermediate
Storage is required, its size may be reduced to
0.
All data in Intermediate and Final Storage are
erased when memory is repartitioned. This
feature may be used to clear memory without
altering programming. The number of locations
does not actually need to be changed; the same
value can be keyed in and entered. After
repartitioning memory, the Tables must be
recompiled. Recompiling with *0 erases Input
Storage; recompiling with *6 leaves Input
Storage unaltered.
If Intermediate Storage size is too small to
accommodate the programs or instructions
entered, the program will not compile and the
"E:04" ERROR CODE will be displayed; the size
of Intermediate Storage must be increased
before the program will compile. Final Storage
size can be maximized by limiting Intermediate
Storage size to the minimum number of
memory locations necessary to accommodate
the programs entered. The number of Final
Storage locations and the rate at which data are
stored determines how long it will take for Final
Storage to fill, at which point new data will write
over old.
1.6 MEMORY TESTING AND SYSTEM
STATUS - *B
The *B Mode is used to 1) read the signature of
the program memory and the software PROMs,
2) display the power-up memory status, 3)
display the number of E08 occurrences
(Section 3.10), 4) display the number of overrun
occurrences (Section 1.1.1), and 5) display
PROM version and revision number. Table 1.61-5
SECTION 1. FUNCTIONAL MODES
1 describes what the values seen in the *B
Mode represent. The correct signatures of the
CR7 PROMs are listed in Appendix B.
A
07: XXXXX
No. of overrun
occurrences (Key in 88 to
reset)
A signature is a number which is a function of
the data and the sequence of data in memory.
It is derived using an algorithm which assures a
99.998% probability that if either the data or its
sequence changes, the signature changes.
The signature of the program memory is used
to determine if the program tables have been
altered. During the self check on power-up, the
signature computed for a PROM is compared
with a signature stored in the PROM to
determine if a failure has occurred. The
algorithm used to calculate the signature is
described in Appendix C.
A
08: X.XXXX
PROM version number
A
09: XXXX.
Version revision number
A
01:00
Enter I/O Module No. to
test (usually 1)
1A
01:XXXXX
I/O Module 1 RAM
Signature
01:XXXXX
I/O Module 1 PROM
Signature
The contents of windows 8 and 9, PROM
version and version revision, are helpful in
determining what PROM is in the datalogger.
Over the years, several different PROM
versions have been released, each with
operational differences. When calling Campbell
Scientific for datalogger assistance, please
have these two numbers available.
TABLE 1.6-1. Description of *B Mode Data
Key
Entry
Display
ID: Data
*B
01: XXXXX
Program memory
Signature. The value is
dependent upon the
programming entered
and memory allotment. If
the Tables have not been
previously compiled, they
will be compiled and run.
A
02: XXXXX
First PROM Signature
03: XXXXX
Second PROM Signature
04: XXXXX
Third PROM Signature
A
05: XXXXX
Memory status, No. K
RAM and ROM
A
06: XXXXX
No. of E08 occurrences
(Key in 88 to reset)
1-6
Description of Data
1.7 *C MODE -- SECURITY
The *C Mode is used to secure the user's
program information. If security is activated,
then the CR7 will block keyboard access to the
*1, *2, *3, *4, and *A Modes. Activated security
will also block Telecommunications access to
the *1, *2, *3, *4, *5, and *D Modes and the
Telecommunications C command. A four digit
password allows entry to the *C Mode and
becomes part of the program memory, affecting
the program signature. If security is enabled
when *C is keyed, the password must be keyed
in before one can advance to window 1. If
security is disabled, keying *C brings up window
1 immediately. In window 1 a command can be
entered to either enter a new password (1), or
temporarily disable security (00) in order to
check or alter the programming. The password
on power-up is 0000 (unless *D was used to
create a custom PROM with the password built
in), which disables security. When security is
temporarily disabled, it is possible to enter all
modes and to alter programming. Keying *0 or
*6 will automatically re-enable security, unless
the password is 0000.
Entering the four digit password as an indexed
value (i.e. xxxx--, entered by keying C after
entering the four digits) blocks access to the *1,
*2, *3, *4, and *A Modes, but allows the user to
view and change the password.
SECTION 1. FUNCTIONAL MODES
TABLE 1.7-1. *C Mode Entries and Codes
Key
Entry
Display
ID: Data
*C
12:0000
A
A
A
01:00
02:XXXX
TABLE 1.8-1. *D Mode Commands
Command
Description
Description
Enter current password.
If correct, then advance,
else exit *C Mode. 12:00
indicates *C Mode is not
in PROMs. If security is
disabled, *C advances
directly to window 1.
Window 1, enter
command:
00 = disable security and
advance to window
2; subsequent *0 or
*6 enables security.
01 = security remains
enabled, but it
advances to window
2 and allows entry of
a new password.
Set new password
(XXXX is current
password).
Returns to window 1.
Entering 0000 disables
security (window 1 must
be set to 0).
1.8 *D MODE -- SAVE OR LOAD
PROGRAM
The *D Mode allows the user's program
information in the *1, *2, *3, *4, *A, *C (if OSX0), and *B Modes to be output to or loaded from
printer/computer (ASCII) or SM192/716 Storage
Module. Table execution and on-line printer
outputs are suspended while in the *D Mode.
When *D is keyed, the CR7 will display "13:00".
1
2
71
Save ASCII Program
Load ASCII Program
Save/Load/Clear Program
from Storage Module
A command is entered by keying the command
number and A. When Command 1, 2, or 71 is
entered, the command number is displayed in
the ID field. The user must then key in a baud
rate code for command 1 or 2 or the command
code for the Storage Module (Table 1.8-2).
After the code is keyed in, key A to execute the
command. After a command is executed,
"13:0000" is displayed; *D must be entered
again before another command can be given.
If the CR7 program has not been compiled
when a command to save the program is
entered, it will be compiled before the command
is executed.
TABLE 1.8-2. *D Mode Baud Rate and
Storage Module Codes
BAUD RATE
CODES
STORAGE MODULE
COMMAND CODES
0 - 300 baud
1 - 1200
2 - 9600
3 - 76,800
1X Save Program X to
Storage Module
(X=1-8)
2X Load Program X from
Storage Module
(X=1-8)
3X Erase Program X from
Storage Module
(X=1-8)
1-7
SECTION 1. FUNCTIONAL MODES
All data in Input, Intermediate and Final
Storage are erased when a command to load
a program is executed or when a program is
written to tape.
If nothing is received within 30-40 seconds after
giving the command to load a program, the
command will be aborted and an error code
displayed (E99 for Storage Module or ASCII).
Commands 1, 2, and 71 are the only
commands that can be executed via
telecommunications (Section 5). For
commands 1 and 2, the CR7 will use the baud
rate already established in telecommunications
and will be ready to receive or send the file as
soon as the command is received.
TABLE 1.8-3. Program Load Error Codes
E 98
E 99
Uncorrectable errors detected
Wrong type of file or no data received
TABLE 1.8-4. Example Program Listing
From *D Command 1
MODE 1
SCAN RATE 2
1:P17
1:1
1:P0
2:P14
1:1
2:1
3:5
4:1
5:1
6:2
7:1
8:0
3:P92
1:0
2:5
3:10
1.8.1 TRANSFER TO COMPUTER/PRINTER
This section describes commands 1 and 2
(Table 1.8-1). The PC208 Software
automatically uses these commands for
uploading and downloading programs.
SENDING ASCII PROGRAM INFORMATION
Command 1 is to send the program listing in
ASCII. At the end of the listing, the CR7 sends
control E (5 hex or decimal) twice. Except when
in telecommunications, the baud rate code must
be entered after command 1.
Table 1.8-4 is an example of the program listing
sent in response to command 1 (the actual
listing is in one column but is printed in two
columns to save space). Note that the listing
uses numbers for each mode: The numbers for
*A, *B, and *C modes are 10, 11, and 12,
respectively.
MODE 1
SCAN RATE 2
4:P71
1:2
2:1
5:P0
MODE 2
SCAN RATE 0
MODE 3
MODE 4
1:0
2:0
MODE 10
1:28
2:64
3:19328
4:934
MODE 12
1:0
2:0
MODE 2
SCAN RATE 0
1-8
SECTION 1. FUNCTIONAL MODES
LOAD PROGRAM FROM ASCII FILE
Command 2 sets up the CR7 to load a serial
ASCII program. The format is the same as sent
in response to command 1 (Table 1.8.4).
Except when in telecommunications, the baud
rate code must be entered after command 2.
A download file need not follow exactly the
same format that is used when listing a program
(i.e., some of the characters sent in the listing
are not really used when a program is loaded).
Some rules which must be followed are:
1. "M" must be the first character other than a
carriage return (CR) or line feed (LF). The
"M" serves the same function as "*" does
from the keyboard. The order that the
Modes are sent in does not matter (i.e., the
information for Mode 4 could be sent before
that for Mode 1).
2. "S" is necessary prior to the execution
interval (Scan rate).
3. The colons (:) are used to mark the start of
actual data.
4. A semicolon (;) tells the CR7 to ignore the
rest of the line and can be used after an
entry so that a comment can be added.
There are 4 two-character control codes which
may be used to verify that the CR7 receives a
file correctly:
As a download file is received, the CR7 buffers
the data in memory; the data is not loaded into
the editor or compiled until the CR7 receives a
command to do so. The minimum file that
could be sent is the program listing, then ^E^E.
^C^C tells the CR7 to send the signature
(Section C.3) for the current buffer of data. If
this signature does not match that calculated by
the sending device, ^B^B can be sent to
discard the current buffer and reset the
signature. If the signature is correct, ^D^D can
be sent to tell the CR7 to load the buffer into the
editor and reset the signature. Once the
complete file has been sent and verified, send
^E^E to compile the program and exit the load
command.
1.8.2 PROGRAM TRANSFER WITH STORAGE
MODULE
The SM192/716 Storage Module must be
connected to the CR7. Key *D, then enter
command 71. The command to save, load, or
clear a program and the program number
(Table 1.8-2) is entered. After the operation is
finished, "13:0000" is displayed.
The datalogger can be programmed on powerup using a Storage Module. Storage Modules
can store up to eight separate programs. If a
program is stored as program number 8, and if
the Storage Module is connected to the
datalogger serial port at power-up, program
number 8 is downloaded to the datalogger and
compiled.
^B ^B
(2hex, 2hex) Discard current buffer
and reset signature
^C ^C (3hex, 3hex) Send signature for
current buffer
^D ^D (4hex, 4hex) Load current buffer and
reset signature
^E ^E (5hex, 5hex) Exit and compile program
1-9
SECTION 1. FUNCTIONAL MODES
This is a blank page.
1-10
SECTION 2. INTERNAL DATA STORAGE
that output array. For example, the ID of
118 in Figure 2.1-2 indicates that the 18th
instruction in Table 1 set the Output Flag
high.
2.1 FINAL STORAGE AREAS, OUTPUT
ARRAYS, AND MEMORY POINTERS
Final Storage is that portion of memory where
final, processed data are stored. Data must be
sent to Final Storage before they can be
transferred to a computer or external storage
peripheral.
The size of Final Storage is expressed in terms
of memory locations or bytes. A low resolution
data point (4 decimal characters) occupies one
memory location (2 bytes), whereas a high
resolution data point (5 decimal characters)
requires two memory locations (4 bytes). Table
1.5-1 shows the default allocation of memory
locations to Input, Intermediate, and Final
Storage. The *A Mode is used to reallocate
memory or erase Final Storage (Section 1.5). A
minimum of 768 memory locations will
ALWAYS be retained in Final Storage.
Final Storage can be represented as ring
memory (Figure 2.1-1) on which the newest
data are written over the oldest data.
FIGURE 2.1-2. Output Array ID
2) The output array ID can be set by the user
with the second parameter of Instruction 80
(Section 11). The ID can be set to any
positive integer up to 511. Instruction 80
must follow the instruction which set the
Output Flag high. This option allows the
user to make the output array ID
independent of the programming. The
program can be changed (instructions
added or deleted) without changing the
output array ID. This avoids confusion
during data reduction, especially on long
term projects where program changes or
updates are likely.
NOTE: If Instruction 80 is used to
designate Final Storage and parameter 2 is
0, the output array ID is determined by the
position of Instruction 80 or by the position
of the instruction setting the Output Flag,
whichever occurs last.
FIGURE 2.1-1. Ring Memory Representation
of Final Data Storage
Output Processing Instructions store data into
Final Storage only when the Output Flag is set
high. The string of data stored each time the
Output Flag is set high is called an output
array. The first data point in the output array is
a 4 digit Output Array ID. This ID number is
set in one of two ways:
1) In the default condition, the ID consists of
the program table number and the
Instruction Location Number of the
instruction which set the Output Flag for
Data are stored in Final Storage before being
transmitted to an external device. There are
four pointers which are used to keep track of
data transmission. These pointers are:
1.
2.
3.
4.
Data Storage Pointer (DSP)
Display Pointer (DPTR)
Printer Pointer (PPTR)
Telecommunications (Modem) Pointer (MPTR)
2-1
SECTION 2. INTERNAL DATA STORAGE
The Data Storage Pointer (DSP) is used to
determine where to store each new data point in
the Final Storage area. The DSP advances to
the next available memory location after each
new data point is stored.
The DPTR is used to recall data to the LCD
display. The positioning of this pointer and data
recall are controlled from the keyboard (*7
Mode).
The PPTR is used to control data transmission
to a printer, Storage Module, or other serial
device. Whenever on-line printer transfer is
activated (*4 Mode or Instruction 96), data
between the PPTR and DSP are transmitted.
When on-line transfer to a SM192/716 Storage
Module is activated by Instruction 96 with output
code 30, data is transmitted each time an
output array is stored in Final Storage IF THE
STORAGE MODULE IS CONNECTED TO THE
CR7. If the Storage Module is not connected,
the CR7 does not transmit the data nor does it
advance the PPTR to the new DSP location. It
saves the data until the Storage Module is
connected. Then, during the next execution of
Instruction 96, the CR7 outputs all of the data
between the PPTR and the DSP and updates
the PPTR to the DSP location (Section 4.1)
The MPTR is used in transmitting data over a
telecommunications interface. When
Telecommunications is first entered, the MPTR
is set to the same location as the DSP.
Positioning of the MPTR is then controlled by
commands from the external calling device
(Section 5.1).
NOTE: All memory pointers are set to the
DSP location when the datalogger compiles
a program. For this reason, ALWAYS
RETRIEVE UNCOLLECTED DATA
BEFORE MAKING PROGRAM CHANGES.
2-2
2.2 DATA OUTPUT FORMAT AND
RANGE LIMITS
Data are stored internally in Campbell
Scientific's Final Storage Format (Appendix
C.2). Data may be sent to Final Storage in
either LOW RESOLUTION or HIGH
RESOLUTION format. Low resolution is the
default. To change the resolution, Instruction
78 (Section 11) must precede the Output
Instructions in the program table.
2.2.1 RESOLUTION AND RANGE LIMITS
Low resolution data is a 2 byte format with 3 or
4 significant digits and a maximum magnitude
of ±6999. High resolution is a 4 byte format
with 5 significant digits and a maximum possible
output value of ±99999 (see Table 2.2-1 below).
TABLE 2.2-1. Resolution Range Limits of
CR7 Data
Resolution
Zero
Minimum Maximum
Magnitude Magnitude
Low
High
0.000
0.0000
±0.001
±.00001
±6999.
±99999.
The resolution of the low resolution format is
reduced to 3 significant digits when the first (left
most) digit is 7 or greater (Table 2.2-2). Thus, it
may be necessary to use high resolution output
or an offset to maintain the desired resolution of
a measurement. For example, if water level is
to be measured and output to the nearest 0.01
foot, the level must be less than 70 feet for low
resolution output to display the 0.01 foot
increment. If the water level is expected to
range from 50 to 80 feet the data could either
be output in high resolution or could be offset by
20 feet (transforming the range to 30 to 60 feet).
SECTION 2. INTERNAL DATA STORAGE
TABLE 2.2-2. Decimal Location in Low
Resolution Format
Absolute Value
0
7
70
700
6.999
- 69.99
- 699.9
- 6999.
Decimal Location
X.XXX
XX.XX
XXX.X
XXXX.
2.3 DISPLAYING STORED DATA ON
KEYBOARD/DISPLAY - *7 MODE
The *7 Mode is used to display Final Storage
data. Enter the Mode by keying *7. The display
will show "07:XXXXX", where XXXXX is the
Final Storage location (DSP) where the next
data will be stored. Two options are available:
1. Press A to advance and display the
output array ID of the oldest array in
Final Storage.
While output data have the limits described
above, the computations performed in the CR7
are done in floating point arithmetic. Values are
rounded when converting to Final Storage
Format.
2. Enter a Final Storage location number.
When A is pressed, the DPTR will jump
to the location entered and, if it is not at
the start of an array, advance to the first
start of array. The display will show the
Array ID.
2.2.2 INPUT AND INTERMEDIATE STORAGE
DATA FORMAT
In Input and Intermediate Storage, numbers are
stored and processed in a binary format with a
23 bit binary mantissa and a 6 bit binary
exponent. The largest and smallest numbers
that can be stored and processed are 9 x 1018
and 1 x 10-19, respectively. The size of the
number determines the resolution of the
arithmetic. A rough approximation of the
resolution is that it is better than 1 in the
seventh digit. For example, the resolution of
97,386,924 is better than 10. The resolution of
0.0086731924 is better than 0.000000001.
A precise calculation of the resolution of a
number may be determined by representing the
number as a mantissa between .5 and 1
multiplied by 2 raised to some integer power.
The resolution is the product of that power of 2
and 2-24. For example, representing 478 as
.9336 * 29, the resolution is 29 * 2-24 = 2-15 =
0.0000305. A description of Campbell
Scientific's floating point format may be found in
the description of the J and K
telecommunications commands in Appendix C.
Repeated use of the A key advances through
the output array, while use of the B key backs
the DPTR through memory.
The Final Storage location of the data point
being viewed may be displayed by keying #. At
this point, another location may be entered
followed by A to jump to the start of the output
array equal to or just ahead of the location
entered. Whenever a location number is
displayed by keying #, the corresponding data
point can be displayed by keying C. To
advance to the start of the next output array,
key #A. To back up one output array, key #B.
TABLE 2.3-1. *7 Mode Command Summary
Key
Action
A
B
#
Advance to next data point
Back-up to previous data point
Display location number of currently
displayed data point value
Display value of current location
Advance to start of next output array
Back-up to previous output array
C
#A
#B
2-3
SECTION 2. INTERNAL DATA STORAGE
This is a blank page.
2-4
SECTION 3. INSTRUCTION SET BASICS
The instructions used to program the CR7 are divided into four types: Input/Output (I/O), Processing,
Output Processing, and Program Control. I/O Instructions are used to make measurements and store
the readings in input locations or to initiate analog or digital port output. Processing Instructions perform
numerical operations using data from Input Storage locations and place the results back into specified
Input Storage locations. Output Processing Instructions provide a method for generating time or event
dependent data summaries from processed sensor readings residing in specified Input Storage
locations. Program Control Instructions are used to direct program execution based on time and/or
conditional tests on input data and to direct output to external devices.
Instructions are identified by a number. Each instruction has a number of parameters which give the
CR7 the information it needs to execute the instruction.
The set of instructions available in the CR7 is determined by the Programmable Read Only Memory
chips (PROMS) that are installed. Appendix B lists the software options available.
3.1 PARAMETER DATA TYPES
There are three different data types used for
Instruction parameters: Floating Point (FP), 4
digit integers (4), and 2 digit integers (2). In the
listings of the instruction parameters (Sections
9-12), the parameter data type is identified by its
abbreviation. Different data types are used to
allow the CR7 to make the most efficient use of
its memory.
Floating Point parameters are used to enter
numeric constants for calibrations or arithmetic
operations. While it is only possible to enter five
digits (magnitude ±.00001 to ±99999.), the
internal format has a much greater range
(1x10-19 to 9x1018, Section 2.2.1).
3.2 REPETITIONS/CARD NUMBER
The repetitions parameter on many of the I/O,
Processing, and Output Processing Instructions
is used to repeat the instruction on a number of
sequential Input Channels or Input Storage
locations. Separate parameters are used to
specify the card and input channel on which to
make the first measurement. For example, if
you have four differential voltage
measurements to make on the same voltage
range, wire the inputs to sequential channels
and instead of entering the Differential Voltage
Measurement Instruction 4 times, enter it once
with four repetitions. The instruction will make
four measurements starting on the specified
channel number and continuing through the
three succeeding differential channels, with the
results being stored in the specified input
location and the three succeeding input
locations. Averages for all four measurements
can be calculated by entering the Average
Instruction with four repetitions.
The CR7 will automatically continue repetitions
from the last channel of one card to the first
channel of the next sequentially numbered
723(-T) Analog Input Card or 725 Pulse Counter
Card. Measurements on the 726 50 volt Analog
Input Card will not advance correctly from one
card to the next; enter separate measurement
instructions for each card.
When several of the same type of
measurements are to be made but the
calibrations of the sensors are different, it
requires less time to use a single measurement
instruction with repetitions and then apply the
calibrations with Instruction 53 than it does to
enter the instruction several times in order to
use different multipliers and offsets. This is due
to the set up and calibration time for each
measurement instruction. However, if time is
not a constraint, separate instructions may
make the program easier to follow.
3.3 ENTERING NEGATIVE NUMBERS
After keying in a number, press C or "-" to
change the number's sign. On floating point
numbers, a minus sign (-) will appear to the left
of the number.
Excitation voltages in millivolts for I/O
Instructions are 4 digit integers; when C is
pressed, minus signs (-) will appear to the right
of the number indicating a negative excitation.
3-1
SECTION 3. INSTRUCTION SET BASICS
Even though this display is the same as that
indicating an indexed input location, (Section
3.4) there is no indexing effect on excitation
voltage.
3.4 INDEXING INPUT LOCATIONS
When used within a Loop, the parameters for
input locations can be Indexed to the loop
counter. The loop counter is added to the
indexed value to determine the actual input
location the instruction acts on. Normally, the
loop counter is incremented by one after each
pass through the loop. Instruction 90, Step
Loop Index, allows the increment step to be
changed. See Instructions 87 and 90, Section
12, for more details.
To index an input location (4 digit integer), key
C after keying the value but before entering the
parameter. Two minus signs (-) will be
displayed to the right of the parameter.
3.5 VOLTAGE RANGE AND
OVERRANGE DETECTION
The RANGE code parameter on Input/Output
Instructions is used to specify the full scale
voltage range of the measurement and the
integration period for the measurement (Table
3.5-1).
Select the smallest full scale range that is
greater than or equal to the full scale output of
the sensor being measured. Using the smallest
possible range will result in the best resolution
for the measurement.
Two different integration sequences are
possible. The slow integration, 16.67
milliseconds, is one 60 Hz cycle and rejects
noise from 60 Hz AC line power as well as
having better rejection of random noise than the
fast integration. A PROM with 50Hz rejection is
available for countries whose electric utilities
operate at 50 Hz (Appendix B).
When a voltage input exceeds the range
programmed, the value stored is the maximum
negative number, displayed in the *6 Mode as
-99999. In output data from Final Storage, this
becomes -6999 in low resolution or -99999. in
high resolution.
An input voltage greater than +8 volts on one of
the analog inputs will result in errors and
possible overranging on the other analog inputs.
Voltages greater than 16 volts may permanently
damage the CR7.
TABLE 3.5-1. Input Voltage Ranges and Codes
Range Code
Slow
Fast
16.67ms
250µs
Integ.
Integ.
1
2
3
4
5
6
7
8
11
12
13
14
15
16
17
18
Full Scale Range
±1500
±5000
±15
±50
±150
±500
±1500
±5000
microvolts
microvolts
millivolts
millivolts
millivolts
millivolts
millivolts
millivolts
Resolution*
50
166
500
1.66
5
16.6
50
166
nanovolts
nanovolts
nanovolts
microvolts
microvolts
microvolts
microvolts
microvolts
*Differential measurement, resolution for single-ended measurement is twice value shown.
3.6 OUTPUT PROCESSING
Most Output Processing Instructions require
both an intermediate processing operation and
a final processing operation. For example,
when the Average Instruction, 71, is executed,
3-2
the intermediate processing operation
increments a sample count and adds each new
Input Storage value to a cumulative total
residing in Intermediate Storage. When the
Output Flag is set, the final processing
operation divides the total by the number of
SECTION 3. INSTRUCTION SET BASICS
sample counts, stores the resulting average in
Final Storage and zeros the value in
Intermediate Storage so that the process starts
over with the next execution.
Final Storage is the default destination of data
output by Output Processing Instructions
(Sections OV2, 1.5, 2.1). Instruction 80 may be
used to direct output to Input Storage or to Final
Storage.
Output Processing Instructions requiring
intermediate processing sample the specified
input location(s) each time the Output
Instruction is executed, NOT necessarily each
time the location value is updated by an I/O
Instruction. For example: Suppose a
temperature measurement is initiated by Table
1 which has an execution interval of one
second. The instructions to output the average
temperature every 10 minutes are in Table 2
which has an execution interval of 10 seconds.
The temperature will be measured 600 times in
the 10 minute period, but the average will be the
result of only 60 of those measurements
because the instruction to average is executed
only one tenth as often as the instruction to
make the measurement.
Final processing occurs only when the Output
Flag is set (Section 3.7.1). The Output Flag,
Flag 0, is set at desired intervals or in response
to specified conditions by using an appropriate
Program Control Instruction (Section 11).
3.7 USE OF FLAGS: OUTPUT AND
PROGRAM CONTROL
There are 10 flags which may be used in CR7
programs. Two of the flags have functions with
Output Processing Instructions: Flag 0 controls
final processing and data storage, and Flag 9
can disable intermediate processing. Flags 1-8
may be used as desired in programming the
CR7. Flags 0 and 9 are automatically set low at
the beginning of the program table. Flags 1-8
remain unchanged until acted on by a Program
Control Instruction or until manually toggled
from the *6 Mode.
TABLE 3.7-1. Flag Description
Flag 0
- Output Flag
Flag 1 to 8 - User Flags
Flag 9
- Intermediate Processing Disable
Flag
Flags are set with Program Control Instructions.
The Output Flag, Flag 0, and the intermediate
processing disable flag, Flag 9, will always be
set low if the set high condition is not met. The
status of flags 1-8 are not changed if a
conditional test is false.
3.7.1 THE OUTPUT FLAG
A set of processed data values is placed in
Final Storage by Output Processing Instructions
when the Output Flag, Flag 0, is set high. This
set of data is called an output array. The
Output Flag is set according to time or event
dependent intervals using Program Control
Instructions specified by the user. The Output
Flag is set low at the beginning of each table.
Each group of Output Processing Instructions
creating an output array must be preceded by a
Program Control Instruction that sets the Output
Flag.
Output is most often desired at fixed intervals;
this is accomplished with Instruction 92, If Time,
which checks the clock to see if it is X minutes
into a Y minute interval. If the time condition is
met, a command is executed. Output at the
beginning of the interval by making Parameter
1, time into the interval, 0. Parameter 2, the
time interval in minutes, is how often output will
occur; i.e., the Output Interval. Enter 10 for
parameter 3, the command code, to set Flag 0
high. Instruction 92 is followed in the program
table by the Output Instructions which define the
output array desired.
The time interval is synchronized to 24 hour
time; output will occur on each integer multiple
of the Output Interval starting from midnight (0
minutes). If the Output Interval is not an even
divisor of 1440 minutes (24 hours), the last
output interval of the day will be less than the
specified time interval. Output will occur at
midnight and will resume synchronized to the
new day.
3-3
SECTION 3. INSTRUCTION SET BASICS
NOTE: If the Output Flag is already set
high and the test condition of a subsequent
Program Control Instruction acting on the
flag fails, the flag is set low. This feature
eliminates having to enter another
instruction to specifically reset the Output
Flag at the end of an output array before
proceeding to another group of Output
Instructions with a different output interval
(see example in OV4.3).
3.7.2 THE INTERMEDIATE PROCESSING
DISABLE FLAG
The Intermediate Processing Disable Flag, Flag
9, suspends intermediate processing when it is
set high. This flag is used to restrict sampling
for averages, totals, maxima, minima, etc., to
times when certain criteria are met. The flag is
automatically set low at the beginning of the
program table.
As an example, suppose it is desired to obtain a
wind speed rose incorporating only wind speeds
greater than or equal to 4.5 m/s. The wind
speed rose is computed using the Histogram
Instruction 75, and wind speed is stored in Input
location 14, in m/s. Instruction 89 is placed just
before Instruction 75 and is used to set Flag 9
high if the wind speed is less than 4.5 m/s:
NOTE: Flag 9 is automatically reset the
same as Flag 0. If the intermediate
processing disable flag is already set high
and the test condition of a subsequent
Program Control Instruction acting on Flag
9 fails, the flag is set low. This feature
eliminates having to enter another
instruction to specifically reset Flag 9 before
proceeding to another group of test
conditions.
3.7.3 USER FLAGS
Flags 1-8 are not dedicated to a specific
purpose and are available to the user for
general programming needs. The user flags
can be manually toggled from the keyboard in
the *6 Mode (Section 1.3) or from a computer
using TERM's monitor feature. By inserting flag
tests (Instruction 91) at appropriate points in the
program, the user can manually set flags to
direct program execution.
3.8 PROGRAM CONTROL LOGICAL
CONSTRUCTIONS
Most of the Program Control Instructions have a
command code parameter which is used to
specify the action to be taken if the condition
tested in the instruction is true. Table 3.8-1 lists
these codes.
TABLE 3.7-2. Example of the Use of Flag 9
TABLE 3.8-1. Command Codes
Inst. Param.
Loc. No.
Entry
X
X+1
X+2
P
1
2
3
89
14
4
4.5
4
P
P
1
19
75
86
29
Description
If wind speed < 4.5 m/s
Wind speed location
Comparison: <
Minimum wind speed for
histogram
Set Flag 9 high
Histogram
Do
Set Flag 9 Low
0
1-9, 79-99
10-19
20-29
30
31
32
41-48
51-58
61-68
71-78
-
Go to end of program table
Call Subroutine 1-9, 79-99
Set Flag 0-9 high
Set Flag 0-9 low
Then Do
Exit loop if true
Exit loop if false
Set port 1 - 8 high*
Set port 1 - 8 low*
Toggle port 1 - 8*
Pulse port 1 - 8* 100 ms
* Port commands default to Excitation Card 1;
Instruction 20 is used to change to another
card.
3.8.1 IF THEN/ELSE COMPARISONS
When Command 30, THEN DO, is used with
one of the IF Instructions, 88-92, the instruction
is followed immediately by instructions to
3-4
SECTION 3. INSTRUCTION SET BASICS
execute if the comparison is true. The Else
Instruction, 94, is optional and is followed by the
instructions to execute if the comparison is
false. The End Instruction, 95, marks the end
of the branching started by the IF Instruction.
Subsequent instructions are executed
regardless of the outcome of the comparison
(Figure 3.8-1).
FIGURE 3.8-1. If Then/Else Execution
Sequence
If Then/Else comparisons may be nested to
form logical AND or OR branching. Figure 3.82 illustrates an AND construction. If conditions A
and B are true, the instructions included
between IF B and the first End Instruction will
be executed. If either of the conditions is false,
execution will jump to the corresponding End
Instruction, skipping the instructions between.
Call subroutine X (86, command=X)
END B (95)
END A (95)
FIGURE 3.8-3. Logical OR Construction
A logical OR can also be constructed by setting
a flag if a comparison is true. (The flag is
cleared before making the comparisons.) After
all comparisons have been made, execute the
desired instructions if the flag is set.
The Begin Case Instruction 93 and If Case
Instruction 83 allow a series of tests on the
value in an input location. The case test is
started with Instruction 93 which specifies the
location to test. A series of Instructions 83 are
then used to compare the value in the location
with fixed values. When the value in the input
location is less than the fixed value specified in
Instruction 83 the command in that Instruction
83 is executed; when the next Instruction 83 is
encountered, execution branches to the END
Instruction 95 which closes the case test (see
Instruction 93).
3.8.2 END, INSTRUCTION 95
END, Instruction 95, is required to mark the end
of:
1. A Subroutine (starts with Instruction 85)
2. A Loop (starts with Instruction 87)
3. An IF ... THEN DO sequence (starts with
one of Instructions 89-93 with the THEN DO
command 30).
4. A case statement (starts with Instruction 93)
The IF instructions 89-93 require Instruction 95
only when the THEN DO command 30 is used.
FIGURE 3.8-2. Logical AND Construction
Figure 3.8-3 illustrates the instruction sequence
that will result in subroutine X being executed if
either A or B is true.
IF A (88-92 with command 30)
Call subroutine X (86, command=X)
ELSE (94)
IF B (88-92 with command 30)
If one of the above instructions is used without
the corresponding END, the CR7 will display
error 22 when compiling the program. Error 21
is displayed if END is used without being
preceded by one of these instructions (Section
3.10).
An END instruction is always paired with the
most recent instruction that requires an END
and does not already have one. A way of
visualizing this is to draw lines between each
instruction requiring an END and the END
paired with it (as in Figure 3.8-2). The lines
must not cross. To debug logic or find a
missing or extra END error, list the program and
draw the lines.
3-5
SECTION 3. INSTRUCTION SET BASICS
Subroutines can be called from other
subroutines; they cannot be embedded within
other subroutines. A subroutine must end
before another subroutine begins (Error 20).
Any loops or IF...THEN DO sequences started
within a subroutine must end before the
subroutine.
3.8.3 NESTING
A branching or loop instruction which occurs
before a previous branch or loop has been
closed with the END instruction is nested. The
maximum nesting level is 9 deep. Error 30 is
displayed when attempting to compile a
program which is nested too deep.
The Loop Instruction, 87, counts as 1 level.
Instructions 86, 88, 89, 91, and 92 each count
as one level when used with the THEN DO
command 30. Use of Else, Instruction 94, also
counts as one nesting level each time it is used.
For example, the AND construction above is
nested 2 deep while the OR construction is
nested 3 deep. Branching and loop nesting
starts at zero within each subroutine and then
returns to the previous level after returning from
the subroutine.
Subroutine calls do not count as nesting with the
above instructions. They have a separate nesting
limit of seven (Instruction 85, Section 12).
Any number of groups of nested instructions
may be used in any of the three Programming
Tables. The number of groups is only restricted
by the program memory available.
3.9 INSTRUCTION MEMORY AND
EXECUTION TIME
The standard CR7 has 1744 bytes of program
memory available for the programs entered in
the *1, *2, and *3 program tables. Each
instruction also makes use of varying numbers
of Input, Intermediate, and Final Storage
locations. The following tables list the memory
used by each instruction and the approximate
time required to execute the instruction.
TABLE 3.9-1. Input/Output Instruction Memory
R = No. of Reps.
D = Delay
INSTRUCTION
1
2
3
4
5
6
7
9
10
11
12
13
14
16
17
18
19
20
21
22
23
26
3-6
VOLT (SE)
VOLT (DIFF)
PULSE
EX-DEL-SE
AC HALF BR
FULL BR
3W HALF BR
FULL BR-MEX
BATT. VOLT
TEMP (107)
RH (207)
TEMP-TC SE
TEMP-TC DIF
TEMP-RTD
TEMP-INTERNL
TIME
SIGNATURE
PORT SET
ANALOG OUT
EXCIT-DEL
SELECT I/O MODULE
TIMER
MEMORY
INPUT
PROG.
LOC.
BYTES
EXECUTION TIME (ms)
Slow or No
Fast
Integration
Integration
R
R
R
R
R
R
R
R
1
R
R
R
R
R
1
1
1
1
1
1
57.4 + 22R
16
+ 2.9R
54
+ 43.4R
19
+ 4.7R
4
+
2R
56.8 + (22.6 + D)R
23.4 + (3.3 + D)R
57.7 + 44R
21.1 + 5.5R
58
+ 87.3R
24.2 + 9.6R
58.8 + 88.7R
24.3 + 11.7R
104
+ 175R
31.5 + 20.4R
22.6
23
+
5.4R
23.3 +
5.4R
59.8 + 21.9R
25.2 + 6.1R
61
+ 43.2R
21.5 + 7.85R
0.4 +
2.7R
116.2
1.4
607.2
2.9
3.6
10.8 + D
0.4
0.54 to reset, 0.25 to load into location
1 or 0
15
15
15
20
18
18
18
19
4
15
17
18
18
15
4
7
4
4
5
11
4
SECTION 3. INSTRUCTION SET BASICS
TABLE 3.9-2. Processing Instruction Memory and Execution Times
R = No. of Reps.
INSTRUCTION
INPUT
LOC.
MEMORY
INTER.
PROG.
LOC.
BYTES
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
53
54
55
56
57
58
59
61
Z=F
Z=X
Z=Z+1
Z=X+Y
Z=X+F
Z=X-Y
Z=X*Y
Z=X*F
Z=X/Y
Z=SQRT(X)
Z=LN(X)
Z=EXP(X)
Z=1/X
Z=ABS(X)
Z=FRAC(X)
Z=INT(X)
Z=X MOD F
Z=XY
Z=SIN(X)
SPA MAX
SPA MIN
SPA AVG
A*X+B
BLOCK MOVE
POLYNOMIAL
SAT VP
WDT-VP
LP FILTER
X/(1-X)
INDIR MOVE
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1 or 2
1 or 2
1
4
R
R
1
1
R
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
R+1
0
0
66
ARC TAN
1
0
8
6
4
8
10
8
8
10
8
6
6
6
6
6
6
6
10
8
6
7
7
7
36
10
31
6
10
13
9
6
8
EXECUTION TIME (ms)
0.3
0.5
0.6
1.1
0.9
1.1
1.2
0.9
2.7
12.0
7.4
5.9
2.6
0.7
0.3
1.0
3.2
13.3
6.5
1.5 + 0.9 (swath-1)
1.7 + 0.9 (swath-1)
3.3 + 0.6 (swath-1)
2.5 + 0.4 scaling pair
0.18 + 0.17R
1.2 + R(2.0 + 0.4 * order)
4.2
8.1
0.5 + 2.2R
0.4 + 3.0R
0.35 neither indexed
0.54 one location indexed
0.73 both locations indexed
6.7
3-7
SECTION 3. INSTRUCTION SET BASICS
TABLE 3.9-3. Output Instruction Memory and Execution Times
R = No. of Reps.
INSTRUCTION
INTER.
LOC.
69 WIND VECTOR
2+9R
MEMORY
FINAL
VALUES1
PROG.
BYTES
70 SAMPLE
71 AVERAGE
72 TOTALIZE
73 MAXIMIZE
74 MINIMIZE
75 HISTOGRAM
0
1+R
R
(1 or 2)R
(1 or 2)R
1+bins*R
(2, 3, or 4)R
12
Options 00, 01, 02
Options 10, 11, 12
R
5
R
7
R
7
(1,2,or3)R
8
(1,2,or3)R
8
bins*R
24
77 REAL TIME
78 RESOLUTION
79 SMPL ON MM
80 STORE AREA
82 STD. DEV.
0
0
R
0
1+3R
1 to 4
0
R
0
R
EXECUTION TIME (ms)
FLAG 0 LOW
FLAG 0 HIGH
3.5 + 17.5R
3.5 + 16R
0.1
0.9+ 0.5R
0.6+ 0.5R
0.9+ 1.7R
0.9+ 1.7R
0.4+ 3.1R
4
3
7
5
7
0.1
0.4
0.3
3.5 + 75R
3.5 + 30R
0.4+ 0.6R
2.1+ 3.0R
1.1+ 1.0R
1.3+ 2.8R
1.3+ 2.8R
0.9+
R(3.3+2.8*bins)
1.0
0.4
1.1
1Output values may be sent to either Final Storage or Input Storage with Instruction 80.
TABLE 3.9-4. Program Control Instruction Memory and Execution Times
INSTRUCTION
MEMORY
INTER.
PROG.
LOC.
BYTES
83 IF CASE <F
85 LABEL SUBR
86 DO
87 LOOP
88 IF X<=>Y
89 IF X<=>F
90 LOOP INDEX
91 IF FLAG
92 IF TIME
93 BEGIN CASE
94 ELSE
95 END
96 SERIAL OUT
98 SEND CHAR.
0
0
0
1
0
0
0
0
1
1
0
0
0
0
3-8
9
3
5
9
10
12
3
6
11
8
4
4
3
4
EXECUTION TIME (ms)
0.5
0.0
0.1
0.2
0.6
0.4
0.5
0.2
0.3
0.2
0.2
0.2
SECTION 3. INSTRUCTION SET BASICS
3.10 ERROR CODES
There are four types of errors flagged by the
CR7: Compile, Run Time, Editor, and *D Mode.
When an error is detected, an E is displayed
followed by the 2 digit error code.
Compile errors are errors in programming
which are detected once the program is keyed
in and compiled for the first time (*0, *6, or *B
Mode entered).
Run Time errors are detected while the
program is running. Error 31 is the result of a
programming error. Error 8 is the result of a
hardware and software "watchdog" that checks
the processor state, software timers, and
program related counters. The watchdog will
attempt to reset the processor and program
execution if it finds that the processor has
bombed or is neglecting standard system
updates, or if the counters are out of allowable
limits. Error code 08 is flagged when the
watchdog performs this reset.
Error 8 is occasionally caused by voltage surges
or transients. Frequent repetitions of E08 are
indicative of a hardware problem or a software
bug and should be reported to Campbell
Scientific. The CR7 keeps track of the number
of times (up to 99) that E08 has occurred. The
number can be displayed and reset with the
Telecommunications A command (Section 5.1).
Editor errors are detected as soon as an
incorrect value is entered and are displayed
immediately.
*D Mode errors indicate problems with saving
or loading a program. Only the error code is
displayed.
TABLE 3.10-1. Error Codes
Code
Type
Description
01
03
04
08
09
11
20
21
22
24
25
26
30
31
40
40
60
61
97
98
99
Run Time
Editor
Compile
Run Time
Run Time
Editor
Compile
Compile
Compile
Compile
Compile
Compile
Compile
Run Time
Compile
Editor
Compile
Compile
*D MODE
*D MODE
*D MODE
I/O Module does not respond
Program table full
Intermediate Storage full
CR7 reset by watchdog timer
Data sent to unallocated Input Storage
Attempt to allocate more Input or Intermediate Storage than is available
SUBROUTINE encountered before END of previous subroutine
END without IF, LOOP or SUBROUTINE
Missing END, nonexistent SUBROUTINE
ELSE in SUBROUTINE without IF
ELSE without IF
EXIT LOOP without LOOP
IF and/or LOOP nested too deep
SUBROUTINES nested too deep
Table 2 Execution interval too short
Instruction not in PROM
Inadequate Input Storage for FFT
Burst Mode Scan Rate too short
Tape data not received within 30 seconds
Uncorrectable errors detected
Wrong file type, editor error or program not received
3-9
SECTION 3. INSTRUCTION SET BASICS
This is a blank page.
3-10
SECTION 4. EXTERNAL STORAGE PERIPHERALS
External data storage devices are used to provide a data transfer medium that the user can carry from
the test site to the lab and to supplement the internal storage capacity of the CR7, allowing longer
periods between visits to the site. The standard data storage peripherals for the CR7 are the Storage
Modules (Section 4.4). Output to a printer or related device is also possible (Section 4.5). These
peripherals are connected to the CR7 through the 9 pin serial connector.
Data output to a peripheral device can take place ON-LINE (automatically, as part of the CR7's routine
operation) or it can be MANUALLY INITIATED. On-line data transfer is accomplished with Instruction 96
or with the *4 Mode (Section 4.1). Manual initiation is done in the *8 or *9 Modes (Section 4.2).
Regardless of the method, the source of any data transferred is Final Storage.
A modem is another type of peripheral that can be connected to the CR7. Communication via a modem
(Telecommunications) is discussed in Section 5.
The CR7 can output data to multiple peripherals (i.e., a modem and Storage Module could be connected
at the same time). However, only one modem may be connected to the CR7 at any one time. It is
possible to connect two Storage Modules, although it is seldom necessary.
The CR7 can tell whether or not a SM192 or SM716 Storage Module is present. When Instruction 96 or
*9 is used to send data to one of these Storage Modules, the CR7 will not send data if the Storage
Module is not connected (Section 4.4.2).
4.1 ON-LINE DATA TRANSFER INSTRUCTION 96, *4 MODE
On-line data transfer is accomplished with
Instruction 96 entered in the datalogger
program. The *4 Mode is retained from earlier
software to maintain compatibility with existing
programs. Use only one method to enable
output. If using Instruction 96, do not enable
output in the *4 Mode.
4. Enter Instruction 96 to enable the on-line
transfer of Final Storage data to the
specified device. If outputting to both tape
and a Storage Module or printer option,
Instruction 96 must be entered twice.
Instruction 96 has a single parameter which
specifies the peripheral to enable. Table 4.1-1
lists the output device codes.
TABLE 4.1-1. Output Device Codes for
Instruction 96
4.1.1 INSTRUCTION 96
Instruction 96 enables output to external
storage peripherals under program control.
This instruction must be included in the
datalogger program for on-line data transfer to
take place. Instruction 96 needs to be included
only once in the program tables and should
follow the Output Processing Instructions. The
suggested programming sequence is:
1. Set the Output Flag.
2. If you wish to set the output array ID, enter
Instruction 80 (Section 11).
3. Enter the appropriate Output Processing
Instructions.
CODE DEVICE
1x
2x
30
31
Printer, Printable ASCII
Printer, Binary
SM192/716 Storage Module
Send filemark to SM192/716
x = BAUD RATE CODE
0
300
1
1200
2
9600
3 76,800
4-1
SECTION 4. EXTERNAL STORAGE PERIPHERALS
Only one of the options 1x, 2x, or 30 may be
used in a program. If using a SM64 Storage
Module, output code 21 should be used. Use of
the SM192/716 is discussed further in Section
4.4, print output formats are discussed in
Section 4.5.
4.1.2 *4 MODE
The *4 Mode may be used in place of
Instruction 96 to enable or disable printer output
and to set the printer baud rate. The first
parameter is a two digit number determining the
printer status. The second is the baud rate
code. To enter a different status, key in the
appropriate code from Table 4.1-2, followed by
"A". Printer data is sent in the printable
ASCII format only (Section 4.5). If printer
status is changed during execution of the
program tables, execution stops until the
programs are recompiled. Instruction 96 should
be used to send data to the SM192/716 Storage
Modules. Do not use *4 if Instruction 96 is used
in the program.
TABLE 4.1-2. *4 Mode Parameters and Codes
Keyboard
Entry
Display
ID: Data
Description of Data
*4
A
A
04:00
01:XX
02:XX
Output Enable Code
Baud Rate Code
Output Enable Codes
Code
00
01
Description
printer disabled
printer enabled, ASCII
Baud Rate Codes
Code
Baud Rate
00
01
02
03
300
1200
9600
76,800
4.2 MANUALLY INITIATED DATA
OUTPUT - *9 MODE
Data may be transferred to tape using the *8
Mode and to printer or Storage Module using
the *9 Mode. These Modes allow the user to
retrieve a specific block of data, on demand,
regardless of whether or not the CR7 is
programmed for on-line data output.
