MDS_Supplement_Installation_Manual_Moore_Industries

MDS_Supplement_Installation_Manual_Moore_Industries
™
®
STATION
EQUATION
Multifunction Distributed I/O System
PID/Programming Supplement
February 1997
236-701-02 A
EQUATION
STATION
®
Multifunction Distributed I/O System
PID/Programming Supplement
Table of Contents
Overview ............................................................................................................................... S-1
Upgrading to Version 4.30 .......................................................................................................................... S-1
Engineering Unit Conversion ...................................................................................................................... S-1
PID Control ........................................................................................................................... S-2
Specifications .............................................................................................................................................. S-2
Configuring the CO Variable for “Host Source” .......................................................................................... S-2
Host Sourcing of “Controller Input Variables” ............................................................................................. S-4
Bumpless Transfer ...................................................................................................................................... S-5
Host Sourcing of “Controller Constants” .................................................................................................... S-5
CO Variable as “Source” to AO Variable .................................................................................................... S-5
Accessing Data From a Host ...................................................................................................................... S-6
Data Format for Host Access ...................................................................................................................... S-7
Configuring CO with other variables as “sources” ...................................................................................... S-7
Other MDS Variables Sourcing “Controller Input Variables” ...................................................................... S-8
Other MDS Variables Sourcing “Controller Constants” .............................................................................. S-9
Application Example: Proportional-only Ratio Control .................................................. S-11
Control Strategy ........................................................................................................................................ S-11
MDS Configuration .................................................................................................................................... S-11
Operation ................................................................................................................................................... S-12
Programming Toolkit ......................................................................................................... S-13
Discrete Output with Deadband ................................................................................................................ S-13
Exponents .................................................................................................................................................. S-14
Removing an Open Input From an Averaging Calculation ....................................................................... S-15
Rate of Change Alarm ............................................................................................................................... S-16
Time Delay Deadband ............................................................................................................................... S-17
Sensor Linearization .................................................................................................................................. S-18
Sensor Transfer ......................................................................................................................................... S-19
Totalizing ................................................................................................................................................... S-20
Resettable Functions ................................................................................................................................. S-21
Example: Manual Reset Alarm ................................................................................................................. S-21
Example: Variable Frequency Output ...................................................................................................... S-22
Event or Edge Triggered Latching ............................................................................................................ S-23
Using an AI as a Discrete Input ................................................................................................................. S-24
ASCII Protocol Description ............................................................................................... S-25
ASCII Message Format ............................................................................................................................. S-25
Field Definitions: ........................................................................................................................................ S-25
ASCII Instruction Set ................................................................................................................................. S-26
I/O EQUATION STATION® PID Viewer Program ............................................................... S-28
Requirements ............................................................................................................................................ S-28
Operation ................................................................................................................................................... S-28
MDS Communication Settings .................................................................................................................. S-28
Starting MDSPID ....................................................................................................................................... S-28
Trend Options ............................................................................................................................................ S-28
Controller Parameters ............................................................................................................................... S-29
Dynamic Data Exchange (DDE) ................................................................................................................ S-29
List of Tables and Figures
Table S-1. CO Variables Database Map .............................................................................................................S-6
Table S-2. Sample Linearization Points ...........................................................................................................S-18
Table S-3. Query without Checksum ...............................................................................................................S-25
Table S-4. Query with Checksum ....................................................................................................................S-25
Table S-5. Response without Checksum .........................................................................................................S-25
Table S-6. Response with Checksum ..............................................................................................................S-25
Table S-7. Start-Delimiter Characters ..............................................................................................................S-25
Table S-8. ASCII Queries and Responses .......................................................................................................S-26
Table S-9. ASCII Field Codes ..........................................................................................................................S-26
Table S-10. Device Identification .....................................................................................................................S-27
Table S-11. Device Information ........................................................................................................................S-27
Table S-12. Status Information ........................................................................................................................S-27
Table S-13. Subsystem Errors .........................................................................................................................S-27
Table S-14. Variable Configuration ..................................................................................................................S-27
Table S-15. Coding Variable Types, Binary Format, and Reset ......................................................................S-27
Table S-16. Data Addresses within MDSPID ...................................................................................................S-29
Figure S-1. Entering Engineering Units ..............................................................................................................S-1
Figure S-2. Converting Engineering Units ..........................................................................................................S-1
Figure S-3. Configuring a Host Sourced System ...............................................................................................S-2
Figure S-4. Configuring the MDS-MAO ..............................................................................................................S-3
Figure S-5. Converting Input Range and Units ..................................................................................................S-3
Figure S-6. Host Sourcing Controller Input Variables ........................................................................................S-4
Figure S-7. Host Sourcing Controller Constants ................................................................................................S-5
Figure S-8. Using a CO Variable as “Source” to an AO Variable .......................................................................S-5
Figure S-9. Overview of Example Modifications ................................................................................................S-7
Figure S-10. Adding Potentiometers to the Configuration ..................................................................................S-7
Figure S-11. Configuring MDS Variables as Sources ........................................................................................S-8
Figure S-12. Sourcing Controller Constants with MDS Variables ......................................................................S-9
Figure S-13. Configuring Controller Constants ................................................................................................S-10
Figure S-14. Overview of Example ..................................................................................................................S-11
Figure S-15. Configuring the MDS with Proportional-Only Control ..................................................................S-11
Figure S-16. Inputting Controller Input Variables .............................................................................................S-12
Figure S-17. Viewing the Measure Window .....................................................................................................S-12
Figure S-18. Configuring a Pump .....................................................................................................................S-13
Figure S-19. Calculating Exponential Equations ..............................................................................................S-14
Figure S-20. Removing Open Input .................................................................................................................S-15
Figure S-21. Configuring a Rate of Change Alarm ..........................................................................................S-16
Figure S-22. Configuring a Time Delay Deadband ..........................................................................................S-17
Figure S-23. Configuring Linearization .............................................................................................................S-19
Figure S-24. Totalizing a Flow of Liquid ...........................................................................................................S-20
Figure S-25. Resetting a Function ...................................................................................................................S-21
Figure S-26. Using the “max” Function to Latch an Alarm ...............................................................................S-21
Figure S-27. Resetting an Integral using Process Result ................................................................................S-22
Figure S-28. Triggering Latching with an Event ...............................................................................................S-23
Figure S-29. Using an AI as a Discrete Input ...................................................................................................S-24
Page S-1
MDS
Supplement
Overview
Engineering Unit Conversion
This document explains how to use the features added
to the I/O EQUATION STATION® with version 4.30 of
the configuration software, MDSCNFG. Version 4.30
features PID control and a new engineering units conversion scheme for analog input variables.
Version 4.30 has a simplified scheme for engineering
conversion.
