CR7 Measurement and Control System Brochure

CR7 Measurement and Control System
Ultimate Precision in a Rugged, Expandable System
Extremely Sensitive: 50 nanovolt
resolution at 20 channels per second
throughput.*
Broad Input Range: 16-bit precision
on 8 software-selectable ranges (±5 V
to ±1.5 mV); input ranges up to ±50 V
are possible with the 726 card.
Signal Conditioning Typically Not
Required: Most thermocouples,
RTDs, pressure transducers, humidity
sensors, thermocouple psychrometers,
soil moisture blocks, magnetic pulse
flow transducers, and pulse transducers are measured directly.
Expandable: Seven or fourteen card
slot modules are available. Expansion is
also possible with SDMs, multiplexers,
and slaved I/O modules.
Remote Programming and Data
Retrieval: Programs and commands
are entered from the CR7’s keyboard
or from a computer with an appropriate communications link. Data are
stored in internal memory (up to 280K
data points) for transfer to a storage
module, printer, modem, or computer.
Operation in Harsh Environments:
Specifications are valid from -25° to
+50°C. On special order, CR7s are
tested over a -40° to +70°C range. The
ENC 7F or ENC 7XL enclosures
provide protection from humidity and
contaminants.
Battery Operated: With the CR7
active 10% of the time (typical
application), fully-charged sealed
Most applications use a seven card slot system, but larger
applications may require a fourteen card system.
rechargeable batteries power the
system for about 5 days. Charging
circuitry is included for solar panels, 12 volt vehicle power, or AC.
Internal Processing: Programmable instructions include algebraic,
statistical, and transcendental functions.
Isothermal Design and Transient Protection: Input terminals in
the I/O module are spark gapped to copper bars. The copper bars,
Portable: In most field applications, a rugged fiberglass enclosure
together with aluminum panels between each I/O card, minimize
houses the system. System weight is ~40 lbs.
thermal gradients.
Warranty: 3-year warranty covering parts and labor.
Analog and Digital Control Outputs: Continuous analog outputs
are available for strip-chart recording or proportional control.
*Throughput rate includes similar measurements on adjacent channels, conversion
to engineering units, and storage in Final Memory. Additional processing
Digital outputs can be used with relays to control external devices,
decreases given rate. The time between signal conversions on adjacent input chanactivate alarms, or provide process control.
nels is the Input Sample Rate and is given in the Specifications.
Environmental Applications
Growth Chambers, Greenhouse Monitoring and Control
The CR7 can measure large numbers of distributed air temperature, relative humidity, soil temperature, and solar radiation sensors. Coupled with its ability to monitor
and control HVAC systems, AC power, and water flow, the CR7 is an ideal instrument for controlled-environment applications. The CR7 can be programmed to
maintain measured parameters within preset limits and sound alarms if monitored
systems fail.
Peltier Psychrometers
Psychrometric water potential measurement of soil, plant leaves, or other porous
media requires measurement of the wet-bulb depression of a thermocouple housed
inside a small chamber. The junction is Peltier-cooled below dew point and the wetbulb temperature is measured as the water evaporates. Wescor, Inc. (Logan, UT)
markets the CR7 in conjunction with their psychrometers.
Other Applications
•
Multi-level meteorologic towers
•
Eddy covariance experiments
•
Soil temperature profiles
•
Lysimeters
A CR7 measures the soil water potential
across a research plot with dozens of thermocouple psychrometers. Results are transmitted
via UHF radio to the researcher’s computer.
Green Canyon, UT.
Cover photos At left: CR7 Measurement and Control System. From top right: Automotive Electric vehicle monitoring, Waterbury, VT; Process Control
Respiration measurements on woodchips at Silsoe Research Institute, Bedford, England; Agricultural/Meteorology USDA/ARS lysimeter installation, Bushland,
TX; Agricultural Research NASA CELSS Research Lab, Utah State University, Logan, UT.