If external storage peripherals are not left online, the maximum allowable time between
visiting the site to retrieve data must be
calculated to insure that data placed in Final
Storage are not written over before they are
collected. In order to make this calculation,
users must determine: (1) the size of Final
Storage, (2) the number of output arrays being
generated, (3) the number of low and/or high
resolution data points included in each output
array, and (4) the rate at which output arrays
are stored in Final Storage. When calculating
the number of data points per output array,
remember to add 1 overhead data point (2
bytes) per array for the output array ID.
For example, assume that 19,296 locations are
assigned to Final Storage (*A Mode), and that 1
output array, containing the Array ID (1 memory
location), 9 low resolution data points (9
memory locations) and 5 high resolution data
points (10 memory locations) is stored each
hour. In addition, an output array with the Array
ID and 5 high resolution data points (11 memory
locations) is stored daily. This is a total of 491
memory locations per day ((20 x 24) + 11).
19,296 divided by 491 = 39.3 days. Therefore,
the CR7 would have to be visited every 39 days
to retrieve data, because write-over would begin
in the 40th day.
4.2.1 MANUAL STORAGE MODULE OR
PRINTER DUMP - *9 MODE
Using the *9 Mode, data in Final Storage can be
transmitted as ASCII or binary data out the
serial port by manually initiating a dump. If online printing is enabled with Instruction 96 or the
*4 Mode, entering *9 will stop it. On-line printing
will be re-enabled if no keyboard entries are
made for 3.4 minutes. Return to the *0 Mode
when the dump is completed.
When on-line Storage Module or printer transfer is
not enabled and the *9 Mode is used to dump new
data, the start of dump pointer (PPTR) will remain
where it was when the dump was completed or
4-2
SECTION 4. EXTERNAL STORAGE PERIPHERALS
aborted until the next time the *9 Mode is entered.
If the End of Dump location (window 2) is changed
while in the *9 Mode, the TPTR will be set to its
previous value when the *9 Mode is exited.
Changing the program and compiling moves the
PPTR to the current DSP location.
NOTE: A printer dump is aborted by
keying #.
TABLE 4.2-2. *9 Mode Entries
Key
Display
ID:DATA
*9
09:00
Description
Output Code
1X Printable ASCII
2X Final Storage Format
30 SM192/716 Storage
Module
31 Send File Mark to
SM192/716 than
send data
x = Baud Rate Code
0
300
1
1200
2
9600
3 76800
A
01:XXXXX
Start of Dump location,
initially the PPTR
location, a different
location may be keyed in
if desired. To dump all
data in Final Storage,
enter into window #1 a
number 1 greater than
the End of Dump
location.
A
02:XXXXX
End of Dump location,
initially the DSP location,
a different location may
be keyed in if desired.
A
03:00
Ready to Dump, to
initiate dump, key any
number then A. While
dumping, "09:" will be
displayed in the ID field
and the location number
in the Data field. The
location number will stop
incrementing when the
dump is complete.
4.3 STORAGE MODULE
The Storage Module stores data in battery
backed RAM. Backup is provided by an internal
lithium battery. The RAM is internal on the
SM192/716 and on a PCMCIA card on the
CSM1. Operating power is supplied by the CR7
over pin 1 of the CS I/O connector. When
power is applied to the Storage Module, a File
Mark is placed in the data (if a File Mark is not
the last data point already in storage).
The File Mark separates data. For example, if
you retrieve data from one CR7, disconnect the
Storage Module and connect it to a second
CR7; a File Mark is placed in the data. This
mark follows the data from the first CR7, but
precedes the data from the second.
The SM192 has 192K bytes of RAM storage;
the SM716 has 716K bytes. Both can be
configured as either ring or fill and stop
memory. The size of memory in the CSM1
depends on the PC card used. The CSM1 is
always fill and stop.
4.3.1 USE OF TWO STORAGE MODULES
It is possible to connect two Storage Modules to
the CR7 for on-line storage. One module must
be configured as fill and stop and the other as
ring memory (see Storage Module operator's
manual for configuring information). Data is
written to both modules simultaneously. The
module configured as fill and stop quits
accepting data once it is full while that with the
ring memory continues to store new data over
old. The Storage Modules must be retrieved
before the module configured as ring memory
wraps around memory a second time.
4.3.2 STORAGE MODULE USE WITH
INSTRUCTION 96
When output to the Storage Module is enabled
with Instruction 96, the Storage Module(s) may
be either left with the CR7 for on-line data
transfer and periodically exchanged, or brought
to the site for data transfer.
USE OF STORAGE MODULE TO PICK UP
DATA
The CR7 can tell when the Storage Module is
connected. Each time Instruction 96 is
executed and there is data to output, the CR7
checks for the presence of the Storage Module.
4-3
SECTION 4. EXTERNAL STORAGE PERIPHERALS
If a Storage Module is not connected no data
are sent and the Printer Pointer (PPTR, Section
2.1) is not advanced.
When a Storage Module is connected, two
things happen:
1. Immediately upon connection, a File Mark is
placed in the Storage Module Memory
following the last data stored.
2. During the next execution of Instruction 96,
the CR7 detects the Storage Module and
outputs all data between the PPTR and the
DSP location.
The File Mark allows the operator to distinguish
blocks of data from different dataloggers or
from different visits to the field.
If the SM is just brought to the site to pick-up
data, the SC90 Serial Line Monitor can be used
to visually confirm that data were transferred.
The SC90 contains an LED which lights during
data transmission. When the light goes OFF,
data transfer is complete and the SM can be
disconnected from the CR7.
4.3.3 *9 DUMP TO STORAGE MODULE
In addition to the on-line data output procedures
described above, output from CR7 Final
Storage to the SM192 and SM716 can be
manually initiated in the *9 Mode. The
procedure for setting up and transferring data is
as follows:
1. Connect the Storage Module to the CR7
using the SC12 cable.
4-4
2. Enter the appropriate commands as listed
in Table 4.2-2.
4.4 PRINTER OUTPUT FORMATS
Printer output can be sent in the binary Final
Storage Format (Appendix C.2) or Printable
ASCII. If using the *4 Mode to enable on-line
output, Printable ASCII is the only format
available.
In the Printable ASCII format, each data point is
preceded by a two digit data point ID and a + or
- sign. The ID and fixed spacing of the data
points make particular points easy to find on a
printed output. This format requires 10 bytes
per data point to store on disk.
Figure 4.5-1 shows both high and low resolution
data points in a 12 data point output array. The
example data contains Day, Hour-Minute, and
Seconds in the 2nd - 4th data points. The
output array ID and time values (year, day,
hour-minute, and seconds) are always four
character numbers, even when high resolution
output is specified.
Each full line of data contains eight data points
(79 characters including spaces), plus a
carriage return (CR) and line feed (LF). If the
last data point in a full line is high resolution, it is
followed immediately with a CR and LF. If it is
low resolution, the line is terminated with a
space, CR and LF. Lines of data containing
less than eight data points are terminated
similarly after the last data point.
SECTION 4. EXTERNAL STORAGE PERIPHERALS
FIGURE 4.4-1. Example of CR7 Printable ASCII Output Format
4-5
SECTION 4. EXTERNAL STORAGE PERIPHERALS
This is a blank page.
4-6
SECTION 5. TELECOMMUNICATIONS
Telecommunications allows a computer to retrieve data directly from Final Storage and may be used to
program the CR7 and monitor sensor readings in real time. Any user communication with the CR7 that
makes use of a computer or terminal instead of the CR7 keyboard is through Telecommunications.
Telecommunications can take place over a variety of links including:
•
•
•
•
•
telephone
radio frequency
short haul modem
SC32A and ribbon cable
multi-drop interface and coax cable
This section does not cover the technical interface details for any of these links. Those details are
covered in Section 6 and in the individual manuals for the devices.
Data retrieval can take place in either ASCII or BINARY. The BINARY format is five times more
compact than ASCII. The shorter transmission times for binary result in lower long distance telephone
charges and more reliable data transfer. On "noisy" links shorter blocks of data are more likely to get
through without interruption.
In addition to more efficient data transfer, binary data retrieval makes use of a signature for error
detection. The signature algorithm assures a 99.998% probability that if either the data or its sequence
changes, the signature changes.
The PC208 Datalogger Support Software for PCs and compatibles contains the programs which
automate data retrieval, program transfer, and real time monitoring. The PC208 package has been
designed to meet the most common needs in datalogger support and telecommunications. This section
in not intended to furnish sufficient detail to write Telecommunications software. Appendix C contains
some details of binary data transfer and Campbell Scientific's binary data format.
This section emphasizes the commands that a person would use when manually (i.e., entered by hand)
interrogating or programming the CR7 via a computer/terminal. These commands and the responses to
them are sent in the American Standard Code for Information Interchange (ASCII). The Remote
Keyboard State (Section 5.2) allows the user with a computer/terminal to use the same commands as
the CR7 keyboard.
5.1 TELECOMMUNICATIONS
COMMANDS
When the CR7 is rung by a modem, it answers
(enables the modem) almost immediately.
Several carriage returns (CR) must be sent
from the computer to allow the CR7 to set its
baud rate to that of the modem/terminal (300,
1200, 9600, or 76,800). Once the baud rate is
set, the CR7 sends the prompt, *, signaling that
it is ready to receive a command.
GENERAL RULES governing the
telecommunications commands are:
1. * from datalogger means "ready for
command".
2. All commands are of the form: [no.]letter,
where the number may or may not be
optional.
3. Valid characters are the numbers 0-9, the
capital letters A-L, the colon (:), and the
carriage return (CR).
4. An illegal character increments a counter
and zeros the command buffer, returning *.
5. CR to datalogger means "execute".
5-1
SECTION 5. TELECOMMUNICATIONS
6. CRLF from datalogger means "executing
command".
7. ANY character besides a CR sent to the
datalogger with a legal command in its
buffer causes the datalogger to abort the
command sequence with CRLF* and to
zero the command buffer.
8. All commands return a response code,
usually at least a checksum.
9. The checksum includes all characters sent
by the datalogger since the last *, including
the echoed command sequence, excluding
only the checksum itself. The checksum is
formed by summing the ASCII values,
without parity, of the transmitted characters.
The largest possible checksum value is
8191. Each time 8191 is exceeded, the
CR7 starts the count over; e.g., if the sum
of the ASCII values is 8192, the checksum
is 0.
10. Commands that return Campbell Scientific
binary format data (F and K commands)
return a signature (Appendix C).
The CR7 sends ASCII data with eight data bits,
no parity, plus one start bit and one stop bit.
After answering a ring, or completing a
command, the CR7 waits about 40 seconds
(147 seconds in the Remote Keyboard State)
for a valid character to arrive. If a valid
character is not received, the CR7 "hangs up".
Some modems are quite noisy when not on line;
it is possible for valid characters to appear in
the noise pattern. To insure that this situation
does not keep the CR7 in telecommunications,
the CR7 counts all the invalid characters it
receives from the time it answers a ring, and
terminates communication after receiving 150
invalid characters.
The CR7 continues to execute its measurement
and processing tasks while servicing the
telecommunication requests. If the processing
overhead is large (short execution interval), the
processing tasks will slow the
telecommunication functions. In a worst case
situation, the CR7 interrupts the processing
tasks to transmit a data point every 0.1 second.
The best way to become familiar with the
Telecommunication Commands is to try them
from a terminal connected to the CR7 via the
SC32A or other modem interface (Section 6.5).
Telecommunications Commands are described
in the following Table. The Data Storage
Pointer (DSP) and Telecommunications Modem
Pointer (MPTR) referred to in the table are
described in Section 2.1.
TABLE 5.1-1. Telecommunications Commands
Command
A
Description
STATUS - Datalogger returns Reference, the DSP location; the number of
filled Final Storage locations; Version of datalogger; Errors #1 and #2 where
#1 is the number of E08 and #2 is the number of overrun that have
occurred (cleared by entering 8888A); Memory status, the decimal number
(in ASCII characters) that is the equivalent of the 8 bit binary number shown
as the result of the memory check on power-up; Location of MPTR; and
Checksum. All in the following format:
R+xxxxx F+xxxxx Vx Exx xx Mxxxx L+xxxxx Cxxxx
If data are stored while in telecommunications, the A command must be
issued to update the Reference to the new DSP.
[no. of arrays]B
5-2
BACK-UP - MPTR is backed-up the specified number of output arrays (no
number defaults to 1) and advanced to the nearest start of array. CR7
sends the MPTR Location and Checksum: L+xxxxx Cxxxx
SECTION 5. TELECOMMUNICATIONS
[YR:DAY:HR:MM:SS]C
[no. of arrays]D
E
[no. of loc.]F
[F.S. loc. no.]G
RESET/SEND TIME - If time is entered the time is reset. If only 2 colons
are in the time string, HR:MM:SS is assumed; 3 colons means
DAY:HR:MM:SS. If only the C is entered, time is unaltered. CR7 returns
year, Julian day, hr:min:sec, and Checksum: Y:xx Dxxxx Txx:xx:xx Cxxxx
ASCII DUMP - If necessary, the MPTR is advanced to the next start of
array. CR7 sends the number of arrays specified (no number defaults to 1)
or the number of arrays between MPTR and Reference, whichever is
smaller, CRLF, Location, Checksum.
End call. Datalogger sends CRLF only.
BINARY DUMP - Used in TELCOM (PC208). See Appendix C.
MOVE MPTR - MPTR is moved to specified Final Storage location. The
location number must be entered. CR7 sends Location and Checksum:
L+xxxxx Cxxxx
2718H
REMOTE KEYBOARD - CR7 sends the prompt ">" and is ready to execute
standard keyboard commands (Section 5.2).
[loc. no.]I
Display/change value at Input Storage location. CR7 sends the value
stored at the location. A new value and CR may then be sent. CR7 sends
checksum. If no new value is sent (CR only) the location value will remain
the same.
3142J
TOGGLE FLAGS AND SET UP FOR K COMMAND - Used in the Monitor
Mode and with the Heads Up Display. See Appendix C for details.
K
CURRENT INFORMATION - In response to the K command, the CR7
sends datalogger time, user flag status, the data at the input locations
requested in the J command, and Final Storage Data if requested by the J
command. Used in the Monitor Mode and with Heads Up Display. See
Appendix C.
[Password]L
Unlocks security (if enabled) to the level determined by the password
entered (See *C Mode, Section 1.7). CR7 sends security level (0-3) and
checksum: Sxx Cxxxx
5.2 REMOTE PROGRAMMING OF THE
CR7
The CR7 can be programmed via
telecommunications using the PC208 software
or manually through the Remote Keyboard
State.
The PC208 Datalogger Support Software was
developed for use with IBM or compatible PCs.
The CR7 is placed in the Remote Keyboard
State by sending "2718H" and a carriage return
(CR). The CR7 responds by sending a CR, line
feed (LF), and the prompt ">". The CR7 is then
ready to receive the standard keyboard
commands (Section OV3); it recognizes all the
standard CR7 keyboard characters plus the
decimal point. While in the Remote Keyboard
State, the CR7 sends the ASCII character
control Q (17 decimal) after each user entry.
Entering *0 returns the CR7 to the
telecommunications command state.
It is important to remember that the Remote
Keyboard State is still within
Telecommunications. Entering *0 exits the
Remote Keyboard and returns the datalogger to
the Telecommunications Command State,
awaiting another command. So, the user can
step back and forth between the
5-3
SECTION 5. TELECOMMUNICATIONS
Telecommunications Command State and the
Remote Keyboard State.
Keying *0 will compile and run the CR7 program
if program changes have been made. To
compile and run the program without leaving the
Remote Keyboard State, use *6 (Section 1.1.4).
The CR7 display will show "LOG" when *0 is
executed via telecommunications. It will not
indicate active tables (enter *0 via the keyboard
and the display will show the tables).
2718H
Telecommunications
Command
State
5-4
*0
Remote
Keyboard
State
SECTION 6. CS I/O 9 PIN SERIAL INPUT/OUTPUT
6.1 PIN DESCRIPTION
All external communication peripherals connect
to the CR7 through the 9-pin CS I/O connector
(Figure 6.1-1). Table 6.1-1 gives a brief
description of each pin's function.
CS I/O
FIGURE 6.1-1. CS I/O 9 Pin Connection
TABLE 6.1-1. Pin Description
ABR
PIN
O
I
=
=
=
=
Abbreviation for the function name.
Pin number.
Signal Out of the CR7 to a peripheral.
Signal Into the CR7 from a peripheral.
PIN
ABR
I/O
Description
PIN
ABR
I/O
Description
1
5V
O
5V: Sources 5V DC, used
to power some peripherals.
6
PE
O
2
G
Printer Enable: Raised to
enable Storage Module or
other print device.
7
G
I/O
Ground, common with pin 2.
8
12 V
O
12 volt power for
peripherals.
9
TXD
O
Transmit Data: Serial data
are transmitted from the
CR7 to peripherals on pin
9; logic low marking (0V)
logic high spacing (5V)
standard asynchronous
ASCII, 8 data bits, no
parity, 1 start bit, 1 stop bit,
300, 1200, 9600, 76,800
baud (user selectable).
Ground: Provides a power
return for pin 1 (5V), and is
used as a reference for
voltage levels.
3
RING
I
Ring: When raised by a
peripheral the CR7 enters
telecommunications.
4
RXD
I
Receive Data: Serial data
transmitted by a peripheral
are received on pin 4.
5
ME
O
Modem Enable: Raised by
the CR7 after the ring line
has been raised.
6-1
SECTION 6. 9 PIN SERIAL INPUT/OUTPUT
6.2 ENABLING PERIPHERALS
Several peripherals may be connected in
parallel to the CS I/O 9-pin port. The CR7
directs data to a particular peripheral by raising
the voltage on a specific pin dedicated to the
peripheral; the peripheral is enabled when the
pin goes high. Two pins are dedicated to
specific devices Modem Enable pin 5 and Print
Enable pin 6.
Modem Enable (ME), pin 5, is raised to enable
a modem that has raised the ring line. Only one
modem/terminal may be connected to the CR7.
Print Enable (PE), pin 6, is raised to enable a
Storage Module or other print peripheral. Print
peripherals are defined as peripherals which
have an asynchronous serial communications
port used to RECEIVE data transferred by the
CR7. In most cases the peripheral is a printer,
but could also be an on-line computer or other
device. It is possible to have more than one
print peripheral connected to the CR7 at one
time, as long as they don't load down the TXD
line (e.g., two Storage Modules, Section 4.4.1);
all connected receive the same data.
6.3 INTERRUPTING DATA TRANSFER
TO STORAGE PERIPHERALS
Instruction 96 is used for on-line data transfer to
peripherals (Section 4.1). Data transfer is
aborted when a modem raises the Ring line and
the CR7 then enters Telecommunications
(Section 5, 6.4). After the CR7 exits
Telecommunications, data transfer to the
peripheral is resumed the next time Instruction
96 is executed, or, if activated by the *4 Mode,
at the completion of the next active table.
The *8 and *9 Modes are used to position the
Memory Pointers, and to manually initiate data
transfer from Final Storage to a peripheral. If
the # key is pressed during data transfer, the
transfer is stopped and the display shows the
Final Storage location where the pointer
stopped.
Data transfer can be stopped as follows:
1. Printable ASCII - after every output array.
2. Binary - after every Final Storage location.
6-2
6.4 TELECOMMUNICATIONS - MODEM
PERIPHERALS
Any serial communication device which raises
the Ring line and holds it high until the ME line
is raised is a modem. The CSI field modem
(DC112, COM200, COM100, or DC1765), RF95
RF modem, MD9 Multi-Drop Interface, and the
SC32A RS232 interface used with computers or
terminals are modems.
When a modem raises the Ring line, the CR7
responds by raising the ME line. The CR7 must
be sent carriage returns until it sets the baud
rate. When the baud rate is set, the CR7 sends
a carriage return, line feed, *.
The ME line is held high until the CR7 receives
an E to exit telecommunications or until a time
limit expires without receiving a character. The
colon in CR7 display is not shown while the
CR7 is in telecommunications.
Some modems are quite noisy when not on line;
it is possible for valid characters to appear in
the noise pattern. For this reason, the CR7
counts all the invalid characters it receives from
the time it answers a ring and terminates
communication (lowers the ME line and returns
to the *0 Mode) after receiving 150 invalid
characters.
6.5 INTERFACING WITH COMPUTERS,
TERMINALS, AND PRINTERS
This section deals with some of the basics of
serial communication between the CR7 and
common computer equipment. If you have an
IBM compatible PC, the PC208(W) Datalogger
Support Software takes care of the software
protocol required in communicating with the
CR7. This section does not discuss modem
interfaces other than the SC32A. Please refer
to the PC208 software and modem operator's
manuals for interfacing details on other
modems.
SECTION 6. 9 PIN SERIAL INPUT/OUTPUT
6.5.1 SC32A INTERFACE
Most computers, terminals, and printers require
the SC32A Optically Isolated RS232 Interface
for a "direct" connection to the CR7. The
SC32A raises the CR7's ring line when it
receives characters from the computer or
terminal, and converts the CR7's logic levels
(0V logic low, 5V logic high) to RS232 logic
levels.
The SC32A 25 pin port is configured as Data
Communications Equipment (DCE) which
allows direct connection to Data Terminal
Equipment (DTE), which includes most PCs
and printers. For connection to DCE devices
such as modems and some computers, use
SC932 interface in place of SC32A.
When the SC32A receives a character from the
computer or terminal (pin 2), 5V is applied to
the datalogger Ring line (pin 3) for one second
or until the Modem Enable line (ME) goes high.
The CR7 waits approximately 40 seconds to
receive carriage returns, which it uses to
establish baud rate. After the baud rate is set
the CR7 transmits a carriage return, line feed, *,
and enters the Telecommunications Command
State (Section 5). If the carriage returns are not
received within the 40 seconds, the CR7 "hangs
up".
TABLE 6.5-1. DTE Pin Configuration
PIN = 25-pin connector number
ABR = Abbreviation for the function name
O = Signal Out of the terminal to another device
I = Signal Into the terminal from another device
PIN
ABR
I/O
FUNCTION
2
TD
O
Transmitted Data: Data is
transmitted from the
terminal on this line.
3
RD
I
Received Data: Data is
received by the terminal on
this line.
4
RTS
O
Request to Send: The
terminal raises this line to
ask a receiving device if the
terminal can transmit data.
5
CTS
I
Clear to Send: The
receiving device raises this
line to let the terminal know
that the receiving device is
ready to accept data.
20
DTR
O
Data Terminal Ready: The
terminal raises this line to
tell the modem to connect
itself to the telephone line.
6
DSR
I
Data Set Ready: The
modem raises this line to
tell the terminal that the
modem is connected to the
phone line.
8
DCD
I
Data Carrier Detect: The
modem raises this line to
tell the terminal that the
modem is receiving a valid
carrier signal from the
phone line.
22
RI
I
Ring Indicator: The
modem raises this line to
tell the terminal that the
phone is ringing.
7
SG
NOTE: The SC32A has a jumper. With the
jumper in place, the SC32A blocks printer
data and passes data only when the CR7 is
in Telecommunications.
6.5.2 COMPUTER/TERMINAL REQUIREMENTS
Computers, terminals and printers are usually
configured as Data Terminal Equipment (DTE).
Pins 4 and 20 are used as handshake lines,
which are set high when the serial port is
enabled. Power for the SC32A is taken from
these pins. For equipment configured as DTE,
a direct ribbon cable connects the
modem/terminal to the SC32A. Clear to Send
(CTS) pin 5, Data Set Ready (DSR) pin 6, and
Received Line Signal Detect (RLSD) pin 8 are
held high by the SC32A (when the RS232
section is powered) which should satisfy
hardware handshake requirements of the
modem/terminal.
Signal Ground: Voltages
are measured relative to
this point.
Table 6.5-1 lists the most common RS232
configuration for Data Terminal Equipment.
6-3
SECTION 6. 9 PIN SERIAL INPUT/OUTPUT
FIGURE 6.5-1. Transmitting the ASCII Character 1
6.5.3 COMMUNICATION PROTOCOL/TROUBLE
SHOOTING
The ASCII standard defines an alphabet
consisting of 128 different characters where
each character corresponds to a number, letter,
symbol, or control code.
An ASCII character is a binary digital code
composed of a combination of seven "bits",
each bit having a binary state of 1 or more. For
example, the binary equivalent for the ASCII
character "1" is 0110001 (decimal 49).
ASCII characters are transmitted one bit at a
time, starting with the first (least significant) bit.
During data transmission the marking condition
is used to denote the binary state 1, and the
spacing condition for the binary state 0. The
signal is considered marking when the voltage
is more negative than minus three volts with
respect to ground, and spacing when the
voltage is more positive than plus three volts.
Most computers use 8-bits (1 byte) for data
communications. The eighth bit is sometimes
used for a type of error checking called parity
checking. Even parity binary numbers have an
even number of 1's, odd-parity characters have
an odd number of 1's. When parity checking is
used, the eighth bit is set to either a 1 or a 0 to
make the parity of the character correct. The
CR7 ignores the eighth bit of a character that is
receives, and transmits the eighth bit as a
binary 0. This method is generally described as
"no parity".
To separate ASCII characters, a Start bit is sent
before the first data bit, and a Stop bit is sent
after the eighth data bit. The start bit is always
a space, and the stop bit is always a mark.
Between characters, the signal is in the marking
condition.
6-4
Figure 6.5-1 shows how the ASCII character "1"
is transmitted. The SC32A interface transmits
spacing and marking voltages which are
positive and negative, as shown. Signal
voltages at the CR7 I/O port are 5 volts in the
spacing condition, and 0 volts in the marking
condition.
BAUD RATE
BAUD RATE is the number of bits transmitted
per second. The CR7 can communicate at 300,
1200, 9600, and 76,800 baud. In the
Telecommunications State, the CR7 will set its
baud rate to match the baud rate of the modem.
The baud rate of the modem or computer is
usually set with dip switches or programmed
from the keyboard. The instrument's instruction
manual should explain how to set it.
DUPLEX
Full duplex means that two devices can
communicate in both directions simultaneously.
Half duplex means that the two devices must
send and receive alternately. Full duplex should
always be specified when communicating with
Campbell Scientific peripherals and modems.
However, communication between some
Campbell Scientific modems (such as the RF95
RF modem) is carried out in a half duplex
fashion. This can affect the way commands
should be sent to and received from such a
modem, especially when implemented by
computer software.
To overcome the limitations of half duplex,
some communications links expect a terminal
sending data to also write the data to the
screen. This saves the remote device having to
echo that data back. If, when communicating
with a Campbell Scientific device, characters
are displayed twice (in pairs), it is likely that the
SECTION 6. 9 PIN SERIAL INPUT/OUTPUT
terminal is set to half duplex rather than the
correct setting of full duplex.
IF NOTHING HAPPENS
If the CR7 is connected via the SC32A interface
to a terminal or computer and * is not received
after sending carriage returns:
1. Verify that the CR7 has power and that the
cables connecting the devices are securely
connected.
2. Verify that the port of the computer or
terminal is an asynchronous serial
communications port configured as DTE
(see Table 6.5-1). The most common
problems occur when the user tries to use a
parallel port, or doesn't know the port
address (i.e. COM1 or COM2). IBM, and
most compatibles come with a Diagnostic
disk which can be used to identify ports,
and their addresses. If the serial port is
standard equipment, then the operators
manual should give you this information.
Some serial ports such as the Super Serial
Card for Apple computers, can be
configured as DTE or DCE with a jumper
block. Pin functions must match with Table
6.5-1.
If you are using a computer without the PC208
software, then a program or communication
software must be used to enable the serial port
and to make the computer function as a
terminal. The port should be enabled for 300,
1200, or 9600 baud, 8 data bits, 1 stop bit, and
no parity.
If you are not sure that your computer or
terminal is sending or receiving characters,
there is a simple way to verify it. Set the duplex
to full. Next, take a paper clip and connect one
end to pin 2, and the other end to pin 3 of the
serial port. Each character typed on the
keyboard will be displayed only if transmitted
from the terminal on pin 2, and received on pin
3 (with half duplex the character will be
displayed once if it is not transmitted, or twice if
it is transmitted).
IF GARBAGE APPEARS
If garbage characters appear on the
modem/terminal, check that the
modem/terminal's baud rate is supported by the
CR7. If the baud rate is correct, verify that the
modem/terminal is set for 8 Data bits, and no
Parity. Garbage will appear if 7 Data bits and
no Parity are used. If the modem/terminal is set
to 8 Data bits and even or odd Parity,
communication cannot be established.
6-5
SECTION 6. 9 PIN SERIAL INPUT/OUTPUT
This is a blank page.
6-6
SECTION 7. MEASUREMENT PROGRAMMING EXAMPLES
This section gives some examples of Input Programming for common sensors used with the CR7. These
examples detail only the connections, Input, Program Control and Processing Instructions necessary to
perform measurements and store the data in engineering units in Input Storage. Output Processing
Instructions are omitted, it is left for the user to program the necessary instructions to obtain the final
data in the form desired. NO OUTPUT TO FINAL STORAGE WILL TAKE PLACE WITHOUT
ADDITIONAL PROGRAMMING.
The examples given in this section would likely be only fragments of larger program tables. In general,
the examples are written with the measurements made by the first channels on the first cards in the I/O
Module, the instructions at the beginning of a program table, and low number Input Storage locations
used to Store the data. Because it is unlikely that an application and CR7 configuration exactly
duplicates that assumed in an example, THESE EXAMPLES ARE NOT MEANT TO BE USED
VERBATIM; CARDS AND CHANNELS REFERENCED, SENSOR CALIBRATION AND INPUT
LOCATIONS SELECTED MUST BE ADJUSTED FOR THE ACTUAL CIRCUMSTANCES. UNLESS
OTHERWISE NOTED, ALL EXCITATION CHANNELS ARE SWITCHED ANALOG OUTPUT.
7.1 SINGLE ENDED VOLTAGE - LI200S
SILICON PYRANOMETER
The silicon pyranometer puts out a current
which is dependent upon the solar radiation
incident upon the sensor. The current is
measured as the voltage drop across a fixed
resistor. The Campbell Scientific LI200S uses a
100 ohm resistor. The calibration supplied by
LI-COR, the manufacturers of the pyranometer,
is given in uA/kW/m2. The calibration in terms
of volts is determined by multiplying the µA
calibration by the resistance of the fixed
resistor.
The calibration of the pyranometer used in this
example is assumed to be 76.9 µA/kW/m2,
which when multiplied by 100 ohms equals 7.69
mV/kW/m2. The multiplier used to convert the
voltage reading to kW/m2 is 1 / 7.69 mV/kW/m2
= 0.13004.
Most LI-COR calibrations run between 60 and
90 µA/kW/m2, which correspond to calibrations
of 6.0 to 9.0 mV/kW/m2. The flux density
through a surface normal to the solar beam
above the earth's atmosphere is 1.36 kW/m2;
radiation on earth will be less than this. Thus,
the 15 mV scale provides an adequate range
(9.0 mV/kW/m2 x 1.36 kW/m2 < 15 mV).
CONNECTIONS
The pyranometer output is measured with a
single ended voltage measurement on channel
5. There are twice as many single ended
channels as differential channels and they are
numbered accordingly: single ended channel 5
is the high side of differential channel 3, and the
low side is single ended channel 6.
FIGURE 7.1-1. Wiring Diagram for LI200S
PROGRAM
01:
01:
02:
03:
04:
05:
06:
07:
P1
1
3
1
5
1
.13004
0
Volt (SE)
Rep
15 mV slow Range
IN Card
IN Chan
Loc [:R kW/m^2 ]
Mult
Offset
7.2 DIFFERENTIAL VOLTAGE
MEASUREMENT
Some sensors either contain or require active
signal conditioning circuitry to provide an easily
measured analog voltage output. Generally, the
output is referenced to the sensor ground. The
associated current drain usually requires a
power source external to the CR7. A typical
connection scheme where AC power is not
available and both the CR7 and sensor are
powered by an external battery is shown in
7-1
SECTION 7. MEASUREMENT PROGRAMMING EXAMPLES
Figure 7.2-1. Since a single ended
measurement is referenced to the CR7 ground,
any voltage difference between the sensor
ground and CR7 ground becomes a
measurement error. A differential
measurement avoids this error by measuring
the signal between the 2 leads without
reference to ground. This example analyzes
the potential error on a water pH measurement
using a Martek Mark V water quality analyzer.
PROGRAM
01:
01:
02:
03:
04:
05:
06:
07:
P2
1
7
1
1
1
0.014
0
Volt (DIFF)
Rep
1500 mV slow Range
IN Card
IN Chan
Loc [:pH
]
Mult
Offset
7.3 THERMOCOUPLE TEMPERATURES
USING 723-T REFERENCE
The use of the 723-T Analog Input Card RTD to
measure the reference temperature is
described in the introductory programming
example (Section OV4).
FIGURE 7.2-1. Typical Connection for Active
Sensor with External Battery
The wire used to supply power from the external
battery is 18 AWG with an average resistance
of 6.5 ohms/1000 ft. The power runs to the
CR7 and pH meter are 2 ft. and 10 ft.,
respectively. Typical current drain for the pH
meter is 300 mA. When making
measurements, the CR7 draws about 100 mA.
Since voltage is equal to current times
resistance (V=IR), ground voltages at the pH
meter and the CR7 relative to battery ground
are:
pH meter ground =
0.3A x 10/1000 x 6.5 Ohms = +0.0195V
CR7 ground =
0.1A x 2/1000 x 6.5ohms = +0.0013V
Ground at the pH meter is 0.0182V higher than
ground at the CR7. The meter output is 0-1 volt
referenced to meter ground, for the full range of
14 pH units, or 0.0714V/pH. Thus, if the output
is measured with a single ended voltage
measurement, it is 0.0182V or 0.25 pH units too
high. If this offset remained constant, it could
be corrected in programming the CR7.
However, it is better to use a differential voltage
measurement which does not rely on the
current drain remaining constant. The Program
that follows illustrates the use of Instruction #2
to make the measurement. A multiplier of
0.014 is used to convert the millivolt output into
pH units.
7-2
7.4 THERMOCOUPLE TEMPERATURES
USING AN EXTERNAL REFERENCE
JUNCTION
When a number of thermocouple measurements
are made at some distance from the CR7, it is
often better to use a reference junction box
located at the site rather than using the panel
temperature of the CR7. This reduces the
required length of expensive thermocouple wire
as regular copper wire can be used between the
junction box (J-box) and CR7. In addition, if the
temperature gradient between the J-box and the
thermocouple measurement junction is smaller
than the gradient between the CR7 and the
measurement junction, thermocouple inaccuracy
is reduced. In the following example, an external
reference junction is used on ten thermocouple
measurements. A Campbell Scientific 107
Temperature Probe is used to measure the
reference temperature. The connection scheme
is shown in Figure 7.4-1.
FIGURE 7.4-1. Thermocouples with External
Reference Junction
SECTION 7. MEASUREMENT PROGRAMMING EXAMPLES
The temperature of the 107 Probe is stored in
Input Location 1 and the thermocouple
temperatures in Locations 2-11.
PROGRAM
01:
01:
02:
03:
04:
05:
06:
07:
08:
P11
1
1
21
1
1
1
1
0
Temp 107 Probe
Rep
IN Card
IN Chan
EX Card
EX Chan
Loc [:Ref. Temp]
Mult
Offset
02:
01:
02:
03:
04:
05:
06:
07:
08:
09:
P14
10
3
1
1
1
1
2
1
0
Thermocouple Temp (DIFF)
Reps
15 mV slow Range
IN Card
IN Chan
Type T (Copper-Constantan)
Ref Temp Loc Ref. Temp
Loc [:TC temp#1]
Mult
Offset
7.5 THERMOCOUPLES FOR
DIFFERENTIAL TEMPERATURE
MEASUREMENT
When configured correctly, thermocouples are
capable of measuring small temperature
gradients very accurately (Section 13.4). In this
example, the CR7 is used to make five
differential temperature measurements with
chromel-constantan thermocouples. The
connections are shown in Figure 7.5-1 where
the voltage measured between the chromel
leads is proportional to the temperature
difference between junctions R and D.
When the temperatures are within the reference
junction compensation range (Table 13.4-3),
three instructions are required in the
measurement sequence:
1. A CR7 Panel Temperature Measurement
(#17) used as a reference temperature for
the measurement at R.
2. A single ended TC measurement (#13) of R
temperatures to be used as reference
temperatures for the measurement D.
3. A differential TC measurement of D
temperatures where the reference
temperature at R are subtracted from the
results as specified in Parameter 5.
The connection shown in Figure 7.4-1 yields the
conventional polarity (sign) for the temperature
difference, i.e., D>R=+T, D<R=-T. Using R as
the reference temperature maintains this
convention whereas using D reverses the sign
of the output.
Prefixing a 2 onto the TC type in Parameter 5 of
Instruction 13 causes the CR7 to skip every
other single ended channel. Keying C before
entering Parameter 6 in Instruction 14 causes
the reference temperature location to be
incremented each rep.
The ±5mV range used in Instruction 13 allows
measurement of temperatures at R within a
range of approximately ±80 oC of the I/O
Module temperature. The ±1.5mV range used in
Instruction 14 allows the temperature difference
between D and R to approach a range of ±24
oC, for temperatures around 25 oC (output = 61
uV/oC). The resolution of the differential
temperature measurement is approximately
0.0008 oC (50 nV/61µV/oC).
The panel temperature is stored in Input
Location 1, the temperatures of the R junctions
in locations 2-6 and the temperature differences
(D-R) in locations 7-11. If it is not necessary to
retain the temperatures of the R junctions, the
temperature differences could be stored in
locations 2-6 by changing Parameter #7 in
Instruction 14 to 2.
FIGURE 7.5-1. Connection for
Thermocouple Differential Temperature
Measurement
7-3
SECTION 7. MEASUREMENT PROGRAMMING EXAMPLES
PROGRAM
01:
01:
02:
P17
1
1
Panel Temperature
IN Card
Loc [:PANL TEMP]
02:
01:
02:
03:
04:
05:
06:
07:
08:
09:
P13
5
2
1
2
22
1
2
1
0
Thermocouple Temp (SE)
Reps
5000 uV slow Range
IN Card
IN Chan
Type E (Skip every other chan)
Ref Temp Loc PANL TEMP
Loc [:S.E. T#1 ]
Mult
Offset
03:
01:
02:
03:
04:
05:
06:
07:
08:
09:
P14
5
1
1
1
12
2-7
1
0
Thermocouple Temp (DIFF)
Reps
1500 uV slow Range
IN Card
IN Chan
Type E (Temp difference)
Ref Temp Loc S.E. T#1
Loc [:DIFF T #1]
Mult
Offset
Another means of applying a correction factor to
a number of thermocouples is to group together
those with a similar correction factor. In
example B, the slope correction factor for a
group of 5 thermocouples is entered as the
multiplier (Parameter 8) in the instruction to
read those thermocouples. The example only
shows one group of thermocouples. If there
were several groups with similar correction
factors, Instruction 14 would be used to read
and correct each group.
After the slope correction is made, a loop is
used to add the reference temperature to the
corrected temperature differences.
CONNECTIONS
When the temperature of the R junction is
outside of the CR7 reference junction
compensation range (Table 13.4-3), the TCs
must be connected in the normal fashion, one
TC per input channel; both temperatures
measured and one subtracted from the other to
find the difference. This must be done because
any error in the reference junction
compensation becomes an error in the
temperature difference.
7.6 TEMPERATURE WITH CALIBRATED
THERMOCOUPLES
Thermocouple calibration (Section 13.4) results
in a slope correction. The correction must be
applied only to the thermocouple output. When
Instructions 13 and 14 are used to measure
temperature, the temperature is the sum of the
reference temperature and the temperature
difference calculated from the thermocouple
output. The correction must be applied to the
temperature difference before the reference
temperature is added.
Example A demonstrates the use of a scaling
array (Instruction 53) to correct the calibration of
four individually calibrated thermocouples.
7-4
The thermocouples are connected in the normal
manner: chromel to Hi and constantan to Low.
In both examples, the first thermocouple is
connected to Channel 1. Care must be taken
that the correction factors called for in the
programming match the channels that the
calibrated thermocouples are connected to.
PROGRAM A
01:
01:
02:
P17
1
1
Panel Temperature
IN Card
Loc [:REF TEMP ]
02:
01:
02:
03:
04:
05:
06:
07:
08:
09:
P14
4
3
1
1
12
1
2
1
0
Thermocouple Temp (DIFF)
Reps
15 mV slow Range
IN Card
IN Chan
Type E (Temp difference)
Ref Temp Loc REF TEMP
Loc [:TC temp#1]
Mult
Offset
03:
01:
02:
03:
04:
05:
06:
07:
08:
09:
P53
2
.99255
0
.99703
0
1.0045
0
1.0075
0
Scaling Array (A*loc +B)
Start Loc [:TC temp#1]
A1
B1
A2
B2
A3
B3
A4
B4
SECTION 7. MEASUREMENT PROGRAMMING EXAMPLES
04:
01:
02:
P87
0
4
Beginning of Loop
Delay
Loop Count
05:
01:
02:
03:
P33
1
2-2--
Z=X+Y
X Loc REF TEMP
Y Loc TC temp#1
Z Loc [:TC temp#1]
06:
P95
End
PROGRAM B
01:
01:
02:
P17
1
1
Panel Temperature
IN Card
Loc [:REF TEMP ]
02:
01:
02:
03:
04:
05:
06:
07:
08:
09:
P14
5
3
1
1
12
1
2
.99253
0
Thermocouple Temp (DIFF)
Reps
15 mV slow Range
IN Card
IN Chan
Type E (Temp difference)
Ref Temp Loc REF TEMP
Loc [:TC temp#1]
Mult
Offset
CONNECTIONS
The black leads from the probes go to excitation
channel 1, the white leads go to ground, and the
red leads go to single ended channels 1, 2, and
3 (high and low sides of differential channel 1
and high side of 2).
PROGRAM
01:
01:
02:
03:
04:
05:
06:
07:
08:
P11
3
1
1
1
1
1
1
0
Temp 107 Probe
Reps
IN Card
IN Chan
EX Card
EX Chan
Loc [:107 T #1 ]
Mult
Offset
7.8 207 TEMPERATURE AND RH PROBE
03:
01:
02:
P87
0
5
Beginning of Loop
Delay
Loop Count
04:
01:
02:
03:
P33
1
2-2--
Z=X+Y
X Loc REF TEMP
Y Loc TC temp#1
Z Loc [:TC temp#1]
Instruction 12 excites and measures the RH
portion of the Campbell Scientific 207
temperature and relative humidity probe. This
instruction relies on a previously measured
temperature to compute the RH from the probe
resistance. Instruction 12 has the option of
using a single temperature to provide the
compensation reference for several RH probes.
In this example, three probes will be measured;
the temperature of each probe will be measured
and used to provide temperature compensation
for that probe. Instruction 11 is used to obtain
the temperatures of the three probes which are
stored in Input locations 1-3, the RH values are
stored in Input locations 4-6. The temperature
measurements are made on single ended input
channels 1-3, just as in example 7.7. The
program listed below is a continuation of the
program given in example 7.7.
05:
P95
End
CONNECTIONS
If there were additional groups of
thermocouples, the Instructions to measure
them would be inserted here and Parameter 2
in Instruction 87 adjusted accordingly.
7.7 107 TEMPERATURE PROBE
Instruction 11 is designed to excite and
measure the Campbell Scientific 107 thermistor
probe (or the thermistor portion of the 207
temperature and relative humidity probe) and
convert the measurement into temperature
(oC). In this example, the temperatures are
obtained from three 107 probes. The
measurements are made on single ended
channels 1-3, and the temperatures are stored
in Input locations 1-3.
The black leads from the probes are connected
to excitation channel 1, the clear leads are
connected to ground. The red leads are from
the thermistor circuit and are connected to
single ended channels 1-3. The white leads are
from the RH circuit and are connected to single
ended channels 4-6. The correct order must be
maintained when connecting the red and white
leads, i.e., the red lead from the first probe is
connected to single ended channel 1 and the
white lead from that probe is connected to
single ended channel 4, etc.
7-5
SECTION 7. MEASUREMENT PROGRAMMING EXAMPLES
PROGRAM
02:
01:
02:
03:
04:
05:
06:
07:
08:
09:
10:
P12
3
1
4
1
1
1
1
4
1
0
RH 207 Probe
Reps
IN Card
IN Chan
EX Card
EX Chan
Meas/Temp
Temperature Loc 207 T#1
Loc [:RH #1 ]
Mult
Offset
7.9 ANEMOMETER WITH
PHOTOCHOPPER OUTPUT
The multiplier and offset to convert pulses per
second to meters per second are:
m/s =
0.01632 m/s/rpm x 6 rpm/(pulse/s)
+ 0.2 m/s = 0.0979 m/s/pulse x
pulses + 0.2 m/s
There are occasionally times when the CR7's
CPU is occupied and does not reset the pulse
counters at the exact time interval programmed.
If the artificially large wind speed that results
from a long interval is used, it causes a false
average or maximum value. To avoid this, the
CR7 is instructed to discard values resulting
from long intervals, and use the previous value
instead.
An anemometer with a photochopper
transducer produces a pulsed output which is
monitored with the Pulse Count Instruction,
configured for High Frequency Pulses. The
Pulse Count Instruction counts the number of
pulses occurring in each execution interval. An
option in the instruction allows this to be
converted to frequency in Hertz (i.e.,
Pulses/Second). The anemometer used in this
example is the R. M. Young Model No. 12102D
Cup Anemometer, with a 10 window chopper
wheel. The photochopper circuitry is powered
from the CR7 12V supply; AC power or backup
batteries should be used to compensate for the
increased current drain.
Wind speed is desired in meters per second.
There is a pulse each time a window in the
chopper wheel, which revolves with the cups,
allows light to pass from the source to the
photoreceptor. Because there are 10 windows
in the chopper wheel, there are 10 pulses per
revolution. Thus, 1 rpm is equal to 10 pulses
per 60 seconds (1 minute) or 6 rpm = 1 pulse
per second. The manufacturer's calibration for
relating wind speed to rpm is:
Wind speed (m/s) =
0.01632 m/s/rpm x rpm +0.2 m/s
7-6
FIGURE 7.9-1. Wiring Diagram for
Anemometer
PROGRAM
(Execution interval 10 seconds)
01:
01:
02:
03:
04:
05:
06:
07:
P3
2
2
2
20
10
.0979
.2
Pulse
Reps
IN Card
Pulse Input Chan
High frequency; Output Hz.