Upgrading to Version 4.30
If your I/O EQUATION STATION® modules were received with an older version of the configuration software MDSCNFG, you will need to download software
into the modules to use the added features. If the modules came with MDSCNFG version 4.30, skip this section. The software version can be found in the “About”
screen or on the diskette label.
Note:
Do not begin the upgrade until the modules
can be upgraded individually (with only one
module on the comm link at a time) and the
upgrade can be performed with a direct
connection (i.e. not through any type of
modem link).
First, upgrade the configuration software on your PC by
following the instructions on the “Installation Diskette”
for MDSCNFG Version 4.30.
After adding an AI variable and selecting the desired
sensor, click on the “Range/Error” field. Fill in the “minimum” and “maximum” range values in terms of the
units of the selected sensor. (e.g., units of mA for “Current” sensor, units of V for “Voltage” sensor.)
The conversion to engineering units is defined in the
“Format” field (see Figure S-1).
Figure S-1. Entering Engineering Units
Enter the engineering units under “Unit” (in this case,
“psig”) and click on “Conversion”. The unit conversion screen appears (see Figure S-2).
Figure S-2. Converting Engineering Units
Run the new version of MDSCNFG and, with the I/O
EQUATION STATION® (MDS) connected to the PC
(see page 78 of the manual), select “Utilities” from the
main menu bar, then “Reprogram Module”. If the connections from PC to MDS (including RS232-RS485
converter) are correct, the “Module Selection” screen
will show the communication details of the MDS being
upgraded. (If not, try “Search All”.) Note the address.
Click on “OK”. From “Reprogramming Files”, select
the Monitor/Update V3.10 file, and click on “OK”. Select “Utilities-Reprogram Module”. At the “Module Selection” screen, highlight the address of the module
being reprogrammed (even though no module information appears beside the address) and then click OK”.
“Reprogramming Files” appears. Select the ModbusRTU V4.30 file for modules with the –MD or –MAO option or version 4.31 for the standard MDS (or Profibus/
ASCII V4.30, if Profibus or ASCII is desired), and click
on “OK”.
The sensor in this example is Current, so we convert
the fundamental measurement units—or “Input”
units—of the selected sensor (in this case Amperes)
to psig. Type in the 0 and 100% engineering units
values ( in this case, 3 and 15) corresponding to the
0 and 100% “Input Units” values.
The Interface Solution Experts
Page S-2
MDS
Supplement
PID Control
Configuring the CO Variable for “Host Source”
One of the MDS variables available with version 4.30
is the Controller variable (CO), which executes a PID
equation. The PID equation is a function of input
variables and controller constants. Its real time result is the value of the CO variable.
All inputs to the CO variable, except PV, can be
“sourced” by a host computer (i.e., a host controls
their values) or sourced by other variables in the
MDS configuration (an Analog Input variable, for instance, configured for potentiometer, to adjust K or
SP). Process variable input must be sourced by another MDS variable.
CO=K•{(SP–PV) + (1/Ti)•∫(SP–PV)dt + Td •d(PV)/dt}
where K, Ti and Td are controller constants. K is Proportional Gain, Ti is Integral Time (in minutes), Td is
Derivative Time (in minutes), and SP (setpoint) and
PV (process variable) are input variables.
The CO variable may then be used by any other
MDS variable (as the source for Analog Output or
Digital Output variables, for instance) or as setpoint
input for another CO variable if cascade control is
required.
Another parameter associated with the CO variable
is Mode. Mode is a “switch” that can be set to Auto
or Manual. In Auto (closed-loop) mode, the value of
CO is the result of the above equation. In Manual
(open-loop) mode the CO result (independent of
controller inputs SP and PV) may be controlled directly.
The CO variable may only be configured in an MDS
equipped with either the -MD or -MAO option. Each
module can have a maximum of two CO variables.
Specifications
Sample Period: 1 second.
Resolution: 0.01% of control range
Gain Range: 0 - 655.35
Integral Time Range: 0 - 655.35 minutes
(0 means no Integral action)
Derivative Time Range: 0 - 655.35 minutes
Integral Wind-up prevented by non-linear
feedback of CO result to Integrator.
“Bumpless Transfer” between Auto and
Manual modes if SP and CO are “Host
sourced”.
The Interface Solution Experts
The following example demonstrates how to use the
MDS for PID control. This configuration requires a
host computer to source all inputs to the CO variable
(except process variable PV). Later the configuration is modified so that adjustments made from external signal sources are fed into the MDS as Analog
Input or Digital Input variables. Figure S-3 gives an
overview of a host sourced system.
Figure S-3. Configuring a Host Sourced System
HOST
(RS485)
K, Ti, Td Mode
SP, CO
MDS
PID
CONTROLLER
CO
(4-20MA)
BOILER
PROCESS
PV
4-20MA
–50°C TO +450°C
Figure S-4 shows the beginning of an MDS-MAO
configuration. Variable 1 is an AI variable configured
for 4-20mA input and named ProcVar. A CO variable is then added, and named COVar. (See page
16 of the manual to start a new configuration and
add variables.)
Page S-3
MDS
Supplement
Figure S-4. Configuring the MDS-MAO
Next, the input range and units of ProcVar are converted from 4-20mA to the engineering units range of
–50°C to +450°C. See “Engineering Units Conversion” on page S-1 for conversion information.
(Figure S-5 shows the configuration screen.)
Figure S-5. Converting Input Range and Units
The Interface Solution Experts
Page S-4
MDS
Supplement
Host Sourcing of “Controller Input Variables”
Click on the Additionals field of COVar to reveal the
“Controller Input Variables” window. Select ProcVar
as the source variable under “Process Variable
Source” (see Figure S-6).
Figure S-6. Host Sourcing Controller Input Variables
The “Control Range” is entered in the engineering
units of the Process Variable. This defines how the
PID controller applies gain in terms of percent error
vs. percent output. Although the range entered may
differ from the range defined for ProcVar, for this example enter the same range: –50°C to +450°C.
“Setpoint Source”, “Mode Switch Source” and “CO
Manual Mode Source” must all be set to “Host” for
this example. The associated “on power-up” values
may also be changed at this time. These values
apply until the Host writes new values to SP, Mode,
and CO.
Set “on power-up” Mode to “Auto” and enter a Setpoint
value of 125. The controller then defaults to Auto mode
with a setpoint of 125°C on power-up. The entered
value for Setpoint is interpreted in terms of Process
Variable engineering units. If “on power-up” mode is
set to “Manual”, then the “on power-up” value under
“Co Manual Mode Source” becomes the default
controller output value. Mode must be entered in
percent of control range (i.e. 0-100).
Note:
CO Manual Mode Source controls CO when
Mode is Manual. When Mode is Auto, CO is
the result of the closed-loop PID equation.
Configured as above, the MDS will initialize as a PID
controller in Auto mode with Setpoint at 125°C.