Industrial Applications
Vehicle Test
HVAC & Utilities
The CR7’s wide operating range (-40° to +70°C, extended), portability, ruggedness, and expandability make it a useful tool in vehicle
testing applications. In automobiles, locomotives, tractors, helicopters, and other vehicles, the CR7 can measure temperature,
pressure, velocity, acceleration, engine RPM, force, displacement,
and electrical system load.
Measured parameters include:
Most sensors can be connected directly to the CR7 without the use
of external signal conditioning. The CR7 is also SDM-OBDII
compatible allowing the user to monitor, record, and compare data
from the vehicle’s onboard computer with the CR7’s sensors.
•
Voltage
•
Current
•
Power
•
Temperature
•
Relative humidity
•
Pressure
•
Flow
The CR7 is usually panelmounted in a NEMA enclosure.
HVAC applications typically
require input/output channel
expandability. Options include:
•
720XL I/O modules
•
AM416 multiplexers
•
Up to four remote I/O
modules
Systems can monitor and control
pumps, fans, and starter motors.
Proportional control of dampers is
also possible.
Remote I/O modules or multiplexers can greatly simplify cabling from remote sensor arrays by
sending data or signals over a few common lines.
Process Control
Above: The CR7 displays and
stores vehicle test data from a
prototype Aston Martin DB7.
Left: Closeup of ENC 7F modified
with custom connectors. Photos
courtesy of Aston Martin, Ltd.
The CR7 is typically housed in an ENC 7F enclosure and interfaced
to the DSP4 Heads Up Display for real-time display. The
SM192/716 Storage Modules or CSM1 Card Storage Module
provide additional data storage. Real-time data can be downloaded
via cellular phone or RF link.
The CR7 can monitor ongoing production allowing operators to
discard items that don’t meet specifications. Real-time measurements can be displayed for operators and stored for review by
quality control personnel. Both product and assembly line status
can be monitored simultaneously, providing on-line quality control
while minimizing production downtime.
Process and control applications include:
•
Maintaining oven/dryer temperature
•
Monitoring conveyor/belt speed
•
Sounding alarms for out-of-specification conditions or
equipment malfunction
•
Maintaining liquid or gas levels
Measurement Examples
Thermocouples
The CR7’s input offset error of less than 100 nV allows inexpensive
thermocouples to be used for precision temperature measurements.
Type T, E, K, J, S, R, and B thermocouples connect directly to a 723
or 723T card; the signal voltage is then linearized relative to a
user-specified reference junction. Measurements of type E thermocouples can be resolved to 0.001°C at throughput rates of 20
channels per second, 0.0125°C at 100 channels per second.
RTDs, Strain Gage Pressure Transducers and Load Cells
Strain gages and RTDs are measured as the ratio of bridge signal to
excitation voltage. Consecutive measurements with reversed excitation polarity eliminate errors due to thermal emfs in connectors
and sensor junctions. The CR7’s measurement precision allows
bridge excitations to be reduced, eliminating self-heating errors
(e.g., a 100 ohm RTD with a 0.5 mA excitation current resolves to
within 0.00025°C at 15°C).
One CR7 can measure large numbers of flow meters, LVDTs, pressure
transducers, thermocouples, strain gages, and accelerometers.
System Description
The CR7 features a modular, multiple-processor design that provides precision measurement and control capability in a
rugged, battery-operated system.
CR
7
Control Module with 9-Pin Serial
Interface and Keyboard Display
I/O Processor Card
Analog Interface Card
Rechargeable Power Supply
Seven I/O Card Slots for any combination
of 723, 723T, 724, 725, and 726 Cards
I/O Cards
Aluminum Frame and Cover Plate
Aluminum Card Dividers
E
LV
F
LIE
RE
VA
N
IO
UT
ON
TT
S BU
RE
E
FO
BE
CAS
NG
CKI
NLO
CA
ES
PR
U
Sensor Ports
ENC 7F
(Enclosure lid and cover plates not shown)
700X Control Module
Control Module functions include task initiation, processing, data
storage, and telecommunications. The control module contains the
CPU with 24K bytes of system PROM and 40K bytes of RAM, the
serial interface for peripheral communication and connection of up to
four I/O modules, the keyboard/display, and the optional memory
expansion card. The system’s 2.5 Amp-hour sealed-rechargeable
batteries and AC-charging circuitry are also in this module.