Loc [:WS m/s ]
Mult
Offset
7.10 TIPPING BUCKET RAINGAGE
WITH LONG LEADS
A tipping bucket raingage is measured with the
Pulse Count Instruction configured for Switch
Closure. Counts from long intervals will be
used, as the final output desired is total rainfall
(obtained with Instruction 72, Totalize). If
counts from long intervals were discarded, less
rainfall would be recorded than was actually
measured by the gage (assuming there were
counts in the long intervals). Output is desired
in millimeters of precipitation; the gage is
calibrated for a 0.01 inch tip so a multiplier of
0.254 is used.
SECTION 7. MEASUREMENT PROGRAMMING EXAMPLES
FIGURE 7.10-1. Wiring Diagram for
Raingage with Long Leads
In a long cable, there is appreciable
capacitance between the lines which is
discharged across the switch when it closes. In
addition to shortening switch life, a transient
may be induced in other wires, packaged with
the rain gage leads, each time the switch
closes. The 100 ohm resistor protects the
switch from arcing and the associated transient
from occurring, and should be included any time
leads longer than 100 ft. are used with a switch
closure.
PROGRAM
01:
01:
02:
03:
04:
05:
06:
07:
P3
1
2
1
2
11
0.254
0
Pulse
Rep
IN Card
Pulse Input Chan
Switch closure
Loc [:RAIN mm ]
Mult
Offset
7.11 100 OHM PRT IN 4 WIRE HALF
BRIDGE
Instruction 9 is the best choice for accuracy
where the Platinum Resistance Thermometer
(PRT) is separated from other bridge
completion resistors by a lead length having
more than a few thousandths of an ohm
resistance. In this example, it is desired to
measure a temperature in the range of -10 to
40 oC. The length of the cable from the CR7 to
the PRT is 500 feet.
FIGURE 7.11-1. Wiring Diagram for PRT in 4
Wire Half-Bridge
Figure 7.11-1 diagrams the circuit used to
measure the PRT. The 10 kohm resistor allows
the use of a high excitation voltage and low
voltage ranges on the measurements. This
insures that noise in the excitation does not
have an effect on signal noise. Because the
fixed resistor (Rf) and the PRT (Rs) have
approximately the same resistance, the
differential measurement of the voltage drop
across the PRT can be made on the same
range as the differential measurement of the
voltage drop across Rf. The use of the same
range eliminates any range translation error that
might arise from the 0.01% tolerance of the
range translation resistors in the CR7.
If the voltage drop across the PRT (V2) is kept
on the 50 mV range, self heating of the PRT
should be less than 0.001 oC in still air. The
resolution of the measurement is increased as
the excitation voltage (Vx) is increased. The
voltage drop across the PRT is equal to Vx
multiplied by the ratio of Rs to the total
resistance, and is greatest when Rs is greatest
(Rs=115.54 ohms at 40 oC). To find the
maximum excitation voltage that can be used,
we assume V2 equal to 50 mV and use Ohm's
Law to solve for the resulting current, I.
I = 50mV/Rs = 50mV/115. 54 Ohms = 0.433mA
Next solve for Vx:
Vx = I(R1+Rs+Rf) = 4.42V
If the actual resistances were the nominal
values, the CR7 would not overrange with Vx =
4.4 V. To allow for the tolerances in the actual
resistances it is decided to set Vx equal to 4.2
volts (e.g., if the 10 kohms resistor is 5% low,
Rs/(R1+Rs+Rf)=115.54/9715.54 and Vx must
be 4.204V to keep Vs less than 50 mV).
The result of Instruction 9 when the first
differential measurement (V1) is not made on
the 5V range is equivalent to Rs/Rf. Instruction
16 computes the temperature (oC) for a DIN
43760 standard PRT from the ratio of the PRT
resistance to its resistance at 0 oC (Rs/R0).
Thus, a multiplier of Rf/R0 is used in Instruction
9 to obtain the desired intermediate, Rs/R0 (=
Rs/Rf x Rf/R0). If Rs and R0 were each exactly
100 ohms the multiplier would be 1. However,
neither resistance is likely to be exact. The
correct multiplier is found by connecting the
PRT to the CR7 and entering Instruction 9 with
7-7
SECTION 7. MEASUREMENT PROGRAMMING EXAMPLES
a multiplier of 1. The PRT is then placed in an
ice bath (0 oC; Rs=R0), and the result of the
bridge measurement is read using the *6 Mode.
The reading is Rs/Rf, which is equal to R0/Rf
since Rs = R0, the correct value of the
multiplier, Rf/R0, is the reciprocal of this
reading. The initial reading assumed for this
example was 0.9890, the correct multiplier is:
Rf/R0 = 1/0.9890 = 1.0111.
The fixed 100 ohm resistor must be thermally
stable. Its precision is not important because
the exact resistance is incorporated, along with
that of the PRT, into the calibrated multiplier.
The 10 ppm/oC temperature coefficient of the
fixed resistor will limit the error due to its change
in resistance with temperature to less than 0.15
oC over the specified temperature range.
Because the measurement is ratiometric
(Rs/Rf), the properties of the 10 kohm resistor
do not affect the result.
PROGRAM
01:
P9
01:
1
02:
4
03:
4
04:
1
05:
1
06:
1
07:
1
08:
1
09: 4200
10:
1
11:
1.0111
12:
0
Full BR w/Compensation
Rep
50 mV slow EX Range
50 mV slow BR Range
IN Card
IN Chan
EX Card
EX Chan
Meas/EX
mV Excitation
Loc [:Rs/Ro ]
Mult
Offset
02:
01:
02:
03:
04:
05:
Temperature RTD
Rep
R/Ro Loc Rs/Ro
Loc [:TEMP degC]
Mult
Offset
P16
1
1
2
1
0
7.12 100 OHM PRT IN 3 WIRE HALF
BRIDGE
The temperature measurement requirements in
this example are the same as in section 7.11.
In this case a three wire half bridge, Instruction
7, is used to measure the resistance of the
PRT. The diagram of the PRT circuit is shown
in Figure 7.12-1.
7-8
Figure 7.12-1. 3 Wire Half-Bridge Used to
Measure 100 ohm PRT
As in the example in section 7.11, the excitation
voltage is calculated to be the maximum
possible yet allow the ±50 mV measurement
range. The 10 kohm resistor has a tolerance of
±1%, thus, the lowest resistance to expect from
it is 9.9 kohms. We calculate the maximum
excitation voltage (Vx) to keep the voltage drop
across the PRT less than 50 mV:
0.050V > Vx 115.54/(9900+115.54); Vx < 4.33V
The excitation voltage used is 4.3V.
The multiplier used in Instruction 7 is
determined in the same manner as in section
7.11. In this example the multiplier (Rf/R0) is
assumed to be 100.93.
The 3 wire half bridge compensates for lead
wire resistance by assuming that the resistance
of wire A is the same as the resistance of wire
B. The maximum difference expected in wire
resistance is 2%, but is more likely to be on the
order of 1%. The resistance of Rs calculated
with Instruction 7, is actually Rs plus the
difference in resistance of wires A and B. The
average resistance of 22 AWG wire is 16.5
ohms per 1000 feet, which would give each 500
foot lead wire a nominal resistance of 8.3 ohms.
Two percent of 8.3 ohms is 0.17 ohms.
Assuming that the greater resistance is in wire
B, the resistance measured for the PRT (R0 =
100 ohms) in the ice bath would be 100.17
ohms, and the resistance at 40 oC would be
115.71. The measured ratio Rs/R0 is 1.1551,
the actual ratio is 115.54/100 = 1.1554. The
temperature computed by Instruction 17 from
the measured ratio would be about 0.1 oC lower
than the actual temperature of the PRT. This
source of error does not exist in the example in
section 7.11, where the 4 wire half bridge is
used to measure PRT resistance.
SECTION 7. MEASUREMENT PROGRAMMING EXAMPLES
The advantages of the 3 wire half bridge are
that it only requires 3 lead wires going to the
sensor, and takes 2 single ended input
channels whereas the 4 wire half bridge
requires 2 differential input channels.
The result given by Instruction 6 (X) is 1000
Vs/Vx (where Vs is the measured bridge output
voltage and Vx is the excitation voltage) which
is:
X = 1000 (Rs/(Rs+R1)-R3/(R2+R3))
PROGRAM
01:
P
01:
1
02:
4
03:
1
04:
1
05:
1
06:
1
07:
1
08: 4300
09:
1
10: 100.93
11:
0
7 3 Wire Half Bridge
Rep
50 mV slow Range
IN Card
IN Chan
EX Card
EX Chan
Meas/EX
mV Excitation
Loc [:Rs/Ro ]
Mult
Offset
02:
01:
02:
03:
04:
05:
16 Temperature RTD
Rep
R/Ro Loc Rs/Ro
Loc [:TEMP degC]
Mult
Offset
P
1
1
2
1
0
7.13 100 OHM PRT IN 4 WIRE FULL
BRIDGE
This example describes obtaining the
temperature from a 100 ohm PRT in a 4 wire
full bridge (Instruction 6). The temperature
being measured is in a constant temperature
bath and is to be used as the input for a control
algorithm. The PRT in this case does not
adhere to the DIN standard (alpha = 0.00385)
used in the temperature calculating Instruction
16. Alpha is defined as (R100/R0-1)/100 where
R100 and R0 are the resistances of the PRT at
100 oC and 0 oC, respectively. In this PRT
alpha is equal to 0.00392.
The resistance of the PRT (Rs) is calculated
with the Bridge Transform Instruction 59:
Rs = R1 X'/(1-X')
Where
X' = X/1000 + R3/(R2+R3)
Thus, to obtain the value Rs/R0, (R0 = Rs @
0oC) for the temperature calculating Instruction
16, the multiplier and offset used in Instruction 6
are 0.001 and R3/(R2+R3), respectively. The
multiplier used in Instruction 59 to obtain Rs/R0
is R1/R0 (5000/100 = 50).
It is desired to control the temperature bath at
50oC with as little variation as possible. High
resolution is desired so the control algorithm will
be able to respond to minute changes in
temperature. The highest resolution is obtained
when the temperature range results in an output
voltage (Vs) range which fills the measurement
range selected in Instruction 6. The full bridge
configuration allows the bridge to be balanced
(Vs = 0V) at or near the control temperature.
Thus, the output voltage can go both positive
and negative as the bath temperature changes,
allowing the full use of the measurement range.
The resistance of the PRT is approximately
119.6 ohms at 50 oC. The 120 ohm fixed
resistor balances the bridge at approximately 51
oC. The output voltage is:
Vs = Vx [Rs/(Rs+R1) - R3/(R2+R3)]
= Vx [Rs/(Rs+5000) - 0.023438]
The temperature range to be covered is 50
+5oC. At 45 oC Rs is approximately 117.6
ohms, or:
Vs = -458.448x10-6 Vx
FIGURE 7.13-1. Full Bridge Schematic For
100 Ohm PRT
Vs can be measured on the ±1500 µV scale.
Setting Vs equal to -1500 µV and solving for Vx
results in Vx = 3.272 V. Vx is entered as 3270
mV in Parameter 8 of Instruction 6.
7-9
SECTION 7. MEASUREMENT PROGRAMMING EXAMPLES
The 5 ppm/oC temperature coefficient of the
fixed resistors was chosen so that their 0.01%
accuracy tolerance would hold over the desired
temperature range.
There is a change of approximately 1500 µV
from the output at 45 oC to the output at 51 oC,
or 250 µV/oC. With a resolution of 50 nV on the
1500 µV range, this means that the temperature
resolution is 0.0002 oC.
The relationship between temperature and PRT
resistance is a slightly nonlinear one.
Instruction 16 computes this relationship for a
DIN standard PRT where the nominal
temperature coefficient is 0.00385/oC. The
change in nonlinearity of a PRT with the
temperature coefficient of 0.00392/oC is minute
compared with the slope change. Entering a
slope correction factor of 0.00385/0.00392 =
0.98214 as the multiplier in Instruction 16
results in a calculated temperature which is well
within the accuracy specifications of the PRT.
PROGRAM
01:
P6
01:
1
02:
1
03:
1
04:
3
05:
1
06:
1
07:
1
08: 3270
09:
11
10:
.001
11:
.02344
Full Bridge
Rep
1500 uV slow Range
IN Card
IN Chan
EX Card
EX Chan
Meas/EX
mV Excitation
Loc [:Rs/Ro ]
Mult
Offset
02:
01:
02:
03:
P59
1
11
50
BR Transform Rf[X/(1-X)]
Rep
Loc [:Rs/Ro ]
Multiplier (Rf)
03:
01:
02:
03:
04:
05:
P16
1
11
12
.98214
0
Temperature RTD
Rep
R/Ro Loc Rs/Ro
Loc :
Mult
Offset
7.14 PRESSURE TRANSDUCER - 4
WIRE FULL BRIDGE
This example describes a measurement made
with a Druck PDCR 10/D depth measurement
pressure transducer. The pressure transducer
was ordered for use with 5 volt positive or
negative excitation (passive temperature
compensation) and has a range of 5 psi or
about 3.5 meters of water. The transducer is
used to measure the depth of water in a stilling
well.
Instruction 6, 4 wire full bridge, is used to
measure the pressure transducer. The high
output of the semiconductor strain gage
necessitates the use of the 50mV input range.
The sensor is calibrated by connecting it to the
CR7 and using Instruction 6 with a multiplier of
1 and an offset of 0, noting the readings (*6
Mode) with 10 cm of water above the sensor
and with 334.6 cm of water above the sensor.
The output of Instruction 6 is 1000 Vs/Vx or
millivolts per volt excitation. At 10 cm the
reading is 0.19963 mV/V and at 334.6 cm the
reading is 6.6485 mV/V. The multiplier to yield
output in cm is:
(334.6 - 10)/(6.6485-.19963) = 50.334 cm/mV/V
The offset is determined after the pressure
transducer is installed in the stilling well. The
sensor is installed 65 cm below the water level
at the time of installation. The depth of water at
this time is determined to be 72.6 cm relative to
the desired reference. When programmed with
the multiplier determined above and an offset of
0, a reading of 65.12 is obtained. The offset for
the actual measurements is thus determined to
be 72.6 - 65.12 = 7.48 cm.
The lead length is approximately 10 feet, so
there is no appreciable error due to lead wire
resistance.
FIGURE 7.14-1. Wiring Diagram for Full
Bridge Pressure Transducer
7-10
SECTION 7. MEASUREMENT PROGRAMMING EXAMPLES
PROGRAM
01:
P6
01:
1
02:
4
03:
1
04:
1
05:
1
06:
1
07:
1
08: 5000
09:
13
10:
50.334
11:
7.48
Full Bridge
Rep
50 mV slow Range
IN Card
IN Chan
EX Card
EX Chan
Meas/EX
mV Excitation
Loc [:HEIGHT cm]
Mult
Offset
FIGURE 7.15-1. Diagrammatic
Representation of Lysimeter Weighing
Mechanism
7.15 LYSIMETER - 6 WIRE LOAD CELL
When a long cable is required between a load
cell and the CR7, the resistance of the wire can
create a substantial error in the measurement if
the 4 wire full bridge (Instruction 6) is used to
excite and measure the load cell. This error
arises because the excitation voltage is lower at
the load cell than at the CR7 due to voltage
drop in the cable. The 6 wire full bridge
(Instruction 9) avoids this problem by measuring
the excitation voltage at the load cell. This
example shows the errors one would encounter
if the actual excitation voltage was not
measured and shows the use of a 6 wire full
bridge to measure a load cell on a weighing
lysimeter (a container buried in the ground, filled
with plants and soil, used for measuring
evapotranspiration).
The lysimeter is 2 meters in diameter and 1.5
meters deep. The total weight of the lysimeter
with its container is approximately 8000 kg. The
lysimeter has a mechanically adjustable
counterbalance, and changes in weight are
measured with a 250 pound (113.6 kg) capacity
Sensotec Model 41 tension/compression load
cell. The load cell has a 4:1 mechanical
advantage on the lysimeter (ie., a change of 4
kg in the mass of the lysimeter will change the
force on the load cell by 1 kg-force or 980 N).
The surface area of the lysimeter is 3.1416 m2
or 31,416 cm2, so 1 cm of rainfall or
evaporation results in a 31.416 kg change in
mass. The load cell can measure ±113.6 kg, a
227 kg range. This represents a maximum
change of 909 kg, or 28 cm of water in the
lysimeter before the counterbalance would have
to be readjusted.
There is 1000 feet of 22 AWG cable between
the CR7 and the load cell. The output of the
load cell is directly proportional to the excitation
voltage. When Instruction 6 (4 wire 1/2 bridge)
is used, the assumption is that the voltage drop
in the connecting cable is negligible. The
average resistance of 22 AWG wire is 16.5
ohms per 1000 feet. Thus, the resistance in the
excitation lead going out to the load cell added
to that in the lead coming back to ground is 33
ohms. The resistance of the bridge in the load
cell is 350 ohms. The voltage drop across the
load cell is equal to the voltage at the CR7
multiplied by the ratio of the load cell resistance
Rs, to the total resistance, RT, of the circuit. If
Instruction 6 were used to measure the load
cell, the excitation voltage actually applied to the
load cell, V1 would be:
V1 = Vx Rs/RT = Vx 350/(350+33) = 0.91 Vx
Where Vx is the voltage applied at the
excitation card. This means that the voltage
output by the load cell would only be 91% of that
expected. If recording of the lysimeter data was
initiated with the load cell output at 0 volts, and
100 mm of evapotranspiration had occurred,
calculation of the change with Instruction 6
would indicate that only 91 mm of water had
been lost. Because the error is a fixed
percentage of the output, the actual magnitude
of the error increases with the force applied to
the load cell. If the resistance of the wire was
constant, one could correct for the voltage drop
with a fixed multiplier. However, the resistance
of copper changes 0.4% per oC change in
temperature. Assume that the cable between
the load cell and the CR7 lays on the soil
surface and undergoes a 25 oC diurnal
temperature fluctuation. If the resistance is 33
7-11
SECTION 7. MEASUREMENT PROGRAMMING EXAMPLES
ohms at the maximum temperature, then, at the
minimum temperature, the resistance is:
(1-25x0.004)33 ohms = 29.7 ohms
The actual excitation voltage at the load cell is:
V1 = 350/(350+29.7) Vx = .92 Vx
The excitation voltage has increased by 1%,
relative to the voltage applied at the CR7. In the
case where we were recording a 91 mm change
in water content, there would be a 1 mm diurnal
change in the recorded water content that would
actually be due to the change in temperature.
Instruction 9 solves this problem by actually
measuring the voltage drop across the load cell
bridge. The drawbacks to using Instruction 9
are that it requires an extra differential channel
and the added expense of a 6 wire cable. In
this case the benefits are worth the expense.
The load cell has a nominal full scale output of
3 millivolts per volt excitation. If the excitation is
5 volts, the full scale output is 15 millivolts; thus
the ±15 millivolt range is selected. The
calibrated output of the load cell is 3.106 mV/V1
at a load of 250 pounds. Output is desired in
millimeters of water, with respect to a fixed
point. The calibration in mV/V1/mm is:
started at the beginning of what is expected to
be a period during which evapotranspiration
exceeds precipitation. Instruction 9 is
programmed with the correct multiplier and no
offset. After hooking everything up, the
counterbalance is adjusted so that the load cell
is near the top of its range, this will allow a
longer period before readjustment is necessary.
The result of Instruction 9 (monitored with the *6
Mode) is 109. The offset needed to give the
desired initial value of 375mm is 266. However,
it is decided to add this offset in a separate
program so that the result of Instruction 9 can
be used as a ready reminder of the strain on the
load cell (range = ±140mm). When the strain
on the load cell nears its rated limits, the
counterbalance is readjusted and the offset
recalculated to provide a continuous record of
the water budget.
The program table has an execution interval of
10 seconds. The average value in millimeters
is output to Final Storage (not shown in Table)
every hour. The average is used, instead of a
sample, in order to cancel out the effects of
wind loading on the lysimeter.
3.106mV/V1/250lb x 2.2lb/kg x
3.1416kg/mm/4 =
0.02147mV/V1/mm
The reciprocal of this gives the multiplier to
convert mV/V1 into millimeters (the result of
Instruction 9 is the ratio of the output voltage to
the actual excitation voltage multiplied by 1000,
which is mV/V1):
FIGURE 7.15-2. 6 Wire Full Bridge
Connection for Load Cell
PROGRAM
1/0.02147mV/V1/mm = 46.583 mm/mV/V1
The output from the load cell is connected so
that the voltage increases as the mass of the
lysimeter increases (if the actual mechanical
linkage was as diagrammed in Figure 7.15-1,
the output voltage would be positive when the
load cell was under tension).
When the experiment is started, the water
content of the soil in the lysimeter is
approximately 25% on a volume basis. It is
decided to use this as the reference, (i.e., 0.25
x 1500mm = 375 mm). The experiment is
7-12
01:
P9
01:
1
02:
8
03:
3
04:
1
05:
1
06:
1
07:
1
08:
1
09: 5000
10:
1
11:
46.583
12:
0
Full BR w/Compensation
Rep
5000 mV slow EX Range
15 mV slow BR Range
IN Card
IN Chan
EX Card
EX Chan
Meas/EX
mV Excitation
Loc [:mm RAW ]
Mult
Offset
SECTION 7. MEASUREMENT PROGRAMMING EXAMPLES
02:
01:
02:
03:
P34
1
266
2
Z=X+F
X Loc mm RAW
F
Z Loc [:mm CORECT]
7.16 227 GYPSUM SOIL MOISTURE
BLOCK
Soil moisture is measured with a gypsum block
by relating the change in moisture to the change
in resistance of the block. An AC Half Bridge
(Instruction 5) is used to determine the
resistance of the gypsum block. Rapid reversal
of the excitation voltage inhibits polarization of
the sensor. Polarization creates an error in the
output so the fast integration time is used. The
output of Instruction 5 is the ratio of the midbridge voltage to the excitation voltage, this
output is converted to gypsum block resistance
with Instruction 59, Bridge Transform.
The Campbell Scientific 227 Soil Moisture Block
uses a Delmhorst gypsum block with a 1 kohm
bridge completion resistor. Using data supplied
by Delmhorst, Campbell Scientific has
computed coefficients for a 5th order polynomial
to convert block resistance to water potential in
bars. There are two polynomials, one to
optimize the range from -0.1 to -2 bars and one
to cover the range from -0.1 to -15 bars (the
minus sign is omitted in the output). The -0.1 to
-2 bar polynomial requires a multiplier of 1 in the
Bridge Transform Instruction (result in Kohms)
and the -0.1 to -15 bar polynomial requires a
multiplier of 0.1 (result in 10,000s of ohms).
The multiplier is a scaling factor to maintain the
maximum number of significant digits in the
coefficients of the polynomial.
In this example, we wish to make
measurements on 12 gypsum blocks and output
the final data in bars. The soil where the
moisture measurements are to be made is quite
wet at the time the data logging is initiated, but
is expected to dry beyond the -2 bar limit of the
wet range polynomial. The dry range
polynomial is used, so a multiplier of 0.1 is
entered in the bridge transform instruction.
When the water potential is computed it is
written over the resistance value. The
potentials are stored in Input locations 1-12
where they may be accessed for output to Final
Storage. If it was desired to retain the
resistance values the potential measurements
could be stored in locations 13-24 by changing
parameter 3 in Instruction 55 to 13.
FIGURE 7.16-1. 12 Gypsum Blocks
Connected to the CR7
The first 6 blocks are excited by excitation
channel 1 and the last 6 by channel 2. Thus, 6
is entered for the number of measurements per
excitation channel in Parameter 7 of Instruction
5.
PROGRAM
01:
01:
02:
03:
04:
05:
06:
07:
08:
09:
10:
11:
P5
12
16
1
1
1
6
6
500
1
1
0
AC Half Bridge
Reps
500 mV fast Range
IN Card
IN Chan
EX Card
EX Chan
Meas/EX
mV Excitation
Loc [:POTEN #1 ]
Mult
Offset
02:
01:
02:
03:
P59
12
1
.1
BR Transform Rf[X/(1-X)]
Reps
Loc [:POTEN #1 ]
Multiplier (Rf)
03:
01:
02:
03:
04:
05:
06:
07:
08:
09:
P55
12
1
1
.15836
6.1445
-8.4139
9.2493
-3.1685
.33392
Polynomial
Reps
X Loc POTEN #1
F(X) Loc [:POTEN #1 ]
C0
C1
C2
C3
C4
C5
7-13
SECTION 7. MEASUREMENT PROGRAMMING EXAMPLES
7.17 NONLINEAR THERMISTOR IN
HALF BRIDGE (CAMPBELL
SCIENTIFIC MODEL 101)
Instruction 11, 107 Thermistor Probe,
automatically linearizes the output of the
nonlinear thermistor in the 107 Probe by
transforming the millivolt reading with a 5th
order polynomial. Instruction 55, Polynomial,
can be used to linearize the output of any
nonlinear thermistor, provided the correlation
between temperature and probe output is
known, and an appropriate polynomial fit has
been determined. In this example, the CR7 is
used to measure the temperature of 5 Campbell
Scientific 101 Probes (used with the CR21).
Instruction 4, Excite, Delay and Measure, is
used because the high source resistance of the
probe requires a long input settling time (See
Section 13.3.1). The excitation voltage is 2000
mV, the same as used in the CR21. The signal
voltage is then transformed to temperature
using the Polynomial Instruction.
The manual for the 101 Probe gives the
coefficients of the 5th order polynomial used to
convert the output in millivolts to temperature (E
denotes the power of 10 by which the mantissa
is multiplied):
C0
C1
C2
C3
C4
C5
-53.7842
0.147974
-2.18755E-4
2.19046E-7
-1.11341E-10
2.33651E-14
The CR7 will only allow 5 significant digits to the
right or left of the decimal point to be entered
from the key board. The polynomial can not be
applied exactly as given in the 101 manual. The
initial millivolt reading must be scaled if the
coefficients of the higher order terms are to be
entered with the maximum number of significant
digits. If 0.001 is used as a multiplier on the
millivolt output, the coefficients are divided by
0.001 raised to the appropriate power, (i.e.,
C0=C0, C1=C1/0.001, C2=C2/.000001 etc.).
With this adjustment, the coefficients entered in
Parameters 4-9 of Instruction 55 become:
C0
C1
C2
C3
C4
C5
7-14
-53.784
147.97
-218.76
219.05
-111.34
23.365
FIGURE 7.17-1. 101 Thermistor Probes
Connected to CR7
PROGRAM
01:
P4
01:
5
02:
8
03:
1
04:
1
05:
1
06:
1
07:
5
08:
10
09: 2000
10:
1
11:
0.001
12:
0
Excite,Delay,Volt(SE)
Reps
5000 mV slow Range
IN Card
IN Chan
EX Card
EX Chan
Meas/EX
Delay (units .01sec)
mV Excitation
Loc [:101 T #1 ]
Mult
Offset
02:
01:
02:
03:
04:
05:
06:
07:
08:
09:
Polynomial
Reps
X Loc 101 T #1
F(X) Loc [:101 T #1 ]
C0
C1
C2
C3
C4
C5
P55
5
1
1
-53.784
147.97
-218.76
219.05
-111.34
23.365
SECTION 8. PROCESSING AND PROGRAM CONTROL EXAMPLES
The following examples are intended to illustrate the use of Processing and Program Control
Instructions, flags, and the capability to direct the results of Output Processing Instructions to Input
Storage.
The specific examples may not be as important as some of the techniques employed, for example:
Directing Output Processing to Input Storage is used in the Running Average and Rainfall Intensity
examples (8.1 and 8.2).
Flags tests are used in the Running Average, Interrupt Subroutine, and Converting Wind Direction
examples (8.1, 8.4, and 8.6)
These examples are not complete programs to be taken verbatim. They need to be altered to fit specific
needs.
8.1 COMPUTATION OF RUNNING
AVERAGE
It is sometimes necessary to compute a running
average (i.e., the average includes a fixed
number of samples and is continuously updated
as new samples are taken). Because the
output interval is shorter than the averaging
period, Instruction 71 cannot be used; the
algorithm for computing this average must be
programmed by the user. The following
example demonstrates a program for
computing a running average.
In this example, each time a new measurement
is made (in this case a thermocouple
temperature) an average is computed for the 10
most recent samples. This is done by saving all
10 temperatures in contiguous input locations
and using the Spatial Average Instruction (51)
to compute the average. The temperatures are
stored in locations 11 through 20. Each time
the table is executed, the new measurement is
stored in location 20 and the average is stored
in location 2. The Block Move Instruction (54) is
then used to move the temperatures from
locations 12 through 20 down by one location;
the oldest measurement (in location 11) is lost
when the temperature from location 12 is
written over it.
Input Location Labels:
1:Panl Temp
2:10smpl av
11:Temp i-9
12:Temp i-8
13:Temp i-7
14:Temp i-6
15:Temp i-5
16:Temp i-4
17:Temp i-3
18:Temp i-2
19:Temp i-1
20:Temp i
Where i is current reading,
i-1 is previous reading, etc.
*
01:
1
1
Table 1 Programs
Sec. Execution Interval
01:
01:
02:
P17
1
1
Panel Temperature
IN Card
Loc [:Panl Temp]
02:
01:
02:
03:
04:
05:
06:
07:
08:
09:
P14
1
1
1
1
1
1
20
1
0.0000
Thermocouple Temp (DIFF)
Rep
1500 uV slow Range
IN Card
IN Chan
Type T (Copper-Constantan)
Ref Temp Loc Panl Temp
Loc [:Temp i ]
Mult
Offset
03:
01:
02:
03:
P51
10
11
2
Spatial Average
Swath
First Loc Temp i-9
Avg Loc [:10smpl av]
8-1
SECTION 8. PROCESSING AND PROGRAM CONTROL EXAMPLES
04:
01:
02:
03:
04:
05:
P54
9
12
1
11
1
Block Move
No. of Values
First Source Loc Temp i-8
Source Step
First Destin. Loc [:Temp i-9 ]
Destination Step
05:
01:
P86
10
Do
Set high Flag 0 (output)
06:
01:
02:
P70
1
2
Sample
Rep
Loc 10smpl av
07:
P
End Table 1
In the above example, all samples for the
average are stored in input locations. This is
necessary when an average must be output
with each new sample. In most cases,
averages are desired less frequently than
sampling. For example, it may be necessary to
sample some parameter every five seconds and
output every hour an average of the previous
three hours' readings. If all samples were
saved, this would require 2160 input locations.
The same value can be obtained by computing
an hourly average and averaging the hourly
averages for the past three hours. To do this
requires that hourly averages be stored in input
locations.
Instruction 80 is used to send the one hour
average to Input Storage and again to send the
three hour average to Final Storage.
Input Location Labels:
1:AVG i-2
2:AVG i-1
3:AVG i
4:3 HR AVG
5:XX mg/M3
*
01:
1
5
01:
01:
02:
03:
04:
05:
06:
07:
P2
1
8
1
3
3
10
0
8-2
Table 1 Programs
Sec. Execution Interval
Volt (DIFF)
Rep
5000 mV slow Range
IN Card
IN Chan
Loc [:XX mg/m3 ]
Mult
Offset
02:
01:
02:
03:
P92
0
60
10
If time is
minutes into a
minute interval
Set high Flag 0 (output)
03:
01:
02:
P80
3
3
Set Active Storage Area
Input Storage Area
Array ID or location
04:
01:
02:
P71
1
5
Average
Rep
Loc
05:
01:
02:
03:
P51
3
1
4
Spatial Average
Swath
First Loc AVG i-2
Avg Loc [:3 HR AVG ]
06:
01:
02:
P80
1
25
Set Active Storage Area
Final Storage Area
Array ID or location
07:
01:
P77
220
Real Time
Day,Hour-Minute
08:
01:
02:
P70
1
4
Sample
Rep
Loc 3 HR AVG
09:
01:
02:
P91
10
30
If Flag
0 (output) is set
Then Do
10:
01:
02:
03:
04:
05:
P54
2
2
1
1
1
Block Move
No. of Values
First Source Loc
Source Step
First Destination Loc [:AVG i-2 ]
Destination Step
11:
P95
End
12:
P
End Table 1
8.2 RAINFALL INTENSITY
In this example, the total rain for the last 15
minutes is output only if any rain has occurred.
The program makes use of the capability to
direct the output of Output Processing
Instructions to Input Storage.
SECTION 8. PROCESSING AND PROGRAM CONTROL EXAMPLES
Every 15 minutes, the total rain is sent to Input
Storage. If the total is greater than 0, output is
redirected to Final Storage, the time is output,
and the total is sampled.
Input Location Labels:
1:Rain (mm)
2:15min tot
*
01:
01:
01:
02:
03:
04:
05:
06:
07:
1
60
Table 1 Programs
Sec. Execution Interval
P3
1
3
1
2
1
.254
0
Pulse
Rep
IN Card
Pulse Input Chan
Switch closure
Loc [:Rain (mm)]
Mult
Offset
02:
01:
02:
03:
P92
0
15
10
If time is
minutes into a
minute interval
Set high Flag 0 (output)
03:
01:
02:
P80
3
2
Set Active Storage Area
Input Storage Area
Array ID or location
04:
01:
02:
P72
1
1
Totalize
Rep
Loc Rain (mm)
05:
01:
02:
03:
04:
P89
2
3
0
30
If X<=>F
X Loc
>=
F
Then Do
06:
01:
02:
P80
1
25
Set Active Storage Area
Final Storage Area
Array ID or location
07:
01:
P77
220
Real Time
Day,Hour-Minute
08:
01:
02:
P70
1
2
Sample
Rep
Loc
09:
P95
End
8.3 SUB 1 MINUTE OUTPUT INTERVAL
SYNCHED TO REAL TIME
Instruction 92 has one minute resolution. If
processed output is required on an interval less
than one minute, Instructions 18 and 89 can be
used to set the Output Flag on a shorter
interval.
Instruction 18 takes time (tenths of seconds into
minute, minutes into day, or hours into year),
performs a modulo divide by a user specified
value and loads it into an input location.
When the modulo divisor divides evenly into the
interval, one gets a counter in an input location
that goes to 0 on a periodic interval. In this
example, tenths of seconds into the minute is
modulo divided by 300. The counter counts up
to 295 then goes to 0 (i.e., every 30 seconds;
tenths of seconds into minute has a resolution
of 0.1 seconds).
Instruction 89 is used to set the Output Flag
when the tenths of seconds counter is less than
5 (the execution interval, 0.5 seconds). With
this short program, the Output Flag could be set
when the seconds counter equaled 0.
However, if Instruction 18 followed a series of
instructions that took longer than 0.1 seconds to
execute or was in Table 2, executed at the
same interval as an extensive Table 1, the time
at which Instruction 18 was executed might be
0.1 seconds or more beyond the modulo divisor.
The value output would not equal 0. Setting the
Output Flag when the seconds counter is less
than the execution interval avoids this problem.
Using Instruction 18 keeps the output interval
synchronized with real time. If a counter
incremented within the program was used to
determine when to set the Output Flag, output
would depend on the number of times the table
was executed. The actual time of output would
depend on when the program was actually
compiled and started running. If the table
overran its execution interval (Section 1.1.1),
the output interval would not be the count
multiplied by the execution interval, but some
longer interval.
In this example a temperature (type E
thermocouple) is measured every 0.5 seconds
and the average output every 30 seconds.
8-3
SECTION 8. PROCESSING AND PROGRAM CONTROL EXAMPLES
Input Location Assignments:
1:TEMP DEG C
10:30 SEC 0
*
01:
1
.5
Table 1 Programs
Sec. Execution Interval
01:
01:
P18
0
02:
03:
300
10
Time
Tenths of seconds into minute
(maximum 600)
Mod/by
Loc [:30 SEC 0 ]
02:
01:
02:
P17
1
1
Panel Temperature
IN Card
Loc [:REF TEMP ]
03:
01:
02:
03:
04:
05:
06:
07:
08:
09:
P14
1
13
1
2
2
1
2
1
0
Thermocouple Temp (DIFF)
Rep
15 mV fast Range
IN Card
IN Chan
Type E (Chromel-Constantan)
Ref Temp Loc REF TEMP
Loc [:TC TEMP ]
Mult
Offset
04:
01:
02:
03:
04:
P
10
4
.5
10
89 If X<=>F
X Loc 30 SEC 0
<
F
Set high Flag 0 (output)
05:
01:
02:
P
1
2
71 Average
Rep
Loc TC TEMP
06:
P
End Table 1
8.4 ANALOG OUTPUT TO STRIP
CHART
This example illustrates the use of the Analog
Output Instruction 21 to output 2 analog
voltages to strip chart.
While of questionable value because of power
requirements and strip chart reliability, some
archaic regulations require strip chart backup
on weather data. Instruction 21 may be used
with the CR7 to provide two continuous analog
8-4
outputs for strip charts. The output values in
this example are wind speed and wind direction.
The following program measures the sensors
every five seconds. The readings are moved to
another two locations and scaled to a 0 to 1000
millivolt output for the strip chart. Wind direction
is changed from a 0-360 degree input to output
representing 0 to 540 degrees. This conversion
is done in a subroutine which is described in the
next example.
The example also includes instructions to
output wind vector every hour.
Input Location Assignments:
01:WS
02:0-360 WD
03:0-540 WD
04:WS output
05:WD output
*
01:
01:
01:
02:
03:
04:
05:
06:
07:
1
3
P3
1
5
1
22
1
1.789
1
Table 1 Programs
Sec. Execution Interval
Pulse
Rep
IN Card
Pulse Input Chan
Switch closure; Output Hz.
Loc [:WS
]
Mult
Offset
02:
P4
01:
1
02:
16
03:
2
04:
1
05:
1
06:
1
07:
1
08:
2
09: 1000
10:
2
11:
.72
12:
0
Excite,Delay,Volt(SE)
Rep
500 mV fast Range
IN Card
IN Chan
EX Card
EX Chan
Meas/EX
Delay (units .01sec)
mV Excitation
Loc [:0-360 WD ]
Mult
Offset
03:
01:
Do
Call Subroutine 1
P86
1
SECTION 8. PROCESSING AND PROGRAM CONTROL EXAMPLES
04:
01:
02:
03:
P37
1
10
4
Z=X*F
X Loc WS
F
Z Loc [:WS output]
05:
01:
02:
03:
P37
3
1.8519
5
Z=X*F
X Loc 0-540 WD
F
Z Loc [:WD output]
06:
01:
02:
03:
P21
1
1
4
Analog Out
EX Card
CAO Chan
mv Loc WS output
07:
01:
02:
03:
P21
1
2
5
Analog Out
EX Card
CAO Chan
mv Loc WD output
08:
01:
02:
03:
P92
0
60
10
If time is
minutes into a
minute interval
Set high Flag 0 (output)
09:
01:
02:
03:
04:
05:
P69
1
180
00
1
2
Wind Vector
Rep
Samples per sub-interval
Polar Sensor/(S, D1, SD1)
Wind Speed/East Loc WS
Wind Dir./North Loc 0-360 WD
To change 0-360 degrees to the 0-540 degrees,
360 degrees must sometimes be added to the
reading when it is in the range of 0 to 180. The
following algorithm does this by assuming that if
the previous reading was less than 270, the
vane has shifted through 180 degrees and does
not need to be altered. If the previous 0-540
reading was greater than 270, 360 degrees is
added.
This example is written as a subroutine which is
used by the previous example to output an
analog voltage to a strip chart.
Input Location Labels:
10:
P
End Table 1
8.5 CONVERTING 0-360 WIND
DIRECTION OUTPUT TO 0-540 FOR
STRIP CHART
If 0-360 degree wind direction is output to a strip
chart, the discontinuity at 0/360 will cause the
pen to jump back and forth full scale when the
winds are varying from the north. In the days of
strip charts this was solved with a 0-540 degree
pot on the wind vane (direction changes from
540 to 180 and from 0 to 360 so the pen only
jumps once when the wind is out of the north or
south).
When faced with the necessity of strip chart
output (see previous example), the following
algorithm can be used to change a 0-360
degree input to 0-540. (If you have a 0-540 pot,
it can be used with the 21X since the Wind
Vector Instruction, 69, will work with this output.)
1:WS
2:0-360 WD
3:0-540 WD
4:WS output
5:WD output
*
3
Table 3 Subroutines
01:
01:
P85
1
Beginning of Subroutine
Subroutine Number
02:
01:
02:
03:
04:
P89
3
3
270
30
If X<=>F
X Loc 0-540 WD
>=
F
Then Do
03:
01:
P86
11
Do
Set high Flag 1
04:
P94
Else
05:
01:
P86
21
Do
Set low Flag 1
06:
P95
End
07:
01:
02:
P31
2
3
Z=X
X Loc 0-360 WD
Z Loc [:0-540 WD ]
08:
01:
02:
03:
04:
P89
3
4
180
30
If X<=>F
X Loc 0-540 WD
<
F
Then Do
8-5
SECTION 8. PROCESSING AND PROGRAM CONTROL EXAMPLES
09:
01:
02:
P91
11
30
If Flag
1 is set
Then Do
10:
01:
02:
03:
P34
3
360
3
Z=X+F
X Loc 0-540 WD
F
Z Loc [:0-540 WD ]
11:
P95
End
12:
P95
End
13:
P95
End
14:
P
the instructions necessary to provide calibrated
inputs, properly ordered to produce the desired
outputs from the Covariance Correlation
(CV/CR) Instruction. Table 8.7-1 groups the
sensors according to measurement type and
gives the CR7 multiplier and offset.
The props can all be measured as single-ended
voltages, but the vertical wind prop calibration
differs from the U and V prop calibration. The
fastest input sequence is to measure both
levels (6 props) with a single instruction using
the U and V calibration and correct the W
measurements with the Fixed Multiply,
Instruction 37.
End Table 3
8.6 COVARIANCE CORRELATION
PROGRAMMING EXAMPLE
The example is a two level meteorological tower
with five sensors at each level. The three
components of the wind are measured using
prop anemometers. Two thermocouples (TC)
are used to measure ambient and wet-bulb
temperatures and calculate water vapor
pressure on-line. All sensors are scanned once
per second (1 Hz) and a five minute averaging
period with a 30 minute Output Interval is
specified. The example optimizes the input
measurement sequence for speed and shows
The type E thermocouples are measured on the
most sensitive input range, 5mV,
accommodating a ±80 oC range between the
measurement and CR7 reference junction. The
resolution is (.33µV/(60µV/oC) or about 0.006
oC. Measuring absolute temperature with TCs
requires a reference junction temperature
measurement. This is measured with
Instruction 17.
The specified outputs determine the input order
required by the CV/CR Instruction. Table 8.6-2
lists the desired outputs from the two levels
along with the Input Storage locations for the
processed results.
TABLE 8.6-1. Example Sensor Description and CR7 Multiplier and Offset
DESCRIPTION
SYMBOL
SENSOR
CALIB
MEAS TYPE
Horiz. Wind
Horiz. Wind
Vert. Wind
Air Temp.
Wet-bulb Temp.
Vap. Pressure
U
V
W
Ta
Tw
e
prop
prop
prop
TC
TC
derived
18m/s/V
18m/s/V
22m/s/V
-
S.E.V.
S.E.V.
S.E.V.
TC DIFF.
TC DIFF.
-
8-6
MULT
.018m/s/mV
.018
.022
o
1.0 C
o
1.0 C
-
OFFSET
0.0
0.0
0.0
0.0
0.0
-
SECTION 8. PROCESSING AND PROGRAM CONTROL EXAMPLES
TABLE 8.6-2. Example Outputs and Input Storage Locations
LEVEL 1 OUTPUTS
MEANS LOC
VARIANCES LOC
COVARIANCES LOC
CORRELATIONS LOC
M(W1)
M(U1)
M(V1)
M(Tal)
M(e1)
V(W1)
V(U1)
V(V1)
V(Tal)
V(e1)
CV(W1,U1)
CV(W1,V1)
CV(W1,Tal)
CV(W1,e1)
CR(W1,U1)
CR(W1,V1)
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
LEVEL 2 OUTPUTS
MEANS LOC
VARIANCES LOC
COVARIANCES LOC
M(W2)
M(U2)
M(V2)
M(Ta2)
M(e2)
V(W2)
V(U2)
V(V2)
V(Ta2)
V(e2)
CV(W2,U2)
CV(W2,V2)
CV(W2,Ta2)
CV(W2,e2)
CV(U2,V2)
CV(U2,Ta2)
CV(U2,e2)
CV(V2,Ta2)
CV(V2,e2)
36
37
38
39
40
Table 8.6-3 lists the input channel configuration
and Input Storage allocation for the measured
values. After reading the new input samples,
the Level 2 measurements are relocated using
the Block Move Instruction 54, then Ta1 is
relocated through a separate move and e1 is
positioned by specifying the destination location
in the Wet/Dry-Bulb Instruction. The CV/CR
Instruction must be entered twice, once for each
level.
In addition to ordering Level 1 and Level 2 in
locations 1-5 and 11-15 respectively, two more
41
42
43
44
45
46
47
48
49
50
51
52
53
54
locations are required. Converting the wet-/drybulb measurements to vapor pressure using
Instruction 57 requires atmospheric pressure.
We'll use the standard atmosphere for the site
elevation and key the value into Location 17
using the C command in the *6 Mode. The
reference junction temperature obtained by
Instruction 17 is stored in Location 16.
This example requires that 54 locations be
allotted to Input Storage and 79 to Intermediate
Storage (35 for the 1st CV/CR Instruction, 43
for the second, and 1 for Instruction 92).
TABLE 8.6-3. Example Input Channel and Location Assignments
INPUT
PARAM CHAN
INPUT
LOC
INPUT
PARAM LOC
W1
U1
V1
W2
U2
V2
Ta2
Tw2
Ta1
Tw1
1
2
3
4
5
6
7
8
9
10
W1
U1
V1
Ta1
Tw1
W2
U2
V2
Ta2
Tw2
1
2
3
4
5
6
7
8
9
10
->Block->
move
INPUT
PARA LOC
1
W1
2
U1
3
V1
9 ----------------------- Ta1
10 Separate moves e1
11
W2
12
U2
13
V2
14
Ta2
15
e2
1
2
3
4
5
11
12
13
14
15
8-7
SECTION 8. PROCESSING AND PROGRAM CONTROL EXAMPLES
*
01:
1
1
01:
01:
02:
P17
1
16
02:
01:
02:
03:
04:
05:
06:
07:
P1
6
8
1
1
1
.018
0
Table 1 Programs
Sec. Execution Interval
Panel Temperature
IN Card
Loc [:PANL TEMP]
Volt (SE)
Reps
5000 mV slow Range
IN Card
IN Chan
Loc [:W1
]
Mult
Offset
03:
01:
02:
03:
04:
05:
06:
07:
08:
09:
P14
4
15
1
7
2
16
7
1
0
Thermocouple Temp (DIFF)
Reps
150 mV fast Range
IN Card
IN Chan
Type E (Chromel-Constantan)
Ref Temp Loc PANL TEMP
Loc [:Ta2
]
Mult
Offset
04:
01:
02:
03:
P37
1
1.22
1
Z=X*F
X Loc W1
F
Z Loc [:W1
05:
01:
02:
03:
P37
4
1.22
4
Z=X*F
X Loc W2
F
Z Loc [:W2
06:
01:
02:
03:
04:
05:
P54
5
4
1
11
1
Block Move
No. of Values
First Source Loc W2
Source Step
First Destination Loc [:W2
Destination Step
]
P57
17
14
15
15
Wet/Dry Bulb Temp to VP
Pressure Loc
Dry Bulb Temp Loc
Wet Bulb Temp Loc Tw2
Loc [:Tw2
]
10:
01:
02:
03:
P92
0
30
10
If time is
minutes into a
minute interval
Set high Flag 0 (output)
11:
01:
02:
03:
04:
05:
06:
07:
08:
09:
P62
5
5
5
0
4
2
300
1
20
CV/CR
No. of Input Values
No. of Means
No. of Variances
No. of Std. Dev.