The Interface Solution Experts
Page S-5
MDS
Bumpless Transfer
Bumpless transfer of control between Auto and Manual
modes occurs when the Setpoint Source and CO
Manual Mode Source are set to “Host”. In bumpless
transfer, the controller output does not change when
Mode is switched. When Mode is switched from
Manual to Auto, setpoint is updated to the value that
maintains controller output at its present value.
Host Sourcing of “Controller Constants”
Clicking on the Range/Error field of COVar yields the
“Controller Constants” window (see Figure S-7).
Figure S-7. Host Sourcing Controller Constants
Supplement
Sources for adjustment of the PID constants may be
set to “Host” or “Source Variable”. When set to Host,
the “initial settings” for the constants are used in the
PID equation until the Host writes new values.
Note:
Values entered as “initial settings” for
controller constants apply until a Host has
written new values to K, Ti, and Td. On
subsequent power ups, the last values written
by the Host become the “initial settings”.
The initial settings are undefined when “Source Variable” is selected as the adjustment source instead of
“Host”. If the values for K, Ti and Td are known and
will not be changed after installation, select Host and
enter the values as initial settings.
Here, we settle for the default initial settings, K = 1
and T i = T d = 0, and assume we will be changing
these values on-line from a Host.
CO Variable as “Source” to AO Variable
The value of COVar is the result of the PID control
algorithm. This value can be used by other variables
in the MDS configuration (i.e. as operand in a formula for an AR variable; as source to AL or DO variables; as source to another CO variable to achieve
cascade control; or as source to an AO variable).
To complete the example configuration, an AO variable is added and named CtrlOut. COVar is declared as CtrlOut’s source (by selecting “V2” in the
Additionals field of CtrlOut). Scaling of the output
current is set so that 0-100% from COVar yields 420mA (by setting the source min & max values to 0
& 100, in the Range/Error field of CtrlOut.) Figure S8 shows the screen after the addition of CtrlOut.
Figure S-8. Using a CO Variable as “Source” to an AO Variable
The Interface Solution Experts
Page S-6
MDS
Supplement
Accessing Data From a Host
When this configuration is downloaded to a module, a
Host computer can change the controller constants and
setpoint, switch the controller mode between Auto and
Manual, and control output directly in Manual mode.
Note:
When using Modbus-RTU, the physical
register address must be modified for SCADA
software to a “30,000” or “40,000” decimal
register address by adding 30,001 or 40,001
to the decimal physical register address.
The CO variables occupy fixed areas of the database.
In Table S-1, “first CO variable” is the first CO variable
added to a configuration and “Second CO variable” is
the second CO variable added. Data can be accessed
in integer or IEEE floating point format.
Table S-1. CO Variables Database Map
Variables in IEEE, 4-byte Floating Point Format (STD 754-1985)
Physical Register Address
Content
Numerical Range
(hi-byte, lo-byte)
0600, 0601 (1536, 1537)
SP, first CO variable
User-defined Control Range, in engineering units
0602, 0603 (1538, 1539)
PV, first CO variable
User-defined Control Range, in engineering units
0604, 0605 (1540, 1541)
CO, first CO variable
0.00-100.00
0606, 0607 (1542, 1543)
K, first CO variable
0-655.35
0608, 0609 (1544, 1545)
Ti, first CO variable
0-655.35 (in minutes), 0 means no Integral
060A, 060B (1546, 1547)
Td, first CO variable
0-655.35 (in minutes)
060C, 060D (1548, 1549)
Mode, first CO variable
0 = Auto, 1 = Manual
0700, 0701 (1792, 1793)
SP, second CO variable
User-defined Control Range, in engineering units
0702, 0703 (1794, 1795)
PV, second CO variable
User-defined Control Range, in engineering units
0704, 0705 (1796, 1797)
CO, second CO variable
0-100.00
0706, 0707 (1798, 1799)
K, second CO variable
0-655.35
0708, 0709 (1800, 1801)
Ti, second CO variable
0-655.35 (in minutes), 0 means no Integral
070A, 070B (1802, 1803)
Td, second CO variable
0-655.35 (in minutes)
070C, 070D (1804, 1805)
Mode, second CO variable
0 = Auto, 1 = Manual
Physical Register Address
Content
Numerical Range
0800 (2048)
SP, first CO variable
User-defined Control Range (in engineering units/100)
0801 (2049)
PV, first variable
User-defined Control Range (in engineering units/100)
0802 (2050)
CO, first CO variable
0-10000
0803 (2051)
K, first CO variable
0-65535 (in units of 1/100)
Variables in Integer Format
0804 (2052)
Ti, first CO variable
0-65535 (in minutes/100), 0 means no Integral
0805 (2053)
Td, first CO variable
0-65535 (in minutes/100)
0806 (2054)
Mode, first CO variable
0 = Auto, 1 = Manual
0900 (2304)
SP, second CO variable
User-defined Control Range, in engineering units
0901 (2305)
PV, second CO variable
User-defined Control Range, in engineering units
0902 (2306)
CO, second CO variable
0-10000
0903 (2307)
K, second CO variable
0-65535 (in units of 1/100)
0904 (2308)
Ti, second CO variable
0-65535 (in minutes/100), 0 means no Integral
0905 (2309)
Td, second CO variable
0-65535 (in minutes/100)
0906 (2310)
Mode, second CO variable
0 = Auto, 1 = Manual
The Interface Solution Experts
Page S-7
MDS
Data Format for Host Access
Floating point data is in engineering units
(for example, CO has range 0-100.00% and Td has
range 0-655.350 minutes) and integer data is in
pseudo-engineering units (CO has range 0-10000 and
Td has range 0-65535 in units of minutes/100). Dividing the real (or floating point) number value by 100 before truncating to an integer allows finer resolution.
For SP and PV, numerical range is defined by
the “Control Range” in the configuration program. (See
“Host Sourcing of Controller Input Variables” on page
S-4.) When accessing the integer registers for SP and
PV, format the values in the units defined by “Control
Range” and divided by 100 to increase resolution.
The integer range of a 16-bit value is 0 to 65,535 for
unsigned integers and –32,768 to 32,767 for signed integers. When accessing the integer values of SP and
PV from a Host, “Control Range” must be limited to 0
to 655.35 for unsigned integer access, and –327.68 to
327.67 for signed integer access. If the process variable range exceeds these limits, the variable acting as
“Process Variable Source” will have to be scaled to fit
within the limits.
Supplement
Configuring CO with Other Variables
as “Sources”
Instead of having a Host computer as source, any
input to the CO variable can be sourced by another
variable in the MDS configuration program. To demonstrate, the example will be modified so that physical inputs to the MDS will: adjust the Setpoint from
a 10-turn pot; drive the controller output directly with
a 10-turn pot when in Manual mode; switch Mode
from a discrete input; and adjust Gain K from a 10turn pot. Figure S-9 gives an overview.