709 512K Memory Card: Provides RAM storage for an additional
262,126 data values. Maximum of one per 700X Control Module.
720 & 720XL I/O Module
The I/O module performs all measurement and control functions; it
consists of a processor card, a precision analog interface card, and
seven card slots. Model 720 has seven I/O card slots; model 720XL
has 14 slots (ENC 7XL required). 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
converter and a precision voltage reference. All I/O module
connections are transient protected with spark gaps.
723 Analog Input Card: Contains 14 differential or 28 singleended inputs. Differential measurements reverse the input
polarities for a second conversion to reduce thermal emfs. Input
ground terminals connect to a heavy copper bar, which reduces
single-ended measurement offsets to less than five microvolts.
723T Analog Input Card With RTD: Identical to the 723 Card
except a platinum resistance thermometer (PRT) is centered below
the terminal strip to provide a reference junction temperature for
the thermocouple measurements. The PRT’s measurement is accurate to ±0.1°C over a -40° to +60°C range.
724 Pulse Counter Card: Provides four pulse counting channels
for switch closures, low-level AC, or high-frequency pulse signals.
725 Excitation Card: Provides eight switched analog excitations
for resistance measurements, two continuous analog outputs, and
eight digital control outputs. All continuous analog outputs and
digital control ports can be active simultaneously; only one
switched excitation output can be active at a time.
726 50 Volt Analog Input Card: Provides 8 differential or 16
single-ended inputs for full-scale ranges of ±50 and ±15 VDC.
Accuracy is ±0.2% FSR; common mode range is ±50 VDC;
maximum sustained input voltage without damage is ≤ ±160 VDC.
Enclosures
ENC 7F Environmentally Sealed Enclosure (cover photo):
20” x 13” x 10” fiberglass enclosure for harsh environments.
Accommodates the 700X control module and 720 I/O module.
It has two sensor ports that fit #14 shell size circular connectors.
A gas-tight connector option is also available.
ENC 7L Aluminum Frame for Lab: 17” x 12” x 6”; provides a
housing for benchtop use. 19” rack mounts and NEMA enclosures
are also available.
ENC 7XL: 19” x 19” x 10” fiberglass enclosure for harsh environments. Accommodates 700X and 720XL modules.
Data Storage and Transfer
Up to 18,800 (expandable to 280K) raw or processed data points can be stored in the CR7’s memory. Data are transferred to a computer via telecommunications or on-site data retrieval options.
+12
720
I/O MODULE
700X CONTROL MODULE
MADE IN USA
CAMPBELL
SCIENTIFIC
INC. LOGAN, UTAH
SERIAL I/O
ANALOG INTERFACE
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
6
H L
7
H L
8
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
11
H L
12
H L
13
H L
14
H L
DIGITAL CONTROL OUT
1 2 3 4
5 6 7 8
CONTINUOUS ANALOG OUT
2
4
725
EXCITATION
1
ON
OFF
Display
Storage
Module
Card Storage
Module
DATA
3
Multidrop
Modem
2
3
A
4
5
6
B
7
8
9
C
*
0
#
D
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
900
800
1800
1700
1600
700
600
500
1500
1400
400
300
1300
1200
1100
200
100
1000
Scale = Auto
Software
Direct Line Options
We offer Windows or DOS-based datalogger support software that
provides telecommunications, programming, data transfer, data
processing, and graphical display functions. With an appropriate
communication link, the software supports two-way communication between the CR7 and IBM-PC or compatible computers.