No. of Covariances
No. of Correlations
Samples per Average
First Sample Loc W1
Loc [:MEAN (W1)]
12:
01:
02:
03:
04:
05:
06:
07:
08:
09:
P62
5
5
5
0
4
2
300
11
36
CV/CR
No. of Input Values
No. of Means
No. of Variances
No. of Std. Dev.
No. of Covariances
No. of Correlations
Samples per Average
First Sample Loc W2
Loc [:MEAN (W2)]
13:
01:
P77
110
Real Time
Day,Hour-Minute
14:
01:
02:
P70
35
20
Sample
Reps
Loc MEAN (W1)
]
15:
P31
9
4
Z=X
X Loc
Z Loc [:W2
08:
01:
02:
03:
04:
P57
17
9
10
5
Wet/Dry Bulb Temp to VP
Pressure Loc
Dry Bulb Temp Loc
Wet Bulb Temp Loc
Loc [:U2
]
]
P
End Table 1
]
*
01:
02:
07:
01:
02:
8-8
09:
01:
02:
03:
04:
A
54
79
Mode 10 Memory Allocation
Input Locations
Intermediate Locations
SECTION 9. INPUT/OUTPUT INSTRUCTIONS
TABLE 9-1. Input Voltage Ranges and Codes
Range Code
Slow
Fast
16.67ms
250µs
Integ.
Integ.
1
11
2
12
3
13
4
14
5
15
6
16
7
17
8
18
Full Scale Range
±1500
±5000
±15
±50
±150
±500
±1500
±5000
Resolution*
microvolts
microvolts
millivolts
millivolts
millivolts
millivolts
millivolts
millivolts
50
166
500
1.66
5
16.6
50
166
nanovolts
nanovolts
nanovolts
microvolts
microvolts
microvolts
microvolts
microvolts
*Differential measurement, resolution for single-ended measurement is twice value shown.
When measuring voltages with the 723
Analog Input Card, the ±1500 µV and
±5000 µV ranges read out in microvolts, the
rest of the ranges have the decimal point
placed to display millivolts. The 726 50V
Analog Input Card divides the input voltages
by 10 before making the measurements,
thus, to shift the decimal point so as to
display millivolts a factor of ten must be
used in the multiplier. Repetitions cannot
be used to advance from one 726 card to
the next.
When a voltage input exceeds the range
programmed, the value which is stored is
set to the maximum negative number
displayed as -99999 in high resolution or 6999 in low resolution.
*** 1 SINGLE ENDED VOLTS ***
FUNCTION
This instruction is used to measure voltage at a
single ended input with respect to ground.
PAR.
NO.
DATA
TYPE
01:
02:
03:
2
2
2
04:
2
05:
4
06:
07:
FP
FP
DESCRIPTION
Repetitions
Range code (Table 9-1)
Card number for first
measurement
Single-ended channel
number for first
measurement
Input location number for first
measurement
Multiplier
Offset
Input locations altered: 1 per repetition
*** 2 DIFFERENTIAL VOLTS ***
FUNCTION
This Instruction reads the voltage difference
between the HI and LO inputs of a differential
channel in the selected range from the selected
card and channel(s) and places it in an input
location(s). Table 9-1 lists the range codes.
Both the high and low inputs must be within ±5V
of the datalogger's ground (Common Mode
Range Section 13.2). Pyranometers and
thermopile sensors require a jumper between
LO and Ground to keep them in Common Mode
Range.
9-1
SECTION 9. INPUT/OUTPUT INSTRUCTIONS
PAR.
NO.
DATA
TYPE
01:
02:
03:
2
2
2
04:
2
05:
4
06:
07:
FP
FP
DESCRIPTION
Repetitions
Range code (Table 9-1)
Card number for first
measurement
Differential channel number
for first measurement
Input location number for first
measurement
Multiplier
Offset
Input locations altered: 1 per repetition
*** 3 PULSE COUNT ***
INPUT RANGE - - - 32767 Counts per input
interval
There are three input configurations which may
be measured with the Pulse Count Instruction.
HIGH FREQUENCY PULSE
In this configuration the minimum pulse width is
2 microseconds. The maximum input
frequency is 250 kilohertz. The count is
incremented when the input voltage changes
from below 1.5 volts to above 3.5 volts. The
maximum input voltage is ±20 volts.
LOW LEVEL AC
This configuration is used for counting the
frequency of AC signals from magnetic pulse
flow transducers or other low voltage, sine wave
inputs. The minimum input voltage is 6 mV
RMS. Input hysteresis is 11 mV. The maximum
AC input voltage is 20 volts RMS. The
maximum input frequency ranges from 100Hz
at 6mV RMS to 10,000Hz at 50mV or greater.
Consult the factory if higher frequencies are
desired.
SWITCH CLOSURE
In this configuration the minimum switch closed
time is 1 millisecond. The minimum switch
open time is 4 milliseconds. The maximum
bounce time is 1.4 milliseconds open without
being counted.
All pulse counters in one I/O Module are reset
at the same time. The reset time interval is
equal to the execution interval of the program
table in which the Pulse Count Instruction(s)
occur. When programs are compiled, the CR7
9-2
will set the reset time interval to the execution
interval of the first program table in which a
Pulse Count Instruction occurs. The execution
intervals of subsequent program tables
containing Pulse Count Instructions will have no
effect on the reset time interval. (The maximum
input frequency is 250KHz. The maximum
number that can be stored in an accumulation
register is 65,535.)
When datalogger time is changed, whether
through the keyboard or with a
telecommunications program, a partial
recompile is automatically done to
resynchronize program execution with real time.
The resynchronization process resets the pulse
accumulation interval resulting in an interval
whose length can be anywhere between one
second too short to almost twice as long.
Pulses are not lost during resynchronization so
totalized values are correct but pulse rate
information such as wind speed can be up to
almost twice the correct value.
The options of discarding counts from long
intervals and pulse input type are selected by
the code entered for the 4th parameter (Table
9-2).
All Pulse count instructions for the same I/O
module and output instructions for the pulse
count data should be kept in the same program
table, preferably Table 1. If the pulse count
instruction is contained in a subroutine, that
subroutine must be called from Table 2.
When the system is interrupted for a task of
sufficient priority to allow the pulse counters to
exceed the programmed reset time interval, the
resulting larger count can either be discarded
leaving the value in the input location
unchanged from the previous value or it can be
used. If pulse counts are being totalized, a
missing count could be significant; the value
from the erroneously long interval should be
used. If the pulse count is being processed a
way in which the resultant value is dependent
upon the sampling interval, such as sample,
average, maximum, or minimum, it should be
discarded. The option of discarding counts
from long intervals and the input configuration
are determined by the 4th parameter according
to the following table.
SECTION 9. INPUT/OUTPUT INSTRUCTIONS
TABLE 9-2. Pulse Count Configuration
Codes
Code
Configuration
00
High frequency pulse, all pulses
counted
Low level AC, all pulses counted
Switch closure, all pulses counted
01
02
1X
2X
Long interval data discarded, where X
is configuration code
Long interval data discarded, frequency
(Hz) output
PAR.
NO.
DATA
TYPE
01:
02:
2
2
03:
2
04:
05:
2
4
06:
07:
FP
FP
DESCRIPTION
Repetitions
Card number for first
measurement
Pulse channel number for
first measurement
Configuration code (Table 9-2)
Input location number for first
measurement
Multiplier
Offset
Input locations altered: 1 per repetition
*** 4 EXCITE, DELAY AND MEASURE **
FUNCTION
This Instruction is used to apply an excitation
voltage, delay a specified time and then make a
single ended voltage measurement.
PAR.
NO.
DATA
TYPE
01:
02:
03:
2
2
2
04:
2
05:
2
06:
2
07:
2
08:
4
DESCRIPTION
Repetitions
Range code (Table 9-1)
Analog card number for first
measurement
Single-ended channel
number for first
measurement
Excitation card for first
measurement
Excitation channel number
for first measurement
Number of measurements
per excitation channel
Delay (0.01 sec)
09:
10:
FP
4
11:
12:
FP
FP
Excitation voltage (millivolts)
Input location number for first
measurement
Multiplier
Offset
Input locations altered: 1 per repetition
*** 5 AC HALF BRIDGE ***
FUNCTION
This Instruction is used to apply an excitation
voltage to a half bridge (Figure 13.5-1), make a
single ended voltage measurement of the
bridge output, reverse the excitation voltage,
then repeat the measurement. The difference
between the two measurements is used to
calculate the resulting value which is the ratio of
the measurement to the excitation voltage.
When the 1500 or 5000 µV input range is
selected, the value is returned as 1000 times
the ratio. For all other input ranges the value is
just the ratio.
The excitation "on time" for each polarity is
exactly the same to ensure that ionic sensors do
not polarize with repetitive measurements. The
range should be selected to be a fast
measurement (range 11-18) limiting the excitation
on time to 800 microseconds at each polarity. A
slow integration time should not be used with
ionic sensors because of polarization error.
PAR.
NO.
DATA
TYPE
01:
02:
03:
2
2
2
04:
2
05:
2
06:
2
07:
2
08:
09:
4
4
10:
11:
FP
FP
DESCRIPTION
Repetitions
Range code (Table 9-1)
Analog card number for first
measurement
Single-ended channel
number for first
measurement
Excitation card for first
measurement
Excitation channel number
for first measurement
Number of measurements
per excitation channel
Excitation voltage (millivolts)
Input location number for first
measurement
Multiplier
Offset
Input locations altered: 1 per repetition
9-3
SECTION 9. INPUT/OUTPUT INSTRUCTIONS
*** 6 FULL BRIDGE WITH SINGLE ***
DIFFERENTIAL MEASUREMENT
FUNCTION
This Instruction is used to apply an excitation
voltage to a full bridge (Figure 13.5-1), make a
differential voltage measurement of the bridge
output, reverse the excitation voltage, then
repeat the measurement. The resulting value is
1000 times the ratio of the measurement to the
excitation voltage.
PAR.
NO.
DATA
TYPE
01:
02:
03:
2
2
2
04:
2
05:
2
06:
2
07:
2
08:
09:
4
4
10:
11:
FP
FP
DATA
TYPE
01:
02:
2
2
03:
2
04:
2
05:
2
06:
2
07:
2
08:
09:
4
4
10:
11:
FP
FP
DESCRIPTION
Repetitions (95 max)
Range code (Table 9-1)
Analog card number for first
measurement
Differential channel number
for first measurement
Excitation card for first
measurement
Excitation channel number
for first measurement
Number of measurements
per excitation channel
Excitation voltage (millivolts)
Input location number for first
measurement
Multiplier
Offset
Input locations altered: 1 per repetition
*** 7 THREE WIRE HALF BRIDGE ***
FUNCTION
This Instruction is used to determine the ratio of
the sensor resistance to a known resistance
using a separate voltage sensing wire from the
sensor to compensate for lead wire resistance.
The measurement sequence is to apply an
excitation voltage, make two voltage
measurements on two adjacent single ended
channels, the first on the reference resistor and
the second on the voltage sensing wire from the
sensor (Figure 13.5-1), then reverse the
excitation voltage and repeat the
measurements. The two measurements are
used to calculate the resulting value which is
the ratio of the voltage across the sensor to the
voltage across the reference resistor.
9-4
PAR.
NO.
DESCRIPTION
Repetitions (95 max)
Range code for both
measurements (Table 9-1)
Analog card number for first
measurement
Single-ended channel number
for first measurement
Excitation card for first
measurement
Excitation channel number
for first measurement
Number of measurements
per excitation channel
Excitation voltage (millivolts)
Input location number for first
measurement
Multiplier
Offset
Input locations altered: 1 per repetition
*** 9 FULL BRIDGE WITH EXCITATION ***
COMPENSATION
FUNCTION
This Instruction is used to apply an excitation
voltage and make two differential voltage
measurements, then reverse the polarity of the
excitation and repeat the measurements. The
measurements are made on sequential
channels. The result is the voltage measured
on the second channel (V2) divided by the
voltage measured on the first (V1). If V1 is
measured on the 5V range (code 8 or 18 in
Parameter 2), then the result is 1000 times
V2/V1. A 1 before the excitation channel
number (1X) causes the excitation channel to
be incremented with each repetition.
When used as a 6 wire full bridge (Figure 13.51), the connections are made so that V1 is the
measurement of the voltage drop across the full
bridge, and V2 is the measurement of the
bridge output. Because the excitation voltage
for a full bridge measurement is usually in the
5V range, the output is usually 1000 V2/V1 or
millivolts output per volt excitation. When used
to measure a 4 wire half bridge, the connections
are made so that V1 is the voltage drop across
the fixed resistor (Rf), and V2 is the drop across
the sensor (Rs). As long as V1 is not measured
on the 5V range, the result is V2/V1 which
equals Rs/Rf.
SECTION 9. INPUT/OUTPUT INSTRUCTIONS
PAR.
NO.
DATA
TYPE
01:
02:
2
2
03:
2
04:
2
05:
2
06:
2
07:
2
08:
2
09:
10:
4
4
11:
12:
FP
FP
Curve Fit Error -DESCRIPTION
Repetitions (47 max)
Excitation range code (Table
9-1)
Bridge range code for (Table
9-1)
Analog card number for first
measurement
Differential channel number
for first measurement
Excitation card for first
measurement
Excitation channel number
for first measurement
Number of measurements
per excitation channel
Excitation voltage (millivolts)
Input location number for first
measurement
Multiplier
Offset
Input locations altered: 1 per repetition
*** 10 BATTERY VOLTAGE ***
FUNCTION
This instruction reads the battery voltage from
the currently active I/O module and writes it to
an input location. The units for battery voltage
are volts.
Range (oC)
-40 to +55
-35 to +48
Error (oC)
±1.0
±0.1
This instruction uses a single excitation channel
since several hundred probes can be driven by
a single excitation output. For this reason,
Instruction 11 does not require a
"measurement/excitation" parameter.
A multiplier of 1 and an offset of 0 yields
temperature in degrees C.
PAR.
NO.
DATA
TYPE
01:
02:
2
2
03:
2
04:
2
05:
2
06:
4
07:
08:
FP
FP
DESCRIPTION
Repetitions
Analog card number for first
measurement
Single-ended channel
number for first
measurement
Excitation card number for
first measurement
Excitation channel number
for first measurement
Input location of first
measurement
Multiplier
Offset
Input locations altered: 1 per repetition
PAR.
NO.
DATA
TYPE
DESCRIPTION
*** 12 207 RELATIVE HUMIDITY PROBE ***
01:
4
Input location number
FUNCTION
This instruction applies a 3 VAC excitation
across Campbell Scientific's Model 207
Temperature and RH Probe, makes a fast
single ended measurement across a series
resistor on the 150 mV range, linearizes the
result with a 5th order polynomial and performs
the required temperature compensation before
outputting the result in % RH.
Input locations altered: 1
*** 11 107 THERMISTOR PROBE ***
FUNCTION
This instruction applies a 4 VAC excitation
voltage to Campbell Scientific's Model 107
Thermistor Probe, makes a fast, single ended
voltage measurement on the 15 mV range
across a resistor in series with the thermistor
and calculates the temperature in oC with a
polynomial. The maximum polynomial error
from -40 oC to +55 oC is given below:
When measuring several probes, all the RH
elements should be connected sequentially.
Any temperature elements used for
compensating the respective RH value should
also be sequentially connected to make use of
the REP feature in Instruction 11.
9-5
SECTION 9. INPUT/OUTPUT INSTRUCTIONS
The temperature value used in
compensating the RH value (Parameter 7)
must be obtained (see Instruction 11) prior
to executing Instruction 12.
The RH results are placed sequentially into the
input locations beginning with the first RH value.
In some situations the RH sensors might be
deployed such that only small temperature
variations exist within a given set of probes. In
these cases a single temperature may be used
to compensate the subset of RH measurements
instead of making a temperature measurement
for each RH probe. If the complete set of
temperature values are not needed, this
approach uses less input channels. Parameter
6 is used to specify how many consecutive RH
values get compensated per temperature
measurement.
In the 207 probe, the RH and temperature
elements use a common excitation line. Since
a single excitation channel can drive several
hundred probes, there is no
"measurements/excitation" parameter in
Instruction 12. NEVER EXCITE THE 207
PROBE WITH DC EXCITATION as the RH chip
will be damaged.
The maximum RH polynomial error is given
below:
Curve Fit Error -Range (%RH)
10 - 100
15 - 94
PAR.
NO.
DATA
TYPE
01:
02:
2
2
03:
2
04:
2
05:
2
06:
2
9-6
Error (%RH)
±4
±1
DESCRIPTION
Repetitions
Analog card number for first
measurement
Single-ended channel for first
measurement
Excitation card number for
first measurement
Excitation channel number
for first measurement
Number of R.H.
measurements per
compensating temperature
measurement
07:
4
08:
4
09:
10:
FP
FP
Input location for first
compensating temperature
measurement
Input location for first
measurement
Multiplier
Offset
Input locations altered: 1 per repetition
*** 13 THERMOCOUPLE ***
TEMPERATURE, SINGLE ENDED
FUNCTION
This Instruction uses the selected thermocouple
calibration to calculate the thermocouple output
voltage at the reference temperature, then it
makes a SINGLE ENDED VOLTAGE
MEASUREMENT (Section 13.2) on the
thermocouple and adds the measured voltage
to the calculated reference voltage, then
converts the voltage to temperature in oC
(Section 13.4).
Table 9-3 gives the thermocouple type codes.
The reference temperature location will be
incremented by one each repetition if C is keyed
before entering Parameter 6. When this option
is exercised, two minus signs (--) will appear as
the right most characters of the display.
A multiplier of 1 and an offset of 0 yields
temperature in degrees C.
TABLE 9-3. Thermocouple Type Codes
Code
1
2
3
4
5
6
7
1X
2X
8X
Thermocouple Type
T (copper - constantan)
E (chromel - constantan)
K (chromel - alumel)
J (iron - constantan)
B (platinum - rhodium)
R (platinum - rhodium)
S (platinum - rhodium)
Output temperature difference between
Reference and Thermocouple
Skip every other single ended channel
TC input from A5B40 Isolation Amplifier
(use 5 V range)
SECTION 9. INPUT/OUTPUT INSTRUCTIONS
PAR.
NO.
DATA
TYPE
01:
02:
03:
04:
2
2
2
2
05:
06:
2
4
07:
08:
09:
4
FP
FP
06:
4
07:
08:
09:
4
FP
FP
DESCRIPTION
Repetitions
Range code (Table 9-1)
Analog card number
Single-ended channel number
for first measurement
TC type code (Table 9-3)
Reference temperature
location. (When indexed (--)
this is incremented with each
rep.)
Input location number
Multiplier
Offset
Input locations altered: 1 per repetition
*** 14 THERMOCOUPLE ***
TEMPERATURE, DIFFERENTIAL
MEASUREMENT
FUNCTION
This instruction calculates the thermocouple
temperature for the thermocouple type selected.
The instruction specifies a DIFFERENTIAL
VOLTAGE MEASUREMENT (Section 13.2) on
the thermocouple, adds the measured voltage
to the voltage calculated for the reference
temperature relative to 0 oC, and converts the
combined voltage to temperature in oC. The
differential inputs are briefly shorted to ground
prior to making the voltage measurement to
insure that they are within the common mode
range. (Section 13.4)
Table 9-3 gives the thermocouple type codes
for Parameter 5, the option of skipping every
other channel applies only to Instruction 13.
The reference temperature location will be
incremented by one each repetition if C is keyed
before entering Parameter 6. When this option
is exercised, two minus signs (--) will appear as
the right most characters of the display.
A multiplier of 1 and an offset of 0 yields
temperature in degrees C.
PAR.
NO.
DATA
TYPE
DESCRIPTION
01:
02:
03:
04:
05:
2
2
2
2
2
Repetitions
Range code (Table 9-1)
Card number
Beginning channel
TC type code (Table 9-3)
Reference temperature
location. (When indexed (--)
this is incremented with each
rep.)
Input location number
Multiplier
Offset
Input locations altered: 1 per repetition
*** 16 TEMPERATURE FROM ***
PLATINUM R.T.D.
FUNCTION
This instruction uses the result of a previous
RTD bridge measurement to calculate the
temperature according to the DIN 43760
specification adjusted (1980) to the pending
International Electrotechnical Commission
standard. The range of linearization is -200 oC
to 850 oC. The error in the linearization is less
than 0.001 oC between -200 and +300 oC, and
is less than 0.003 oC between -180 and
+830 oC. The error (T calculated - T standard)
is +0.006o at -200o and -0.006 at +850 oC.
The input must be the ratio R/R0, where R is
the RTD resistance and R0 the resistance of
the RTD at 0 oC.
A multiplier of 1 and an offset of 0 yields
temperature in degrees C.
PAR.
NO.
DATA
TYPE
01:
02:
2
4
03:
4
04:
05:
FP
FP
DESCRIPTION
Repetitions
Input location number of
(R/Ro)
Input location number of
result
Multiplier
Offset
Input locations altered: 1 per repetition
*** 17 TEMPERATURE OF INPUT PANEL ***
FUNCTION
This instruction measures the temperature in
oC of the specified analog input card with RTD
(Model 723-T).
PAR.
NO.
DATA
TYPE
DESCRIPTION
01:
02:
2
4
Analog card number
Input location number
Input locations altered: 1
9-7
SECTION 9. INPUT/OUTPUT INSTRUCTIONS
*** 18 MOVE TIME TO INPUT LOCATION ***
*** 20 PORT SET ***
FUNCTION
This instruction takes the current time in tenths
of seconds into the minute, minutes into the
day, or hours into the year and does a modulo
divide (see Instruction 46) on the time value
with the number specified in the second
parameter. The result is stored in the specified
input location. Entering 0 or a number which is
greater than the maximum value of the time for
the modulo divide will result in the actual time
value being stored.
FUNCTION
This instruction sets a specified Digital Control
output port or is used to set the active excitation
card for port commands with Program Control
Instructions or manual toggling (Section 1.3.3).
Ports may be set as specified by a flag or
unconditionally.
PARAMETER 1 OPTION CODES
CODE TIME UNITS
0
Tenths of seconds into minute
(maximum 600)
Minutes into current day (maximum
1440)
Hours into current year (maximum
8784)
1
2
PAR.
NO.
DATA
TYPE
DESCRIPTION
01:
02:
03:
2
4
4
Option Code (see above)
Number to modulo divide by
Input location number
PARAMETER 1 OPTION CODES
Code
00
01
1X
2X
30
Function
Set port low
Set port high
Set port according to flag X
Set opposite to flag X
Set active port card
PAR.
NO.
DATA
TYPE
DESCRIPTION
01:
02:
03:
2
2
2
Option code (see above)
Excitation card number
Port number (1-8)
Input locations altered: 0
Input locations altered: 1
*** 19 MOVE SIGNATURE INTO ***
INPUT LOCATION
FUNCTION
This instruction stores the signature of the Read
Only Memory (ROM) and user program memory
(RAM) into an input location. This signature is
not the same as the signatures given in the *B
mode. Recording the signature allows detection
of any program change or ROM failure.
PAR.
NO.
DATA
TYPE
DESCRIPTION
01:
4
Input location number
Input locations altered: 1
9-8
*** 21 ANALOG OUTPUT ***
FUNCTION
This instruction sets the continuous Analog
Output (CAO) to a voltage level specified in an
input location. The analog output degrades
approximately 0.17mV every seven seconds
requiring the instruction to be periodically
repeated to maintain a given output accuracy.
PAR.
NO.
DATA
TYPE
01:
02:
03:
2
2
4
DESCRIPTION
Excitation card number
CAO channel number
Input location number
containing analog output
magnitude in millivolts
Input locations altered: 0
Input locations read: 1
SECTION 9. INPUT/OUTPUT INSTRUCTIONS
*** 22 EXCITATION WITH DELAY ***
*** 26 TIMER ***
FUNCTION
This instruction is used in conjunction with
others for measuring a response to a timed
excitation using the switched analog outputs. It
sets the selected excitation output to a specific
value, waits for a specified time, turns off the
excitation and waits an additional specified time
before continuing execution of the following
instruction. The excitation on time can be set to
zero and the off time delay can be used if the
only requirement is the delay of Program
execution.
FUNCTION
This instruction will reset a timer or store the
elapsed time registered by the timer in an Input
Storage location. Instruction 26 can be used
with Program Control Instructions to measure
the elapsed time between specific input
conditions. There is only one timer and it is
common to all tables (e.g., if the timer is reset in
Table 1 and later in Table 2, a subsequent
instruction in Table 1 to read the timer will store
the elapsed time since the timer was reset in
Table 2).
This instruction cannot be interrupted by
Program Table 1 in order to make a
measurement. This means that if it resides
in Table 2 or Table 3 then Table 1 may be
delayed.
Elapsed time is tracked in 0.1 second
increments but displayed as an integer. For
example, a 20 second elapsed time is displayed
as "200".
PAR.
NO.
DATA
TYPE
01:
02:
03:
2
2
4
04:
4
05:
FP
DESCRIPTION
Excitation card number
Excitation channel number
Delay that excitation is on
(0.01 sec)
Delay time after excitation is
turned off (0.01 sec)
Excitation voltage (millivolts)
Input locations altered: 0
*** 23 SELECT I/O MODULE ***
FUNCTION
This instruction is used when more than one I/O
Module is under control and is used to specify
which I/O Module subsequent instructions refer
to. The I/O Module to which Instructions are
addressed defaults to #1 at the start of each
program table.
PAR.
NO.
DATA
TYPE
DESCRIPTION
01:
2
Module number (1,2,3 or 4)
Input locations altered: 0
The timer is also reset in response to certain
keyboard entries:
1. When tables are changed and compiled
with the *0 Mode, the timer is reset
automatically.
2. When tables are changed and then
compiled in the *B Mode, the timer is
automatically reset and Tables 1 and 2 are
disabled. Entering "*0" at this point enables
both tables and resets the timer.
3. Entering "*6" after changing the tables
compiles the programs, but does NOT reset
the timer.
PAR.
NO.
DATA
TYPE
01:
4
DESCRIPTION
Input location number (enter
0 to reset)
Input locations altered: 1 (0 if timer is being
reset)
*** 101 SDM-INT8 ***
The 8 channel Interval Timer (INT8) is a
measurement module which provides processed
timing information to the datalogger. Each of
the 8 input channels may be independently
configured to detect either rising or falling edges
of either high level or a low level signal. Each
channel may be independently programmed.
See the SDM-INT8 manual for detailed
9-9
SECTION 9. INPUT/OUTPUT INSTRUCTIONS
instructions and examples. This instruction is
not in all PROM options.
PARAM.
NUMBER
DATA
TYPE
01:
2
02:
4
03:
4
04:
05:
06:
07:
4
4
4
4
08:
09:
FP
FP
DESCRIPTION
SDM address (base
4:00..33)
*Input configuration;
channels 8,7,6,5
*Input configuration;
channels 4,3,2,1
**Function; channels 8,7,6,5
**Function; channels 4,3,2,1
***Output option
Starting input location
number
Mult
Offset
* Input configurations:
0 = high level, rising edge
1 = high level, falling edge
2 = low level, rising edge
3 = low level, falling edge
** Functions:
0 = no value returned
1 = period in ms
2 = frequency in kHz
3 = time since previous channel's edge
in ms
4 = time since channel 1 in ms
5 = counts on channel 2 since channel
1, linear interpolation
6 = frequency in kHz (low resolution)
7 = counts
8 = counts on Channel 2 since Channel
1, no interpolation
*** Output option:
0
Average over execution interval
0-Continuous averaging
XXXX Averaging interval in msec,
XXXX>0
XXXX-- Capture all events until
XXXX edges of channel 1
(0<XXXX,9999)
9999-- Test memory
Input locations altered: 1 per function
*** 102 SDM-SW8A ***
The 8 channel SDM-SW8A Switch Closure Input
Module is a peripheral for measuring up to 8
channels of switch closure or voltage pulse
inputs. Each channel may be configured to read
single-pole double-throw (SPDT) switch closure,
or single-pole single-throw (SPST) switch
closure, or voltage pulse. Output options
include counts, duty cycle, and state. This
instruction is not in all PROM options.
The SW8A is addressed by the datalogger,
allowing multiple SW8A's to be connected to one
datalogger. 16 addresses are available.
If more channels are requested than exist in one
module, the datalogger automatically increments
the address and continues to the next SW8A.
The address settings for multiple SW8A's must
sequentially increase. For example, assume 2
SW8A's addressed as 22 and 23 are connected,
and 12 Reps are requested. 8 channels from
the first SW8A and the first 4 channels from the
next will be read.
Only one Function Option (Parameter 3) may be
specified per Instruction 102. If all 4 functions are
desired, the instruction must be entered 4 times.
Function Option 0 provides the state of the
signal at the time P102 is executed. A 1 or
0 corresponds to high or low states,
respectively.
Function Option 1 provides signal duty
cycle. The result is the percentage of time
the signal is high during the sample interval.
Function Option 2 provides a count of the
number of positive transitions of the signal.
Function Option 3 provides the signature of
the SW8A PROM. A positive number
(signature) indicates the PROM and RAM
are good, a zero (0) indicates bad PROM,
and a negative number indicates bad RAM.
Function Option 3 is not used routinely, but
is helpful in "debugging". Only one Rep is
required for Option 3.
Parameter 4 specifies the first SW8A channel to
be read (1..8). One or more sequential channels
are read depending on the Reps. To optimize
program efficiency, the sensors should be wired
sequentially.
9-10
SECTION 9. INPUT/OUTPUT INSTRUCTIONS
Data are stored in sequential datalogger input
locations, starting at the location specified in
Parameter 5. The number of input locations
consumed is equal to the number of Reps.
PARAM.
NUMBER
01
2
The scaling multiplier and offset (Parameters 6
and 7) are applied to all readings. If a multiplier
is not entered, all readings are set to 0.
02
2
03
4
If the SW8A does not respond, -99999 will be
loaded into input locations. Modules which do
not respond when addressed by the datalogger
may be wired or addressed incorrectly. Verify
that the address specified in Parameter 2
corresponds to the jumper setting and that all
connections are correct and secure. See the
SDM-SW8A Manual for examples.
C1 is Data line
C2 is Clk/Hand Shake line
C3 is SDE (Enable) line
PARAM.
NUMBER
DATA
TYPE
01:
2
02:
2
03:
2
04:
2
05:
4
06:
07:
FP
FP
DESCRIPTION
Repetitions (number of
channels)
SDM Address (base
4:00..33)
Function Option (0=State,
1=Duty 2=Counts,
3=Signature)
SDM-SW8A Starting
Channel (1..8)
Starting input location
number
Mult
Offset
Input locations altered: 1 per repetition
*** 103 SDM-AO4 ***
Instruction 103 is used to activate a SDM-AO4 4
Channel Continuous Analog Output Module
connected to ports C1, C2, and C3. This
instruction is not in all PROM options.
There are 4 analog voltage outputs per SDMAO4. The output voltages in millivolts must be
stored in 4 adjacent input locations starting with
the location entered in parameter 4. Four reps
are required for each SDM-A04. Every 4 reps
another device at the next higher address is
selected.
DATA
TYPE
DESCRIPTION
Repetitions (number of
outputs)
SDM address (base
4:00..33)
Starting input location
number
Input locations read: 1 per repetition
*** 104 SDM-CD16AC ***
The SDM-CD16AC Control Port Expansion
Module has 16 digital control ports with drivers.
Each port can be controlled by a datalogger or
controlled manually with an override toggle
switch. Each port can be thought of as a switch
to ground; closed when active, open when
inactive. The primary function is to activate DC
powered external relays, solenoids, or resistive
loads under datalogger control. This instruction
is not in all PROM options.
The SDM-CD16AC is a synchronously
addressed datalogger peripheral. Datalogger
control ports 1, 2 and 3 are used to address the
SDM-CD16AC then clock out the desired state
of each of the 16 control ports. Up to 16 SDMCD16AC 's may be addressed, making it
possible to control a maximum of 256 ports
from the first three datalogger control ports.
For each Rep, the 16 ports of the addressed
SDM-CD16AC are set according to 16 sequential
input locations starting at the input location
specified in parameter 3. Any non-zero value
stored in an input location activates (connects to
ground) the associated SDM-CD16AC port. A
value of zero (0) deactivates the port (open
circuit). For example, assuming 2 Reps and a
starting input location of 33, OUTPUT 1 through
16 of the first SDM-CD16AC are set according to
Input Locations 33 through 48, and OUTPUT 1
through 16 of the second SDM-CD16AC are set
according to Input Location 49 through 64. See
the SDM-CD16AC manual for detailed
instructions and examples.
9-11
SECTION 9. INPUT/OUTPUT INSTRUCTIONS
PARAM.
NUMBER
1
DATA
TYPE
2
2
2
3
4
DESCRIPTION
Reps (# of CD16AC
modules sequentially
addressed)
Starting SDM address
(base 4: 00..33)
Starting input location
number
PARAM.
NUMBER
01:
FUNCTION
Instruction 114 can be used to set the CR7
clock from values in input locations.
PARAM.
NUMBER
01:
02:
DATA
TYPE
2
4
DESCRIPTION
Option code:
0 set time with
hr,min,sec with
values in 3 input
locations.
1 set time with
day,hr,min,sec
using 4 input
locations.
2 set time with
yr,day,hr,min,sec
using 5 input
locations.
Input location number
Input locations read: 3-5 depending on option
*** 115 SET SDM BAUD ***
FUNCTION
Instruction 115 may be used to set the SDM
communication rate. This may be necessary
when communicating over longer cable lengths.
The default bit period is 10 microseconds
(entering either 0 or 1 will result in this period).
9-12
Bit period, 10µs units
NOTE: The SDM-SI04 Instruction 113
automatically adjusts the SDM
communication rate to the fastest that will
work.
*** 113 SDM-SI04 ***
*** 114 SET TIME ***
4
DESCRIPTION
Normally this parameter represents the bit
period. If the parameter is indexed (--), the
value entered is an Input Location that contains
the bit period to use.
Input locations read: 16 per repetition
FUNCTION
Instruction 113 communicates with the
SDM-SI04 serial input multiplexer. See the
SDM-SI04 manual for directions.
DATA
TYPE
*** 118 SDM-OBD2 ***
FUNCTION
Instruction 118 is used to read sensor values in
from an On-Board Data Acquisition II device. The
On-Board Data Acquisition II device is used to
measure different functions of a vehicle’s engine.
PARAM
NUMBER
DATA
TYPE
01:
2
02:
2
03:
4
DESCRIPTION
SDM Address (base
4:00..33)
# of PIDs (Number of
values to store)
Starting Input Location
Instruction 118 must be followed by
Instruction(s) 63 or 68. An E68 error will be
displayed when Instruction 118 is not followed
enough Instruction 63 or 68. If an “E68 104”
appears, this means that the Instruction 118 is
the 3rd instruction in Table 1 and that not
enough Instruction 63/68 are following it. The
instructions are used to list the sensor numbers
in the order one wants to store the information.
For example, to store the first 5 readings and the
12th reading in a specific order (4th, 3rd, 1st,
5th, 12th, and 2nd), use the below Instruction 63:
P63
1:
2:
3:
4:
5:
6:
7:
8:
4
3
1
5
12
2
0
0
Input Locations Altered: 1 per # of PIDs
SECTION 10. PROCESSING INSTRUCTIONS
To facilitate cross referencing, parameter
descriptions are keyed [] to the values given on
the PROMPT SHEET. These values are
defined as follows:
[Z] = User specified input location number
destination
[X] = Input location no. of source X
[Y] = Input location no. of source Y
[F] = Fixed data (user specified, entered via the
keyboard)
*** 33 X + Y ***
FUNCTION
Add the value in Input location X to the value in
location Y and place the result in location Z.
PAR. DATA
NO. TYPE DESCRIPTION
01:
02:
03:
4
4
4
Input location of X
Input location of Y
Dest. input location of X + Y
[X]
[Y]
[Z]
*** 30 LOAD FIXED DATA, Z = F ***
Input locations altered: 1
FUNCTION
Store a fixed value into input location Z.
*** 34 X + F ***
PAR. DATA
NO. TYPE DESCRIPTION
01:
02:
FP
4
Fixed data
Destination for input location
FUNCTION
Add the fixed number F to the value in location
X and place the result in location Z.
[F]
[Z]
PAR. DATA
NO. TYPE DESCRIPTION
Input locations altered: 1
01:
02:
03:
*** 31 MOVE INPUT DATA, Z = X ***
FUNCTION
Move data from one input location to another.
4
FP
4
4
4
Input location of X
Destination for input location
[X]
[F]
[Z]
Input locations altered: 1
PAR. DATA
NO. TYPE DESCRIPTION
01:
02:
Input location of X
Value to add
Dest. input location of X + F
*** 35 X - Y ***
[X]
[Z]
Input locations altered: 1
FUNCTION
Subtract the value in location Y from the value
in location X and place the result in location Z.
PAR. DATA
NO. TYPE DESCRIPTION
*** 32 INCREMENT INPUT LOCATION, ***
Z = Z+1
FUNCTION
Add 1 to the current value in input location Z.
01:
02:
03:
4
4
4
Input location of X
Input location of Y
Dest. input location for X - Y
[X]
[Y]
[Z]
Input locations altered: 1
PAR. DATA
NO. TYPE DESCRIPTION
01:
4
Destination for input location
[Z]
Input locations altered: 1
10-1
SECTION 10. PROCESSING INSTRUCTIONS
PAR. DATA
NO. TYPE DESCRIPTION
*** 36 X * Y ***
FUNCTION
Multiply the value in location X by the value in
location Y and place the result in location Z.
01:
02:
4
4
Input location of X
1/2
Dest. input location for X
[X]
[Z]
Input locations altered: 1
PAR. DATA
NO. TYPE DESCRIPTION
*** 40 LN(X) ***
01:
02:
03:
4
4
4
Input location of X
Input location of Y
Dest. input location for X * Y
[X]
[Y]
[Z]
Input locations altered: 1
FUNCTION
Take the natural logarithm of the value in
location X and place the result in location Z. If
the value in X is 0 or negative, -99999 will be
stored as the result.
*** 37 X * F ***
PAR. DATA
NO. TYPE DESCRIPTION
FUNCTION
Multiply the value in location X by the fixed
number F and place the result in location Z.
01:
02:
PAR. DATA
NO. TYPE DESCRIPTION
01:
02:
03:
4
FP
4
Input location of X
Fixed multiplier
Dest. input location for X * F
4
4
Input location of X
[X]
Dest. input location for LN(X) [Z]
Input locations altered: 1
[X]
[F]
[Z]
Input locations altered: 1
*** 41 EXP(X) ***
FUNCTION
Raise the exponential base e to the value in
location X power and place the result in location
Z.
*** 38 X / Y ***
FUNCTION
Divide the value in location X by the value in
location Y and place the result in location Z.
Division by 0 will cause the result to be set to
the maximum CR7 number (+99999 if positive, 99999 negative).
PAR. DATA
NO. TYPE DESCRIPTION
01:
02:
4
4
Input locations altered: 1
PAR. DATA
NO. TYPE DESCRIPTION
01:
02:
03:
4
4
4
Input location of X
Input location of Y
Dest. input location for X / Y
Input location of X
[X]
Dest. input location for EXP(X) [Z]
*** 42 1/X ***
[X]
[Y]
[Z]
Input locations altered: 1
FUNCTION
Take the inverse of the value in location X and
place the result in location Z. If X=0, 99999 will
be stored as the result.
PAR. DATA
NO. TYPE DESCRIPTION
*** 39 SQUARE ROOT ***
FUNCTION
Take the square root of the value in location X
and place the result in location Z. If the value in
X is negative, 0 will be stored as the result.
10-2
01:
02:
4
4
Input location of X
Dest. input location for 1/X
Input locations altered: 1
[X]
[Z]
SECTION 10. PROCESSING INSTRUCTIONS
*** 43 ABS(X) ***
FUNCTION
Take the absolute value of the value in location
X and place the result in location Z.
PAR. DATA
NO. TYPE DESCRIPTION
01:
02:
4
4
PAR. DATA
NO. TYPE DESCRIPTION
01:
02:
03:
4
FP
4
Input locations altered: 1
*** 47 XY ***
Input location of X
[X]
Dest. input location for ABS(X) [Z]
Input locations altered: 1
*** 44 FRACTIONAL VALUE ***
FUNCTION
Take the fractional value (i.e., the non-integer
portion) of the value in location X and place the
result in location Z.
PAR. DATA
NO. TYPE DESCRIPTION
Input location of X
[X]
Fixed divisor
[F]
Dest. input location for X MOD F [Z]
FUNCTION
Raise the value in location X to the value in
location Y power and place the result in location
Z.
PAR. DATA
NO. TYPE DESCRIPTION
01:
02:
03:
4
4
4
Input location of X
Input location of Y
Y
Dest. input location for X
[X]
[Y]
[Z]
Input locations altered: 1
01:
02:
4
4
Input location of X
[X]
Dest. input location for FRAC(X)[Z]
Input locations altered: 1
*** 45 INTEGER VALUE ***
FUNCTION
Take the integer portion of the value in location
X and place the result in location Z.
PAR. DATA
NO. TYPE DESCRIPTION
01:
02:
4
4
Input location of X
[X]
Dest. input location for INT(X) [Z]
*** 48 SIN(X) ****
FUNCTION
Calculate the sine of the value in location X
(assumed to be in degrees) and place the result
in location Z. The cosine of a number can be
obtained by adding 90 to the number and taking
the sine (COSX = SIN (X + 90)).
PAR. DATA
NO. TYPE DESCRIPTION
01:
02:
4
4
Input location of X
[X]
Dest. input location for SIN(X) [Z]
Input locations altered: 1
Input locations altered: 1
*** 49 SPATIAL MAXIMUM ***
*** 46 X MOD F ***
FUNCTION
Do a modulo divide of the value in location X by
the fixed value F and place the result in location
Z. X MOD F is defined as the REMAINDER
obtained when X is divided by F (e.g., 3 MOD 2
= 1). X MOD 0 returns X.
FUNCTION
Find the maximum value in the given set or
SWATH of contiguous input locations and place
the result in location Z. To find the input
location where the maximum value occurs,
enter 1000 + the input location number (1000 +
Z) as Parameter 03. The input location of the
maximum value observed will then be stored in
destination [Z] plus 1.
10-3
SECTION 10. PROCESSING INSTRUCTIONS
Parameter 3 cannot be entered as an indexed
location within a loop (Instruction 87). To use
Instruction 49 within a loop, enter Parameter 3
as a fixed location and follow 49 with Instruction
31 (Move Data). In Instruction 31, enter the
location in which 49 stores its result as the
source (fixed) and enter the destination as an
indexed location.
PAR. DATA
NO. TYPE DESCRIPTION
01:
02:
03:
2
4
4
Swath
[SWATH]
Starting input location [1ST LOC]
Dest. input location for average
[AVG or Z]
Input locations altered: 1
PAR. DATA
NO. TYPE DESCRIPTION
01:
02:
03:
2
4
4
Swath
[SWATH]
Starting input location [1ST LOC]
Dest. input location for maximum
[MAX or Z]
Input locations altered: 1 or 2
*** 53 SCALING ARRAY WITH ***
MULTIPLIER AND OFFSET
FUNCTION
Take 4 input location values, multiply each by a
floating point constant, then add another floating
point constant to the resulting products and
place the results back into each of the original 4
input locations.
*** 50 SPATIAL MINIMUM ***
FUNCTION
Find the minimum value in the given set or
SWATH of contiguous input locations and place
the result in location Z. To find the input
location where the minimum value occurs,
follow the instructions given above for SPATIAL
MAXIMUM.
Parameter 3 cannot be entered as an indexed
location in a loop. Within a loop, Instruction 50
must be used in conjunction with Instruction 31
as described for Instruction 49.
PAR. DATA
NO. TYPE DESCRIPTION
01:
02:
03:
04:
05:
06:
07:
08:
09:
4
FP
FP
FP
FP
FP
FP
FP
FP
First input location
Multiplier 1
Offset 1
Multiplier 2
Offset 2
Multiplier 3
Offset 3
Multiplier 4
Offset 4
[STRT LOC]
[A1]
[B1]
[A2]
[B2]
[A3]
[B3]
[A4]
[B4]
Input locations altered: 4
PAR. DATA
NO. TYPE DESCRIPTION
01:
02:
03:
2
4
4
Swath
[SWATH]
Starting input location [1ST LOC]
Dest. input location for minimum
[MIN or Z]
Input locations altered: 1 or 2
*** 51 SPATIAL AVERAGE ***
FUNCTION
Calculate the average of the values in the given
set or SWATH of contiguous input locations and
place the result in location Z.
10-4
*** 54 BLOCK MOVE ***
FUNCTION
Moves a block of data from one set of input
locations to another. Parameters specify the
number of values to move, the source, source
step, destination, and destination step. The
"step" parameters designate the increment of
the source and destination Input locations for
each value that is moved. For example, a
"source step" of 2 and a "destination step" of 1
will move data from every other Input location to
a contiguous block of Input locations.
SECTION 10. PROCESSING INSTRUCTIONS
PAR. DATA
NO. TYPE DESCRIPTION
01:
02:
03:
04:
05:
4
4
2
4
2
Number of values to move
1st source location
Step of source
1st destination location
Step of destination
1976: An Approximating Polynomial for
Computation of Saturation Vapor Pressure.
J. Appl. Meteor. 16, 100-103.
Saturation vapor pressure over ice (SVPI) in
kilopascals for a 0 oC to -50 oC range can be
obtained using Instruction 55 and the
relationship
SVPI = -.00486 + .85471 X + .2441 X2
Input locations altered: number of values to
move
*** 55 5TH ORDER POLYNOMIAL ***
FUNCTION
Evaluate a 5th order polynomial of the form.