Figure S-9. Overview of Example Modifications
ProcVar
Setpoint
AI1
AI2
AI3
ManDrive
DI1
MDS
PID
CONTROLLER
CO
(4-20mA)
Mode
To accomplish this, first add 2 AI variables of sensor
type Potentiometer, and name them Setpoint and
ManDrive (see Figure S-9).
Note:
When accessing the registers holding
integer values of SP, PV, CO, K, Ti and Td,
the values are formatted as the real
number values divided by 100, and
then truncated.
Figure S-10. Adding Potentiometers to the Configuration
The Interface Solution Experts
Page S-8
MDS
Supplement
Other MDS Variables Sourcing
“Controller Input Variables”
Now click on the Additionals field of COVar to bring
up the “Controller Input Variables” window (shown in
Figure S-11).
The ranges and units of variables “Setpoint” and
“ManDrive” in Figure S-10 were converted. When
Potentiometer is selected, it defaults to a unitless
range of 0 to 1 representing the position of the potentiometer wiper as a fraction of end-to-end travel.
In “Setpoint” this range has been converted to –50°C
to +450°C, the same range and units as ProcVar.
To configure the other MDS variables as “Setpoint
Source” and “CO Manual Mode Source”, click
the “Source Variable” button, then select a variable
from the adjacent list. Select the variable “Setpoint”
for the Setpoint Source, and the variable “ManDrive”
for the CO Manual Mode Source.
Note:
When another MDS variable is the source for
setpoint, that variable must be formatted in
the units of the Process Variable.
The variable ManDrive will source the controller output in Manual mode, so the potentiometer range
must be converted to 0-100%.
Note:
When another MDS variable is the Manual
mode source of CO, that variable must be
converted to a range of 0-100%.
Figure S-11. Configuring MDS Variables as Sources
The Interface Solution Experts
For Mode Switch Source, click the button labeled
“Digital Input 1”. Clicking “Manual on Variable Result” allows selection of another variable (an AL variable, for instance, configured to go high when the
Process Variable reaches a high alarm level). In this
case, the controller would be in Manual mode when
the result of the selected variable is greater than 0.5,
and in Auto mode otherwise.
Note:
When a “Digital Input” is selected as the
Mode Switch source, an active (shorted)
input puts the controller in Manual mode.
Page S-9
MDS
Other MDS Variables Sourcing
“Controller Constants”
For the example, controller gain K is adjusted from
a 10-turn pot, so another AI variable of sensor type
Potentiometer is added and named “Gain” (see Figure S-12).
The default input range of variable “Gain” (0-1) has
been converted to 0-10. The engineering unit range
of K’s source variable must be within the overall
range defined in the database map table on page S7. (In this case, the range is 0-655.35.) This example limits the range of values that “Gain” can map
into K, to include only the values 0-10.
Supplement
In this example, Ti and Td have no adjustment source
variables. Their values will be fixed by entering “initial settings” of Ti = 3 minutes and Td = 0.75 minutes.
Note:
If another MDS variable is the adjustment
source for Integral Time Ti, then Ti = 0 is a
discontinuity. (i.e. 0 means no integral
action, while small Ti means large integral
action.) Consequently, the source
variable’s range should not include Ti = 0.
Note:
When another MDS variable is the
adjustment source for controller constant
K, Ti or Td, that source variable’s range
must fit within the range defined in
Table S-1 on page S-6.
Figure S-12. Sourcing Controller Constants with MDS Variables
The Interface Solution Experts
Page S-10
MDS
Supplement
Click on the “Range/Error” field of COVar: The “Controller Constants” field is shown (see Figure S-13).
Figure S-13. Configuring Controller Constants
To configure the variable “Gain” as an adjustment
source for K, click the “Source Variable” button under “Proportional Gain” and select “Gain” from the
list box. Set “Integral Time Adjust” and Derivative
Time Adjust” to “Host”, then enter initial settings for
Ti and Td of 3 and 0.75 minutes, respectively.
Note:
If the values for K, Ti and Td are known and
will not be changed after installation, select
Host as adjustment source and enter the
known values as “initial settings”.
The Interface Solution Experts
Page S-11
MDS
Application Example:
Proportional-only Ratio Control
Without Integral action in a closed-loop controller, nonzero error or a bias term is required to yield non-zero
controller output.
Here, the flow of dye added to a chemical delivery pipeline is regulated by an MDS. The amount of dye added
is proportional to the flow of product, but the proportions do not have to be exact. Ease of installation—including minimization of controller tuning effort—is more
important, so Proportional-only control is used. Figure
S-14 gives an overview of the process.
Figure S-14. Overview of Example
Supplement
The MDS is configured to accept a bias adjustment at
commissioning to nullify error at expected delivery flow.
MDS Configuration
From MDSCNFG, add two AI variables configured
for sensor type Current, ranged to 4-20mA input with
0-100% engineering units, and named “FP” and “Fd”.
Add two SP variables. Range the first, “BIAS”, to allow
host writes from 0-100%. Range the second, “MODE”
(to switch controller mode between Auto and Manual),
to write 0 or 1. Select “Host”, and “Save to Non-volatile Memory”, within the “Range/Error” field, to allow PC
adjustments at commissioning (see page 50 of the
manual). Figure S-15 shows the Configuration Screen.
The remaining variables are:
PRODUCT PIPELINE
PC INPUT
(RS485)
FP
SETPOINT
(4-20MA)
PROCESS VARIABLE
FD
(4-20MA)
MDS-MAO
CONTROLLER
OUTPUT
(4-20MA)
DYE PIPELINE
Control Strategy
With product flow, FP, as Setpoint, the MDS controls the
dye so that dye flow, FD, is proportional to FP. The mixture ratio is determined by the relative scalings of the
flow transmitters. For instance, with 50% output from
the product flow transmitter, the correct mixture requires 50% output from the dye flow transmitter.
• “CTRLR”, a CO variable computing control
equation;
• “CTRLout”, an AO (Analog Output) variable
sourced by SUM and supplies the valve actuator
current;
• “SUM”, an AR (Arithmetic) variable that adds
BIAS to CTRLR when MODE = 0 (Auto mode),
and is simply BIAS when MODE = 1.
The formula entered for SUM is:
SUM = BIAS + (1 – MODE)•CTRLR
Figure S-15. Configuring the MDS with Proportional-Only Control
The Interface Solution Experts
Page S-12
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Supplement
Click on the “Range/Error” field of CTRLR and enter an
“initial setting” of 5 for “Proportional Gain Adjust”. A
gain of 5, in this case, is a compromise between control loop stability and Setpoint variation error.