Direct Datalogger-to-Computer Interface
The SC32A RS-232 Interface supplies an optically isolated connection between the CR7 and a computer over distances up to 50 ft.
Display
The CR7’s keyboard/display provides on-site review of data and
programs. Annotated datalogger programs and labeled data values
can be displayed on a computer monitor. The DSP4 Heads Up
Display provides a dashboard-mounted luminescent display for
vehicle test applications.
Storage Modules
Rugged, battery-backed RAM SM192 or SM716 Storage Modules
(96K or 358K data values, respectively) can be left connected to the
CR7 or carried to the field to retrieve data from the CR7’s memory.
Two storage modules can be connected to one CR7. Operational
temperature range is -35° to +65°C (extended range available). The
SC532 Interface is used to transfer data and/or programs between
the storage module and a PC.
Card Storage Module
The CSM1 Card Storage Module is a read/write module that either
remains with the CR7 or is transported to the datalogger site.
Battery-backed RAM memory cards are inserted into the CSM1 for
data and/or program transfer. The system operates over a
-20° to +50°C range (extended range available).
Short Haul Modems
The SRM-6A short haul modems provide local communication
between the CR7 and a computer with an RS-232 serial port. The
modem transmits data up to 11.2 miles over a four-wire unconditioned line (two twisted pairs).
Coax Network
The MD9 Multidrop Interface links a central computer to over 200
dataloggers on a single coaxial cable. Total coax cable length can be
up to three miles.
Radio Frequency (RF) Communication
Campbell Scientific’s RF communication system uses the RF95
modem and a low-powered transceiver at the remote station(s) with
a transceiver connected to an RF232 Base Station at the computer
site. Up to 255 stations can be interrogated over a VHF or
UHF frequency.
Telephone Networks
Telephone communication links require a DC112 modem at the CR7
site and a Hayes-compatible modem at the calling end. Cellular
communications are supported with our COM100 transceiver.
Phone-to-RF and phone-to-MD9 networks are also available.
Datalogger Support Software
We offer Windows- and DOS-based software packages that simplify the exchange of data, programs, and commands
between the CR7 and a computer.
Creating a CR7 Program
EDLOG software allows you to create an application-specific
program. If application requirements change, the program can be
easily modified. EDLOG helps you create or edit a CR7 program
by providing:
•
Select-from-a-list and fill-in-the-blank programming sequences
•
Annotated instructions, parameters, and labels
•
Automatic checking of program structure and syntax when
program is compiled
•
Extensive on-line help
•
The ability to enter algebraic expressions directly into the program
and insert comments for documentation
Once programmed, the CR7 automatically:
•
Measures sensors at specified scan rate(s)
•
Processes data using arithmetic operators, math functions,
spatial functions, and time-series functions
Processing and Splitting Data Files
•
Stores measurements and processed data
Reports can be generated by using Split software. Split allows you to:
•
Makes logic decisions based on time or data
•
Split large data files into smaller, more easily analyzed files
•
Controls external devices
•
Sort and combine data based on time or conditions
•
Process data using arithmetic operators, math functions, spatial
functions, and time-series functions
•
Create output files that are compatible with spreadsheet programs
The Windows-based TCOM graphs real-time data from the CR7.
Communicating with a Storage Module
We offer Windows- and DOS-based software packages that handle
storage module communication. The packages support:
•
Use of solid-state and card storage modules
•
Transfer of CR7 programs to and from storage module and
cards
•
Retrieval of all or part of a storage module or card’s data
•
The ability to reset, clear, and configure storage modules or
cards
SMS (Windows-based) also provides:
EDLOG is a powerful software program for creating and editing
CR7 programs.