F(X)=C0+C1X+C2X2+C3X3+C4X4+C5X5
where C0 through C5 are the coefficients for the
argument X raised to the zero through fifth
power, respectively. The magnitude of the user
entered coefficient is limited to a range of
+99999 to -99999. Polynomials with
coefficients outside this range can be modified
by pre-scaling the X value by an appropriate
factor to place the coefficients within the entry
range. Pre-scaling can also be used to modify
coefficients which are very close to 0 in order to
increase the number of significant digits.
PAR. DATA
NO. TYPE DESCRIPTION
01:
02:
03:
2
4
4
04:
05:
06:
07:
08:
09:
FP
FP
FP
FP
FP
FP
Repetitions
[REPS]
Starting input location for X
[X]
Dest. input location for F(X)
[F(X) or Z]
C0 coefficient
[C0]
C1 coefficient
[C1]
C2 coefficient
[C2]
C3 coefficient
[C3]
C4 coefficient
[C4]
C5 coefficient
[C5]
where X is the SVPW derived by Instruction 56.
This relationship was derived by Campbell
Scientific from the equations for the SVPW and
the SVPI given in Lowe's paper.
PAR. DATA
NO. TYPE DESCRIPTION
01:
4
02:
4
o
Input location of air temperature C
[TEMP.]
Dest. input location for saturated
vapor pressure
[VP or Z]
Input locations altered: 1
*** 57 VAPOR PRESSURE FROM ***
WET-/DRY-BULB TEMPERATURES
FUNCTION
This instruction calculates vapor pressure in
kilopascals from wet- and dry-bulb
temperatures in oC. The algorithm is of the
type used by the National Weather Service:
VP = VPW - A(1 + B*TW)(TA - TW) P
VP = ambient vapor pressure in
kilopascals
VPW = saturation vapor pressure at the wetbulb temperature in kilopascals
TW = wet-bulb temperature, deg. C
TA = ambient air temperature, deg. C
P = air pressure in kilopascals
A = 0.000660
B = 0.00115
Input locations altered: 1 per repetition
*** 56 SATURATION VAPOR PRESSURE ***
FUNCTION
Calculate saturation vapor pressure over water
(SVPW) in kilopascals from the air temperature
(oC) and place it in an input location. The
algorithm for obtaining SVPW from air
temperature (oC) is taken from: Lowe, Paul R.,
Although the algorithm requires an air pressure
entry, the daily fluctuations are small enough
that for most applications a fixed entry of the
standard pressure at the site elevation will
suffice. If a pressure sensor is employed, the
current pressure can be used.
10-5
SECTION 10. PROCESSING INSTRUCTIONS
PAR. DATA
NO. TYPE DESCRIPTION
01:
4
02:
4
03:
4
04:
4
Input location no. of atmospheric
pressure in kilopascals
[PRESSURE]
Input location no. of dry-bulb
temp.
[DB TEMP.]
Input location no. of wet-bulb
temp.
[WB TEMP.]
Dest. input location for vapor
pressure
[VP or Z]
Input locations altered: 1
*** 59 BRIDGE TRANSFORM ***
FUNCTION
This instruction is used to aid in the conversion
of a ratiometric Bridge measurement by
obtaining the value for Rs which is equivalent to
Rf[X/(1-X)], where X is the value derived by the
standard CR7 Bridge Measurement Programs
(with appropriate multiplier and offset, Section
13.5) and Rf represents the MULTIPLIER value.
The result of Instruction 59 is stored in the
same location that X was.
PAR. DATA
NO. TYPE DESCRIPTION
*** 58 LOW PASS FILTER ***
FUNCTION
Apply a numerical approximation to an analog
resistor capacitor (RC) low pass (LP) filter using
the following algorithm:
01:
02:
2
4
03:
FP
Repetitions
[REPS]
Starting input location and
destination
[X]
[MULT.]
Multiplier (Rf)
Input locations altered: 1 per repetition
F(Xi) = W*Xi + F(Xi-1) * (1-W)
Where, X = input sample,
W = user entered weighting function,
O< W <1
If W=O, F(Xi)=O; if W=1, F(Xi)=X,
F(Xi-1)
= output calculated for previous sample.
The equivalent RC time constant is given by
T/W, where T is the sampling time in seconds.
For values of W less than 0.25, the analogous
"cut off" frequency (the frequency where the
ratio of output to input is .707) is accurately
represented by W/(2ΠT). For larger values of
W, this "analog" estimate of the cutoff frequency
becomes less representative.
On the first execution after compiling, F(x) is set
equal to X.
PAR. DATA
NO. TYPE DESCRIPTION
01:
02:
2
4
03:
4
04:
FP
Repetitions
[REPS]
First input location for input data
[X]
Dest. input location for filtered
data
[F(X) or Z]
Weighting function, W
[W]
Input locations altered: 1 per repetition
10-6
*** 61 INDIRECT INDEXED MOVE ***
FUNCTION
Moves input data from location X to location Y,
where X and Y are indirectly addressed. The
values of the location numbers X and Y are
stored in the locations specified by Parameters
1 and 2. The CR7 looks in the locations
specified in the parameters to find the locations
to use as the source and destination of the data.
When used within a LOOP, a location
parameter can be specified as "indexed"
(xxxx-), then the actual Input location
referenced is calculated by adding the current
index counter to the value in the specified Input
location.
PAR. DATA
NO. TYPE DESCRIPTION
01:
4
02:
4
Input location containing source
location X
Input location containing destination
location Y
*** 62 COVARIANCE/CORRELATION ***
FUNCTION
The special Covariance/Correlation Instruction
(CV/CR) for the CR7 calculates: 1) means (M),
2) variances (V), 3) standard deviations (SD), 4)
covariances (CV), and 5) correlations (CR) for a
set of input values and stores the results in
SECTION 10. PROCESSING INSTRUCTIONS
Input Storage. The instruction requires the set
of input values to be located contiguously in
Input Storage. The user specifies the location
of the first value and how many total values
exist. The number of input values processed by
each type of calculation (means, variances,
etc.) is independently specified for each type.
The order of the input values determines which
inputs are processed for each type of
calculation.
The instruction does not conform to the CR7's
four instruction types. Data located in Input
Storage is processed, and the results returned
to Input Storage whenever an averaging period
is completed (Parameter 7) or the Output Flag
is set. The instruction controlling the Output
Flag must precede the CV/CR Instruction. The
reason the calculated results are returned to
Input Storage is to allow the user access for
additional processing before storing the values
in Final Storage. Sample Instruction 70 must
be used to transfer final results from Input to
Final Storage.
To accommodate cases where it is desirable to
calculate the statistical quantities over time
periods shorter than the Output Interval, an
averaging period shorter than the Output
Interval may be specified. The final values
obtained at the Output Interval are the properly
weighted average of the values calculated at
the subinterval averaging periods. This feature
allows the recording of statistical data over
longer time periods by removing the effect of
longer period frequencies in the input signals;
i.e., it provides a high pass filter. For example,
assume the variance of an input is desired. It is
determined that the averaging period should not
exceed five minutes due to variation in the
mean over longer time intervals. One approach
is to calculate and record the variance every
five minutes. By specifying the subinterval
averaging period as five minutes and the Output
Interval as one hour, however, the average of
the five minute variances are recorded every
hour. The averaging period is entered as the
number of input samples in Parameter 7 of the
CV/CR Instruction. The number of samples for
a given period is given by:
Number of Samples =
Averaging period in seconds
Table execution interval in seconds
PAR. DATA
NO. TYPE DESCRIPTION
01:
2
02:
03:
04:
2
2
2
05:
06:
07:
2
2
FP
08:
4
09:
4
Number of input values located
sequentially in input memory
Number of means desired
Number of variances desired
Number of standard deviations
desired
Number of covariances desired
Number of correlations desired
Number of input samples in
averaging period
Input storage location of first
value in sequential input string
First Input Storage location to
store string of final results
If the specified number of samples in the
averaging period (Parameter 7) exceeds the
actual number of samples occurring in the
Output Interval, the Output Interval becomes the
averaging period.
10-7
SECTION 10. PROCESSING INSTRUCTIONS
TABLE 10-1. Maximum Number of Outputs and Output Order for K Input Values.
(The output order flows from left to right and from top to bottom)
INPUTS:
X1
X2
X3
X4
TYPE
MAX NO.
OUTPUTS
(1st)
(2nd)
(3rd)
OUTPUTS
(4th)
Means
K
M(X1)
M(X2)
M(X3)
M(X4)
.....
M(XK)
Variances
K
V(X1)
V(X2)
V(X3)
V(X4)
.....
V(XK)
Std. Deviation
K
SD(X1)
SD(X2)
SD(X3)
SD(X4)
.....
SD(XK)
Covariance
K/2(K-1)
CV(S1,X2)
CV(X1,X3)
CV(X2,X3)
CV(X1,X4)
CV(X2,X4)
CV(X3,X4)
.....
.....
.....
...
..
.
CV(X1,XK)
CV(X2,XK)
CV(X3,XK)
.
.
.
CV(XK-1,XK)
Correlation
K/2(K-1)
CR(X1,X2)
CR(X1,X3)
CR(X2,X3)
CR(X1,X4)
CR(X2,X4)
CR(X3,X4)
.....
.....
.....
...
..
.
CR(X1,XK)
CR(X2,XK)
CR(X3,XK)
.
.
.
CR(XK-1,XK)
SYMBOL
DEFINITION
M(XK)
V(XK)
SD(XK)
CV(XK,X1)
CR(XK,X1)
Mean of Kth value
Variance of Kth value
Standard deviation of Kth value
Covariance of Kth and Ith value
Correlation of Kth and Ith value
MAXIMUM NUMBER OF POSSIBLE
OUTPUTS
No limitation exists on the number of inputs that
can be processed by the CV/CR Instruction, but
the processing time and Intermediate Storage
requirements increase rapidly. The instruction
requires that the input values reside sequentially
in Input Storage. Since the number of outputs
is specified for each type of statistical
calculation, the instruction starts with the first
value, working sequentially through the input
values. For this reason, the order of the input
values determines which values are processed.
10-8
.....
XK
(Kth)
Table 10-1 shows the maximum number of
outputs which can be generated and the output
order for K input values located sequentially in
Input Storage. The output order shown in Table
10-1 flows from left to right and top to bottom.
INSTRUCTION PROCESSING
The CV/CR Instruction contains three separate
processing phases:
1. Input Processing
2. Averaging Period Processing
3. Output Processing
SECTION 10. PROCESSING INSTRUCTIONS
The Input Processing phase is where new input
values are received, the necessary squares or
cross products formed, and the appropriate
summations calculated as required by the
desired final output. The rate at which the
measurements can be made, the input values
ordered, and the input processing phase
completed without interruption determines the
maximum rate of execution (see Execution
Time).
The Averaging Period Processing occurs
whenever the number of input samples entered
in Parameter 7 is satisfied or whenever an
Output Interval occurs (i.e., whenever the
Output Flag is set). Results from these
calculations are stored sequentially in Input
Storage locations starting with the location
specified in Parameter 9. The calculations
performed are shown below, where N is the
number of input samples in the averaging
period:
1. Means:
M(X) = ΣX/N
2. Variances:
V(X) = ΣX2/N - (ΣX/N)2
3. Standard Deviations:
SD(X) = V(X)1/2
4. Covariances:
CV(X,Y) = ΣXY/N - ΣX ΣY/N2
5. Correlations:
CR(X) = CV(X,Y)/(SD(X)SD(Y))
NOTES: 1. The square root algorithm in
the CR7 returns a result of 0 for negative
arguments.
2. The divide algorithm returns the largest
floating point number possible (±1018
displayed as ±99999) for a divide by 0.
3. When computing the variance of a
constant signal, round off error produces a
small negative result. The CR7 returns a 0
for the square root of a negative number;
therefore, the standard deviation is set to 0.
If the signal is also used in a correlation
calculation, division by 0 returns an
overrange value for the correlation result.
If a fast execution interval is specified, it is
possible that the combined execution times of
the input and averaging period processing may
exceed the program table execution interval.
The occurrence of an execution interval
Overrun (see Section 2.1 of CR7 Operator's
Manual) is noted by decimal points on either
side of the G in LOG (*0 MODE). This results in
the omission of one input sample. The
calculations are not affected, however, since the
number of input samples is incremented only
when valid input processing occurs. Averaging
period processing occurs only when the number
of input samples specified in Parameter 7 is
accumulated.
Regardless of whether all of the input samples
for the averaging period (specified in Parameter
7) have occurred or not, averaging period
processing occurs whenever the Output Flag is
set. This accommodates situations where the
Output Interval may not be an integer multiple of
the averaging period. If for example a 30
minute Output Interval is set by Instruction 92
and an 8 minute averaging period is specified
by Parameter 7, then three 8 minute and one 6
minute calculations will occur. The proper
weighting of these values in producing the final
output is described below.
The Output Processing occurs only at the
Output Interval and involves averaging the
statistical results obtained at the averaging
periods. These final results are then stored
sequentially in Input Storage beginning with the
location specified in Parameter 9. The Sample
Instruction 70 must be used to transfer the data
to Final Storage. All but the last averaging
period in the Output Interval will contain the
same number of input scans as specified by
Parameter 7. To insure that results from the
averaging periods contribute to the final result
proportional to their averaging periods, the
output processing uses the following equation:
RF = (NR1 + NR2 + .... + N'RL)/NT
RF is the final result
R1 R2, etc., are the results from the averaging
period processing
RL is the result from the last averaging period
in the Output Interval
N is the number of input samples in the
specified averaging period (Parameter 7)
N' is the number of input scans in the last
averaging period
10-9
SECTION 10. PROCESSING INSTRUCTIONS
NT is the total number of input samples
processed in the Output Interval
INTERMEDIATE STORAGE REQUIREMENTS
The number of Intermediate locations will
depend upon the number of input values and
outputs desired:
1. Define K as the number of input values.
2. Define S as the maximum of either the
variances, standard deviations, or C, where
C = K if K < the number of correlations
requested, or
C = number of correlations + 1 if K > the
number of correlations requested.
3. Define Q as the maximum of either the
covariances or correlations desired.
4. Define P as the total number of outputs
desired.
The amount of intermediate memory locations
(IML) required, is then given by:
IML = K + S + Q + P + 2
EXECUTION TIME
If K, S, and Q are defined as in the previous
section, the execution time of the CV/CR
Instruction in milliseconds can be approximated
by:
that less overhead time is required in going
from one measurement to another within a
single instruction (using the "repetitions"
feature) than in going from one measurement
instruction to another.
In many situations, the CR7 must perform
measurement and processing tasks in addition
to those associated with the CV/CR Instruction.
Uninterrupted operation of the CV/CR
Instruction is assured by entering it in Program
Table 1 (highest priority) and placing the
additional tasks in Program Table 2.
A covariance correlation example is given in
Section 8.
*** 66 ARCTAN ***
FUNCTION
Calculate the angle in degrees whose tangent is
X/Y. The polarity of X and Y must be known to
determine the quadrant of the angle, as shown
here. If 0 is entered for Parameter 2, the
Arctangent of X is the result (limits of the
function are -90o < ARCTAN < 90o).
Quadrant
Sign of X
Sign of Y
I
II
III
IV
+
+
+
+
T(ms) = 1.1K + 0.5S + 0.9Q + 1.8
When evaluating how frequently input samples
can be processed by the CV/CR Instruction
(i.e., determining the minimum program table
execution interval), the time required to make
the measurements and order the input values
must be added to the CV/CR execution time.
Two alternatives exist for the measurement
portion of the programming. The fastest
method is to group as many sensors as
possible into the fewest measurement
instructions, ignoring the Input location order
required by the CV/CR Instruction. After the
measurements are made, use "move"
instructions (i.e., 31 and 54) to obtain the proper
input order. The slower alternative is to order
separate measurement instructions directly as
required by the CV/CR Instruction. While
avoiding "move" instructions, this approach
uses more measurement instructions. The
reason the first method is in general faster is
10-10
PAR. DATA
NO. TYPE DESCRIPTION
01:
02:
03:
4
4
4
Input location of X
Input location of Y
Destination input location for
ARCTAN(X/Y)
[X]
[Y]
Input locations altered: 1
*** 68 EXTENDED PARAMETERS 4 DIGIT ***
FUNCTION
This instruction is used to give other instructions
additional parameters. Each of the eight
parameters in Instruction 68 is defined by the
instruction it follows. Refer to the specific
instruction that uses extended parameters.
Input location altered: 0
SECTION 11. OUTPUT PROCESSING INSTRUCTIONS
*** 69 WIND VECTOR ***
FUNCTION
Instruction 69 processes the primary variables
of wind speed and direction from either polar
(wind speed and direction) or orthogonal (fixed
East and North propellers) sensors. It uses the
raw data to generate the mean wind speed, the
mean wind vector magnitude, and the mean
wind vector direction over an output interval.
Two different calculations of wind vector
direction (and standard deviation of wind vector
direction) are available, one of which is
weighted for wind speed.
When used with polar sensors, the instruction
does a modulo divide by 360 on wind direction,
which allows the wind direction (in degrees) to
be 0 to 360, 0 to 540, less than 0, or greater
than 540. The ability to handle a negative
reading is useful in an example where a difficult
to reach wind vane is improperly oriented and
outputs 0 degrees at a true reading of 340
degrees. The simplest solution is to enter an
offset of -20 in the instruction measuring the
wind vane, which results in the correct output
following processing.
When a wind speed sample is 0, the instruction
uses 0 to process scalar or resultant vector
wind speed and standard deviation, but the
sample is not used in the computation of wind
direction. The user may not want a sample less
than the sensor threshold used in the standard
deviation. If this is the case instruction 89 can
be used to check wind speed, and if less than
the threshold, Instruction 30 can set the input
location equal to 0.
Standard deviation can be processed one of
two ways: 1) using every sample taken during
the output period (enter 0 for parameter 2), or 2)
by averaging standard deviations processed
from shorter sub-intervals of the output period
(enter the number of scans in the sub-interval
for parameter 2). Averaging sub-interval
standard deviations minimizes the effects of
meander under light wind conditions, and it
provides more complete information for periods
1
of transition .
Standard deviation of horizontal wind
fluctuations from sub-intervals is calculated as
follows:
σ(θ)=[((σθ1)2+(σθ2)2 ...+( σθM)2)/M]1/2
where σ(θ) is the standard deviation over the
output interval, and σθ1 ... σθM are sub-interval
standard deviations.
PARAM.
NUMBER
DATA
TYPE
01:
02:
2
4
03:
2
04:
4
05:
4
DESCRIPTION
Repetitions
Samples per sub-interval
(number of scans)
Sensor/Output 2 digits:
AB
A Sensor type:
0 = Speed and
Direction
1 = East and North
B Output option:
0 S, θ1, σ(θ1)
1 S, θ1
2 S, U, θu, σ(θu)
First wind speed input
location number
(East wind speed)
First wind direction input
location number
(North wind speed)
Outputs Generated: 2-4 (depending on output
option) per repetition
A sub-interval is specified as a number of
scans. The number of scans for a sub-interval
is given by:
Desired sub-interval (secs) / scan rate (secs)
In an example where the scan rate is one
second and the Output Flag is set every 60
1
EPA On-site Meteorological Program Guidance
for Regulatory Modeling Applications.
11-1
SECTION 11. OUTPUT PROCESSING INSTRUCTIONS
minutes, the standard deviation is calculated
from all 3600 scans when the sub-interval is 0.
With a sub-interval of 900 scans (15 minutes),
the standard deviation is the average of the four
sub-interval standard deviations. The last subinterval is weighted if it does not contain the
specified number of scans.
Calculations:
There are three Output Options, which specify
the values calculated.
Unit vector mean wind direction, θ1:
Option 0:
where
Scalar mean horizontal wind speed, S:
S=(ΣSi)/N
where in the case of orthogonal sensors:
Si=(Uei2+Uni2)1/2
θ1=Arctan (Ux/Uy)
Ux=(Σsin θi)/N
Mean horizontal wind speed, S.
Unit vector mean wind direction, θ1.
Standard deviation of wind direction, σ(θ1).
Uy=(Σcos θi)/N
or, in the case of orthogonal sensors
Standard deviation is calculated using the
Yamartino algorithm. This option complies
with EPA guidelines for use with straightline Gaussian dispersion models to model
plume transport.
Option 1:
Mean horizontal wind speed, S.
Unit vector mean wind direction, θ1.
Option 2:
Ux=(Σ(Uei/Ui))/N
Uy=(Σ(Uni/Ui))/N
where Ui=(Uei2+Uni2)1/2
Standard deviation of wind direction, σ(θ1),
using Yamartino algorithm:
σ(θ1)=arc sin(ε)[1+0.1547 ε3]
where,
ε=[1-((Ux)2+(Uy)2)]1/2
and Ux and Uy are as defined above.
Mean horizontal wind speed, S.
Resultant mean wind speed, U.
Resultant mean wind direction, θu.
Standard deviation of wind direction, σ(θu).
This standard deviation is calculated using
Campbell Scientific's wind speed weighted
algorithm.
Use of the resultant mean horizontal wind
direction is not recommended for straightline Gaussian dispersion models, but may
be used to model transport direction in a
variable-trajectory model.
Measured raw data:
Si = horizontal wind speed
θi = horizontal wind direction
Uei = east-west component of wind
Uni = north-south component of wind
N = number of samples
11-2
Resultant mean horizontal wind speed, U:
U=(Ue2+Un2)1/2
where for polar sensors:
Ue=(ΣSi Sin θi)/N
Un=(ΣSi Cos θi)/N
or, in the case of orthogonal sensors:
Ue=(ΣUei)/N
Un=(ΣUni)/N
Resultant mean wind direction, θu:
θu=Arctan (Ue/Un)
Standard deviation of wind direction, σ(θu),
using Campbell Scientific algorithm:
σ(θu)=81(1-U/S)1/2
SECTION 11. OUTPUT PROCESSING INSTRUCTIONS
*** 70 SAMPLE ***
FUNCTION
This instruction stores the value from each
specified input location.
PAR.
NO.
DATA
TYPE
DESCRIPTION
01:
02:
2
4
Repetitions
Starting input location number
PAR.
NO.
DATA
TYPE
DESCRIPTION
01:
02:
03:
2
2
4
Repetitions
Time of maximum (optional)
Starting input location number
Outputs generated: 1 per repetition (plus 1 or 2
with time of max. option)
CODE OPTIONS
Outputs generated: 1 per repetition
00
*** 71 AVERAGE ***
01
FUNCTION
This instruction stores the average value over
the given output interval for each input location
specified.
Output the maximum (or minimum)
value ONLY
Output the max. (or min.) value with
SECONDS information
Output the max. (or min.) value with
HOUR-MINUTE information
Output the max. (or min.) value with
HR-MIN,SEC information
10
11
*** 74 MINIMUM ***
PAR.
NO.
DATA
TYPE
DESCRIPTION
01:
02:
2
4
Repetitions
Starting input location number
Outputs generated: 1 per repetition
FUNCTION
Operating in the same manner as Instruction
73, this instruction is used for storing the
MINIMUM value sensed (for each input location
specified) over a given output interval.
PAR.
NO.
DATA
TYPE
DESCRIPTION
FUNCTION
This instruction stores the totalized value over
the given output interval for each input location
specified.
01:
02:
03:
2
2
4
Repetitions
Time of minimum (optional)
Starting input location number
PAR.
NO.
DATA
TYPE
DESCRIPTION
Outputs generated: 1 per repetition (plus 1 or 2
with time of min. option)
01:
02:
2
4
Repetitions
Starting input location number
*** 72 TOTALIZE ***
Outputs generated: 1 per repetition
*** 73 MAXIMUM ***
FUNCTION
This instruction stores the MAXIMUM value
taken (for each input location specified) over a
given output interval. An internal FLAG is set
whenever a new maximum value is seen. This
FLAG may be tested by Instruction 79. Time of
maximum value(s) is OPTIONAL output
information, which is selected by entering the
appropriate code for Parameter 2.
*** 75 STANDARD AND WEIGHTED ***
VALUE HISTOGRAM
FUNCTION
Processes input data as either a standard
histogram (frequency distribution) or a weighted
value histogram.
The standard histogram outputs the fraction of
time that the value in a specified input location
(defined as the bin select value) is within a
particular subrange of the total specified range.
The count in the bin associated with each
subrange is incremented whenever the value
falls within that subrange. The value which is
output to Final Storage for each bin is computed
by dividing the accumulated total in each bin by
11-3
SECTION 11. OUTPUT PROCESSING INSTRUCTIONS
the total number of scans. This form of output
is also referred to as a frequency distribution.
The weighted value histogram uses data from
two input locations. One location contains the
bin select value; the other contains the weighted
value. Each time the instruction is executed,
the weighted value is added to a bin. The subrange that the bin select value is in determines
the bin to which the weighted value is added.
When the Output Flag is set, the value
accumulated in each bin is divided by the
TOTAL number of input scans to obtain the
values that are output to Final Storage. These
values are the contributions of the sub-ranges
to the overall weighted value. To obtain the
average of the weighted values that occurred
while the bin select value was within a particular
sub-range, the value output to Final Storage
must be divided by the fraction of time that the
bin select value was within that particular subrange (i.e., a standard histogram of the bin
select value must also be output).
For either histogram, the user must specify: 1)
the number of repetitions, 2) the number of
bins, 3) a form code specifying whether a
closed or open form histogram is desired (see
below), 4) the bin select value input location, 5)
the weighted value input location (see below),
6) the lower range limit, and 7) the upper range
limit.
The standard histogram (frequency distribution)
is specified by entering "0" in the weighted value
input location parameter. Otherwise, this
parameter specifies the input location of the
weighted value. With more than one repetition
the bin select value location will be incremented
each repetition and the weighted value location
will remain the same (same weighted value
sorted on the basis of different bin select
values). The weighted value location will be
incremented if it is entered as an indexed
location (key "C" at some point while keying in
Parameter 5; two dashes, --, will appear on the
right of the display).
At the user's option, the histogram may be
either closed or open. The open form includes
all values below the lower range limit in the first
bin and all values above the upper range limit in
the last bin. The closed form excludes any
values falling outside of the histogram range.
11-4
The difference between the closed and open
form is shown in the following example for
temperature values:
Lower range limit
Upper range limit
Number of bins
10 oC
30 oC
10
Closed Form Open Form
Range of first bin
Range of last bin
10 to 11.99o <12o
28 to 29.99o >28o
A common use of a closed form weighted value
histogram is the wind speed rose. Wind speed
values (the weighted value input) are
accumulated into corresponding direction
sectors (bin select input).
PAR.
NO.
DATA
TYPE
01:
02:
03:
2
4
2
04:
05:
4
4
06:
07:
FP
FP
DESCRIPTION
Repetitions
Number of bins
Form code (0=open form,
1=closed form)
Bin select value input location no.
Weighted value input location no.
(0 = frequency distribution option)
Lower limit of range
Upper limit of range
Outputs generated: number of bins * repetitions
*** 77 RECORD REAL TIME ***
FUNCTION
This instruction stores the current time in Final
Storage. At midnight the clock rolls over from
23:59 to 00:00. The day also changes.
If hourly or daily summary data is output, it may
be desirable to have the previous day specified
with the output, since that is when the
measurements were made. Entering a 2 for the
day code causes the previous day to be output
if it is the first minute of the day. Similarly,
entering 2 for the hour-minute code causes
2400 instead of 0000 to be output (the next
minute is still 0001). When day and hourminute are both output, a 2 for either code
results in the previous day at 2400.
SECTION 11. OUTPUT PROCESSING INSTRUCTIONS
The year is output as 19xx if xx is greater than
85, otherwise it will be output as 20xx. The
CR7 will require a PROM update in the year
2085. If year is output along with a 2 option in
day or hour-minute, the previous year will be
output during the first minute of the new year.
CODE RESULTS
xxx1
xx1x
xx2x
x1xx
x2xx
1xxx
SECONDS (with a resolution of 0.1 sec.)
HOUR-MINUTE
HOUR-MINUTE, 2400 instead of 0000
DAY OF YEAR
DAY OF YEAR, previous day during
first minute of new day
YEAR
Any combination of Year, Day, HR-MIN, and
seconds is possible (e.g., 1011: YEAR, HRMIN, SEC).
PAR.
NO.
DATA
TYPE
01:
4
DESCRIPTION
Enter appropriate TIME
option code
Outputs generated: 1 for each time parameter
selected
*** 79 SAMPLE ON MAXIMUM ***
OR MINIMUM
FUNCTION
Instruction 79 samples specified input location
values at the time a new maximum or minimum
value is detected by a previous Maximize (73)
or Minimize (74) Instruction. When the Output
Flag is set, the values are transferred to Final
Storage.
Instruction 79 must directly follow the maximum
or minimum Instruction to which it refers. If the
previous Instruction 73 or 74 has more than 1
repetition, Instruction 79 will sample whenever a
new maximum or minimum is detected in any of
the locations. If sampling is to occur only when
a specific input location shows a new maximum
or minimum, the previous Maximize or Minimize
Instruction should have 1 repetition referring to
that input location.
PAR.
NO.
DATA
TYPE
01:
2
02:
4
DESCRIPTION
Repetitions (number of
sequential locations to sample)
Starting input location number
Outputs generated: 1 per repetition
*** 78 SET HIGH OR LOW RESOLUTION ***
FINAL STORAGE FORMAT
FUNCTION
This instruction sets the Final Storage Format to
high resolution (5 character) or low resolution
(4 character, Section 2.2). Instruction 78 should
be entered ahead of the output instructions for
which the specified resolution is desired. The
default format is low resolution. At the
beginning of each program table execution, the
low resolution format is automatically enabled.
PAR.
NO.
01:
DATA
TYPE
2
DESCRIPTION
0 = low resolution;
1 = high resolution
*** 80 SET ACTIVE OUTPUT AREA ***
Instruction 80 is used to direct Output data to
Final Storage or to Input Storage. At the
beginning of each table the Active Output area
is set to Final Storage. When directed to Final
Storage, the second parameter can be used to
set the output array ID. If 80 is used to direct
output to Final Storage, and Parameter 2 is 0,
the array ID is determined by the instruction
location number of Instruction 80 or by the
Instruction that set the Output Flag, whichever
came last. When data is sent to Input Storage,
no array ID is sent.
Outputs generated: 0
11-5
SECTION 11. OUTPUT PROCESSING INSTRUCTIONS
PAR.
NO.
DATA
TYPE
01:
2
02:
4
DESCRIPTION
Storage area option
01 = Final Storage (00 and
02 also default to
Final Storage)
03 = Input Storage Area
Starting input location
destination if option 03
Output Array ID if options 0-2
(1-511 are valid IDs)
*** 82 STANDARD DEVIATION IN TIME ***
FUNCTION
Calculate the standard deviation (STD DEV) of
a given input location. The standard deviation
is calculated using the formula:
S = ((ΣXi2 - (ΣXi)2/N)/N)1/2
where Xi is the ith measurement and N is the
number of samples.
PAR.
NO.
DATA
TYPE
DESCRIPTION
01:
02:
2
4
Repetitions
Starting input location number
Outputs generated: 1 per repetition
11-6
SECTION 12. PROGRAM CONTROL INSTRUCTIONS
*** 85 LABEL SUBROUTINE ***
TABLE 12-1. Flag Description
Flag 0
Flag 1 to 8
Flag 9
Output Flag
User Flags
Intermediate Processing Disable
Flag
TABLE 12-2. Port Command Codes
0
1-9, 79-99
10-19
20-29
30
31
32
41-48*
51-58*
61-68*
71-78*
-
Go to end of program table
Call Subroutine 1-9, 79-99
Set Flag 0-9 high
Set Flag 0-9 low
Then Do
Exit loop if true
Exit loop if false
Set port 1 - 8 high
Set port 1 - 8 low
Toggle port 1 - 8
Pulse port 1 - 8 100 ms
* The port commands operate on excitation card
1 or on the excitation card set active by
Instruction 20.
FUNCTION
This instruction marks the start of a subroutine.
A subroutine is a series of instructions
beginning with Instruction 85 and terminated
with Instruction 95, END. All subroutines must
be placed in Table 3 (Subroutine Table). When
a subroutine is called by a command in a
Program Control Instruction, the subroutine is
executed, then program flow continues with the
instruction following that which called the
subroutine.
Subroutines cannot be embedded within other
subroutines; a subroutine must end before the
next one begins. Subroutines may be called
from within other subroutines (nested). The
maximum nesting level for subroutines is 7
deep. Attempts to nest more than 7 deep will
not be detected at compilation, but will result in
a run time error. When the seventh subroutine
attempts to call the eighth, error 31 will be
displayed. Execution will not branch to the
eighth subroutine; it will continue with the
Instruction following that calling the subroutine.
*** 83 IF CASE X < F ***
FUNCTION
Instruction 83 tests the value in an input location
specified in the Begin Case Instruction 93. A
series of Instructions 83 are used to compare
the value in the input location to ever increasing
fixed values. If the value in the location is less
than the fixed value entered as Parameter 1,
then the command in Parameter 2 is executed
and when the next Instruction 83 is encountered
execution branches to the end of the case
statement. If the fixed value is less, the next
Instruction 83 is executed. See Instruction 93
for an example.
PAR.
NO.
DATA
TYPE
DESCRIPTION
01:
02:
FP
2
Fixed value
Command (Table 12-2)
PAR.
NO.
DATA
TYPE
DESCRIPTION
01:
2
Subroutine number (1-9, 79-99)
*** 86 DO ***
FUNCTION
This instruction unconditionally executes the
specified command.
PAR.
NO.
DATA
TYPE
DESCRIPTION
01:
2
Command (Table 12-2)
*** 87 LOOP ***
FUNCTION
Instructions included between the Loop
Instruction and the End Instruction (95) are
repeated the number of times specified by the
iteration count (Parameter 2), or until an Exit
Loop command (31, 32) is executed by a
Program Control Instruction within the Loop. If
12-1
SECTION 12. PROGRAM CONTROL INSTRUCTIONS
0 is entered for the count, the loop is repeated
until an Exit Loop command is executed.
The first parameter, delay, controls how
frequently passes through the loop are made.
The delay unit is the table execution interval:
A delay of 0 means that there is no delay
between passes through the loop. Each
time the table is executed all iterations of
the loop will be completed and execution
will pass on to the following instructions.
If the delay is 5, every fifth time that the
execution interval comes up, one pass
through the loop is made; only those
instructions in the loop will be executed and
other portions of the table are not executed
in the interim. When the loop is executed,
execution starts at the loop, skipping over
any previous instructions in the table.
When a fixed number of iterations are
executed, the time spent in the loop is equal to
the product of the execution interval, delay, and
the number of iterations. For example, a loop
with a delay of 1 and a count of 5 will take 5
seconds if the execution interval is 1 second.
When the loop is first entered, one pass through
the loop is made, then the CR7 delays until the
next execution interval and makes the second
pass through the loop. After making the fifth
pass through the loop, there is the fifth delay,
after which execution passes to the instruction
following the END instruction which goes with
the loop.
While in a loop with delay, the table will not be
initiated at each execution interval. (However,
the overrun decimals will not be displayed.)
Some consequences of this are: The Output
Flag will not be automatically cleared between
passes through the loop. Because Table 2
cannot interrupt Table 1, Table 2 will not be
executed while Table 1 is in a loop with delay.
Table 1 will not interrupt Table 2 in the middle of
an output array. Thus, if the Output Flag is set
in Table 2 prior to entering the loop or within the
loop, the flag must be specifically cleared before
the end of the pass or Table 1 will not be able to
interrupt.
Input locations for Processing Instructions within
a loop can be entered as Indexed locations. An
Indexed location causes the input location to be
incremented by 1 with each pass through the
12-2
loop. (The Index counter is added to the
location number in the program table.) Input
locations which are not indexed will remain
constant.
To specify an Indexed location, depress the C
key at some point while keying in the digits for
the input location and before entering the
location with the A key. Two dashes, --, appear
in the two right most characters of the display,
indicating the entry is Indexed.
When the same output processing is required
on values in sequential input locations, it must
be accomplished by using the repetitions
parameter of the Output Instruction, not by
indexing the input location within a loop.
An Output Instruction within a loop is allotted the
same number of Intermediate Storage locations
as it would receive if it were not in the loop. For
example, the Average instruction with a single
repetition is allotted only two Intermediate
locations: one for the number of samples and
one for the running total. Each time through the
loop the sample counter is incremented and the
value in the referenced input location is added
to the total. If the input location is indexed, the
values from all input locations are added to the
same total. If the Average instruction with 1
repetition and location 1 indexed is placed
within a loop of 10 and the Output Flag set high
prior to entering the loop, 10 values will be
output. These will not be the averages for
locations 1-10. The first will be the average of
all the readings in locations 1-10 since the
previous output. Because the Intermediate
locations are zeroed each time an output
occurs, the next nine values will be the current
values (samples at the time of output) of
Locations 2-10.
Loops can be nested. Indexed locations within
nested loops are indexed to the inner most loop
that they are within. The maximum nesting
level in the CR7 is 9 deep. This applies to If
Then/Else comparisons and Loops or any
combination thereof. An If Then/Else
comparison which uses the Else Instruction, 94
counts as being nested 2 deep.
SECTION 12. PROGRAM CONTROL INSTRUCTIONS
PAR.
NO.
DATA
TYPE
DESCRIPTION
01:
02:
2
4
Delay
Iteration count
The following example involves the use of the
Loop Instruction, without a delay, to perform a
block data transformation.
The user wants one hour averages of the vapor
pressure calculated from the wet- and dry-bulb
temperatures of five psychrometers. One
pressure transducer measurement is also
available for use in the vapor pressure
calculation.
1. The input locations are assigned as follows:
a) pressure
-location 10
b) dry-bulb temperatures
-location 11-15
c) wet-bulb temperatures
-location 16-20
d) calculated vapor pressure -location 16-20
(vapor pressure is written over the wet-bulb
temperatures.)
2. The program flow is as follows:
a) Enter the Loop Instruction 87 with
delay=0 and iteration count=5.
b) Calculate the vapor pressure with
Instruction 57 using a normal location
entry of 10 for atmospheric pressure
and Indexed locations of 11, 16, and 16
for the dry-bulb, wet-bulb and
calculated vapor pressure, respectively.
c) End loop with Instruction 95.
d) Use the If Time Instruction 92 to set the
Output Flag every hour.
e) Use the Average Instruction 71 with 5
repetitions starting at Input Location 16
to average the vapor pressure over the
hour.
The actual keyboard entries for the examples
are shown below with the first example
Instruction location equal to 10. The Input
Instructions to make the pressure and
temperature measurements are assumed.
TABLE 12-3. Loop Example: Block Data
Transform
10:
01:
02:
P87
0
5
Beginning of Loop
Delay
Loop Count
11:
01:
02:
03:
04:
P57
10
11-16-16--
Wet/Dry Bulb Temp to VP
Pressure Loc
Dry Bulb Temp Loc DRY BLB#1
Wet Bulb Temp Loc VP #1
Loc [:VP #1 ]
12:
P95
End
13:
01:
02:
03:
P92
0
60
10
If time is
minutes into a
minute interval
Set high Flag 0 (output)
14:
01:
02:
P71
5
16
Average
Reps
Loc VP #1
The Loop with a delay may be used so that only
those instructions within the Loop are executed
while certain conditions are met. As a simple
example, suppose it is desired to execute one
set of instructions from midnight until 6 AM,
another set between 6 AM and 4 PM, and a
third set between 4 PM and midnight. Between
6 AM and 4 PM, samples are desired every ten
seconds; the rest of the time one minute
between samples is sufficient. The execution
interval is set to ten seconds; when a one
minute sample rate is desired, a delay of 6 (6 x
10s = 60s) is used in the loop.
TABLE 12-4. Example: Loop with Delay
Execution Interval = 10 seconds
*
01:
1
10
Table 1 Programs
Sec. Execution Interval
01:
01:
02:
P87
6
0
Beginning of Loop
Delay
Loop Count
11:
01:
P86
1
Do
Call Subroutine 1
12-3
SECTION 12. PROGRAM CONTROL INSTRUCTIONS
12:
01:
02:
03:
04:
P89
25
3
6
31
If X<=>F
X Loc DAY
>=
F
Exit Loop if true
13:
P95
End
14:
01:
02:
P87
1
0
Beginning of Loop
Delay
Loop Count
PAR.
NO.
DATA
TYPE
DESCRIPTION
27:
01:
P86
1
Do
Call Subroutine 1
28:
01:
02:
03:
04:
P89
25
3
16
31
If X<=>F
X Loc DAY
>=
F
Exit Loop if true
01:
02:
03:
04:
4
2
4
2
Input location for X
Comparison code (Table 12-5)
Input location for Y
Command (Table 12-2)
29:
P95
End
30:
01:
02:
P87
6
0
Beginning of Loop
Delay
Loop Count
36:
01:
P86
1
Do
Call Subroutine 1
37:
01:
02:
03:
04:
P89
25
3
5
32
If X<=>F
X Loc DAY
>=
F
Exit Loop if false
38:
P95
End
39:
P
End Table 1
*
3
Table 3 Subroutines
*** 88 IF X COMPARED TO Y ***
FUNCTION
This instruction compares two input locations
and, if the result is true, executes the specified
Command. The comparison codes are given in
Table 12-5.
Input locations altered: 0
Execution time:
0.6ms
TABLE 12-5. Comparison Codes
01:
01:
P85
1
Beginning of Subroutine
Subroutine Number
02:
01:
P18
2
02:
03:
24
25
Time
Hours into current year
(maximum 8784)
Mod/by
Loc [:DAY
]
03:
12-4
P95
End
Parameter 1
1
2
3
4
Function
IF X = Y
IF X ≠ Y
IF X ≥ Y
IF X < Y
*** 89 IF X COMPARED TO F ***
FUNCTION
This instruction compares an input location to a
fixed value and, if the result is true, performs
the specified Command. The comparison codes
are given in Table 12-5.
PAR.
NO.
DATA
TYPE
DESCRIPTION
01:
02:
03:
04:
4
2
FP
2
Input location for X
Comparison code (Table 12-5)
Fixed value
Command (Table 12-2)
*** 90 STEP LOOP INDEX ***
FUNCTION
When used within a Loop (Instruction 87),
Instruction 90 will increment the index counter
by a specified amount after the first time
through the loop, thus affecting all indexed input
location parameters in subsequent instructions
within the loop. For example, if 4 is specified,
the index counter will count up by 4 (0, 4, 8,
12,...) inside the loop. Instruction 90 does not
affect the loop counter which still counts by 1.
SECTION 12. PROGRAM CONTROL INSTRUCTIONS
PAR.
NO.
DATA
TYPE
01:
2
DESCRIPTION
Increment for the loop index
counter
PAR.
NO.
DATA
TYPE
DESCRIPTION
01:
02:
03:
4
4
2
Time into interval (minutes)
Time interval (minutes)
Command (Table 12-2)
*** 91 IF FLAG ***
*** 93 BEGIN CASE STATEMENT ***
FUNCTION
This instruction checks one of the ten flags and
conditionally performs the specified command.
The first parameter specifies the flag to check
and the flag status (high or low) on which to
execute the command.
1X = execute Command if Flag X is high
2X = execute if Flag X is low
PAR.
NO.
DATA
TYPE
DESCRIPTION
01:
02:
2
2
Flag/status
Command (Table 12-2)
*** 92 IF TIME ***
FUNCTION
The user specifies the number of minutes into
an interval, the duration of the interval, and a
command. The command is executed each
time the real time is the specified number of
minutes into the interval.
The time interval is synchronized with real time;
if a 60 minute time interval is specified with 0
minutes into the interval, the Command will be
executed each hour on the hour. The time
interval is automatically synchronized by making
a modulo divide of the number of minutes since
midnight by the specified real time interval. If
the result is 0, the interval is up. Thus, the first
interval of the day always starts at midnight (0
minutes). Only one execution is allowed in any
minute (e.g., if the command is to set the
Output Flag, and the execution interval of the
table is ten seconds, there will only be one
output generated by this instruction, not six.)
The Output Flag (Flag 0) is a special case in
that it will automatically be set low if it is not time
to set it high.
Instruction 93 specifies an input location for
comparison with fixed values in subsequent If
Case instructions (83). When a comparison is
true, the command in the If Case instruction is
executed and at the next Instruction 83
execution jumps to the End Instruction 95
associated with the Begin Case Instruction.
PAR.
NO.
DATA
TYPE
01:
4
DESCRIPTION
Input location for subsequent
comparisons
EXAMPLE:
01:
01:
P93
2
Case
Case Loc
02:
01:
02:
If Case Location < F
F
Call Subroutine 3
04:
01:
02:
P83
69.4
3
else
P83
72
10
else
P83
77.3
30
05:
01:
02:
03:
P30
0
0
25
Z=F
F
Exponent of 10
Z Loc :
06:
P95
End Then Do
07:
P95
End of Case Statement
03:
01:
02:
If Case Location < F
F
Set high Flag 0 (output)
If Case Location < F
F
Then Do
*** 94 ELSE ***
FUNCTION
When Command 30 (Then/Else) is used with an
If Instruction, the Else Instruction is used to
mark the start of the instructions to execute if
the test condition is false (Figure 3.8-1). The
12-5
SECTION 12. PROGRAM CONTROL INSTRUCTIONS
Else Instruction is optional; when it is omitted, a
false comparison will result in execution
branching directly to the End Instruction.
Instruction 94 has no parameters.
PAR.
NO.
DATA
TYPE
01:
2
*** 95 END ***
FUNCTION
Instruction 95 is used to indicate the end/return
of a subroutine (Instruction 85), the end of a
loop (Instruction 87), the end of an If Then/Else
sequence, or the end of the Case statement
(Instructions 88-93 when used with command
30). The End Instruction has no parameters.
DESCRIPTION
The left digit specifies the
Option and the right specifies
the baud rate for the printer.
The code for Storage Module
is 30.
Option
X = Baud Rate
0 -300
1X -- PRINTER, ASCII
1 -- 1200
2X -- PRINTER, Binary
2 -- 9600
30 -- SM192 or SM716
3 -- 76,800
31 -- Send filemark to SM192/716
*** 96 ACTIVATE SERIAL DATA OUTPUT ***
*** 98 SEND CHARACTER ***
FUNCTION
Instruction 96 is used instead to activate the
Storage Module or serial port output. By using
Program Control Instructions to allow execution
of Instruction 96 only at certain times, the user
can control when the output is active.
When used to send data to the SM192 or
SM716 Storage Module, the CR7 can determine
whether or not the Storage Module is
connected. If the Storage Module is not
connected, the data will not be sent until it is
connected. Instruction 96 also allows for faster
data output via the serial port with the Binary
Option, which outputs FINAL STORAGE
FORMAT (2 bytes per low resolution data point)
instead of ASCII (10 bytes per data point,
Section 4.5). Appendix C describes FINAL
STORAGE FORMAT.