Click on CTRLR’s Additionals field to open the Controller Input Variables Window (see Figure S-16). FP is
Setpoint, and FD is Process Variable. “Control Range”
is equal to the flow ranges of 0-100%. “Mode Switch
Source” is set to “Manual on Variable Result: MODE
> 0.5”. Writing 1 to MODE from a PC opens the control loop, writing 0 closes it.
Operation
At commissioning, the User can observe variables and
change writable variables on-line from a PC running
MDSCNFG. By clicking “Utilities” on the main menu
bar and selecting “Measure”, the Measure Window
appears (see Figure S-17).
In Manual mode, SUM = BIAS. At commissioning, put
the controller in Manual mode and set BIAS, the direct
valve actuating signal, to the desired level. FP is at
operational level and error between FP and FD is zeroed
by adjusting BIAS. In Auto MODE, the actuating signal
is SUM = CTRLR + BIAS. Zero closed-loop error will
occur with Setpoint, FP, at operational flow level.
Figure S-16. Inputting Controller Input Variables
The Interface Solution Experts
Figure S-17. Viewing the Measure Window
Page S-13
MDS
Supplement
Programming Toolkit
This section contains several commonly used programming techniques for creating I/O EQUATION
STATION® configurations with the configuration software MDSCNFG.
Discrete Output with Deadband
In alarm applications, or where a discrete output is
used as an on/off controller, deadband is often required. Each discrete output, when configured as a
“Process Out” measurement type, is equipped with
four adjustable deadband configurations: High
Failsafe, High Non-failsafe, Low Failsafe and Low
Non-failsafe. These configurations require assigning
values for “Threshold 1” and “Threshold 2”, where
Threshold 1 is the trip point and Threshold 2 is the
deadband.
In this example, the DO variable “Pump” will turn a
pump on and off. The pump is activated when the
level exceeds 60 feet and is de-activated when the
level drops below 40 feet (see Figure S-18).
Figure S-18. Configuring a Pump
1
1
Source: Level
Threshold Type: High Non-failsafe
Threshold1: 60
Threshold2: 20
2
1
The Interface Solution Experts
Page S-14
MDS
Supplement
Exponents
Applications that require calculating exponential
equations can use the logarithmic functions (i.e., “ln”
and “exp”) provided in modules with the -MD or MAO options. The following equation calculates exponential equations:
xy = e(y ln(x))
In this example, 2 AI variables, “X” and “Y”, convert
4-20mA to engineering units and an AR variable, “A”,
calculates xy (see Figure S-19).
Figure S-19. Calculating Exponential Equations
1
1
The Interface Solution Experts
A = exp(X•ln(Y))
Page S-15
MDS
Removing an Open Input From an
Averaging Calculation
In a signal averaging application, it is often desirable
to obtain an average based only on good process
signals. Upon open input, the system must detect the
failure and eliminate the input from the averaging
equation.
When an input to the I/O EQUATION STATION ®
opens, internal circuitry drives the reading out of
range. Thermocouple and Voltage inputs are driven
upscale while current inputs are driven down-scale.
A multi-wire sensor (i.e. RTD, potentiometer, bridge)
goes up- or downscale depending on which wire
opens. To detect the failed sensor, an alarm (AL)
variable changes state when an input reading goes
out of range. This logic is then used to eliminate the
sensor from the averaging equation.
Supplement
In Figure S-20, two type K thermocouple sensors
connected to a boiler are averaged. Upon open input, the average temperature will be represented by
the remaining active sensor.
The status of T1 and T2 are indicated by the AL variables T1GD and T2GD. This logic could also be
made externally available by using DO variables
configured as “Process Controlled” Type of Measurement instead of AL variables. Using this
method, digital output 1 can be assigned to change
state when T1 opens and digital output 2 can be assigned to T2.
Figure S-20. Removing Open Input
1
2
3
4
1
Source: T1
Change: Low Logic
Threshold: 500
2
Source: T2
Change: Low Logic
Threshold: 500
3
Good = T1GD + T2GD
4
Average = [T1GD•T1+T2GD•T2] / #Good
500
500
The Interface Solution Experts
Page S-16
MDS
Supplement
Rate of Change Alarm
Analog signal rate of change can be measured by
taking the derivative of an AI variable. The derivative function is available in -MD or -MAO modules.
The “deriv” function determines rate of change by
taking the difference between two consecutive
samples of the analog signal, and dividing by the
sample period. The derivative’s time unit is seconds.
The DO variable “ALARM” activates and latches
when MAX exceeds the rate of change threshold of
10 RPM per second. When the DI variable “RST” is
equal to 1 (activated by a contact closure input),
MAX is reset, and ALARM becomes inactive (see
Figure S-21).
In this example, conveyor belt speed is monitored.
The variable “ACCEL” is the derivative of belt speed
(in units of RPM per second). “ABSVAL” is its absolute value. The MDS’s max function is a peak detector, so the variable “MAX” is the maximum rate
of change.
Figure S-21. Configuring a Rate of Change Alarm
1
2
3
4
The Interface Solution Experts
1
ACCEL = deriv (SPD)
2
ABSVAL = abs(ACCEL)
3
MAX = max(ABSVAL); reset on RST.0.5
4
Source: MAX
Change: High Logic
Threshold: 10
10
Page S-17
MDS
Time Delay Deadband
In some alarm applications, it is desirable to ignore
transients and noise spikes and only trip when the dc
level exceeds the trip point. To do so, insert a timer in
the logic path between detecting the alarm condition
and the actual tripping of the alarm output. If the process variable exits alarm condition before the time delay period, the output will not trip and the timer is reset.
In Figure S-22, an AL (Alarm) variable, “ALM”, goes
high when the process variable, “TEMP”, exceeds “TP”
(for trip point). TP and the time delay variable, “DLY”,
are SP (Setpoint) variables, which are programmed to
be written to by a Host computer. The written values
are saved to non-volatile memory.
Supplement
Since the integrator is based on time units of seconds,
taking the integral of ALM, in variable “TMR”, yields a
timer when ALM goes high (i.e., 1) that counts off seconds. TMR is only enabled when the process variable
is in alarm condition. The actual alarm output, the DO
variable “ALOUT”, is active only after the value of TMR
exceeds DLY.
The Timer variable, TMR, requires a reset mechanism.
Create another AL variable, called “NOTALM” (the logical inverse of variable ALM) and program TMR to “Reset on NOTALM > 0.5”. Then, when TEMP goes below
TP, TMR gets reset to 0. If the reset does not occur
before TMR reaches DLY, ALOUT is not activated.