•
The ability to view data before storing it on disk
•
The choice of appending data to an existing file or creating a
new file
Communicating with the CR7
Our DOS-based PC208E or Windows-based TCOM software will:
•
Place a call to the CR7 via one of our telecommunications links
•
Transfer a program to the CR7
•
Monitor and display real-time measurements in tabular or
graphical form
•
Collect CR7 data on demand or schedule; integrity is ensured
during transmission
TCOM also provides:
•
New network capabilities that simplify interactions with the CR7
•
Log files that track communications with the CR7
•
The ability to run while other Windows software is active (also
depends on operating system and computer)
•
Simultaneous data collection via multiple COM ports
The Windows-based SMS displays the status of a solid-state
storage module.
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
Transient Protection
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
100
1,000
3,000
10,000
Digital Control Outputs
(725 Card)
Each card includes 8 digital control outputs.
Range: ±5 V
Resolution: 166 µV
Normal Mode Rejection: 70 dB (60 Hz with
slow differential measurement)
Accuracy: Same as voltage measurements.
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.
Data Storage: 18.8K values, standard; 280K
values, expanded.
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.
to
to
to
to
Common Mode Rejection: > 140 dB (DC to 100 Hz)
Sustained Input Voltage without Damage:
≤ ±16 VDC
Memory: 24K ROM; 40K RAM, 709 Card
provides an additional 512K RAM.
1
1
1
1
Common Mode Range: ±5 V
Input Resistance: 2.5 GΩ typical
Processor: Hitachi 6303
Display: 8 digit LCD (0.5” digits).
Output Voltages (no load):
High: 5.0 V ±0.1 V
Low: < 0.1 V
Input Current Noise: 9 pA RMS (slow differential)
Control Module
Range (Hz)
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: 100 pA max
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.
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.
Clock Accuracy: ±1 minute per month.
Analog Outputs
Maximum Program Execution Rate: System
tasks can be initiated in sync with real-time up
to 80 Hz.
(725 Card)
System Power Requirements
Each card contains 8 switched and 2 continuous
analog outputs.
Voltage: 9.6 to 15 VDC
Output Resistance: 400 Ω
Switched: Provides a precision voltage for
resistance measurement, then switches off
(high impedance). Only one switched output
can be active at a time.
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.
Output Current: 25 mA at ±5 V, 50 mA at ±2 V
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.
Internal Batteries: Sealed rechargeable with
2.5 Ahr capacity per charge.
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.
Additional Information
Assurance of Quality
For More Information
Campbell Scientific has produced research-grade dataloggers for
more than twenty years. The workmanship and design of our CR7
demonstrates our commitment to quality.
Pricing and ordering information is provided by our:
•
Price lists
•
Order Entry Staff
Technical information on our products is provided by our:
•
Product Literature
•
Product Configuration Guide
•
World Wide Web site at http://www.campbellsci.com
•
Applications Engineers
•
Authorized representative in your area (for a list of representatives, visit our web site or contact us by e-mail, phone, or fax)
•
Training sessions
Customers may also contact our U.S. factory via e-mail or phone:
If repair is required, our professional staff of technicians will
repair and recalibrate the CR7 to original specifications.
•
Environmental group: enviro@csius.com or 801-750-9691
•
Industrial group: industrial@csius.com or 801-750-9692
Every CR7 is calibrated and thoroughly tested to ensure consistent,
dependable performance. The CPU, system components, and all
I/O connections are tested.
The results are calibrated against a standard traceable to the
National Institute of Standards and Technology (NIST). A test
report and calibration certificate including NIST traceable numbers
are shipped with each CR7.
Warranty and Repair
The CR7 has a three-year warranty covering parts and labor.
The Mean Time Between Failures (MTBF) of the CR7 is more than
24 years.
Campbell Scientific’s U.S. factory is located in Logan, Utah.
Please call us today. We would like to discuss your application needs with you.
815 W. 1800 N.
Logan, Utah 84321-1784
(435) 753-2342
FAX (435) 750-9540
Offices also located in:
Australia
Canada
England
France
Copyright © 1989, 1996
Campbell Scientific, Inc.
Printed November 1996