A single parameter is used to select whether the
instruction is to control the tape, Storage
Module, or the printer output, and if the printer is
selected, the format and baud rate. Instruction
96 must be entered separately for each output
device used.
Instruction 96 uses the same Printer pointer as
the *9 mode which can be used to get a residual
or partial dump of Final Storage (Section 4).
Do not use *4 to activate a device that is
activated by Instruction 96.
12-6
Instruction 98 is used to send a character to the
printer. The single parameter sets the baud
rate and gives the decimal equivalent of the 7
bit character (sent as 8 bits, no parity). For
example, to send the ASCII character control R
at 9600 baud, 2018 would be entered for
Parameter 1. This instruction can be used to
send a control character to activate some
device. The specified character is sent at the
time Instruction 98 is executed; this will cause it
to precede any output arrays generated in the
same table, since the output data is sent to the
printer at the completion of the table.
PAR.
NO.
DATA
TYPE
01:
4
DESCRIPTION
Decimal Value of ASCII character:
yxxx xxx=ASCII value (1-127)
y=Baud rate code
0
300 baud
1
1200 baud
2
9600 baud
3
76,800 baud
SECTION 13. CR7 MEASUREMENTS
13.1 FAST AND SLOW MEASUREMENT
SEQUENCE
The CR7 makes voltage measurements by
integrating the input signal for a fixed time and
then holding the integrated value for the analog
to digital (A/D) conversion. The A/D conversion
is made with a 16 bit successive approximation
technique which resolves the signal voltage to
approximately one part in 30,000 of either the +
or - side of the full scale range (e.g., 1/30,000 x
5V = 166µV).
Integrating the signal removes noise that could
create an error if the signal were
instantaneously sampled and held for the A/D
conversion. The slow integration time provides
a more noise-free reading than the fast
integration time. One of the most common
sources of noise is 60 Hz from AC power lines.
The slow integration time of 16.67 milliseconds
is equal to one 60 Hz cycle so that during the
integration time the AC noise would integrate to
0.
There are several situations where the fast
integration time of 250 microseconds is
preferred. The fast integration time minimizes
time skew between measurements and
increases the throughput rate. The current drain
on the CR7 batteries is lower when fast
integration time is used because the I/O CPU is
switched on for shorter time periods. The fast
integration time should ALWAYS be used with
the AC half bridge (Instruction 5) when
measuring AC resistance or the output of an
LVDT. An AC resistive sensor will polarize if a
DC voltage is applied, causing erroneous
readings and sensor decay. The induced
voltage in an LVDT decays with time as current
in the primary coil shifts from the inductor to the
series resistance, a long integration time would
result in most of the integration taking place
after the signal had disappeared.
FIGURE 13.1-1. Timing of Single Ended
Measurement
Before making a series of measurements
prescribed by an Input Instruction, the CR7
makes a calibration measurement. The
calibration is accomplished by measuring two
known voltages which are sent through the
same amplifier circuit that will be used for the
measurements. The calibration for a single
ended measurement consists of measuring a
voltage which is 4/5ths of full scale and then
making a measurement with the input
grounded. A differential measurement is made
once with the inputs as connected and a second
time with the inputs reversed (Section 13.2):
calibration for differential measurements uses
voltages at ±4/5ths of full scale.
An offset error of up to 1 least significant bit can
occur in a slow, single ended measurement as
a result of dielectric absorption in the integrating
capacitor. This error is a function of the
previous measurement. If the CR7 is
programmed to make a single ended
measurement on the 5 volt range with the inputs
shorted, an error of -166 µV can be observed.
13.2 SINGLE ENDED AND DIFFERENTIAL
VOLTAGE MEASUREMENTS
NOTE: The channel numbering on the
Analog Input cards refers to differential
channels. Either the high or low side of a
differential channel can be used for single
ended measurements so each side must be
counted when numbering single ended
channels, e.g., the high and low sides of
differential channel 14 are single ended
channels 27 and 28, respectively.
The timing and sequence of a single ended
measurement is shown in Figure 13.1-1. A
single ended measurement is made on a single
input which is referenced to ground. A single
integration is performed for each measurement.
A differential measurement measures the
difference in voltage between two inputs. The
measurement sequence on a differential
measurement involves two integrations: first
with the high input referenced to the low, then
with the inputs reversed. (Figure 13.2-1). The
CR7 computes the differential voltage by
averaging the magnitude of the results from the
two integrations and using the polarity from the
first.
13-1
SECTION 13. CR7 MEASUREMENTS
FIGURE 13.2-1. Differential Voltage
Measurement Sequence
Because a single ended measurement is
referenced to CR7 ground, any difference in
ground potential between the sensor and the
CR7 will result in an error in the measurement.
For example, if the measuring junction of a
copper-constantan thermocouple, being used to
measure soil temperature, is not insulated and
the potential of earth ground is 1 mV greater at
the sensor than at the point where the CR7 is
grounded, the measured voltage would be 1 mV
greater than the thermocouple output, or
approximately 25 oC high. Another instance
where a ground potential difference creates a
problem is in a case such as described in
Section 7.2, where external signal conditioning
circuitry is powered from the same source as
the CR7. Despite being tied to the same
ground, differences in current drain and lead
resistance result in different ground potential at
the two instruments. For this reason, a
differential measurement should be made on an
analog output from the external signal
conditioner. Differential measurements MUST
be the choice where the inputs are known to be
different from ground, such as the output from a
full bridge.
In order to make a differential measurement,
however, the inputs must be within the CR7
common mode range of ±5V. The common
mode range is the voltage range, relative to
CR7 ground, within which both inputs of a
differential measurement must lie, in order for
the differential measurement to be made. For
example, if the high side of a differential input is
at 4V and the low side is at 3V relative to CR7
ground, there is no problem, a measurement
made on the ±1.5V range would indicate a
signal of 1V. However, if the high input is at
5.8V and the low input is at 4.8V, the
measurement can not be made because the
high input is outside of the CR7 common mode
range (the CR7 will indicate the overrange with
the maximum negative number, Section 2.2).
13-2
Problems with exceeding common mode range
may be encountered when the CR7 is used to
read the output of external signal conditioning
circuitry if a good ground connection does not
exist between the external circuitry and the
CR7. When operating where AC power is
available, it is not always safe to assume that a
good ground connection exists through the AC
wiring. If a CR7 is used to measure the output
from a laboratory instrument (both plugged into
AC power and referencing ground to outlet
ground), it is best to run a ground wire between
the CR7 and the external circuitry. Even with
this ground connection, the ground potential of
the two instruments may not be at exactly the
same level, which is why a differential
measurement is desired.
A differential measurement has better noise
rejection than a single ended measurement.
Integrating the signal in both directions also
reduces input offset voltage due to thermal
effects in the amplifier section of the CR7. Input
offset voltage on a differential measurement is
on the order of 0.1 microvolts, the input offset
voltage on a single ended measurement may be
as high as 1 to 2 microvolts.
A single ended measurement is quite
satisfactory in cases where noise is not a
problem and care is taken to avoid ground
potential problems. Twice as many single
ended measurements can be made per Analog
Input Card. A single ended measurement takes
about half the time of a differential
measurement which is valuable in cases where
rapid sampling is a requirement.
NOTE: Sustained voltages in excess of
±16 VDC applied to the analog inputs will
damage the CR7 input circuitry.
SECTION 13. CR7 MEASUREMENTS
13.3 THE EFFECT OF SENSOR LEAD
LENGTH ON THE SIGNAL SETTLING
TIME
Whenever an analog input is switched into the
CR7 measurement circuitry prior to making a
measurement, a finite amount of time is
required for the signal to stabilize at it's correct
value. The rate at which the signal settles is
determined by the input settling time constant
which is a function of both the source resistance
and input capacitance (explained below). The
CR7 allows a 0.5ms settling time before
initiating the measurement. In most
applications, this settling time is adequate but
the additional wire capacitance associated with
long sensor leads can increase the settling time
constant to the point that measurement errors
may occur. There are three potential sources of
error which must settle before the measurement
is made:
FIGURE 13.3-1. Input Voltage Rise and
Transient Decay
Vs = Vso (1 − e
− t /RoC T
Vs = Vso + ( Veo − Vso )e
), rise
− t /RoC T
[13.3-1]
, decay [13.3-2]
1. The signal must rise to its correct value.
where Vs is the input voltage, Vso the true
signal voltage, Veo the peak transient voltage, t
is time in seconds, Ro the source resistance in
ohms and CT is the total capacitance between
the signal lead and ground (or some other fixed
reference value) in farads.
2. A small transient (5mV) caused by
switching the analog input into the
measurement circuitry must settle.
The settling time constant, τ in seconds, and the
capacitance relationships are given in
Equations 13.3-3 through 13.3-5,
3. A larger transient, usually about 40 mV/V,
caused by the switched, precision excitation
voltage used in resistive bridge
measurements must settle.
The purpose of this section is to bring attention
to potential measurement errors caused when
the input settling time constant gets too large
and discuss procedures whereby the effects of
lead length on the measurement can be
estimated. In addition, physical values are
given for three types of wire used in Campbell
Scientific sensors and error estimates for given
lead lengths are provided. Finally, techniques
are discussed for minimizing input settling error
when long leads are mandatory.
τ = RoCT
[13.3-3]
CT = Cf + CwL
[13.3-4]
Cf = 0.01 nfd
[13.3-5]
where Cf is the fixed CR7 input capacitance in
farads, Cw is the wire capacitance in farads/foot
and L is the wire length in feet.
Equations 13.3-1 and 13.3-2 can be used to
estimate the input settling error, Ve, directly.
For the rising case, Vs = Vso-Ve whereas for
the decaying transient Vs = Vso+Ve.
Substituting these relationships for Vs in
Equations 13.3-1 and 13.3-2, respectively,
yields expressions in Ve, the input settling error:
13.3.1 THE INPUT SETTLING TIME CONSTANT
The rate at which an input voltage rises to its full
value or that a transient decays to the correct
input level are both determined by the input
settling time constant. In both cases the
waveform is an exponential. Figure 13.3-1
shows both a rising and decaying waveform
settling to the signal level, Vso. The rising input
voltage is described by Equation 13.3-1 and the
decaying input voltage by Equation 13.3-2,
Ve = Vso e
Ve = V 'eo e
− t /RoC T
− t /RoC T
, rise
[13.3-6]
, decay
[13.3-7]
Where V'eo = Veo-Vso, the difference between
the peak transient voltage and the true signal
voltage.
13-3
SECTION 13. CR7 MEASUREMENTS
Since the peak transient, Veo, causes
significant error only if it is several times larger
than the signal, Vso, error calculations made in
this section approximate Ve'o by Veo, i.e., Veo
≈ Veo-Vso.
If the input settling time constant, τ , is known, a
quick estimation of the settling error as a
percentage of the maximum error (Vso for
rising, V'eo for decaying) is obtained by knowing
how many time constants (t/τ) are contained in
the 0.5 ms CR7 input settling interval (t). The
familiar exponential decay relationship is given
in Table 13.3-1 for reference.
FIGURE 13.3-2. Typical Resistive Half-Bridge
TABLE 13.3-1. Exponential Decay, Percent
of Maximum Error vs. Time in Units of τ
Time
%
Time
%
Constants Max. Error Constants Max. Error
0
1
3
100.0
36.8
5.0
5
7
10
0.7
0.1
0.004
Before proceeding with examples of the effect
of long lead lengths on the measurement, a
discussion on obtaining the source resistance,
Ro, and lead capacitance, CwL, is necessary.
DETERMINING SOURCE RESISTANCE
The source resistance used to estimate the
settling time constant is the resistance the CR7
input "sees" looking out at the sensor. For our
purposes the source resistance can be defined
as the resistance from the CR7 input through all
external paths back to the CR7. Figure 13.3-2
shows a typical resistive sensor, (e.g., a
thermistor) configured as a half-bridge. Figure
13.3-3 shows Figure 13.3-2 redrawn in terms of
the resistive paths determining the source
resistance Ro, is given by the parallel
resistance of Rs and Rf, as shown in Equation
13.3-8.
13-4
FIGURE 13.3-3. Source Resistance Model
for Half-Bridge Connected to the CR7
Ro = RsRf/(Rs+Rf)
[13.3-8]
If Rf is much smaller, equal to or much greater
than Rs, the source resistance can be
approximated by Equations 13.3-9 through
13.3-11, respectively.
Ro ≈ Rf, Rf<<Rs
Ro = Rf/2, Rf=Rs
[13.3-9]
[13.3-10]
Ro ≈ Rs, Rf>>Rs
[13.3-11]
The source resistance for several Campbell
Scientific sensors are given in column 3 of
Table 13.3-5.
DETERMINING LEAD CAPACITANCE
Wire manufacturers typically provide two
capacitance specifications 1) the capacitance
between the two leads with the shield floating
and 2) the capacitance between the two leads
with the shield tied to one lead. Since the input
lead and the shield are tied to ground (often
through a bridge resistor, Rf) in single ended
measurements such as Figure 13.3-2, the
second specification is used in determining lead
capacitance. Figure 13.3-4 is a representation
of this capacitance, Cw, usually specified as
pfd/ft. Cw is actually the sum of capacitance
between the two conductors and the
capacitance between the top conductor and the
shield. Capacitance for 3 Belden leadwires
used in Campbell Scientific sensors is shown in
column 6 of Table 13.3-2.
SECTION 13. CR7 MEASUREMENTS
TABLE 13.3-2. Properties of Three Belden Lead Wires Used by Campbell Scientific
Belden
Wire #
Conductors
Insulation
8641
8771
8723
1 shld. pair
1 shld. 3 cond.
2 shld. pair
polyethylene
polyethylene
polypropylene
FIGURE 13.3-4. Wire Manufacturers
Capacitance Specifications, Cw
DIELECTRIC ABSORPTION
The dielectric absorption of insulation
surrounding individual conductors can seriously
effect the settling waveform by increasing the
time required to settle as compared to a simple
exponential. Dielectric absorption is difficult to
quantify but it can have a serious effect on low
level measurements, for example 50mV or less.
The primary rule to follow in minimizing
dielectric absorption is: AVOID PVC
INSULATION around conductors. PVC cable
jackets are permissible since the jackets don't
contribute to the lead capacitance because the
jacket is outside the shield. Campbell Scientific
uses only polyethylene and polypropylene
insulated conductors in CR7 sensors (see Table
13.3-2) since these materials have negligible
dielectric absorption. Teflon insulation is also
very good but quite expensive.
13.3.2 EFFECT OF LEAD LENGTH ON SIGNAL
RISE TIME
In the 024A Windvane, a potentiometer sensor,
the peak transient voltage is much less than the
true signal voltage (Table 13.3-5). This means
the signal rise time is the major source of error
and the time constant is the same as if Cw were
between the signal lead and ground as
represented below.
AWG
Rl
(ohms/1000ft.)
Cw
(pfd/ft.)
24
22
22
23
15
15
42
41
62
FIGURE 13.3-5. Model 024A Wind Direction
Sensor
Ro, the source resistance, is not constant
because Rb varies from 0 to 10 kohms over the
0 to 360 degree wind direction range. The
source resistance is given by:
Ro = Rb(Rs-Rb+Rf)/(Rs+Rf) = Rb(20k-Rb)/20k
[13.3-12]
Note that at 360o, Ro is at a maximum of 5k
(Rb=10k) and at 0o, Ro is 0 (Rb=0). It follows
that settling errors are less at lower direction
values.
The value of Rb for any direction D (degrees) is
given by:
Rb(kohms) = (10k)(D)/360
[13.3-13]
Equation 13.3-6 can be rewritten to yield the
settling error of a rising signal directly in units of
degrees.
Error (degrees) = De
− t /(Ro ( C f + C wL ))
[13.3-14]
Equation 13.3-12, -13 and -14 can be combined
to estimate the error directly in degrees at
various directions and lead lengths (Table 13.33). Constants used in the calculations are given
below:
Cf = 0.01 ufd
Cw = 41 pfd/ft, Belden #8771 wire
t = 0.5 ms
13-5
SECTION 13. CR7 MEASUREMENTS
TABLE 13.3-3. Settling Error (Degrees) for
024A Wind Direction Sensor vs. Lead Length
Wind
Direction
- - - - - Error - - - - L=1000 ft.
L=500 ft.
360o
270o
180o
90o
47o
31o
12o
1o
NOTE: Excitation transients are eliminated
if an option exists to contain excitation leads
in a shield independent from the signal
leads.
8o
5o
1o
0o
The values in Table 13.3-3 show that significant
error occurs at large direction values for leads
in excess of 250 feet. Instruction 4, Excite,
Delay and Measure should be used to eliminate
errors in these types of situations. Using a
10ms delay, settling errors are eliminated up to
lengths that exceed the drive capability of the
excitation channel (≈2000 ft.).
13.3.3 TRANSIENTS INDUCED BY SWITCHED
EXCITATION
Figure 13.3-6 shows a typical half-bridge,
resistive sensor such as Campbell Scientific's
Model 107 Temperature probe, connected to
the CR7. The leadwire is a single shielded pair,
used for conducting the excitation, Vx and
signal, Vs voltages. When Vx is switched on, a
transient is capacitively induced in Vs, the signal
voltage. If the peak transient level, Veo, is less
than the true signal, Vso, the transient has no
effect on the measurement but if Veo is greater
than Vso it must settle to the correct signal
voltage to avoid errors.
FIGURE 13.3-6. Resistive Half-Bridge
Connected to Single-Ended CR7 Input
The size of the peak transient is linearly related
to the excitation voltage and increases as the
bridge resistor, Rf, increases. Table 13.3-4
shows measured levels of Veo for 1000 foot
lengths of three Belden wires used in Campbell
Scientific sensors. Values are given for Rf
equal 1 kohm and 10 kohm. Table 13.3-4 is
meant only to provide estimates of the size of
excitation transients encountered since the
exact level will depend upon the specific sensor
configuration.
Equation 13.3-7 can be solved for the maximum
lead length, L, permitted to maintain a specified
error limit. Combining Equations 7 and 4 and
solving for L gives:
L = -(RoCf + (t/ln(Ve/Veo)))/RoCw
[13.3-15]
where Ve is the measurement error limit.
TABLE 13.3-4. Measured Peak Excitation Transients for 1000 Foot Lengths of Three Belden Lead
Wires Used by Campbell Scientific
Vx(mV)
5000
4000
3000
2000
1000
13-6
#
8641
125
100
75
50
25
- - - - - - - - - - - Veo(mV) - - - - - - - - Rf=1 kohm
Rf=10 kohm
#
#
#
#
8771
8723
8641
8771
200
130
215
320
165
110
180
260
130
90
140
200
100
60
100
140
65
40
60
90
#
8723
180
150
110
80
40
SECTION 13. CR7 MEASUREMENTS
13.3.4 SUMMARY OF SETTLING ERRORS FOR
CAMPBELL SCIENTIFIC RESISTIVE
SENSORS.
EXAMPLE LEAD LENGTH CALCULATION
FOR CAMPBELL SCIENTIFIC 107
TEMPERATURE SENSOR
Table 13.3-5 summarizes the data required to
estimate the effect of lead length on settling
errors for Campbell Scientific's resistive
sensors. Comparing the transient level, Veo, to
the input range, one suspects that transient
errors are the most likely limitation for the 107
sensor. The sensors in the WVU-7 are the
same as in the Model 107 (the lead wire is
different) but the signal leads for the WVU-7 wet
and dry bulbs are not subject to excitation
transients because they are shielded
independently from the excitation.
Assume a limit of 0.05oC over a 0oC to +40oC
range is established for the transient settling
error. This limit is a reasonable choice since it
approximates the linearization error over that
range. The output signal from the thermistor
bridge varies non-linearly with temperature
(refer to 107 Operator's Manual), ranging from
about 200 µV/oC at 0oC to 100 µV/oC at 40oC.
Taking the most conservative figure yields an
error limit of Ve = 5 µV. The other values
needed to calculate the maximum lead length
are summarized in Table 13.3-5 and listed
below:
1) Veo ≈ 100mV, peak transient at 4V excitation
2) Ve ≈ 5µV, allowable measurement error
3) t = 500µs, CR7 input settling time
The comparatively small transient yet large
source resistance of the 024A sensor indicates
that signal rise time may be the most important
limitation. The analysis in Section 13.3.2
confirms this.
The Model 227 Soil Moisture Block has a
relatively short time constant and essentially no
transient. Lead lengths in excess of 2000 feet
produce less than a 0.1 bar (0-10 bar range)
input settling error. With this sensor, the drive
capability of the excitation channel limits the
lead length. If the capacitive load exceeds 0.1
ufd and the resistive load is negligible, Vx will
oscillate about it's control point. If the capacitive
load is 0.1 ufd or less, Vx will settle to within
0.1% of its correct value in 150µs. A lead
length of 2000 feet is permitted for the Model
227 before approaching the drive limitation.
4) Ro = 1kohm, 107 probe source resistance
5) Cf = 0.01nfd, CR7 input capacitance
6) Cw = 42pfd/ft., lead wire capacitance
Solving Equation 13.3-15 gives a maximum
lead length of:
L ≈ 965 ft., error ≈ 0.05oC
Setting the allowable error at 0.1oC or
approximately 10µV, the maximum lead length
increases to:
L ≈ 1050 ft., error ≈ 0.1oC
TABLE 13.3-5. Summary of Input Settling Data for Campbell Scientific Resistive Sensors
Sensor
Model #
Belden
Wire #
107
207(RH)
WVU-7
227
237
024A
8641
8771
8723
8641
8641
8771
*
**
Ro
Cw
(kohms) (pfd/ft.)
1
1
1
0.1-1
1
0-5
42
41
62
42
42
41
τ*
(us)
52
51
72
5-52
52
1-255
Input
Range(mV)
Vx(mV)
15
150
15
500
50
500
4000
3000
4000
500
5000
1000
Veo(mV)**
100
130
0
0
125
0-90
Estimated time constants are for 1000 foot lead lengths and include 0.01nfd CR7 input capacitance.
Measured peak transients for 1000 foot lead lengths at corresponding excitation, Vx.
13-7
SECTION 13. CR7 MEASUREMENTS
high source resistance shown in column 3
of Table 13.3-7. Adding another 1K
resistor, Rf, as shown in Figure 13.3-7B
lowers the source resistance of the CR7
input but offers no improvement over
configuration A because R'f still combines
with the lead capacitance to slow the signal
response at point P. The source resistance
at point P (column 5) is essentially the
same as the input source resistance of
configuration A. Moving Rf' out to the
thermistor as shown in Figure 13.3-7C
optimizes the signal settling time because it
becomes a function of Rf and Cw only.
Table 13.3-6 summarizes maximum lead
lengths for corresponding error limits in six
Campbell Scientific sensors. Since the first
three sensors are non-linear, the voltage error,
Ve, is the most conservative value
corresponding to the error over the range
shown.
MINIMIZING SETTLING ERRORS IN NONCAMPBELL SCIENTIFIC SENSORS
When long lead lengths are mandatory in
sensors configured by the user, the following
general practices can be used to minimize or
measure settling errors:
1. When measurement speed is not a prime
consideration, Instruction 4 (Excite, Delay
and Measure) can be used to ensure ample
settling time for half-bridge, single-ended
sensors.
Columns 4 and 7 list the signal voltages as a
function of temperature with a 5V excitation for
configurations A and C, respectively. Although
configuration A has a higher output signal (5V
input range), it does not yield any higher
resolution than configuration C which uses the
±150 mV input range.
2. An additional low value bridge resistor can
be added to decrease the source
resistance, Ro. For example, assume a YSI
non-linear thermistor such as the model
44032 is used with a 30 kohm bridge
resistor, R'f. A typical configuration is
shown in Figure 13.3-7A. The
disadvantage with this configuration is the
NOTE: Since Rf' attenuates the signal in
configurations B and C, one might consider
eliminating it altogether. However, its
inclusion "flattens" the non-linearity of the
thermistor, allowing more accurate curve
fitting over a broader temperature range.
TABLE 13.3-6. Maximum Lead Length vs. Error for Campbell Scientific Resistive Sensors
Sensor
Model #
Error
Range
Ve(µV)
Maximum
Length(ft.)
107
207(RH)
WVU-7
024A
227
237
0.05oC
1%RH
0.05oC
3o
10 kohm
0oC to 40oC
20% to 90%
0oC to 40oC
@ 360o
20k to 300k
5
500
5
1390
500
9651
19503
8502
2502
20003
19003
1 based on transient settling
2 based on signal rise time
3 limit of excitation drive
13-8
SECTION 13. CR7 MEASUREMENTS
TABLE 13.3-7. Source Resistances and Signal Levels for YSI #44032 Thermistor Configurations
Shown in Figure 13.3-7 (2V Excitation)
T
Rs
(kohms)
---A--Ro
Vs(mV)
(kohms)
-40
-20
0
+25
+40
+60
884.6
271.2
94.98
30.00
16.15
7.60
29.0
27
22.8
15.0
10.5
6.1
3. Where possible run excitation leads and
signal leads in separate shields to minimize
transients.
4. AVOID PVC INSULATED CONDUCTORS
to minimize the effect of dielectric
absorption on input settling time.
164
498
1200
2500
3250
3989
[email protected]
(kohms)
30.0
27.8
23.4
15.2
10.6
6.1
---C--Ro
Vs(mV)
(kohms)
1
1
1
1
1
1
5.5
16.5
39.5
82.0
106.0
129.5
required but the lead capacitance, Cw, is
unknown. Configure Rf on a length of cable
similar to the measurement. Leave the
sensor end open as shown in Figure 13.3-8
and measure the result using the same
instruction parameters to be used with the
sensor. The measured deviation from 0V is
the input settling error.
5. Use the CR7 to measure the input settling
error associated with a given configuration.
For example assume long leads are
13-9
SECTION 13. CR7 MEASUREMENTS
FIGURE 13.3-8. Measuring Input Settling
Error with the CR7
6. Most Campbell Scientific sensors are
configured with a small bridge resistor, Rf,
(typically 1 kohm) to minimize the source
resistance. If the lead length of a Campbell
Scientific sensor is extended by connecting
to the pigtails directly, the effect of the lead
resistance, Rl, on the signal must be
considered. Figure 13.3-9 shows a
Campbell Scientific Model 107 sensor with
500 feet of extension lead connected
directly to the pigtails. Normally the signal
voltage is proportional to Rf/(Rs+Rb+Rf) but
when the pigtails are extended the signal is
proportional to (Rf+Rl)/(Rs+Rb+Rf+Rl). Rl is
much smaller than the other terms in the
denominator and can be discarded. The
effect on the signal can be analyzed by
taking the ratio of the signal with extended
leads, Vsl to the normal signal, Vs:
Vsl/Vs = (Rf+Rl)/Rf
Plugging in values of Rf=1k and Rl=.012k (500o
at 23ohms/1000o, Table 13.3-2) gives an
approximate 1% error in the signal with
extended leads. Converting the error to oC
gives approximately a 0.3oC error at 0oC,
0.6oC error at 20oC and a 1.5oC error at 40oC.
The error can be avoided by maintaining the
pigtails on the CR7 end of the extended leads
because Rl does not add to the bridge
completion resistor, Rf, and its influence on the
thermistor resistance is negligible.
FIGURE 13.3-7. Half-Bridge Configuration
for YSI #44032 Thermistor Connected to CR7
Showing: A) Large source resistance, B)
Large source resistance at point P, and C)
Configuration optimized for input settling.
13-10
SECTION 13. CR7 MEASUREMENTS
the CR7 has been instructed to calculate the
temperature difference between the reference
and measuring junctions it will subtract the
reference temperature before storing the
temperature value.
13.4.1 ERROR ANALYSIS
FIGURE 13.3-9. Incorrect Leadwire Extension
on Model 107 Temperature Sensor
13.4 THERMOCOUPLE
MEASUREMENTS
A thermocouple consists of two wires, each of a
different metal or alloy, which are joined
together at each end. If the two junctions are at
different temperatures, a voltage proportional to
the difference in temperatures is induced in the
wires. When a thermocouple is used for
temperature measurement, the wires are
soldered or welded together at the measuring
junction. The second junction, which becomes
the reference junction, is formed where the
other ends of the wires are connected to the
measuring device. (With the connectors at the
same temperature, the chemical dissimilarity
between the thermocouple wire and the
connector does not induce any voltage.) When
the temperature of the reference junction is
known, the temperature of the measuring
junction can be determined by measuring the
thermocouple voltage and adding the
corresponding temperature difference to the
reference temperature.
The CR7 determines thermocouple
temperatures using the following sequence.
First the temperature of the reference junction is
measured. If the reference junction is the CR7
I/O Module, the temperature is measured with
the PRT in the 723-T Analog Input Card
(Instruction 17). The reference junction
temperature in oC is stored in an input location
which is accessed by the thermocouple
measurement instruction (Instruction 13 or 14).
The CR7 calculates the voltage that a
thermocouple of the type specified would output
at the reference junction temperature if its
reference junction were at 0oC, and adds this
voltage to the measured thermocouple voltage.
The temperature of the measuring junction is
then calculated from a polynomial
approximation of the NBS TC calibrations. If
The error in the measurement of a
thermocouple temperature is the sum of the
errors in the reference junction temperature, the
thermocouple output (deviation from standards
published in NBS Monograph 125), the
thermocouple voltage measurement, and the
linearization error (difference between NBS
standard and CR7 polynomial approximations).
The discussion of errors which follows is limited
to these errors in calibration and measurement
and does not include errors in installation or
matching the sensor to the environment being
measured.
REFERENCE JUNCTION TEMPERATURE
WITH 723-T
The PRT in the CR7 is mounted in the center of
the 723-T terminal strip. This resistance
temperature device (RTD) is accurate to ±0.1oC
over the CR7 operating range. The I/O Module
was designed to minimize thermal gradients. It
is encased in an aluminum box which is
thermally isolated from the CR7 enclosure.
Heavy copper grounding bars underlying the
terminal strips on the I/O cards and large brass
bars running the length of the I/O Module
provide thermal conduction for rapid
equilibration of thermal gradients. Sources of
heat within the CR7 enclosure exist due to
power dissipation by the electronic components
or charging batteries. In a situation where the
CR7 is at an ambient temperature of
approximately 20oC and no external
temperature gradients exist, the temperature
gradient between one end of an Analog Input
card to the other is likely to be 0.05oC, and the
gradient between the cards, from one end of the
I/O Module to the other, is likely to be 0.1 to
0.2oC. The end of the module with the CPU
card will be warmer due to heat dissipated by
the processor.
Given the above conditions, if it is desired to
make a series of thermocouple measurements
with the reference junctions within 0.05oC of the
RTD temperature, the temperature obtained
from the 723-T card can be used for
13-11
SECTION 13. CR7 MEASUREMENTS
thermocouples attached to it and to one 723
Analog Input card to either side of it (i.e. Analog
Input cards 1,2, and 3, where card 2 contains
RTD). If more than these three cards are used,
it is necessary to measure a new reference
temperature to stay within the desired 0.05oC
limit. This can be done by using one of the
thermocouples from the first set of
measurements to measure the reference
temperature for the next set. The second
reference temperature could provide the
reference for another bank of three cards. The
measuring junction for this reference should be
clamped (along with the lead from the
thermocouple being measured) into one of the
inputs in the center of the second card in this
bank. If more severe temperature gradients
within the I/O Module are anticipated or
suspected this technique can be used to
quantify these gradients and supply additional
reference temperatures if necessary.
THERMOCOUPLE LIMITS OF ERROR
The standard reference which lists
thermocouple output voltage as a function of
temperature (reference junction at 0oC) is the
National Bureau of Standards Monograph 125
(1974). The American National Standards
Institute has established limits of error on
thermocouple wire which is accepted as an
industry standard (ANSI MC 96.1, 1975). Table
13.4-1 gives the ANSI limits of error for
standard and special grade thermocouple wire
of the types accommodated by the CR7.
TABLE 13.4-1. Limits of Error for Thermocouple Wire (Reference Junction at 0oC)
Thermocouple
Type
T
Temperature
Range oC
o
-200 to 0
0 to 350
± 1.0 C or 1.5%
o
± 1.0 C or 0.75%
J
0 to 750
± 2.2 C or 0.75%
E
-200 to 0
0 to 900
± 1.7 C or 1.0%
o
± 1.7 C or 0.5%
-200 to 0
0 to 1250
± 2.2 C or 2.0%
o
± 2.2 C or 0.75%
R or S
0 to 1450
± 1.5 C or 0.25%
± 0.6 C or 0.1%
B
800 to 1700
± 0.5%
Not Estab.
K
When both junctions of a thermocouple are at
the same temperature there is no voltage
produced (law of intermediate metals). A
consequence of this is that a thermocouple can
not have an offset error; any deviation from a
standard (assuming the wires are each
homogeneous and no secondary junctions
exist) is due to a deviation in slope. In light of
this, the fixed temperature limits of error (e.g.,
±1.0oC for type T as opposed to the slope error
of 0.75% of the temperature) in the table above
are probably greater than one would experience
when considering temperatures in the
environmental range (i.e., the reference
junction, at 0oC, is relatively close to the
13-12
Limits of Error
(Whichever is greater)
Standard
Special
o
o
± 0.5 C or 0.4%
o
± 1.1 C or 0.4%
o
o
± 1.0 C or 0.4%
o
o
o
± 1.1 C or 0.4%
o
temperature being measured, so the absolute
error - the product of the temperature difference
and the slope error - should be closer to the
percentage error than the fixed error).
Likewise, because thermocouple calibration
error is a slope error, accuracy can be
increased when the reference junction
temperature is close to the measurement
temperature. For the same reason differential
temperature measurements, over a small
temperature gradient, can be extremely
accurate.
SECTION 13. CR7 MEASUREMENTS
In order to quantitatively evaluate thermocouple
error when the reference junction is not fixed at
0 oC, one needs limits of error for the Seebeck
coefficient (slope of thermocouple voltage vs.
temperature curve) for the various
thermocouples. Lacking this information, a
reasonable approach is to apply the percentage
errors, with perhaps 0.25% added on, to the
difference in temperature being measured by
the thermocouple.
TABLE 13.4-2. Limits of Error on CR7
Thermocouple Polynomials (Relative to NBS
Standards)
TC
Type
T
ACCURACY OF THE THERMOCOUPLE
VOLTAGE MEASUREMENT
The accuracy of a CR7 voltage measurement is
specified as 0.02% (0.01% 0 to 40 oC) of the
full scale range being used to make the
measurement. The actual accuracy may be
better than this as it involves a slope error (the
error is proportional to the measurement being
made, though limited by the resolution). The
error in the temperature due to inaccuracy in the
measurement of the thermocouple voltage is
worst at temperature extremes, where a
relatively large scale is necessary to read the
thermocouple output. For example, assume
type K (chromel-alumel) thermocouples are
used to measure temperatures at 1000 oC.
The TC output is on the order of 40mV,
requiring the ±50mV input range. The accuracy
specification of 0.01% FSR is 10µV which is a
measurement error of about 0.2 oC. In the
environmental temperature range with voltage
measured on an appropriate scale, error in
temperature due to the voltage measurements
is a few hundredths of a degree.
THERMOCOUPLE POLYNOMIAL: Voltage to
Temperature
NBS Monograph 125 gives high order
polynomials for computing the output voltage of
a given thermocouple type over a broad range
of temperatures. In order to speed processing
and accommodate the CR7's math and storage
capabilities, 4 separate 6th order polynomials
are used to convert from volts to temperature
over the range covered by each thermocouple
type. Table 13.4-2 gives error limits for the
thermocouple polynomials.
Range oC
Limits of
Error oC
-270
-270
-200
-100
100
+18 @ -270
±0.08
±0.001
±0.015
to
to
to
to
to
400
-200
-100
100
400
J
-150 to 760
-100 to 300
±0.008
±0.002
E
-240
-240
-130
200
±0.4
±0.005
±0.02
K
to 1000
to -130
to 200
to 1000
-50 to 1372
-50 to 950
950 to 1372
±0.01
±0.04
REFERENCE JUNCTION COMPENSATION:
Temperature to Voltage
The polynomials used for reference junction
compensation (converting reference
temperature to equivalent TC output voltage) do
not cover the entire thermocouple range.
Substantial errors will result if the reference
junction temperature is outside of the
linearization range. The ranges covered by
these linearizations include the CR7
environmental operating range, so there is no
problem when the CR7 is used as the reference
junction. External reference junction boxes
however, must also be within these temperature
ranges. Temperature difference measurements
made outside of the reference temperature
range should be made by obtaining the actual
temperatures referenced to a junction within the
reference temperature range and subtracting as
described in Section 7.5. Table 13.4-3 gives
the reference temperature ranges covered and
the limits of error in the linearizations within
these ranges.
Two sources of error arise when the reference
temperature is out of range. The most
significant error is in the calculated
compensation voltage, however error is also
created in the temperature difference calculated
13-13
SECTION 13. CR7 MEASUREMENTS
from the thermocouple output. For example,
suppose the reference temperature for a
measurement on a type T thermocouple is 300
oC. The compensation voltage calculated by
the CR7 corresponds to a temperature of 272.6
oC, a -27.4 oC error. The type T thermocouple
with the measuring junction at 290 oC and
reference at 300 oC would output -578.7 µV;
using the reference temperature of 272.6 oC,
the CR7 calculates a temperature difference of 10.2 oC, a -0.2 oC error. The temperature
calculated by the CR7 would be 262.4 oC, 27.6
oC low.
TABLE 13.4-3. Reference Temperature
Compensation Range and Polynomial Error
Relative to NBS Standards
TC
Type
Range oC
Limits of Error oC
T
J
E
K
-100 to 100
-150 to 296
-150 to 206
-50 to 100
± 0.001
± 0.005
± 0.005
± 0.01
ERROR SUMMARY
The magnitude of the errors described in the
previous sections illustrate that the greatest
sources of error in a thermocouple temperature
measurement with the CR7 are likely to be due
to the limits of error on the thermocouple wire
and in the reference temperature determined
with the 723-T RTD. Errors in the thermocouple
and reference temperature linearizations are
extremely small, and error in the voltage
measurement is negligible.
To illustrate the relative magnitude of these
errors in the environmental range, we will take a
worst case situation where all errors are
maximum and additive. A temperature of 45 oC
is measured with a type T (copper-constantan)
thermocouple, using the ±5 mV range. The
nominal accuracy on this range is 1µV(0.01% of
10mV) which at 45 oC changes the temperature
by 0.012 oC. The RTD is 25 oC but is
indicating 25.1 oC, and the terminal that the
thermocouple is connected to is 0.05 oC cooler
than the RTD.
13-14
TABLE 13.4-4. Example of Errors in
Thermocouple Temperature
Source
Error oC
% of Total Error
1oC 1% Slope
Error
Error
Reference Temp. 0.15
12.8
TC Output
ANSI
o
0.01 x 20 C
1.0
0.2
85.0
Voltage
Measurement
0.024
2.0
6.3
Reference
Linearization
0.001
0.1
0.3
Output
Linearization
0.001
0.1
0.3
Total Error
With ANSI error 1.176
Assuming 1%
slope error
0.376
39.9
53.2
100
100
13.4.2 USE OF EXTERNAL REFERENCE
JUNCTION OR JUNCTION BOX
An external junction box is often used to
facilitate connections and to reduce the
expense of thermocouple wire when the
temperature measurements are to be made at a
distance from the CR7. In most situations it is
preferable to make the box the reference
junction in which case its temperature is
measured and used as the reference for the
thermocouples and copper wires are run from
the box to the CR7 (Section 7.4). Alternatively,
the junction box can be used to couple
extension grade thermocouple wire to the
thermocouples being used for measurement,
and the CR7 I/O Module used as the reference
junction. Extension grade thermocouple wire
has a smaller temperature range than standard
thermocouple wire, but meets the same limits of
error within that range. The only situation where
it would be necessary to use extension grade
wire instead of a external measuring junction is
where the junction box temperature is outside
the range of reference junction compensation
provided by the CR7. This is only a factor when
using type K thermocouples, where the upper
limit of the reference compensation linearization
SECTION 13. CR7 MEASUREMENTS
is 100 oC and the upper limit of the extension
grade wire is 200 oC. With the other types of
thermocouples the reference compensation
range equals or is greater than the extension
wire range. In any case, errors can arise if
temperature gradients exist within the junction
box.
Figure 13.4-1 illustrates a typical junction box.
Terminal strips will be a different metal than the
thermocouple wire. Thus, if a temperature
gradient exists between A and A' or B and B',
the junction box will act as another
thermocouple in series, creating an error in the
voltage measured by the CR7. This
thermoelectric offset voltage is a factor whether
or not the junction box is used for the reference.
it can be minimized by making the thermal
conduction between the two points large and
the distance small. The best solution in the
case where extension grade wire is being
connected to thermocouple wire would be to
use connectors which clamped the two wires in
contact with each other.
Figure 13.4-1. Diagram of Junction Box
An external reference junction box must be
constructed so that the entire terminal area is
very close to the same temperature. This is
necessary so that a valid reference temperature
can be measured and to avoid a thermoelectric
offset voltage which will be induced if the
terminals at which the thermocouple leads are
connected (points A and B in Figure 13.4-2) are
at different temperatures. The box should
contain elements of high thermal conductivity,
which will act to rapidly equilibrate any thermal
gradients to which the box is subjected. It is not
necessary to design a constant temperature
box, it is desirable that the box respond slowly
to external temperature fluctuations.
Radiation shielding must be provided when a
junction box is installed in the field. Care must
also be taken that a thermal gradient is not
induced by conduction through the incoming
wires. The CR7 can be used to measure the
temperature gradients within the junction box.
13.5 BRIDGE RESISTANCE
MEASUREMENTS
There are five bridge measurement instructions
included in the standard CR7 software. Figure
13.5-1 shows the circuits that would typically be
measured with these instructions. In the
diagrams, the resistors labeled Rs would
normally be the sensors and those labeled Rf
would normally be fixed resistors. Circuits other
than those diagrammed could be measured,
provided the excitation and type of
measurements were appropriate.
With the exception of Instruction 4, which
applies an excitation voltage then waits a
specified time before making a single ended
measurement, all of the bridge measurements
make one set of measurements with the
excitation as programmed and another set of
measurements with the excitation polarity
reversed. The error in the two measurements
due to thermal emfs can then be accounted for
in the processing of the measurement
instruction. In Instructions 6-9 the excitation
channel maintains the excitation voltage until
after the analog to digital conversion is
completed. In Instruction 5, the AC half bridge
grounds the excitation channel as soon as the
integration portion of the measurement is
completed. Figure 13.5-2 shows the excitation
and measurement sequence for Instruction 6, a
4 wire full bridge. When more than one
measurement per sensor is necessary
(Instructions 7 and 9), excitation is applied
separately for each measurement (e.g., in
Instruction 9 used for a 4 wire half bridge, the
differential measurement of the voltage drop
across the sensor is made with the excitation at
both polarities and then excitation is again
applied and reversed for the single ended
measurement of the voltage drop across the
fixed resistor.
13-15
SECTION 13. CR7 MEASUREMENTS
FIGURE 13.5-1. Circuits Used with Instructions 4-9
13-16
SECTION 13. CR7 MEASUREMENTS
Excitation
+Vx
0V
-Vx
Measurement Sequence
A/D Conversion
Integration
Integration
A/D Conversion
-1
0
1
2
3
4
5
6
7
8
9
Integration (ms)
FIGURE 13.5-2. Excitation and Measurement Sequence for 4 Wire Full Bridge
TABLE 13.5-1. Comparison of Bridge
Measurement Instructions
Instr.
4
Circuit
Description
DC Half Bridge
User entered settling
time allows
compensation for
capacitance in long
lead lengths. No
polarity reversal. One
single-ended
measurement.
Measured voltage
output.
5
AC Half Bridge
Rapid reversal of
excitation polarity for
ion depolarization.
One single-ended
measurement at each
excitation polarity.
Ratiometric output.
6
4 Wire
Full Bridge
Slightly lower noise than
9. One differential
measurement at each
excitation polarity.
Ratiometric output.
7
3 Wire
Half Bridge
Compensates for lead
wire resistance,
assuming resistance is
same in both wires.
Two single-ended
measurements at each
excitation polarity.
Ratiometric output.
9
6 Wire
Full Bridge
or 4 Wire
Half Bridge
Compensates for lead
wire resistance. Two
differential
measurements at each
excitation polarity.
Ratiometric output.
Calculating the actual resistance of a sensor
which is one of the legs of a resistive bridge
usually requires the use of one or two
Processing Instructions in addition to the bridge
measurement instruction. Instruction 59 takes a
value, X, in a specified input location and
computes the value MX/(1-X), where M is the
multiplier and stores the result in the original
location. Instruction 42 computes the reciprocal
of a value in an input location. Table 13.5-2 lists
the instructions used to compute the resistance
of any single resistor shown in the diagrams in
Figure 13.5-1, provided the values of the other
resistors in the bridge circuit are known.
13-17
SECTION 13. CR7 MEASUREMENTS
TABLE 13.5-2. Calculating Resistance Values from Bridge Measurement
Instr.
Result
4
Rf =
X / Vx
1 − X / Vx
1
(( X / Vx ) / (1 − X / Vx )) / Rs
4.
59.
Mult. = 1/Vx; ofs. = 0
Mult. = Rf
4.
59.
42.
Mult. = 1/Vx; ofs. = 0
Mult. = 1/Rs
5.
59.
Mult. = 1; ofs. = 0
Mult. = Rf
5.
59.
42.
Mult. = 1; ofs. = 0
Mult. = 1/Rs; ofs. = 0
X = Rs / (Rs + Rf )
Rs = Rf
Rf =
6 or 9*
Multiplier and Offset
X = Vx (Rs / (Rs + Rf ))
Rs = Rf
5
Instr.
X
1− X
1
( X / (1 − X )) / Rs
X = 1000[R3 / (R3 + R4 ) − R2 / (R1 + R2 )]
R1 =
1
( X 1 / (1 − X1 )) / R2
*used for full bridge
6 or 9.
59.
42.
Mult. = -0.001; ofs. = R3/(R3+R4)
Mult. = 1/R2
6 or 9.
59.
Mult. = -0.001; ofs. = R3/(R3+R4)
Mult. = R1
6 or 9.
59.
Mult. = 0.001; ofs. = R2/(R1+R2)
Mult. = R4
6 or 9.
59.
42.
Mult. = 0.001; ofs. = R2/(R1+R2)
Mult. = 1/R3
where X1 = − X / 1000 + R3 / (R3 + R4 )
R2 = R1( X 2 / (1 − X 2 ))
where X 2 = X 1
R3 = R4 ( X 3 / (1 − X 3 ))
where X 3 = X / 1000 + R2 / (R1 + R2 )
R4 =
1
( X 4 / (1 − X 4 )) / R3
where X 4 = X 3
7&9*
13-18
X = Rs / Rf
*used as half bridge
Rs = Rf X
7 or 9.
Mult. = Rf; ofs. = 0
Rf = Rs / X
7 or 9
42.