Figure S-22. Configuring a Time Delay Deadband
1
2
3
4
5
6
1
0-500°F, Host-selected, Save to non-volatile
2
0-60 seconds, Host-selected, Save to non-volatile
3
Source: TEMP
Change: High Logic
Threshold: TP
TP
4
TMR = integ(ALM), Reset on NOTALM > 0.5
5
Source: TMR
Change: High Logic
Threshold: DLY
DLY
Source: TEMP
Change: Low Logic
Threshold: TP
TP
6
The Interface Solution Experts
Page S-18
MDS
Supplement
Sensor Linearization
To calculate the Measured Value from Level:
The sensor definition function can linearize any standard sensor. You can create new RTD or Thermocouple tables or transform a signal from a level
transmitter to volume of liquid in a container.
Measured Value = Mmin + [(Mmax - Mmin) ÷ (Lmax –
Lmin)] • (Level – Lmin) = 1.00 + 0.02 • (Level – 50)
To define/linearize a sensor:
where Mmin = minimum Measured Value; Mmax =
maximum Measured Value; Lmax = maximum Level;
and Lmin = minimum Level.
To calculate the Displayed Value from Volume:
I
I
1. Click on the “sensor” field of an AI
variable to access the Sensor
Selection screen. Click on “Define” to
access the Sensor Database screen.
2. From this screen add, copy, delete or
change the sensors in the database.
Click on “Add” to define a new sensor.
3. Enter the following information: Name
of sensor, Principles (type of sensor),
Unit, Min and Max Values of the input
signal. For this example, a 1-5 volt
signal from a level transmitter is
converted to a non-linear volume, so a
“1” is entered for Min Value, a “5” for
Max Value, and “V” for Unit.
Displayed Value = Dmin + [(Dmax - Dmin) ÷ (Vmax
– Vmin)] • (Volume – Vmin) = 1.00 + 0.1081 • (Volume – 8)
where Dmin = minimum Displayed Value;
Dmax = maximum Displayed Value; Vmin = minimum
Volume; and Vmax = maximum Volume.
Table S-2. Sample Linearization Points
Level
Measured Value
Volume
Displayed Value
(in inches)
(in volts)
(in cubic feet)
(in volts)
Lmin = 50
Mmin = 1.00
Vmin = 8
Dmin = 1.00
100
2.00
11
1.32
150
3.00
29
3.27
200
4.00
32
3.59
Lmax = 250
Mmax = 5.00
Vmax = 45
Dmax = 5.00
4. Click on “LINEARIZATION” to access
the linearization table for the sensor.
6. Click on “Add” and then enter the
“Measured” and corresponding
“Displayed” values. (See Table S-2.)
5. Calculate the Measured and Displayed
values (See Table S-2).
A list of ordered pairs (Level, Volume)
defines the process. Each pair is
converted to a new pair (Displayed
Value, Measured Value) where the
Displayed Value Range and the
Measured Value range are both
1-5 volts.
Note:
The range of Displayed Values must equal
the range of Measured Values.
The Interface Solution Experts
7. Click on “OK” to save and exit
linearization. Once the table has been
generated, the linearized value can be
scaled to the desired engineering units
(8-45 psig) in the “Format” field of the
input variable.
I
I
Page S-19
MDS
Supplement
Figure S-23. Configuring Linearization
“The Sensor <new sensor’s name> is
not in the Sensor Database. Shall this
Sensor be added to the Sensor
Database? “
Sensor Transfer
To transfer a user-defined sensor from one PC to another, create a configuration file (*.ISK) that uses the
sensor and transfer the file. To transfer the sensor:
I
4. Click on “Yes”.
5. Before creating a configuration using
the new sensor, go to the Linearization
screen and click on the “Sensor” field
for the AI variable.
I
1. Select “File” from the main menu bar,
then “New” to create a configuration
file. Add an AI variable of the sensor
type to be transferred.
6. Click on “Define” and select the new
sensor from “Sensor Database”.
7. Click “Change” and then click
“Linearization” in the “Change
Sensor” screen.
Note:
Do not change any of the entries in the
Range/Error or format fields.
8. The table and graph for the new
sensor will be on the “Linearization”
screen. Click on “OK”.
2. Select “Save” from the “File” menu
and then save the configuration file
(*.ISK) to a floppy diskette.
3. From the PC running MDSCNFG, open
the file with the User-defined sensor
(select “Open” from the “File” menu).
MDSCNFG will detect the new sensor
and the following message will appear:
9. Click “OK”, “End” and “OK” to exit.
I
I
This new sensor can also be used in other configurations.
The Interface Solution Experts
Page S-20
MDS
Supplement
Totalizing
Totalizing integrates a signal proportional to, for instance, flow or power. The integral over a given period of time represents the amount of product or
energy delivered during that time. The Integrator
function is available in the extended math package
of the I/O EQUATION STATION® (MDS with -MD or
-MAO option).
Time units of seconds are used in the integrator.
Thus, for a constant input, the integrator output increases in time at a rate of 1 Count / Unit Input /
Second:
integ(C) = Ct,
where C is a constant and t is the time in seconds,
and assuming integ(C) = 0 at time t = 0.
In the following example, flow of a liquid is totalized
based on the linear signal provided by a flow meter
(see Figure S-24).
An AI variable (FLOW) measures 4-20mA from the
flow meter output and converts the signal to engineering units of 0-100 gallons per minute. If we assume the flow signal is at full scale (100 GPM), the
integral of FLOW will increase at a rate of 100
counts/second. The count after 1 second will be 100
(assuming an initial condition with the integrator out1
put zero), the count after 1 minute will be
6000, etc.
2
In engineering units (i.e., gallons), the amount of liquid transferred is calculated by dividing the integrator output by the number of seconds in the input
variable’s time base (i.e., 60, for gallons per minute).
A practical totalizing application requires resetting
the integrator. Clicking on the “Range/Error” field of
an AR variable brings up the “Reset” window, which
applies if the formula for the AR variable contains integral, maximum or minimum functions. (See Example: Variable Frequency Output, on page S-22.)
Figure S-24. Totalizing a Flow of Liquid
1
2
The Interface Solution Experts
1
INTEGRAL = integ(flow)
2
TOTAL = integrator / 60
Page S-21
MDS
Supplement
Resettable Functions
The reset can be generated in 3 different ways:
Three MDS math functions have a reset property:
maximum, minimum and integral.
“Direct Digital Input” Reset allows a contact closure input to a digital I/O terminal to reset a resettable function
by clicking on “Dig. Input 1” or “Dig. Input 2”.
The max and min functions accept a single operand
and are “peak” and “valley” detectors. So, if a configuration has an AI variable named “PV” and an AR variable named “MOST”, and MOST = max(PV), then
MOST is the maximum value of PV since the last time
MOST was reset. Upon reset, MOST is set to the
present value of PV.
“Host” Reset allows a reset when the Host writes to the
variable containing the resettable function.
Note:
On a Host generated reset, the value the Host
writes to the AR variable containing the
resettable function is irrelevant. An integral is
set to zero, and maximum or minimum is set
to the present value of the operand.
The integral function accepts a single operand and is
the time integral of the operand. When an AR variable
with an integ function is reset, the integral becomes 0.
To configure how the reset is generated, click on
the “Range/Error” field of an AR variable with a
resettable function. The following window appears:
Figure S-25. Resetting a Function
“On Variable Result” Reset allows reset when another
variable in the present configuration exceeds 0.5. Click
on the arrow for the list of configured variables. You can
select an AL (Alarm) variable to generate the reset when
the AL variable changes state from 0 or 1.
Example: Manual Reset Alarm
In Figure S-26, the “max” function latches an alarm that
is only reset by a contact closure to a discrete input.
The AL variable “ALARM” is high when “TMP” > 425°C.
Using the max function, “LATCH” goes and stays high
when ALARM is high. The max function in LATCH is
resedt by input to DI1 (i.e. if TMP goes below the high
alarm threshold of 425°C and a contact closure has
been applied to DI1). The DO variable “ALOUT” supplies a discrete output that is active when LATCH is high.
Figure S-26. Using the “max” Function to Latch an Alarm
1
2
3
1
Source: TMP
Change: High Logic
Threshold: 425
425
2
LATCH = max(ALARM), Reset on DI 1
3
Source: LATCH
Change: High Logic
Threshold: 0.5
0.5
The Interface Solution Experts
Page S-22
MDS
Supplement
Example: Variable Frequency Output
In this example, an integral is reset by a DO variable
changing state from 0 to 1 (see Figure S-27). An AI
variable configured for potentiometer input, “FRQ”, is
scaled to an engineering units range of 0-100 p/m
(pulses per minute). “INT” takes the integral of FRQ.
The integral time base is seconds, so if FRQ = 1, INT
will ramp up at a rate of 1 count per second. If, for
FRQ = 1, you want 1 pulse output after 1 minute,
configure a DO variable, “SIXTY”, to change state
when INT reaches 60.
INT is configured to reset when SIXTY > 0.5 (i.e.,
when SIXTY changes state.). The I/O EQUATION
STATION ® executes each variable in sequence—
variable 1, then 2, then 3; then back to 1. During
each cycle, FRQ (the potentiometer input) is updated, then INT is updated. Next, the value of
SIXTY is checked to see if the integral should be reset or updated, then SIXTY checks if INT > 60. Until this is true, INT = 0.
Eventually, an execution cycle occurs when the
value of INT reaches 60. At that time, SIXTY
changes its value from 0 to 1; FRQ is updated; INT
checks its reset condition and, since SIXTY > 0.5
the integral is reset to 0. Next, SIXTY sees that
INT < 60 and changes its value back to 0.
The output pulse duration is approximately 1 execution cycle, which in this configuration is 8 milliseconds. (See Table 2 on page 8 of the Manual.) The
execution cycle time is also the resolution of the output waveform. The period of the output waveform
can never be less than twice the execution
cycle time.
Figure S-27. Resetting an Integral using Process Result
1
2
The Interface Solution Experts
1
INT = integ(FRQ), Reset on 1 MIN > 0.5
2
Source: INT
Change: High Logic
Threshold: 60
60
Page S-23
MDS
Event or Edge Triggered Latching
Latching can be triggered by a logic variable changing
state. A DI variable representing a contact closure input or an AL variable that changes state when a given
event takes place can trigger latching.
In this example, an event is defined by the tank level
exceeding 70%. When this occurs, a monitored temperature is latched (see Figure S-28).
The AL variable “EDG” goes from low to high when
“LVL” increases through 70%. “EDGNOT” is the logical inverse of EDG. “TRGR” (the product of EDG and
EDGNOT) should always be 0. Since the I/O EQUATION STATION® executes each variable in sequence
(i.e., variable 1, then 2, then 3, etc., and then back to
1), TRGR becomes 1 (i.e., for 1 execution cycle) as
LVL increases through 70%.
Supplement
LVL was less than 70% going into the execution cycle
when the triggering event occurs, so EDG = 0,
EDGNOT = 1 and TRGR = 0.
First, LVL is updated to a value greater than 70%, then
EDG changes from 0 to 1. Next, TRGR becomes 1,
since EDG = 1 and EDGNOT = 1, and then EDGNOT
changes from 1 to 0. In the next execution cycle,
TRGR will go back to 0.
TRGR = 1 for only 1 unique execution cycle. (Note that
TRGR will remain 0 when LVL decreases through 0 as
well as during steady state.)
The variable “LTCH” is the sum of 2 terms, one of
which is always 0. So long as TRGR = 0, LTCH =
LTCH, (i.e. its value doesn’t change). When TRGR =
1 (this is a momentary event as LVL increases through
70%), LTCH = T (i.e. it has a new value assigned to it).
Figure S-28. Triggering Latching with an Event
1
2
3
4
1
Source: LVL
Change: High Logic
Threshold: 70
70
2
TRGR = EDG•EDGNOT
3
Source: LVL
Change: Low Logic
Threshold: 70
4
70
LTCH = TRGR•T+(1–TRGR)•LTCH
The Interface Solution Experts
Page S-24
MDS
Supplement
Using an AI as a Discrete Input
Sometimes the I/O EQUATION STATION® would fit
an application if the MDS had 1 or 2 more discrete
inputs. An analog input channel can also determine
the status of a contact closure input.
Add an Analog Input variable configured for sensor
type “Resistance” and 2-wire “Type of Measurement”. Set the ohm range to 0-1000 ohms and convert it to an engineering units range of 1-0 (1 for 0
ohms, 0 for 1000 ohms). This yields the same logic
as a DI status input (contact closure, or 0 ohms, is
logic 1, while open input is logic 0).
Figure S-29. Using an AI as a Discrete Input
The Interface Solution Experts
In the following example (Figure S-29), a contact closure applied to the AI variable “STATUS” will result
in STATUS = 1 when the contact is open and STATUS = 0 when the contact is closed.
Page S-25
MDS
Supplement
ASCII Protocol Description
Field Definitions:
This section gives an overview of the ASCII protocol
that can be used with the I/O EQUATION STATION®. To use ASCII protocol, the unit must be programmed with the Profibus/ASCII protocol file.
ACK Acknowledge (Length = 1 character) A Slave
response to a query, that does not require return
data, is a single “Acknowledge” character (HEX 06),
signifying the orderly execution of the instruction.
To program the module with the Profibus ASCII file,
select “Utilities” from the main menu bar and then
“Reprogram Module”. If the connections from PC to
MDS (including the RS232-RS485 converter) are
correct, the “Module Selection” screen will show the
communication details of the MDS being upgraded.
(If not, try “Search All”.) Click on “OK”. From the
“Reprogramming Files” list, select the Profibus/ASCII
file and click on “OK”.