Mult. = 1/Rs; ofs. = 0
SECTION 13. CR7 MEASUREMENTS
13.6 RESISTANCE MEASUREMENTS
REQUIRING AC EXCITATION
Some resistive sensors require AC excitation.
These include the 207 relative humidity probe,
soil moisture blocks, water conductivity sensors
and wetness sensing grids. The use of DC
excitation with these sensors can result in
polarization, which will cause an erroneous
measurement, and may shift the calibration of
the sensor and/or lead to its rapid decay.
The AC half bridge Instruction 5 (incorporated
into the 207 relative humidity measurement
Instruction 12) reverses excitation polarity to
provide ion depolarization and, in order to
minimize the time excitation is on, grounds the
excitation as soon as the signal is integrated
(Figure 13.6-1). The slow integration time
should never be used with a sensor requiring
AC excitation because it results in the excitation
lasting about 20 times as long, allowing
polarization to affect the measurement.
FIGURE 13.6-2. Model of Resistive Sensor
with Ground Loop
In Figure 13.6-2, Vx is the excitation voltage, Rf
is a fixed resistor, Rs is the sensor resistance,
and RG is the resistance between the excited
electrode and CR7 earth ground. With RG in
the network, the measured signal is:
V1 = Vx
Rs
(Rs + Rf ) + RsRf / RG
[13.6-1]
RsRf/RG is the source of error due to the
ground loop. When RG is large the equation
reduces to the ideal. The geometry of the
electrodes has a great effect on the magnitude
of this error. The Delmhorst gypsum block
used in the 227 probe has two concentric
cylindrical electrodes. The center electrode is
used for excitation; because it is encircled by
the ground electrode, the path for a ground loop
through the soil is greatly reduced. Moisture
blocks which consist of two parallel plate
electrodes are particularly susceptible to ground
loop problems. Similar considerations apply to
the geometry of the electrodes in water
conductivity sensors.
FIGURE 13.6-1. AC Excitation and
Measurement Sequence for AC Half-Bridge
INFLUENCE OF GROUND LOOP ON
MEASUREMENTS
When measuring soil moisture blocks or water
conductivity the potential exists for a ground
loop which can adversely affect the
measurement. This ground loop arises
because the soil and water provide an alternate
path for the excitation to return to CR7 ground,
and can be represented by the model
diagrammed in Figure 13.6-2.
The ground electrode of the conductivity or soil
moisture probe and the CR7 earth ground form
a galvanic cell, with the water/soil solution
acting as the electrolyte. If current was allowed
to flow, the resulting oxidation or reduction
would soon damage the electrode, just as if DC
excitation was used to make the measurement.
Campbell Scientific probes are built with series
capacitors in the leads to block this DC current.
In addition to preventing sensor deterioration,
the capacitors block any DC component from
affecting the measurement.
13-19
SECTION 13. CR7 MEASUREMENTS
13.7 PULSE COUNT MEASUREMENTS
Many pulse output type sensors (e.g.,
anemometers and flow-meters) are calibrated in
terms of frequency (counts/second). For these
measurements the accuracy is related directly
to the accuracy of the time interval over which
the pulses are accumulated. Variation in the
pulse sampling interval DOES NOT effect those
cases where the pulse measurement is
independent of time, i.e., where the total pulse
count is of interest instead of frequency.
The Pulse Count Instruction (#3) causes the
pulse channel counters to be read and reset to
zero every time the program table is executed.
The CR7 operating system checks the program
tables every 0.1 seconds to determine whether
or not a table should be executed. If any of the
3 tables requires execution and contains a
Pulse Count Instruction, ALL active pulse
channels in the specified I/O Module are read
and reset to zero before the table is executed.
Reading the pulse channels immediately
instead of when the Pulse Count Instruction is
encountered in the program sequence
eliminates variation in the pulse sampling
interval caused by variable program execution
times.
If the table execution is delayed, for example by
lengthy output processing, the pulse channel
counters are not read until the next execution
interval occurs. Whenever a table execution
overrun occurs, a decimal point appears below
the colon that separates the ID and Data field of
the display. Frequency data taken during an
overrun is invalid because the pulse sampling
interval is extended. The configuration code
(Parameter 4) entered in the Pulse Counting
Instruction allows measurements taken during
overruns to be discarded and replaced by the
count obtained during the previous, correct
sampling interval.
13-20
PULSE COUNT MEASUREMENTS USING
MULTIPLE I/O MODULES
Pulse channels contained in multiple I/O
Modules are read and reset based on the
program table priority. Within a specific
program table, the channels are reset according
to the priority of the I/O Module, i.e., Module 1
first and Module 4 last. For example, if Table 1
and 2 have simultaneous execution intervals, all
the active pulse channels in the I/O Modules
referenced by Pulse Count Instructions in Table
1 are read and reset first, followed by the I/O
Modules referenced in Table 2. Within Table 1
however, pulse channels contained in I/O
Module 1 are read first, followed by I/O Module
2, etc. All Pulse Counting Instructions
referencing the same I/O Module should be
contained in the same program table.
Approximately 0.6ms is required to read and
reset the pulse channels contained in one I/O
Module. Thus different I/O Modules having the
same pulse sample intervals are offset in real
time by 0.6ms per I/O Module. The pulse
sample interval associated with an I/O Module
is constant however, as long as the
programming rules listed below are observed.
1. If possible place all Pulse Count
Instructions in the same program table.
2. If more than one program table contains
Pulse Count Instructions, give Table 1 the
fastest execution interval and make the
other execution intervals even multiples of
Table 1's interval.
If these rules are violated a 0.6ms variation
could exist in an I/O module's sample interval.
For example, suppose Table 1 resets the pulse
counters in I/O Module 1 every 3 seconds and
Table 2 resets the pulse counters I/O Module 2
every second. When Table 1 is executed the
pulse counters in I/O Module 2 will be reset
0.6ms later than when only Table 2 is executed.
The frequencies must exceed 1.67 kHz before
the measurement is affected by a 0.6ms
variation in the pulse sampling interval.
SECTION 14. INSTALLATION
14.1 ENVIRONMENTAL ENCLOSURE,
CONNECTORS AND JUNCTION
BOXES
The standard CR7 is equipped with the Model
ENC-7F Fiberglass Case. During the
manufacturing of the case, the base and lid are
formed together to insure a perfectly matched
fit. A six digit serial number is stamped into the
extruded aluminum rims on both the base and
lid. When more than one CR7 is owned, care
should be taken to avoid a mismatch which
could prevent a gas-tight seal.
In addition to the AC power input connector and
pressure relief valve, the STANDARD ENC-7F
enclosure has two 1.040" dia. access ports,
located to the left side of the I/O Module (Figure
OV.1-1). These access ports are provided to
allow the entry of sensor leads, power cables,
etc. Unless otherwise specified at time of
ordering, these two access ports are fitted with
0.75" dia. conduit bushings, 0-Ring seals and
removable neoprene plugs. The neoprene
plugs can be used to form a reasonable seal by
drilling holes in them for accommodating the
passage of sensor leads to the I/O Module.
NOTE: Users wishing to punch additional
access ports should be aware that the
1.040" dia. punch is a special size. The
greenlee punch normally used to make
holes for 0.75" conduit bushings is 1.07"
dia. This diameter is too large for mounting
the 19 pin connector option.
Access ports fitted with drilled neoprene plugs
may not be sufficient for certain data acquisition
situations. Alternatively, the access ports can
have connectors installed.
14.1.1 ACCESS PORTS FITTED WITH ELBOWS
Standard 0.75" dia. male conduit elbows may
be screwed directly into the conduit bushings
provided with the standard environmental
enclosure. Elbows allow entry of individual
sensor leads and power cables while preventing
precipitation from entering the enclosure
directly. Silicon sealer can be used to seal off
the space between the elbow wall and leads.
Conduit elbows are inexpensive and well suited
for field applications where sensor arrays are
frequently changed and a gas-tight seal is NOT
required.
NOTE: Larger conduit elbows (1.5" dia.)
are required for allowing a 9 pin D-type
connector with ribbon cable attached to
pass through and access port. In order to
accommodate the larger elbows, access
ports must be enlarged and fitted with the
appropriate conduit bushings and O-Ring
seals.
14.1.2 SOCKET CONNECTORS
Access ports may be reconfigured as connector
ports by replacing the conduit bushings with
sealed (shell size 14) 19-pin circular socket
connectors. Individual leads are soldered to the
backside of the mounted connector and routed
to appropriate I/O terminals. Socket connectors
are recommended for applications where a gastight seal IS required.
The connector utilizes a compression screwactuated sealing gland. This connector is
recommended when multi-connector sensor
cable is used between the CR7 and a junction
box.
14.1.3 JUNCTION BOXES
Factors which may influence selection of the
appropriate connector type are (1) the seal
required, (2) the permanent or temporary nature
of the CR7 installation, and (3) cost
considerations.
Individual sensor leads (and multiconductor
cables) may be routed directly from the sensor
locations to the CR7 or routed to a junction box
and then to the CR7. Advantages of using a
junction box are two-fold: it provides a
convenient method for changing sensors/sensor
leads quickly and can provide additional
protection against instrumentation damage as a
result of lightning induced high voltages.
Junction boxes generally do not require a gas14-1
SECTION 14. INSTALLATION
tight seal but do require protection from thermal
gradients when used for thermocouple lead
wires (Section 13.4).
14.2 SYSTEM POWER REQUIREMENTS
AND OPTIONS
The standard CR7 is equipped with sealed lead
acid battery packs and charging circuitry for
accommodating (1) 120/240 VAC line power,
(2) solar panels, (3) vehicular 12V power
sources, and (4) external 12V batteries. When
fully charged, the internal batteries of the CR7
are capable of providing 2.5 Amp-Hours of
service or about 5 days of operation in a typical
application where the CR7 is active 10% of the
time.
14.2.1 POWER SUPPLY AND AC CHARGER
Power for charging the internal batteries from
an external AC source is provided to the CR7's
12V charging regulator circuit board through the
power input connector located on the outside of
the case to the right of the Control Module.
The LABORATORY ENCLOSURE has a 4position voltage select (100, 120, 220 or 240)
insert chip and 0.1 amp slow blow fuse located
next to the power input connector (on the
outside of the enclosure). CR7s leave the
Factory with the voltage insert chip set to 120
VAC. If the intended line voltage is not 120V,
reposition the chip to correspond as closely as
possible with the AC line voltage available (the
number showing when the chip is inserted
specifies the voltage level).
ENVIRONMENTAL ENCLOSURES are
equipped with a weather-tight bayonet mount 3pin circular power connector. Access to the 2position (115 and 230) voltage select switch and
0.1 amp slow blow fuse is by lifting up the
Control Module Panel. The switch is set to 115
VAC at the factory.
A temperature compensated 12V CHARGING
REGULATOR CIRCUIT BOARD beneath the
Control Module regulates the charging voltage
supplied to the lead acid batteries and the
voltage to the CR7 operating system. DC
Power sources are connected to the terminal
block on the charging regulator board. The
terminals labeled "EXT BATT" are for
connecting a 12V power source. The terminals
labeled "SOLAR" are for connecting a solar
panel or DC source with sufficient voltage (1514-2
25 VDC) to charge the internal lead acid
batteries.
The LED auxiliary power light located on the
face of the Control Module, is activated by the
charging regulator when solar or AC charging
circuitry are connected to the CR7. The LED
operates with the ON/OFF switch in either
position but is NOT designed to operate when
an external 12V battery only is connected to the
CR7.
Power to the CR7 operating system is
controlled by the position of the ON/OFF toggle
switch located on the face of the Control
Module.
The sealed lead acid battery packs, located
below the Control Module, are rated at 6V each
and are connected in series to provide 12 VDC.
TABLE 11.2-1. CR7 Battery and Charging
Circuitry Specifications
BATTERY Type
Float Life @ 25 oC
Gates #810-0011X
8 yrs minimum
Amp Hour Rating
2.5 amp-hour
Open Circuit Voltage
@ Full Charge
12.95 typ. with
charging circuitry
deactivated, 14.1
@ 25 oC when
activated
Open Circuit Voltage
@ Full (SAFE) Discharge
11.76 VDC
minimum
Shelf Life, Full Charge
Check twice yearly
Charging Time from Full
Discharge (AC Source)
40 hrs for full
charge, 20 hrs for
95% full charge
Charging Circuit
Float charge with
temperature
compensated
voltage regulation
AC Line Filter (LAB.)
6 amp max, 48-440
Hz, 250 VAC max.
AC Line Filter (ENVIR.)
1 amp max, 50-60
Hz, 250 VAC max.
Power Supply Transformer 6 watt output
SECTION 14. INSTALLATION
Battery voltage should NOT be allowed to
drop below 11.76V before recharging;
otherwise, permanent damage to the lead
acid cells may occur. CSIs warranty does
NOT cover battery or cell damage resulting
from deep discharge.
Avoid deep discharge states by periodically
monitoring voltage level of the CR7s internal
batteries, using Input/Output Instruction 10.
Incorporate the battery voltage measurement to
the data acquisition program to avoid deep
discharge of the CR7 internal batteries.
All external charging devices must be
disconnected from the CR7 in order to measure
the true voltage level of the internal batteries.
The internal lead acid batteries of the CR7 will
continue to discharge with the CR7 turned on
but not scanning or processing data. This
quiescent current drain will vary depending on
the number of I/O Modules, Excitation and
Pulse Counter cards contained in the CR7, and
the number and type of external devices
powered by the CR7's Power Supply. Users
can approximate the quiescent current drain of
their specific CR7 System from the information
provided in Table 14.2-2.
TABLE 14.2-2. Calculating Quiescent
Current Drain
Module/Card
Control Module
I/O Module
Excitation card
Pulse Counter card
Analog Input card
Current Drain
0.4
2.5
2.0
0.8
0.7
mA
mA
mA
mA
mA
As an example, the quiescent current drain of a
CR7 System containing a Control Module, an
I/O Module, 1 Excitation card, 2 Pulse Counter
cards and 4 Analog Input cards is about 9.3mA.
At this rate of quiescent current drain, fully
charged internal batteries (2.5 AH) are depleted
to a full SAFE discharge level (11.76V) after
268 hours (about 11 days). When the CR7 is
active, it draws approximately 100mA so the
actual current drain is a function of the program
being executed.
14.2.2 SOLAR PANELS
Auxiliary photovoltaic power sources, such as
Solarex Models MSX5, MSX10, and MSX18
Solar Panels may be used to maintain charge
on lead acid batteries.
TABLE 14.2-1. Solar Panel Specifications
MSX5 MSX10 MSX18
Typical Peak Power
(Watts)
Current @ Peak
(Amps)
Amp Hrs/week
4.2
.27
6.4
8.9
.59
14.4
18.6
1.06
26.4
NOTE: Specifications assume 1 kW/m2
illumination at a panel cell temperature of
25oC. Individual panel performance may
vary as much as 10%.
When selecting a solar panel, a rule-of-thumb is
that on a stormy overcast day the panel should
provide enough charge to meet the system
current drain (assume 10% of average annual
global radiation, kW/m2). Specific site
information, if available, could strongly influence
the solar panel selection. For example, local
effects such as mountain shadows, fog from
valley inversion, snow, ice, leaves, birds, etc.
shading the panel should be considered.
Guidelines are available from the Solarex
Corporation for solar panel selection called
"DESIGN AIDS FOR SMALL PV POWER
SYSTEMS". It provides a method for
calculating solar panel size based on general
site location and system power requirements. If
you need help in determining your system
power requirements, contact Campbell
Scientific's Marketing Department.
The solar panel is connected to the CR7 by
attaching the 2 lead wires of the power cable to
the terminal block located on the charging
regulator circuit board (Figure 14.2-1). The free
end of the solar panel power cable is equipped
with a 12V power plug for use with the 21XL
Micrologger. Cut this plug off with side cutters
and remove about 1.5" of the cable's outer
insulation. Remove about 0.5" of insulation
from the exposed black and clear leads. The
BLACK lead is GROUND and the CLEAR lead
is positive (+).
14-3
SECTION 14. INSTALLATION
Regulated solar panels (e.g., MSX18R) limit
voltage to approximately 14V. The CR7
Solar Panel input requires 15-25 VDC to
charge.
14.2.3 EXTERNAL BATTERY CONNECTION
An external battery may be used to supplement
the internal lead acid batteries of the CR7. The
ground and +12 leads are connected to the
appropriate "EXT BATT" terminals.
The recommended procedure for connecting
the CR7 to an external battery is to make all
required ground lead connections before
connecting the battery. Accidental shorting can
be prevented by insulating one of the power
leads until cable routing is completed. When
disconnecting a battery, remove the positive
lead before disconnecting the ground lead.
Power for operating the CR7 may also be
provided by connecting the power leads from an
external 12V battery to the 2 terminals located
on the left side of the I/O Module CPU card.
This is a quick and convenient method of
connecting an alternate power supply to the
CR7 if it is necessary to disconnect or replace
the CR7s internal lead acid batteries. However,
the primary purpose of the terminals on the I/O
Module is to provide access to 12V for powering
external devices such as sensors.
Reverse polarity protection is NOT provided
on these terminals and CR7 damage will
occur if external power is connected with
reverse polarity.
If an external power supply is connected to the
I/O Module terminals the CR7 remains
powered-up even when the power switch is off.
The external supply must be removed to power
the CR7 down.
CSI recommends using 22 AWG lead wires or
larger when connecting an external battery to
the CR7.
14.2.4 CONNECTING TO VEHICLE POWER
SUPPLY
When the starting motor of a motor vehicle with
a 12 Volt electrical system is engaged, the
voltage drops considerably below the nominal
12 volts. If the CR7 were connected directly to
the vehicle power supply, the CR7 batteries
would be pulled down as well, causing the CR7
to "bomb" any time the vehicle was started. To
avoid this problem, a diode (i.e., 1N4001) and a
3 ohm 5 watt resistor must be placed in series
in the positive lead going to the EXTERNAL
BATTERY terminal. The diode allows the
vehicle to power the CR7 without the CR7
attempting to power the vehicle (diode installed
with bar end toward datalogger). To reduce the
potential for ground reference errors in
measurements, the ground lead should be 16
AWG or larger.
FIGURE 14.2-1. Connecting Vehicle Power
Supply to CR7
14.2.5 SAFETY PRECAUTIONS
There are inherent hazards associated with the
use of sealed lead acid batteries. Under normal
operation, lead acid batteries generate a small
amount of hydrogen gas. This gaseous byproduct is generally insignificant because the
hydrogen dissipates naturally before build up to
an explosive level (4%) occurs. However, if the
batteries are shorted or overcharging takes
place, hydrogen gas may be generated at a rate
sufficient to create a hazard. Because the
potential for excessive hydrogen build up does
exist, CSI makes the following
recommendations:
1. A CR7 equipped with standard lead acid
batteries should NEVER be used in
environments requiring INTRINSICALLY
SAFE EQUIPMENT.
2. When attaching an external battery to the
CR7, insulate the bare lead ends to protect
against accidental shorting while routing the
power leads.
14-4
SECTION 14. INSTALLATION
3. When the CR7 is to be located in a gastight enclosure or used in a gas-tight mode
with the standard ENVIRONMENTALLY
SEALED FIBERGLASS CASE, the internal
lead acid batteries SHOULD BE REMOVED
and an external battery substituted.
14.3 HUMIDITY EFFECTS AND
CONTROL
The CR7 system is designed to operate reliably
under environmental conditions where the
relative humidity inside its enclosure does not
exceed 90% (noncondensing). Situations where
the humidity tolerances are exceeded may
result in damage to IC chips, microprocessor
failure and/or measurement inaccuracies due to
condensation on the various PC board runners.
Effective humidity control is the responsibility of
the user and is particularly important in
operational environments where the CR7 is
exposed to salty air.
Several precautionary methods are available for
protecting the CR7 against excessive humidity
and subsequent component damage. Selection
of the appropriate method or combination of
methods will depend on the environmental
characteristics prevailing at a specific data
acquisition site. Humidity control methods
include:
1. the use of desiccant
2. sealing the CR7 enclosure gas-tight
3. the nitrogen purging technique
14.3.1 DESICCANT
As a minimal precaution, the packets of HUMISORB desiccant shipped with the CR7 should
be placed inside the Control Module. These
packets should be routinely removed from the
CR7 and reactivated by warming them in an
oven for about 16 hours at a temperature of 120
oC (250 oF). The recommended time between
reactivations varies from one location to
another. Obviously, the desiccant requires more
frequent attention in environments where the
relative humidity is high.
14.3.2 GAS-TIGHT ENVIRONMENT
Another method for controlling humidity involves
the proper selection of connectors for use with
the sealed fiberglass enclosure such that the
CR7 operates in a gas-tight environment.
Various connector options and associated
details are described in Section 12. Desiccant
is still required with this method.
14.3.3 NITROGEN PURGING
Several CSI customers have had success in
preventing humidity-related equipment
malfunctions in harsh environments by allowing
nitrogen gas to slowly bleed into the datalogger
enclosure. The sensor leads, power cables,
etc., are routed to the terminal blocks of the
datalogger through simple, inexpensive conduit
elbows which are left unplugged. A nitrogen
bottle is then left at the field site with its
regulator valve slightly open so that nitrogen is
allowed to escape slowly through a rubber tube
which is routed along with the sensor leads
through the conduit elbows into the CR7
enclosure. The tube vent should be positioned
underneath the Control Module.
Equipment required for this method of humidity
control generally can be obtained from any local
welding supply shop and includes a nitrogen
bottle, regulator with tube adapter (content
gauge, optional), hose clamp and a suitable
length of small diameter rubber tubing.
Nitrogen bottles are available in various sizes
and capacities. The size of the nitrogen bottle
used depends on the transport facilities
available to and from the field site and on the
time interval between site visitations. Where
practical, larger nitrogen bottles should be used
to reduce cost and refilling frequency.
14.4 RECOMMENDED GROUNDING
PRACTICES
14.4.1 PROTECTION FROM LIGHTNING
Primary lightning strikes are those where the
lightning hits the datalogger or sensors.
Secondary strikes occur when the lightning
strikes somewhere near the lead in wires and
induces a voltage in the wires. All input and
output connections in the I/O Module are
protected using spark gaps that are rated to
10,000 amps. The spark gaps are connected
directly to the heavy copper grounding bar on
each input card with no more than 2 inches of
14-5
SECTION 14. INSTALLATION
20 AWG wire. This transient protection is
useless if there is not a good connection
between the CR7 and earth ground.
All dataloggers in use in the field should be
grounded. A 12 AWG or larger wire should be
run from the grounding terminal on the left side
of the I/O Module (Figure OV1-1) to a grounding
rod driven far enough into the soil to provide a
good earth ground.
A modem/phone line connection to the CR7
provides another pathway for transients to enter
and damage the datalogger. The DC112
Modem has spark gaps on the phone lines. A
ground wire should be run between the ground
terminal on the modem and earth ground.
14.4.2 EFFECT ON MEASUREMENTS: COMMON
MODE RANGE
The effects that a difference in ground potential
between a sensor or signal conditioner and the
CR7 can have on a measurement were
discussed in Sections 7.2 and 13.2. These
sections stress that differential voltage
measurement gets rid of offset caused by a
difference in ground potential. However, in
order to make a differential measurement, the
inputs must be within the CR7 common mode
range of ±5V.
The common mode range is the voltage range,
relative to CR7 ground, within which both inputs
of a differential measurement must lie, in order
for the differential measurement to be made.
For example, if the high side of a differential
input is at 4V and the low side is at 3V relative
to CR7 ground, there is no problem, a
measurement made on the ±1.5V range would
indicate a signal of 1V. However, if the high
input is at 5.8V and the low input is at 4.8V, the
measurement cannot be made because the
high input is outside of the CR7 common mode
range.
Problems with exceeding common mode range
may be encountered when the CR7 is used to
read the output of external signal conditioning
circuitry if a good ground connection does not
exist between the external circuitry and the
CR7. When operating where AC power is
available, it is not always safe to assume that a
good ground connection exists through the AC
wiring. If a CR7 is used to measure the output
from a laboratory instrument (both plugged into
14-6
AC power and referencing ground to outlet
ground), it is best to run a ground wire between
the CR7 and the external circuitry. Even with
this ground connection, the ground potential of
the two instruments may not be at exactly the
same level, which is why a differential
measurement is desired.
14.5 USE OF DIGITAL CONTROL
PORTS FOR SWITCHING RELAYS
Each of the eight digital control output ports can
be set high or low by the PORT SET command
(Instruction 20). Because of current supply
limitations, a digital control output port normally
is used to operate an external relay driver.
These relays may be used for activating an
external power source to run a fan motor or for
altering an external circuit as a means of
multiplexing signal lines, etc.
Figure 14.5-1 is a schematic representation of a
typical external coil driven relay configuration
which may be used in conjunction with one of
the CR7s digital control output ports. The
example shows a DC fan motor (typical of a
ventilated psychrometer) and 6V battery in the
circuit, but the configuration may be used for
other purposes. This particular configuration
has a coil current limitation of 75mA because of
the NPN Medium Power Transistors used (Part
No. 2N2222). CSI's Model A21REL-12 and A6
REL12 are 12 VDC Relay Controllers available
for use with the CR7 system.
FIGURE 14.5-1. Typical Connection for
Activating/Powering External Devices, Using a
Digital Control Output Port and Relay Driver.
15. I/O CARD ADDRESSING AND MULTIPLE I/O MODULES
15.1 I/O CARD IDENTIFICATION
NUMBER DECODING
Each I/O card must be assigned a unique card
identification number and have jumpers set for
that number. The numbers allow the cards to
decode signals addressed to them by the I/O
Module. CR7s leave the factory with card
numbers assigned. These numbers may be
reassigned by the user when a CR7 needs to
be expanded with additional cards or
reconfigured for a particular application.
15.1.1 ASSIGNING CARD IDENTIFICATION
NUMBERS
Cards fall into one of two Categories. Category
1 includes all Excitation and Pulse Counter
cards; Category 2 includes Analog Input cards
only. NUMBERS MUST NOT BE
DUPLICATED WITHIN A CATEGORY, but a
number assigned in one category may be
duplicated in the other category. While the
identification numbers do not need to follow
physical order of the cards, it simplifies wiring
sensors if the card ID numbers match the
physical order.
Tables 15.1-2 and 15.1-3 list card numbers and
the corresponding jumper placement. The bus
structure allows one CR7 Control Module to
address up to 16 Excitation cards, 16 Pulse
Counter cards and 32 Analog Input cards. One
Control Module can control up to 4 I/O Modules.
15.1.2 PLACING JUMPERS IN THEIR PROPER
LOCATIONS
Jumpers are blue rectangular plastic and metal
sleeves, approximately 0.2" in length, with two
holes which are slipped over pins on the circuit
board.
Category 1 cards have 2 jumpers and Category
2 cards have 3 jumpers. Jumper positions are
labeled on the card. Figure 15.1-1 shows the
location of the jumpers on the Excitation, Pulse
Counter and Analog Input cards. Jumper
settings are listed in Tables 15.1-2 and 15.1-3.
TABLE 15.1-1. Jumper Locations and Labels
Card
Type
Cat.
Jmp/
Card
Card
Loc.
No.
Pins
When assigning card numbers the user can
avoid confusion by following 4 steps:
Excitation
1
2
R2
R6
6
6
1. Categorize the cards.
Pulse Count
1
2
R36
T32
6
6
Analog Input
2
3
R3
R4
R8
3
6
6
2. Assign a valid number to each card.
3. Set the jumpers on the cards according to
the numbers assigned.
4. Insert the cards into the Control Module,
making certain that the correct number tag
is secured with each card (Figure 10.1-1).
15-1
SECTION 15. I/O CARD ADDRESSING AND MULTIPLE I/O MODULES
FIGURE 15.1-1. Position of Decoding Jumpers on Excitation, Pulse Counter and Analog Input Cards.
15-2
SECTION 15. I/O CARD ADDRESSING AND MULTIPLE I/O MODULES
TABLE 15.1-2. Jumper Settings for Excitation and Pulse Counter Cards
15-3
SECTION 15. I/O CARD ADDRESSING AND MULTIPLE I/O MODULES
TABLE 15.1-3. Jumper Settings for Analog Input Cards.
15.2 USE OF MULTIPLE I/O MODULES
Up to four I/O Modules can be connected to one
control module. Additional I/O Modules may be
remotely located from the Control Module.
Two enclosures are available for the 720 I/O
Module; the standard ENC-7F Fiberglass
Environmental Enclosure or the ENC-7L
Aluminum Laboratory Enclosure. Options also
are available for 19" rack mounting (M197) or
mounting in a NEMA type enclosure (uses
M720 Back Mount Brackets).
The 720XL I/O Module mounts directly in a 19"
rack or may be mounted in a NEMA type
enclosure with the Model M720 Back Mount
Brackets.
15-4
TABLE 15.2-1. SC94 Pin Description.
Pin ID Control Module
I/O Module
A
B
C
D
Receive data
Receive data return
Transmit data return
Transmit data
Transmit data
Transmit data return
Receive data return
Receive data
NOTE: Interconnect cable lengths in
excess of a 1000 ft. limit the maximum
baud rate at which data may be transmitted
between the Control Module and the
Remote I/O Module. Cable length and
recommended baud rates are listed in
Table 15.2-3.
SECTION 15. I/O CARD ADDRESSING AND MULTIPLE I/O MODULES
TABLE 15.2-2. Hardware Components in SC94
Component
Description
Interconnect Cable (1 ea.)
Length of the 4-wire cable is made to order, circular connectors
attached at both ends.
Mating Circular Connector (2 ea.)
One connector affixed to Control Module enclosure; other
connector affixed to remote I/O Module enclosure; each joined
to a SC94 circuit card.
SC94 Circuit Card (2 ea.)
One card fastens to the remote I/O Module enclosure, the other
to the Control Module enclosure; both have circular socket
connectors.
10-Conductor Ribbon Cable
Ribbon cable connects SC94 circuit card to Control Module's
Serial Interface cord or to remote I/O Module's Controller card.
Grounding Wire (2 ea.)
12 AWG; wires are routed between terminals located on SC94
cards and 1 of 3 available terminals on the grounding bar on
left side of I/O Module framework; provides transient protection
at both ends of Interconnect cable.
Mating connectors and the associated circuitry
are installed at the factory when the CR7
System and multiple I/O Modules are purchased
together. An SC94 Four Wire Current Loop
Interconnect assembly is required for each
remote I/O Module operating in a CR7 System.
Table 15.2-2 describes the SC94 hardware.
Remote I/O Modules require their own power
supply. When remote I/O Modules are ordered
with either the Model ENC-7F or the Model
ENC-7L enclosure option, the space normally
taken up by the Control Module can be used for
housing the PS12-LA Power Supply. The
PS12-LA 12V charging regulator and battery
may also be mounted with a remote I/O Module
inside a NEMA type enclosure. Multiple I/O
Modules can be powered by a single Power
Supply if the distance is not too great.
Once all grounding leads are in place the power
supply leads are usually connected to the
terminal block located on the top left of the I/O
Module's Controller card. Alternatively, the two
power leads can be routed to the terminals,
marked +12V and, ground positioned on the
SC94 card.
NOTE: Whenever power is connected to
the I/O Module, it draws current even when
the power switch on the Control Module is
in the OFF position.
15.2.1 PROGRAMMING CONSIDERATIONS
The mating connector(s) affixed to CR7
Systems configured to operate with multiple I/O
Modules are labeled with a unique I/O Module
identification number (e.g., 1, 2, 3, 4) before
they leave the Factory. Instruction 23 is used to
address subsequent programming instructions
to a particular I/O Module.
At the start of each Program Table, the Control
Module assumes all instructions are meant for
I/O Module #1, the I/O Module housed with the
Control Module. Instruction 23 must be used to
address instructions to I/O Modules other than
#1. Once Instruction 23 is executed,
subsequent instructions are addressed to the
specified I/O Module until Instruction 23 is
executed again or the I/O Module again defaults
to #1 at the start of a Program Table.
15-5
SECTION 15. I/O CARD ADDRESSING AND MULTIPLE I/O MODULES
A typical programming example for a CR7
System containing two I/O Modules is given in
the following Program Table. A separate Power
Supply powers the remote I/O Module. The
objective of the programming example is to
conduct a preliminary system check-out by
measuring the battery voltage of the remote
Power Supply and of the power supply powering
the Control Module and I/O Module #1.
PROGRAM
Execution Interval 1 Second
Inst.
Loc.
Param.
No.
Entry
1
P
10
1
1
Description
Measure Control
Module voltage
Store result in Input
Loc. 1
2
P
1
23
2
Select I/O Module
I/O Module 2
3
P
10
1
2
Measure remote
battery voltage
Store result in Input
Loc. 2
Any subsequent instructions in the example
would address I/O Module #2 unless Instruction
23 were executed again specifying I/O Module
#1.
15.2.2 SETTING BAUD RATE BETWEEN I/O AND
CONTROL MODULES
The baud rate that data are transmitted
between the Control and I/O Modules is pre-set
to 38.4 k baud at the Factory. This baud rate
can be used for most datalogging applications
provided the distance separating the Control
Module and the I/O Module(s) does not exceed
1,000 ft. Distances in excess of 1,000 ft.
15-6
require a slower baud rate setting to
compensate for connector capacitance. Slower
baud rates may limit table Execution Intervals or
throughput rate. Table 15.2-3 lists
recommended baud rates for communicating
with I/O Modules at varying distance from the
Control Module.
TABLE 15.2-3. Recommended Baud Rates
for Remote I/O Modules
Distance
in
Feet
Maximum
Recommended
Baud Rate
0 to 1000
1000 to 2000
38.4 k baud
19.2 k baud
The baud rate is determined by jumper
placement at location S5 of the Control
Module's Serial Interface card (Figure 15.2-1)
and position G7 of the Model 720 I/O Module
Controller card (Figure 15.2-2).
Position S5 has eight pairs of pins. Starting
with the pair nearest to the adjacent board edge
and moving left, baud rates of 1200, 2400,
4800, 9600, 19200, 38400, 76300 or 153600
baud can be selected. The 76.3 and 153.6 k
baud settings are not recommended.
Figure 15.2-2 shows the I/O Module Controller
card. Position G7 has 14 vertically aligned pin
pairs with the 8 uppermost pairs determining
baud rate. A baud rate of 153.6 k baud is
obtained by jumpering the uppermost pair. The
baud rates from the top pair working down are:
153600, 76300, 38400, 19200, 9600, 4800,
2400, and 1200 baud.
Baud rate settings for the Control Module and
the I/O Module(s) must be the same.
SECTION 15. I/O CARD ADDRESSING AND MULTIPLE I/O MODULES
Figure 15.2-1. Location of Jumper Controlling Baud Rate to I/O Modules
15-7
SECTION 15. I/O CARD ADDRESSING AND MULTIPLE I/O MODULES
Figure 15.2-2. Location of I/O Module Jumper Controlling Baud Rate between the I/O Module and
the Control Module
15-8
APPENDIX A. GLOSSARY
ASCII: Abbreviation for American Standard
Code for Information Interchange
(pronounced "askee"). A specific binary
code of 128 characters represented by 7 bit
binary numbers.
BAUD RATE: The speed of transmission of
information across a serial interface,
expressed in units of bits per second. For
example, 9600 baud refers to bits being
transmitted (or received) from one piece of
equipment to another at a rate of 9600 bits
per second. Thus, a 7 bit ASCII character
plus parity bit plus 1 stop bit (total 9 bits)
would be transmitted in 9/9600 sec = .94
ms or about 1000 characters/sec. When
communicating via a serial interface, the
baud rate settings of two pieces of
equipment must match each other.
DATA POINT: A data value which is sent to
Final Storage as the result of an Output
Instruction. Strings of data points output at
the same time make up Output Arrays.
EXECUTION INTERVAL: The time interval
between initiating each execution of a given
Program Table. If the Execution Interval is
evenly divisible into 24 hours (86,400
seconds), the Execution Interval will be
synchronized with 24-hour time so that the
table is executed at midnight and every
execution interval thereafter. The table will
be executed for the first time at the first
occurrence of the Execution Interval after
compilation. If the Execution Interval does
not divide evenly into 24 hours, execution
will start on the first even second after
compilation.
EXECUTION TIME: The time that it actually
takes the CR7 to execute an instruction or
group of instructions. If the execution time
of a Program Table exceeds the table's
Execution Interval, the Program Table will
be executed less frequently than
programmed.
oldest. Data in Final Storage may be
displayed using the *7 Mode or sent to
various peripherals.
HIGH RESOLUTION: A high resolution data
value has 5 significant digits and may range
in magnitude from ±.00001 to ±99999. A
high resolution data value requires 2 Final
Storage locations (4 bytes). All Input and
Intermediate Storage locations are high
resolution. Output to Final Storage defaults
to low resolution: high resolution output
must be specified by Instruction 78.
INDEXED INPUT LOCATION: An Input
location entered as an instruction parameter
may be indexed by keying "C" before
entering by keying "A", two dashes (--) will
appear at the right of the display. Within a
loop (Instruction 87), this will cause the
location to be incremented each pass
through the loop. Indexing is also used with
Instructions 13, 14 and 75 to cause an Input
location, which normally remains constant,
to be incremented with each repetition.
INPUT/OUTPUT INSTRUCTIONS: These
Instructions tell the I/O Module what to do.
Input/Output Instructions are used to initiate
measurements and store the results in
Input Storage or to set Digital Control Ports
or Continuous Analog Output channels.
INPUT STORAGE: That portion of memory
allocated for storing the results of Input and
Processing Instructions. The values in
Input Storage can be displayed and altered
from the *6 Mode.
INSTRUCTION LOCATION NUMBER: As
instructions are entered in a Program Table
they are numbered sequentially. The
instruction location number is the number
giving an instruction's order in the Program
Table. When programming a table, the
instruction location number and a P (e.g.,
04: P00) prompts the user when it is time to
enter an instruction.
FINAL STORAGE: That portion of memory
allocated for storing Output Arrays. Final
Storage may be viewed as a ring memory,
with the newest data being written over the
A-1
APPENDIX A. GLOSSARY
INTERMEDIATE STORAGE: That portion of
memory allocated for storing the results of
intermediate calculations necessary for
operations such as averages or standard
deviations. Intermediate storage is not
accessible to the user.
LOW RESOLUTION: This is the default output
resolution. A low resolution data value has
4 significant decimal digits and may range
in magnitude from ±0.001 to ±6999. A low
resolution data value requires 1 Final
Storage location (2 bytes).
OUTPUT ARRAY: A string of data points
output to Final Storage. Output occurs only
when the output flag is set. The first point
of an Output Array is the Output Array ID,
which gives the table and the Instruction
Location Number of the Instruction which
set the Output Flag. The data points which
complete the Array are the result of the
Output Processing Instructions which are
executed while the Output Flag is set. The
Array ends when the Output Flag is reset at
the end of the table or when another
Instruction acts upon the Output Flag.
Output occurs only when the output flag is
set.
OUTPUT INTERVAL: The time interval
between initiation of a particular Output
Array. Output occurs only when the output
flag is set. The flag may be set at fixed
intervals or in response to certain
conditions.
OUTPUT PROCESSING INSTRUCTIONS:
These Instructions process data values and
generate Output Arrays. Examples of
Output Processing Instructions include
Totalize, Maximize, Minimize, Average, etc.
The data sources for these Instructions are
values in Input Storage. The results of
intermediate calculations are stored in
Intermediate Storage. The ultimate
destination of data generated by Output
Processing Instructions is Final Storage.
The transfer of processed summaries to
Final Storage takes place when the Output
Flag is set by a Program Control Instruction.
A-2
PARAMETER: When used in conjunction with
CR7 instructions, parameters are numbers
or codes which are entered when
programming the CR7 to specify exactly
what the instruction is to do. Once the
instruction number has been entered in a
Program Table, the CR7 will prompt for the
parameters by displaying the parameter
number in the ID Field of the display.
PROCESSING INSTRUCTIONS: These
Instructions allow the user to further
process input data values and return the
result to Input Storage where it can be
accessed for output processing.
Arithmetic and transcendental functions are
included in these Instructions.
PROGRAM CONTROL INSTRUCTIONS:
These Instructions are used to modify the
sequence of execution of Instructions
contained in Program Tables, and to set or
clear flags.
PROGRAM TABLE: That portion of memory
allocated for storing programs consisting of
a sequence of user instructions which
control data acquisition and processing.
Programming can be separated into 2
tables, each having its own user entered
Execution Interval. A third table is available
for programming subroutines which may be
called by instructions in Tables 1 or 2. The
*1 and *2 Modes are used to access Tables
1 and 2. The *3 Mode is used to access
Subroutine Table 3. The length of the
tables are constrained only by the total
memory available for programming.
SAMPLE RATE: The rate at which
measurements are made by the I/O
Module. The measurement sample rate is
primarily of interest when considering the
effect of time skew (i.e., how close in time
are a series of measurements). The
maximum sample rates are the rates at
which the measurements are made when
initiated by a single instruction with multiple
repetitions. When the I/O Module is told to
make several repetitions of a measurement
it will make those measurements as fast as
possible and buffer the data for use by the
Control Module. In normal operation the
Control Module will complete all processing
called for by the Input Instruction before
instructing the I/O Module to make a
APPENDIX A. GLOSSARY
measurement specified by a subsequent
instruction. The time involved in processing
the measurement data to obtain the values
stored in Input, Intermediate, and Final
Storage makes the throughput rate slower
than the measurement sample rate.
SIGNATURE: A number which is a function of
the data and the sequence of data in
memory. It is derived using an algorithm
which assures a 99.998% probability that if
either the data or its sequence changes, the
signature changes.
THROUGHPUT: CR7 throughput rate is the
rate at which a measurement can be made,
scaled to engineering units and the reading
stored in Final Storage. The CR7 I/O
Module has the ability to scan sensors at a
rate exceeding the throughput rate (see
SAMPLE RATE). The primary factor
affecting throughput rate is the amount of
processing specified by the user. In normal
operation, all processing called for by an
instruction must be completed before
moving on to the next instruction. With the
700X Control Module (6303 CPU board),
the maximum throughput rate for fast,
single-ended measurements is
approximately 310 measurements per
second (1 second execution: Instruction 1
entered 4 times, 3 times with 99 repetitions,
once with 11 repetitions).
A-3
APPENDIX A. GLOSSARY
This is a blank page.
A-4
APPENDIX B. CR7 PROM SIGNATURES FOR SYSTEMS EQUIPPED
WITH STANDARD SOFTWARE
KEY
ENTRY
DISPLAY
ID
DATA
FIELD
FIELD
*B
A
A
A
A
A
A
A
A
A
1A
01:
02:
03:
04:
05:
06:
07:
08:
09:
11:00
01:
XXXX
22764
50101
15398
XXXXX
XX
XX
.10000
0004
21444
12196
OR 11:00
PROM
NO.
10437-A
10437-B
10437-C
357
38407
REMARKS
Program Memory Sig.
Control Mod. PROM #8
Control Mod. PROM #7
Control Mod. PROM #6
Number of K RAM + PROM
Number of E08s
Number of overruns
PROM Version 0.1
PROM Revision 4
RAM Sig. of I/O Mod. #1
EPROM Sig. of I/O Mod. #1
357A*1
* PROM 357A and a hardware modification make the slow integration time 20 ms (one 50 Hz cycle).
This option is available for countries where 50 Hz Ac power is used.
- - - - - CR7 SYSTEMS WITH 2 OR MORE I/O MODULES - - - - "2A"
02:
21444
RAM Sig. of I/O Mod. #2
12196
357
EPROM Sig. of I/O Mod. #2
21444
-
RAM Sig. of I/O Mod. #3
12196
357
EPROM Sig. of I/O Mod. #3
21444
-
RAM Sig. of I/O Mod. #4
12196
357
EPROM Sig. of I/O Mod. #4
11:00
"3A"
03:
11:00
"4A"
04:
11:00
B-1
This is a blank page.
B-2
APPENDIX C. BINARY TELECOMMUNICATIONS
The response time and size of the input buffer of the datalogger must be accounted for when attempting
to write a program to make use of the binary commands. The datalogger may delay up to 100 ms before
responding to a command or between bytes in a response. The input buffer in the CR10, 21X, and CR7
will now hold 64 bytes of commands; earlier versions of the 21X and CR7 software would only buffer 7
bytes.
C.1 TELECOMMUNICATIONS
COMMAND WITH BINARY
RESPONSES
Command
Description
[no. of loc.]F
BINARY DUMP - CR7 sends, in
Final Storage Format (binary,
the number of Final Storage
locations specified (from
current MPTR locations), then
Signature (no prompt).
DATALOGGER J AND K COMMANDS
3142J The 3142J command is used to toggle
datalogger user flags, request Final
Storage data, and to establish the input
locations returned by the K command.
The format of the command is as
follows:
3142J<CR>abcd...nNULL
where
1) "3142J<CR>" is the command.
2) "a" is a 1 byte value representing the user
flags to be toggled. The most significant bit
(MSB), if set, will toggle datalogger user flag
8. Likewise, the 2nd most significant bit, if
set, will toggle user flag 7, and so on to the
least significant bit which, if set, toggles
user flag 1. Toggle means that if a flag is
set, it will be then reset, or if it is reset, it will
be set.
3) "b" is a 1 byte value whose MSB will
determine whether Final Storage Data is
returned after the K command. If the bit is
set, Final Storage Data, if any, will be
returned after the next K command. The
datalogger initially has this bit reset upon
entering telecommunications, but once set
by a J command, it will remain set until
reset by another J command or
telecommunications is terminated.
The 2nd MSB set means a port toggle byte
will follow and port status is to be returned
with the K command. Like the MSB, this bit
is reset upon entering telecommunications,
but remains set once set until reset by
another J command or telecommunications
is terminated.
The remaining bits are reserved.
4) If the 2nd MSB in "b" was set then "c" is a
port toggle byte, otherwise "c,d,...,n" are
each 1 byte binary values each
representing a datalogger Input Storage
location. The data at those locations will be
returned after the next K command. ASCII
code 1 (0000001 binary) represents input
location 1. ASCII codes 2 (00000010
binary) represents input location 2, and so
on. The order of the location requests is not
important. The list is limited, however, to 62
total location requests.
5) "Null" or ASCII code 0 (00000000 binary )
terminates the J command. Alternately,
11111111 binary aborts the J command. If
aborted, flags will not be toggled and
location requests will not be saved.
User
Enters
Datalogger
Echo
3
1
4
2
J
CR
3
1
4
2
J
CR
LF
<
a
b
c
d
n
Null
a
b
c
d
n
Null
C-1
APPENDIX C. BINARY TELECOMMUNICATIONS
K
The K command returns datalogger time,
user flag status, port status if requested, the
data at the input locations requested in the
J command, and Final Storage Data if
requested by the J command. The format
of the command is K<CR> (K Return). The
datalogger will echo the K and Return and
send a Line Feed. The amount of data that
follows depends on the J command
previously executed; four time bytes, a user
flags byte, four bytes for each input location
requested in the J command, Final Storage
data in Campbell Scientific's binary format if
requested by the J command, and
terminating in 7F 00 HEX and two signature
bytes.
User
Enters
Datalogger
Echo
K
CR
K
CR
LF
Time Minutes byte 1
Time Minutes byte 2
Time Tenths byte 1
Time Tenths byte 2
Flags byte
Ports byte (if requested)
Data1 byte 1
Data1 byte 2
Data1 byte 3
Data1 byte 4
Data2 byte 1
Data2 byte 2
Data2 byte 3
Data2 byte 4
DataN byte 1
DataN byte 2
DataN byte 3
DataN byte 4
Final Storage Data bytes
01111111 binary byte
00000000 binary byte
Signature byte 1
Signature byte 2
Time Minutes byte 1 is most significant.
Convert from binary to decimal. Divide by 60 to
get hours, the remainder is minutes. For
example, 00000001 01011001 (01 59 HEX) is
345 decimal minutes or 5:45.
Time Tenths byte 1 is most significant. Convert
from binary to decimal. Divide by 10 to get
seconds and tenths of seconds. For example,
00000001 11000110 (01 C6 HEX) is 454
decimal or 45.4 seconds. Thus the datalogger
time for 01 59 01 C6 HEX is 5:45:45.4.
The Flags byte expresses datalogger user flag
status. The most significant bit represents Flag
8, and so on to the least significant bit which
represents Flag 1. If a bit is set, the user flag is
set in the datalogger.
The optional ports byte expresses the
datalogger port status. The most significant bit
represents Port 8, and so on to the least
significant bit which represents Port1.
For each input location requested by the J
command, four bytes of data are returned. The
bytes are coded in Campbell Scientific, Inc.
Floating Point Format. The format is decoded
to the following:
(Exponent)
Sign(Mantissa*2
Data byte 1 contains the Sign and the
Exponent. The most significant bit represents
the Sign; if zero, the Sign is positive, if one, the
Sign is negative. The signed exponent is
obtained by subtracting 40 HEX (or 64 decimal)
from the 7 remaining least significant bits.
Data bytes 2 to 4 are a binary representation of
the mantissa with byte 2 the most significant and
4 the least. The mantissa ranges in value from
80 00 00 hex (0.5 decimal) to FF FF FF HEX
-24
(1-2 decimal). The one exception is for zero
which is 00 00 00 00 HEX.
The Mantissa is calculated by converting Data
bytes 2 to 4 into binary. Each bit represents
some fractional value which is summed for all
24 bits. The bits are arranged from MSB to
LSB with the most significant as bit23 and least
significant as bit0. The value that each bit
n-24
represents = 2 ; where n=bit location. For
example, if there was a 1 at bit20, it’s value
(20-24)
-4
or 2 .
would be 2
A simple method for programming this is as
follows:
Set Mantissa = 0.
Set Bit Value = 0.5.
C-2
)
APPENDIX C. BINARY TELECOMMUNICATIONS
For loop count = 1 to 24 do the following:
If the MSB is one, then add Bit Value to the
Mantissa.
Shift the 24 bit binary value obtained from
Data bytes 2 to 4 one bit to the left.
Multiply Bit Value by 0.5.
End of loop.
Another method that can be used as an
estimate is to convert Data bytes 2 to 4 from a
long integer to floating point and dividing this
value by 16777216.
As an example of a negative value, the
datalogger returns BF 82 0C 49 HEX.
The most significant bit is 0 so the Sign is
POSITIVE.
The exponent is found by subtracting 40 HEX
from the remaining least significant bits.
Converting the binary to hexadecimal, 1000100
BINARY = 44 HEX (or 68 decimal).
44 - 40 HEX = 4 HEX. Or in decimal:
68 - 64 = 4.
Exponent is 4 decimal.
The binary equivalent of Data bytes 2 to 4 is:
11011001 10011001 10011010.
Summing all the fractional values:
Data byte 1 = BF HEX.
Data byte 2 to 4 = 82 0C 49 HEX (or 8522825
decimal).
Data byte 1 is converted to binary to find the
Sign. BF HEX = 10111111 BINARY.
The most significant bit is 1 so the Sign is
NEGATIVE.
-1
-2
-4
-5
-8
-9
-12
-13
2 +2 +2 +2 +2 +2 +2 +2
-17
-20
-21
-23
2 + 2 + 2 + 2 = 0.85000.
-16
+2
+
Using the estimate method to find the Mantissa =
D9 99 9A HEX / 1 00 00 00 HEX (or 14260634 /
16777216) which is 0.85000 decimal.
4
The exponent is found by subtracting 40 HEX
from the remaining least significant bits.
Converting the binary to hexadecimal, 111111
BINARY = 3F HEX (or 63 decimal).
3F - 40 HEX = FF FF FF FF FF HEX. Or in
decimal: 63 - 64 = -1.
Exponent is -1 decimal.
The binary representation of Data bytes 2 to 4
is: 10000010 00001100 01001001.
-1
Using the estimate method to find the Mantissa =
82 0C 49 HEX / 1 00 00 00 HEX (or 8522825 /
16777216) which is 0.50800 decimal.
-1
which equals
As an example of a positive value, the
datalogger returns 44 D9 99 9A HEX.
Data byte 1 = 44 HEX.
Data byte 2 to 4 = D9 99 9A HEX (or 891290
decimal).
Data byte 1 is converted to binary to find the
Sign. 44 HEX = 01000100 BINARY.
NOTE: Don’t lose the leading zero!
If appropriately requested by a J command,
Final Storage data, if any, will immediately
follow the input location data. Refer to the
datalogger manual for a description of how to
decode Final Storage data in Campbell
Scientific's binary data format. Final Storage
data will be limited to not more than 1024 bytes
per K command.
-7
Summing all the fractional values: 2 + 2 +
-13
-14
-18
-21
-24
2 + 2 + 2 + 2 + 2 = 0.50800.
The value is then (-)0.508*2
-0.254.
The value is then (+)0.85*2 which equals
13.60.
The K command data is terminated with 7F 00
HEX (a unique binary format code) followed by
two signature bytes. Refer to the datalogger
manual for the meaning and calculation of the
signature bytes. The signature in this case is a
function of the first time byte through the 7F 00
HEX bytes. Calculate the signature of the bytes
received and compare with the signature
received to determine the validity of the
transmission.
C.2 FINAL STORAGE FORMAT
CR7 data is formatted as either 2 byte LO
Resolution or 4 byte HI Resolution values. The
first two bytes of an output array contain a code
noting the start of the output array and the
output array ID, followed by the 2 or 4 byte data
values. At the end of the data sent in response
C-3
APPENDIX C. BINARY TELECOMMUNICATIONS
to the telecommunications F command a 2 byte
signature is sent (see below).
The decimal locators can be viewed as a
negative base 10 exponent with decimal
locations as follows:
Representing the bits in the first byte of each
two byte pair as ABCD EFGH (A is the most
significant bit, MSB), the byte pairs are
described below.
LO RESOLUTION FORMAT - D,E,F, NOT ALL
ONES
BITS
byte
C
0
0
1
1
0
1
0
1
Decimal Location
XXXX.
XXX.X
XX.XX
X.XXX
DATA TYPE WHEN D,E,F, ALL EQUAL ONE
DESCRIPTION
A
B, C
D-H plus
second
B
Polarity, 0 = +, 1 = -.
Decimal locators as defined below.
13 bit binary value (D=MSB).
Largest possible number without D,
E, and F all 1 is 7167,
but CAMPBELL SCIENTIFIC
defines the largest allowable range
as 6999.
If D, E, and F are all ones, the data type is
determined by the other bits as shown below. X
implies a "don't care" condition; i.e., the bit can
be either 1 or 0 and is not used in the decode
decision.
A
B
C
D
E
F
G
H
DATA TYPE AND SECOND BYTE FORMAT
1
1
1
1
1
1
0
X
A,B,C, = 1 - Start of output array, G=0. H is the most significant bit
of the output array ID. All 8 bits of the 2nd byte are also included in
the ID.
X
X
0
1
1
1
X
X
C = 0 - First byte of a 4 byte value.
0
0
1
1
1
1
X
X
A,B = 0; C = 1 - Third byte of a 4 byte value.
0
1
1
1
1
1
1
1
A = 0; remaining bits = 1 - First byte of a 2 byte "dummy" word. The
CR10 always transmits a 0 for the 2nd byte, but the word can be
decoded on the basis of the 1st byte only.
HI RESOLUTION FORMAT
Continuing to use the A-H bit representation, the four byte number is shown below as two two byte pairs.
AB0111GH
C-4
XXXXXXXX
001111GH
XXXXXXXX
APPENDIX C. BINARY TELECOMMUNICATIONS
BITS, 1ST BYTE,
1ST PAIR
DESCRIPTION
CDEF = 0111
Code designating 1st byte pair of four byte number.
B
Polarity , 0 = +, 1 = -.
G,H,A,
Decimal locator as defined below.
2nd byte
16th - 9th bit (left to right) of 17 bit binary value.
ABCDEF = 001111
Code designating 2nd byte pair of four byte number.
G
Unused bit.
H
17th and MSB of 17 bit binary value.
2nd byte
8th - 1st bit (left to right) of 17 bit binary value.
CAMPBELL SCIENTIFIC defines the largest
allowable range of a high resolution number to
be 99999.
Interpretation of the decimal locator for a 4 byte
data value is given below. The decimal
equivalent of bits GH is the negative exponent
to the base 10.
BITS
G H A
0
0
0
0
1
1
0
0
1
1
0
0
0
1
0
1
0
1
DECIMAL FORMAT
5 digits
XXXXX.
XXXX.X
XXX.XX
XX.XXX
X.XXXX
.XXXXX
C.3 GENERATION OF SIGNATURE
At the end of a binary transmission, a signature
is sent. The signature is a 2 byte integer value
which is a function of the data and the
sequence of data in the output array. It is
derived with an algorithm that assures a
99.998% probability of detecting a change in the
data or its sequence. The CR7 calculates the
signature using each transmitted byte except
the 2 byte signature itself. By calculating the
signature of the received data and comparing it
to the transmitted signature, it can be
determined whether the data was received
correctly.
SIGNATURE ALGORITHM
-
S1,S0
-
M
represent the high and low bytes
of the signature, respectively
represents a transmitted data
byte
-
n
n+1
T
C
represents the existing byte
represents the new byte
represents a temporary location
represents the carry bit from a
shift operation
1. The signature is initialized with both bytes
set to hexadecimal AA.
S1(n) = S0(n) = AA
2. When a transmitted byte, M(n+1), is
received, form a new high signature byte by
setting it equal to the existing low byte.
Save the old high byte for later use.
T1 = S1(n)
S1(n+1) = S0(n)
3. Form a temporary byte by shifting the old
low signature byte one bit to the left and
adding any carry bit which results from the
shift operation. A "shift left" is identical to a
multiply by 2. Ignore any carry bit resulting
from the add.
T2 = shift left (S0(n)) + carry
4. Form the new low signature byte by adding
the results of operation 3 to the old high
signature byte and the transmitted byte.
Ignore any carry bits resulting from these
add operations.
S0(n+1) = T2 + S1(n) + M(n+1)
As each new transmitted byte is received, the
procedure is repeated.
C-5
APPENDIX C. BINARY TELECOMMUNICATIONS
This is a blank page.
C-6
APPENDIX D. CALIBRATION PROCEDURES
The CR7 requires very little maintenance or calibration. Measurements are made in such a way that
small errors in the calibration are automatically removed. Over time, shifts in the calibration are
possible, however. Measurements can be made to determine whether the accuracy of the CR7 is within
the specifications given in Section I.3. If needed, the calibration procedures described in this section can
be performed by an experienced technician having the suggested equipment.
NOTE: The precision of the CR7 exceeds that of most standard electronic equipment. These
procedures require that the test equipment have a precision equal to or better than the CR7.
The following procedures are for calibrating the voltage reference and the clock. Other factors such as
range ratios, DAC non-linearity, and offset in either the switched excitation or the CAO voltage require
that the CR7 be returned to the factory for repair. Please call the factory to obtain authorization before
sending in the unit.
D.1 VOLTAGE REFERENCE
CALIBRATION PROCEDURE
The following procedure assumes that the CR7
being calibrated has an analog input card
configured as analog input card #1 and an
excitation card configured as excitation card #1.
Adjustments would need to be made in the
programming example if the cards are
numbered differently.
SUGGESTED INSTRUMENTS:
Five and one half digit digital volt meter (DVM)
with 10 microvolt resolution. The accuracy of
the DVM needs to be equal to that of the CR7
which is ±1 mV at 5 VDC.
PROCEDURE:
1. With a small, flat screw driver, pry off the
three silver caps on the top of the Analog
Interface Card in the I/O module (see
Figure D.2-1).
2. Monitor the Digital to Analog Converter
(DAC) output by connecting the positive
lead of the DVM to the DAC OUTPUT
TEST JUMPER. Connect the negative lead
of the DVM to a ground on the analog input
card. Set the DVM to read on its most
sensitive DC Volt scale.
3. Set the DAC to output 0.000 volts DC, by
programming the CR7 as follows:
*
01:
1
1
Table 1 Programs
Sec. Execution Interval
01:
P22
01:
1
02:
1
03: 900
04: 0000
05:
0.0000
Excitation with Delay
EX Card
EX Chan
Delay w/EX (units=.01sec)
Delay after EX (units=.01sec)
mV Excitation CHANGE
AS INSTRUCTED
02:
P
End Table 1
*
0
Compiles the instructions
4. Adjust the DAC OFFSET
POTENTIOMETER for a DVM reading of
0.0000 V (±0.0001 V).
5. Change the CR7's program given in step
three so that parameter 5 reads 4000 to
change the DAC output to 4 V. Set up the
DVM to read 4 VDC.
6. Adjust the VOLTAGE REFERENCE GAIN
POTENTIOMETER until a DVM reading of
4.0000 V (±0.001 V) is obtained.
7. Change the CR7s program given in step 3
so that parameter 5 reads -4000 to change
the DAC output to -4V.
8. A DVM reading of -4.000 V (±0.001 V)
verifies the DAC linearity.
9. Lock both potentiometers into position with
a dab of finger nail polish.
D-1
APPENDIX D. CALIBRATION PROCEDURES
D.2 CLOCK CALIBRATION
PROCEDURE
The 700X control module contains 3, 4, or 5
cards. The CPU card has one blue connector
with a ribbon cable connecting it to the 9 pin
SERIAL I/O port on the front of the CR7. The
clock circuitry resides on this card.
The frequency of the crystal exhibits a parabolic
response to temperature. The frequency
maximum occurs at room temperature and
drops off slowly at hotter or colder
temperatures. When the CR7 leaves the
factory it is calibrated to be 20 ppm fast. If the
CR7 is placed in a controlled environment with
the temperature close to room temperature, it is
better to set the crystal frequency exactly on.
SUGGESTED INSTRUMENTS:
Digital frequency counter
STD Bus extender card
PROCEDURE:
1. Remove the CPU card from the control
module. Insert an STD Bus extender card
into the emptied slot. Plug the CPU card
into the extender card. This is the best way
to gain access to the adjustment points.
However, if an "extender card" cannot be
obtained, remove all the other cards and
move the CPU card into the back most slot
for better, though still difficult, accessibility.
D-2
2. Set up the frequency counter to measure
period and connect to pin 3 of the
Integrated Circuit shown at Location B16 on
Figure D.2-2. Connect the ground lead to
the negative (flat) side of the 10 µF
capacitor at location F21. Adjust the
variable capacitor at location E21 on the
same figure for a period of 49,999.00
microseconds (20 ppm fast) or 50,000.00
microseconds (exactly on).
3. Lock the variable capacitor into position with
a dab of finger nail polish.
APPENDIX D. CALIBRATION PROCEDURES
FIGURE D.2-1. Calibration Points for the Analog Interface Card
D-3
APPENDIX D. CALIBRATION PROCEDURES
FIGURE D.2-2. CR7X CPU Card
D-4
LIST OF TABLES
PAGE
OVERVIEW
OV3-1
OV3-2
OV4-1
OV4-2
OV4-3
OV4-4
OV4-5
OV4-6
OV5-1
OV5-2
1.
FUNCTIONAL MODES
1.2-1
1.3-1
1.5-1
1.5-2
1.6-1
1.7-1
1.8-1
1.8-2
1.8-3
1.8-4
2.
Sequence of Time Parameters in *5 Mode .............................................................................1-2
*6 Mode Commands ...............................................................................................................1-3
Memory Allocation in Standard 21X ........................................................................................1-5
Description of *A Mode Data...................................................................................................1-5
Description of *B Mode Data...................................................................................................1-6
*C Mode Entries and Codes....................................................................................................1-7
*D Mode Commands...............................................................................................................1-7
*D Mode Baud Rate and Storage Module Codes ...................................................................1-7
Program Load Error Codes .....................................................................................................1-8
Example Program Listing From *D Command 1.....................................................................1-8
INTERNAL DATA STORAGE
2.2-1
2.2-2
2.3-1
3.
Resolution Range Limits of 21X Data .....................................................................................2-2
Decimal Location in Low Resolution Format...........................................................................2-3
*7 Mode Command Summary.................................................................................................2-3
INSTRUCTION SET BASICS
3.5-1
3.7-1
3.7-2
3.8-1
3.9-1
3.9-2
3.9-3
3.9-4
3.10-1
4.
4.1-1
4.1-2
4.2-2
*Mode Summary ................................................................................................................. OV-8
Key Description/Editing Functions....................................................................................... OV-8
Thermocouple Measurement Programming Example ...................................................... OV-11
Using *6 Mode to Observe Example TC Measurements
(User with Model 723-T RTD Card) .................................................................................. OV-12
Using *6 Mode to Observe Example TC Measurements
(User with Model 723 Card, No RTD) ............................................................................... OV-12
Example Programming to Obtain Five Minute Averages .................................................. OV-13
Using *7 Mode to View Values in Final Storage................................................................ OV-14
EDLOG Listing of Example Program ................................................................................ OV-14
Data Retrieval Methods and Related Instructions............................................................. OV-15
Data Retrieval Sections in Manual .................................................................................... OV-15
Input Voltage Ranges and Codes ...........................................................................................3-2
Flag Description ......................................................................................................................3-3
Example of the Use of Flag 9..................................................................................................3-4
Command Codes ....................................................................................................................3-4
Input/Output Instruction Memory.............................................................................................3-6
Processing Instruction Memory and Execution Times ............................................................3-7
Output Instruction Memory and Execution Times ...................................................................3-8
Program Control Instruction Memory and Execution Times ...................................................3-8
Error Codes.............................................................................................................................3-9
EXTERNAL STORAGE PERIPHERALS
Output Device Codes for Instruction 96 ..................................................................................4-1
*4 Mode Parameters and Codes.............................................................................................4-2
*9 Mode Entries.......................................................................................................................4-3
LT-1
LIST OF TABLES
5.
TELECOMMUNICATIONS
5.1-1
6.
Telecommunication Commands ............................................................................................ 5-2
9 PIN SERIAL INPUT/OUTPUT
6.1-1
6.5-1
8.
Pin Description ....................................................................................................................... 6-1
DTE Pin Configuration ........................................................................................................... 6-3
PROCESSING AND PROGRAM CONTROL EXAMPLES
8.6-1
8.6-2
8.6-3
9.
Example Sensor Description and 21X Multiplier and Offset .................................................. 8-6
Example Outputs and Input Storage Locations...................................................................... 8-7
Example Input Channel and Location Assignments............................................................... 8-7
INPUT/OUTPUT INSTRUCTIONS
9-1
9-2
9-3
Input Voltage Ranges and Codes .......................................................................................... 9-1
Pulse Count Configuration Codes .......................................................................................... 9-3
Thermocouple Type Codes.................................................................................................... 9-6
10. PROCESSING INSTRUCTIONS
10-1
Maximum Number of Outputs and Output Order for K Input Values ................................... 10-8
12. PROGRAM CONTROL INSTRUCTIONS
12-1
12-2
12-3
12-4
12-5
Flag Description ................................................................................................................... 12-1
Command Codes ................................................................................................................. 12-1
Loop Example: Block Data Transform ................................................................................ 12-3
Example: Loop With Delay Execution Interval = 10 seconds.............................................. 12-3
Comparison Codes .............................................................................................................. 12-4
13. CR7 MEASUREMENTS
13.3-1
13.3-2
13.3-3
13.3-4
13.3-5
13.3-6
13.3-7
13.4-1
13.4-2
13.4-3
13.4-4
13.5-1
13.5-2
LT-2
Exponential Decay, Percent of Maximum Error vs. Time in Units of τ................................. 13-4
Properties of Three Belden Lead Wires Used by Campbell Scientific ................................. 13-5
Settling Error, in Degrees, for 024A Wind Direction Sensor vs. Lead Length...................... 13-6
Measured Peak Excitation Transients for 1000 Foot Lengths of Three Belden
Lead Wires Used by Campbell Scientific ............................................................................. 13-6
Summary of Input Settling Data for Campbell Scientific Resistive Sensors ........................ 13-7
Maximum Lead Length vs. Error for Campbell Scientific Resistive Sensors ....................... 13-8
Source Resistances and Signal Levels for YSI #44032 Thermistor Configurations
Shown in Figure 13.3-7 ........................................................................................................ 13-9
Limits of Error for Thermocouple Wire............................................................................... 13-12
Limits of Error on CR7 Thermocouple Polynomials ........................................................... 13-13
Reference Temperature Compensation Range and Polynomial Error Relative to
NBS Standards................................................................................................................... 13-14
Example of Errors in Thermocouple Temperature............................................................. 13-14
Comparison of Bridge Measurement Instructions.............................................................. 13-17
Calculating Resistance Values from Bridge Measurement................................................ 13-18
LIST OF FIGURES
PAGE
OVERVIEW
OV1-1
OV1-2
OV2-1
OV2-2
OV5-1
2.
INTERNAL DATA STORAGE
2.1-1
2.1-2
3.
Ring Memory Representation of Final Data Storage ..............................................................2-1
Output Array ID .......................................................................................................................2-1
INSTRUCTION SET BASICS
3.8-1
3.8-2
3.8-3
4.
If Then/Else Execution Sequence ...........................................................................................3-5
Logical AND Construction .......................................................................................................3-5
Logical OR Construction .........................................................................................................3-5
EXTERNAL STORAGE PERIPHERALS
4.4-1
6.
Example of CR7 Printable ASCII Output Format ....................................................................4-5
9 PIN SERIAL INPUT/OUTPUT
6.1-1
6.5-1
7.
CR7 Measurement and Control System ............................................................................. OV-3
CR7 Wiring Panel and Associated Programming Instructions............................................ OV-4
Instruction Types and Storage Areas.................................................................................. OV-5
Program and Subroutine Tables ......................................................................................... OV-7
Data Retrieval Hardware Options ..................................................................................... OV-16
9 Pin Connector ......................................................................................................................6-1
Transmitting the ASCII Character 1 ........................................................................................6-4
MEASUREMENT PROGRAMMING EXAMPLES
7.1-1
7.2-1
7.4-1
7.5-1
7.9-1
7.10-1
7.11-1
7.12-1
7.13-1
7.14-1
7.15-1
7.15-2
7.16-1
7.17-1
Wiring Diagram for LI200S......................................................................................................7-1
Typical Connection for Active Sensor with External Battery ...................................................7-2
Thermocouples with External Reference Junction..................................................................7-2
Connection for Thermocouple Differential Temperature Measurement .................................7-3
Wiring Diagram for Anemometer ............................................................................................7-6
Wiring Diagram for Raingage with Long Leads ......................................................................7-7
Wiring Diagram for PRT in 4 Wire 1/2 Bridge .........................................................................7-7
3 Wire Half-Bridge Used to Measure 100 ohm PRT ...............................................................7-8
Full Bridge Schematic for 100 ohm PRT.................................................................................7-9
Wiring Diagram for Full Bridge Pressure Transducer ...........................................................7-10
Diagrammatic Representation of Lysimeter Weighing Mechanism ......................................7-11
6 Wire Full Bridge Connection for Load Cell.........................................................................7-12
12 Gypsum Blocks Connected to the CR7............................................................................7-13
101 Thermistor Probes Connected to CR7...........................................................................7-14
LF-1
LIST OF FIGURES
PAGE
13. CR7 MEASUREMENTS
13.1-1
13.2-1
13.3-1
13.3-2
13.3-3
13.3-4
13.3-5
13.3-6
13.3-7
13.3-8
13.3-9
13.4-1
13.5-1
13.5-2
13.6-1
13.6-2
Timing of Single-Ended Measurement................................................................................. 13-1
Differential Voltage Measurement Sequence....................................................................... 13-2
Input Voltage Rise and Transient Decay.............................................................................. 13-3
Typical Resistive Half-Bridge ............................................................................................... 13-4
Source Resistance Model for Half-Bridge Connected to the CR7 ....................................... 13-4
Wire Manufacturers Capacitance Specifications, Cw .......................................................... 13-5
Model 024A Wind Direction Sensor ..................................................................................... 13-5
Resistive Half-Bridge Connected to Single-Ended CR7 Input ............................................. 13-6
Half-Bridge Configuration for YSI #44032 Thermistor Connected to CR7......................... 13-10
Measuring Input Settling Error with the CR7 ...................................................................... 13-10
Incorrect Lead Wire Extension on Model 107 Temperature Sensor.................................. 13-11
Diagram of Sensor Junction Box........................................................................................ 13-15
Circuits Used with Instructions 4-9..................................................................................... 13-16
Excitation and Measurement Sequence for 4 Wire Full Bridge ......................................... 13-17
AC Excitation and Measurement Sequence for AC Half-Bridge ........................................ 13-19
Model of Resistive Sensor with Ground Loop .................................................................... 13-19
14. INSTALLATION
14.2-1
14.5-1
Connecting Vehicle Power Supply to CR7 ........................................................................... 14-4
Typical Connection for Activating/Powering External Devices ............................................. 14-6
15. I/O CARD ADDRESSING AND MULTIPLE I/O MODULES
15.1-1
15.1-2
15.1-3
15.2-1
15.2-2
Position of Decoding Jumpers on Excitation, Pulse Counter & Analog Input Cards............ 15-2
Jumper Settings for Excitation and Pulse Counter Cards .................................................... 15-3
Jumper Settings for Analog Input Cards .............................................................................. 15-4
Location of Jumper Controlling Baud Rate to I/O Modules .................................................. 15-7
Location of I/O Module Jumper Controlling Baud Rate........................................................ 15-8
APPENDIX D. CALIBRATION PROCEDURES
D.2-1
LF-2
Calibration Points for the Analog Interface Card....................................................................D-3
CR7 INDEX
-6999 9-1
-99999 9-1
* Modes, see Modes
1/X [Instruction 42] 10-2
101 Thermistor Probe
Programming example 7-14
107 Thermistor Probe [Instruction 11] 9-5
Calculating lead lengths 13-7
Programming examples 7-5
207 Relative Humidity Probe [Instruction 12] 9-5
Programming example 7-5
227 Soil Moisture Block
Programming example 7-13
3 Wire Half Bridge [Instruction 7] 9-4
Programming example 7-8
4 Wire Full Bridge [Instruction 6] 9-4
Programming example 7-9, 7-10
6 Wire Full Bridge [Instruction 9] 9-4
Programming example 7-11
5th Order Polynomial [Instruction 55] 10-5
Programming example 7-13, 7-14
700 Control Module OV-1
720 I/O Module OV-2
723-T, Reference junction temperature with 13-11
A
A*X + B Scaling Array [Instruction 53] 10-4
ABS(X) [Instruction 43] 10-3
AC excitation, Resistance measurements
requiring 13-19
AC Half Bridge [Instruction 5] 9-3, 13-19
Programming example 7-13
AC Noise, Eliminating 13-1
Activate Serial Data Output [Instruction 96] 12-6
Analog Input voltage, Maximum 13-2
Analog Output [Instruction 21] 9-8
Programming example 8-5
Analog to Digital (A/D) conversion 13-1
AND construction, Logical 3-5
Arctan [Instruction 66] 10-10
ASCII
Characters 6-4
Definition A-1
Dumping (in Telecommunications Mode) 5-3
Program listing (*D Mode) 1-7
Standard 6-4
Transmission 6-4
Average - [Instruction 71] 11-3
Computing running 8-1
B
Battery power options
External 14-4
Caution vi
Sealed lead acid 14-2
Solar panels with 21XL 14-3
Vehicle power supply 14-4
Battery Voltage - [Instruction 10] 9-5
Baud rate
Definition A-1, 6-4
Output Codes 4-1
Setting between I/O and Control Module 15-6
Begin case statement [Instruction 93] 12-5
Binary telecommunications C-1
Block Move - [Instruction 54] 10-4
Programming example 8-1
Branching, Logical AND or OR 3-4
Bridge measurements 13-16
3 Wire Half Bridge 100 ohm PRT 7-8
4 Wire Full Bridge (Pressure Transducer) 7-10
4 Wire Full Bridge 100 ohm PRT 7-9
4 Wire Half Bridge 100 ohm PRT 7-7
6 Wire Full Bridge (Lysimeter) 7-11
Comparison of bridge measurement
instructions 13-17
Diagram of bridge measuring circuits 13-16
AC excitation 13-19
Bridge Transform - [Instruction 59] 10-6
Programming example 7-9
C
Cables/Leads
Avoid PVC insulated conductors 13-9
Determining lead capacitance 13-4
Lead length on signal settling time,
Effect of 13-3
Tipping bucket rain gauge with long leads
programming example 7-6
Card number 3-1
Cassette recorder 4-4
Cautionary Notes vi
Checksum 5-2
Clock
Setting/displaying time (*5 Mode) 1-2
Programming example OV-13
Common mode range 13-2, 14-6
I-1
CR7 INDEX
Communicating with the CR7
Protocol/Troubleshooting 6-4
Via telecommunications 5-1
With external peripherals 4-1
Compiling 1-2
Errors 3-9
Computer
Baud rate, Setting 6-4
Saving/loading program (*D Mode) 1-7
Using with SC32A Interface 6-3
Control ports
Description OV-3
Expansion Module SDM-CD16 9-9
Resetting with *0, *B, or *D Mode 1-2
Using switch relays 14-6
Cosine 10-3
Counter, Pulse Count [Instruction 3] 9-2
Covariance/Correlation [Instruction 62] 10-6
Programming example 8-6
D
Data point A-1
Data retrieval
External storage peripherals 4-1
Manually initiated (*8 and *9 Modes) 4-2
Methods and related instructions OV-15
On-line (Instruction 96, *4 Mode) 4-1
Printer output formats 4-6
Storage Module 4-6
Tape recorder 4-4
Telecommunications 5-1
Data Storage Pointer (DSP) 2-1
Data Terminal Equipment (DTE) 6-3
Data type, Parameter 3-1
Date (*5 Mode), Setting/displaying 1-2
Desiccant 14-5
Differential measurement 13-1
Differential Volts [Instruction 2] 9-1
Programming examples 7-1, 8-2
Display Pointer (DPTR) 2-1
Displaying/setting Clock (*5 Mode) 1-2
Divide
X / Y [Instruction 38] 10-2
X Mod F [Instruction 46] 10-3
DO [Instruction 86] 12-1
DPTR 2-1
DSP, see Data Storage Pointer
DTE pin configuration 6-3
Duplex, Definition 6-4
I-2
E
Editing datalogger programs OV-14
Editor errors 3-9
EDLOG OV-7, 5-3
ELSE [Instruction 94] 12-5
Enclosures, Environmental 14-1
Gas-tight vi
END [Instruction 95] 3-5, 12-6
Programming example 8-2
Error codes 3-9
Overranging 3-2
Overrun occurrences 1-1
Ex-Del-SE [Instruction 4] 9-3
Excit-Del [Instruction 22] 9-8
Excitation outputs OV-3
Excitation with Delay [Instruction 22] 9-8
Excite, Delay, and Measure - [Instruction 4] 9-3
Programming example 7-14
Execution interval OV-7, 1-1, A-1
Execution time 1-1
Definition A-1
Program instruction 3-6
EXP(X) [Instruction 41] 10-2
External storage peripherals 4-1
F
File Mark in Storage Module 4-6
Fill and stop memory, Storage Module 4-6
Final Storage
Changing size of 1-5
Data format 2-2, C-3
Definition A-1
Displaying on keyboard (*7 Mode) 2-3
Erasing 1-5
Format C-3
Output data resolution & range limits 2-2
Redirecting data [Instruction 80] 11-5
Ring memory 2-1
Flags 3-3
Description 12-1
Displaying and toggling 1-2
Intermediate Processing Disable 3-3
Manually toggling (*6 Mode) 1-2
Output 3-3
Resetting with *0, *B or *D Mode 1-2
With J, K commands C-1
Floating point (FP)
Data type 3-1
Final Storage Format C-3
Input Intermediate Storage format 2-2
Fractional Value [Instruction 44] 10-3
CR7 INDEX
Full Bridge with Excitation Compensation
[Instruction 9] 9-4
Programming examples 7-8, 7-12
Full Bridge with Single Differential Measurement
[Instruction 6] 9-4
Full duplex, Definition 6-4
G
Glossary A-1
Ground loop influence on resistance
measurements 13-19
Grounding 14-5
Gypsum Soil Moisture block 7-13
H
Half duplex, Definition 6-4
High frequency pulse, Measuring 9-2
High resolution A-1
High resolution data 2-2
Histogram [Instruction 75] 11-3
Hydrogen gas buildup vi
I
I/O, see Input/Output Instructions
I/O modules, Use of multiple 15-4
I/O module [Instruction 23] 9-9
IF Case X<F [Instruction 83] 12-1
If Flag [Instruction 91] 12-5
Programming examples 8-2
IF Then/Else comparisons 3-4
If Time [Instruction 92] 12-5
Programming example OV-13
If X Compared to F [Instruction 89] 12-4
Programming example 8-3
If X Compared to Y [Instruction 88] 12-4
Increment Input Location [Instruction 32] 10-1
Indexed input location 3-2, A-1
Indirect Indexed Move [Instruction 61] 10-6
Intermediate Processing Disable Flag 3-4
Input setting time constant 13-3
Input Storage
Altering 1-2
Changing size of 1-5
Data format 2-3
Definition OV-3, A-1
Displaying (*6 Mode), Example of OV-12
Erasing with *0, *B or *D Mode 1-2
Input/Output Instructions (I/O) 9-1
Definition OV-5, A-1
Memory and execution times 3-6
Voltage range parameter 3-2
Installation and maintenance 14-1
Instruction location number A-1
Instruction memory and execution time 3-6
Instruction Set
Format OV-9
Types OV-6
Integer data type parameter 3-1
Integer Value - [Instruction 45] 10-3
Integration time 13-1
Intermediate Processing Disable Flag
(Flag 9) 3-3
Intermediate Storage
Changing size of 1-4
Data format 2-3
Definition OV-3, A-2
Erasing with *0, *6, *8 or *D Mode 1-2
Internal temperature [Instruction 17] 9-7
Inverse, 1 / X [Instruction 42] 10-2
Interval Timer, SDM-INT8 9-13
J
J command C-1
Junction boxes 14-1
Jumper setting 15-3
K
K command C-2
Key functions OV-7
Keyboard State, Remote 5-3
L
Label Subroutine - [Instruction 85] 12-1
Subroutine Program Table 1-1
Leads, see Cables/Leads
LI-COR LI200S Silicon Pyranometer
Programming example 7-1
LN(X) [Instruction 40] 10-2
Load Fixed Data, Z = F - [Instruction 30] 10-1
Logging data 1-3
Loop [Instruction 87] 12-1
Index 3-2
Step Loop Index [Instruction 90] 12-4
Low level AC, measuring 9-2
Low Pass Filter [Instruction 58] 10-6
Low resolution 2-2, A-2
LP Filter [Instruction 58] 10-6
Lysimeter, weighing 7-11
LVDT, integration time for 13-1
I-3
CR7 INDEX
M
P
Manually initiated data transfer (*8 and *9
Modes) 4-2
Maximum [Instruction 73] 11-3
Memory
Allocation 1-4
Automatic RAM check on power-up 1-4
Description of areas OV-3
Erasing all 1-5
Pointers 2-1
Minimize [Instruction 74] 11-3
Minus sign (-) & (--), Entering 3-1
Modem 6-2
Modem/terminal 6-3
Modulo divide, X Mod F [Instruction 46] 10-3
Move Input Data, Z = X [Instruction 31] 10-1
Move Signature into Input Location
[Instruction 19] 9-8
Move Time to Input Location
[Instruction 18] 9-8
MPTR (Modem Pointer) 2-1
Parameter
Definition A-2
Data types 3-1
Parity, Checking 6-4
PC201 Tape Read Card 4-5
PC208 Datalogger Support Software 5-3
Password, Security 1-6
Peripherals
Enabling 6-2
General 4-1
Power requirements 14-1
Physical description of CR7 OV-1
Pin configuration
9 pin serial I/O port 6-1
Polynomial [Instruction 55] 10-5
Programming example 7-13, 7-14
Port Set [Instruction 20] 9-8
Ports, commands 12-1
Power, XY [Instruction 47] 10-3
Power supply options 14-2
Power up status 1-4, 5-2
PPTR 2-1
Pressure transducer 7-10
Printer
Interfacing with CR7 6-2
Manually initiated data dump (*9 Mode) 4-3
Output formats 4-6
Printer Pointer (PPTR) 2-2
Send Character [Instruction 98] 12-8
Use with Instruction 96 or *4 Mode 4-2
Processing Instructions
Definition OV-5, A-2
Memory and execution times 3-7
Program Control Flags 3-3
Program Control Instructions 10-1
Definition A-2
Command code parameter 10-1
Logical constructions 3-4
Memory and execution times 3-8
Program memory
Allocation 1-5
Viewing number of bytes remaining 1-5
Program Tables
Execution interval OV-6
Compiling 1-2
Definition OV-6, 1-1, A-2
Entering Subroutines (*3 Mode) 1-1
Example of entering program OV-9
Exceeding execution interval 1-1
Priority/interrupts 1-2
N
Natural logarithm LN(X) [Instruction 40] 10-2
Negative numbers 3-1
Nesting 3-5
Nitrogen purging 14-5
Noise
Common sources 13-1
Modem 6-2
Rejection 3-2
O
On-line data transfer 4-1
Operating details v
OR construction, Logical 3-5
Output Array
Calculating data points 4-2
Definition 2-1, A-2
Setting ID 2-1
Output device codes [Instruction 96] 4-1
Output Flag
Description 3-3
Example of setting OV-12
Interval 3-3
Intervals less than one minute 8-3
Output Processing Instructions
Definition A-2
Memory and execution times 3-8
Overranging analog inputs 3-2
Overrunning execution interval 1-1
Overview of CR7 OV-1
I-4
CR7 INDEX
Programming
Displaying available program memory 1-4
Entering negative numbers 3-1
Examples OV-9, 7-1, 8-1
Logical constructions 3-4
Manual control of program execution 1-3
Maximum program size 1-5
Overview of Instruction Set OV-7
Remote 5-3
Saving/loading programs (*D Mode) 1-7
Sequence OV-8
Voltage overrange detection 3-2
Pulse Count [Instruction 3] 9-2
Measurements 13-20
Programming examples 7-6, 8-3, 8-6
Pulse inputs 9-2
PVC insulated conductors, Avoid 13-9
R
Rain gauge, Tipping bucket 7-6
RAM (Random Access Memory) 1-4
RC35 Cassette Recorder 4-4
Record Real Time [Instruction 77] 11-4
Programming example OV-13
Reference junction compensation 13-11
Relays, Using digital ports for switching 14-6
Relative Humidity Probe, 207 RH Probe
[Instruction 12] 7-5, 9-5
Remote Keyboard State 5-3
Repetitions parameter 3-1
Resetting CR7 1-5
Resistance measurements requiring AC
excitation 13-19
Resolution, Set Final Storage
[Instruction 78] 11-5
Retrieval options, Data storage OV-15
RH (207) [Instruction 12] 9-5
Ring memory
Final Storage 2-1
SM192/716 Storage Modules 4-6
ROM (Read Only Memory) 1-4
Checking on power-up 1-4
Recording signature 9-8
RS232 Interface SC32A 6-3
Run Time errors 3-9
S
Sample [Instruction 70] 11-3
Sample on Maximum or Minimum
[Instruction 79] 11-5
Sample rate 1-1
Definition A-2
Saturation Vapor Pressure [Instruction 56] 10-5
SC32A RS232 Interface 6-3
SC92A/93A, Use tape recorder 4-4
Scaling Array with Multiplier & Offset
[Instruction 53] 10-4
SDM-CD16 16 Channel Port Expansion Module
[Instruction 29] 9-9
Security 1-6, 5-3
Select I/O Module [Instruction 23] 9-9
Send Character [Instruction 98] 12-8
Sensors
Effect of lead length on signal settling time 13-3
Effect of lead length resistance 7-7
Program examples 7-1
Serial Input/Output
Interface details 6-1
External peripherals 4-1
Telecommunication 5-1
Serial Out [Instruction 96] 12-6
Set Active Output Area [Instruction 80] 11-5
Programming examples 8-2, 8-3
Set Resolution Data Final Storage Format
[Instruction 78] 11-5
Settling errors 13-7
Sign, Changing number 3-1
Signal settling time, Effect of sensor lead length
on 13-3
Signature
Definition A-3
PROM 1-6, B-1
Generation of C-4
Move Signature into Input Location
[Instruction 19] 9-8
Sin(X) [Instruction 48] 10-3
Single-ended Volts [Instruction 1] 9-1
Programming example 7-1
SM192/716, Storage Modules 4-1
Smpl on MM [Instruction 79] 11-5
Solar panels 14-3
Spatial Average [Instruction 51] 10-4
Programming example 8-1, 8-2
Spatial Maximum [Instruction 49] 10-3
Spatial Minimum [Instruction 50] 10-4
Specifications of CR7 OV-17
Square Root [Instruction 39] 10-2
Standard and Weighted Value Histogram
[Instruction 75] 11-3
Standard Deviation in Time
[Instruction 82] 11-6
Step Loop Index [Instruction 90] 12-4
Storage and retrieval options, Data 4-1
I-5
CR7 INDEX
Storage Modules, SM192/SM716
Interrupting card transfer to 6-2
Manually initiated data output (*9 Mode) 4-2
Operating power 4-6
Output device codes for Instruction 96 4-1
Saving/loading program (*D Mode) 1-9
Use of two 4-6
Storage peripherals, External 4-1
Strip charts 8-5
Subroutines
Entering 1-1
Label Subroutine [Instruction 85] 12-1
Switch closure, Measuring 9-2
System memory OV-3
System power requirements and options 14-2
System status (*B Mode) 1-6
T
Tables, Program 1-1
Tape Pointer (TPTR) 2-1
Tape recorder 4-4
Connecting to CR7 4-5
Manually initiated data transfer
(*8 Mode) 4-2
On-line data transfer (Instruction 96 and *4
Mode) 4-1
TPTR (Tape Pointer) 2-1
Telecommunication commands 5-1
Automatic time-out 5-2
Baud rate 5-1
with Binary responses C-1
Initiate [Instruction 97] 12-6
Telecommunications (Modem) Pointer
(MPTR) 2-1
Temp-(107) [Instruction 11] 9-5
Temp-Panel [Instruction 17] 9-7
Temp-RTD [Instruction 16] 9-7
Temp-TC SE [Instruction 13] 9-6
Temp-TC DIFF [Instruction 14] 9-7
Temperature from Platinum R.T.D.
[Instruction 16] 9-7
Programming example 7-6
Temperature from thermocouples, see
Thermocouple temperature
Temperature of Input Panel [Instruction 17] 9-7
Programming example OV-11
Temperature range, CR7 14-1
TERM 5-3
I-6
Thermocouple temperature
Calibration 7-4
Differential voltage [Instruction 14] 9-7
Programming examples 7-3
Single-Ended Voltage [Instruction 13] 9-6
Programming example 7-4, 7-5
Technique/error analysis 13-11
Using external reference junction 7-2
Thermocouple types 9-6
Three Wire Half Bridge - [Instruction 7] 9-4
Programming example 7-3
Throughput rate 1-1, A-1
Time
Into Input Location [Instruction 18] 9-8
Record Real Time [Instruction 77] 11-4
Resetting/sending in telecommunications
Mode 5-3
Setting/displaying (*5 Mode) 1-2
Timer - [Instruction 26] 9-9
Totalize - [Instruction 72] 11-3
TPTR 2-1
U
User flags (1-8) 3-4
V
Vapor Pressure From Wet-/Dry-Bulb
Temperatures [Instruction 57] 10-5
Vehicle power supply 14-4
Volts (SE) [Instruction 1] 9-1
Programming example 7-1
Volts (Diff) [Instruction 2] 9-1
Programming example 7-1
Voltage measurements
Differential/single-ended 13-1
Instructions 9-1
Integration 13-1
Ranges/codes and overrange
detection 3-2, 9-1
W
WB/DBT-VP [Instruction 57] 10-5
Programming example 8-8
WVector [Instruction 69] 11-1
Watchdog reset 3-9
Wind speed rose 11-4
Wind Vector [Instruction 69] 11-1
Programming example 8-5
CR7 INDEX
X
X * F [Instruction 37] 10-2
X * Y [Instruction 36] 10-2
X + F [Instruction 34] 10-1
X + Y [Instruction 33] 10-1
X - Y [Instruction 35] 10-1
X / (1-X) [Instruction 59] 10-6
X / Y [Instruction 38] 10-2
X Mod F [Instruction 46] 10-3
XY [Instruction 47] 10-3
Y
Year, Day or time (*5 Mode),
Setting/displaying 1-2
Z
Z = 1 / X [Instruction 42] 10-2
Z = ABS(X) [Instruction 43] 10-3
Z = ARCTAN (X/Y) [Instruction 66] 10-10
Z = EXP(X) [Instruction 41] 10-2
Z = F [Instruction 30] 10-1
Z = FRAC(X) [Instruction 44] 10-3
Z = INT(X) [Instruction 45] 10-3
Z = LN(X) [Instruction 40] 10-2
Z = SIN(X) [Instruction 48] 10-3
Z = SQRT(X) [Instruction 39] 10-2
Z = X [Instruction 31] 10-1
Z = X * F [Instruction 37] 10-2
Z = X + F [Instruction 34] 10-1
Z = X * Y [Instruction 36] 10-2
Z = X + Y [Instruction 33] 10-1
Z = X - Y [Instruction 35] 10-1
Z = X / Y [Instruction 38] 10-2
Z = X MOD F [Instruction 46] 10-3
Z = XY [Instruction 47] 10-3
Z = Z + 1 [Instruction 32] 10-1
I-7
CR7 INDEX
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I-8
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