CS Check Sum (Length = 2 characters) The Check
Sum field, CS, is the binary byte-wise sum of the
message, modulo 256. It is calculated by summing
the Start-Delimiter (SD), Device Address (DA) and
Data (ReqData or ResData) fields.
ASCII Message Format
An ASCII message sent from a host to a module
(Slave) is called a “Query”. When a Slave receives
a Query, it replies with a “Response” message.
The following tables show the Query and Response
message formats, identifying the fields within the
message and the number of characters in each field.
CheckSum_ASCII = [SD+DA+Data] mod 256.
The value is given as a two digit ASCII coded HEX
number: ASCII “00”...”FF”.
DA Device Address. (Length = 2 characters) The
Device Address field, DA, only appears in a Query
message. It identifies the Slave being queried. Device Addresses are in the range 1 to 127. The value
is given as a two digit ASCII coded HEX number
(i.e.ASCII “01”..“7F”).
ED End Delimiter (Length = 1 character) The End
Delimiter field, ED, identifies the end of the message. It is the carriage return character (HEX 0D).
Table S-3. Query without Checksum
SD
DA
ReqData
ED
1
2
n
1
NAK No Acknowledge (Length = 1 character) When
a request to the Slave is invalid, the Slave responds
with a “No Acknowledge” character (HEX 15).
Table S-4. Query with Checksum
SD
DA
ReqData
CS
ED
1
2
n
2
1
Table S-5. Response without Checksum
SD
ResData
ED
1
n
1
Table S-6. Response with Checksum
SD
ResData
CS
ED
1
n
2
1
or
ACK
ReqData Request Data (Length = 1 ... n characters)
The Request Data field contains the host’s instruction and data for the indicated Slave.
ResData Response Data (Length = 1 ... n characters) The Response Data field contains the Slave’s
reply to the host’s instruction.
SD Start-Delimiter . (Length = 1 character) The
Start-Delimiter field, SD, is a single ASCII character
that marks the beginning of a message. Its value
identifies whether or not a checksum will be included
in the message.
1
Table S-7. Start-Delimiter Characters
SD
Query
NAK
with checksum
#
>
1
without checksum
$
=
or
Response
The Interface Solution Experts
Page S-26
MDS
Supplement
ASCII Instruction Set
Table S-8 lists Queries and expected Slave Responses. Table S-9 explains the field codes used in
Table S-8. Tables S-10-S-15 give Device Identification, Device Information, and Status Information.
Table S-8. ASCII Queries and Responses
Checksum
Query
Response with Orderly
Execution
Response in Case of
Error
Read Device Identification
with
without
# aa V cc <cr>
>v..v cc <cr>
NAK
$ aa V
= v..v
NAK
<cr>
<cr>
Read Device Information
with
without
# aa S cc <cr>
>s..s cc <cr>
NAK
$ aa S
=s..s
<cr>
NAK
z..z cc <cr>
NAK
<cr>
Read Status Information
with
without
# aa Z cc <cr>
$ aa Z
<cr>
= z..z
<cr>
NAK
# aa B k cc <cr>
>b..b cc <cr>
NAK
$ aa B k
=b..b
<cr>
NAK
# aa R k cc <cr>
>d..d cc <cr>
NAK
$ aa R k
=d..d
NAK
Read Variable Information
with
without
<cr>
Read Variable Value
with
without
<cr>
<cr>
Write Value to a Variable
with
# aa W k d..d cc
ACK
NAK
without
$ aa W k d..d <cr>
ACK
NAK
with
# aa D k cc <cr>
ACK
NAK
$ aa D k
ACK
NAK
Reset Variable
without
<cr>
Table S-9. ASCII Field Codes
Code
Length
Range
#
Start delimiter for query with checksum
1
ASCII “#”
>
Start delimiter for response with checksum
1
ASCII “>”
$
Start delimiter for query without checksum
1
ASCII “$”
=
Start delimiter for response without checksum
1
ASCII “=”
<cr>
End delimiter (carriage return)
1
HEX 0D
ACK
Positive Acknowledge
1
HEX 06
NAK
No Acknowledge
1
HEX 15
aa
Destination Address
2
ASCII “01”..“7F”
cc
Checksum
2
ASCII “00”..“FF”
Variable Number
1
ASCII “1” “C”
max. 8
ASCII - String
k
Definition
d..d
value as formatted for the channel
v..v
Device Identification (see below)
26
ASCII - String
s..s
Device Information (see below)
27
ASCII - String
z..z
Status Information (see below)
2
ASCII - String
b..b
Variable Configuration (see below)
29
ASCII - String
The Interface Solution Experts
Page S-27
MDS
Table S-10. Device Identification
Supplement
Table S-13. Subsystem Errors
Device Identification
(v..v)
Length
(26 Characters Total)
Byte
Subsystem
b1
EEPROM
<vendor name>
ASCII 8 characters
b2
Flash
<module name>
ASCII, 8 Characters
b3
ADC
<hw-revision>
ASCII, 5 Characters (“__x.xx”)
b4
Configuration
<sw-revision>
ASCII, 5 Characters (“__x.xx”)
Table S-14. Variable Configuration
Table S-11. Device Information
Variable Configuration
(b..b)
Length
(29 bytes total)
Device Information
(s..s)
Length
(27 Characters Total)
<variable type>
ASCII, 1 Character
<location>
ASCII, 20 Characters
<variable name>
ASCII, 20 Characters
<Serial Number>
ASCII, 6 Characters
<binary format>
ASCII, 1 Character
<number of variables>
ASCII, 1 Character
<field length>
ASCII, 1 Character
Table S-12. Status Information
Status Information
(z..z)
Length
(2 Characters Total)
<byte 1>
ASCII, 1 Character (“variable status”)
<byte 2>
ASCII, 1 Character (“module status”)
<byte n> = b8 b7 b6 b5 b4 b3 b2 b1
If bit bn is set in byte 1, then an error occurred in
variable n. A variable error occurs when the input to
an Analog Input variable is outside of the configured
range.
If a bit is set in byte 2, then an error occurred in one
of the subsystems (b5-b8 are not used).
<decimals>
ASCII, 1 Character
<unit>
ASCII, 4 Characters
<reset>
ASCII, 1 Character
Table S-15. Coding Variable Types, Binary Format, and Reset
Code
Variable Type
Binary Format
Reset
ASCII
“0”
Empty Variable
(EM)
No Format
Reset
Disabled
ASCII
“1”
Analog Input
Variable
Boolean
Reset
Enabled
ASCII
“2”
Arithmetic
Variable (AR)
Integer
n/a
ASCII
“3”
Digital Output
Variable (DO)
Real
n/a
ASCII
“4”
Digital Input
Variable (DI)
n/a
n/a
ASCII
“5”
Setpoint Variable
(SP)
n/a
n/a
ASCII
“6”
Alarm Variable
(AL)
n/a
n/a
The Interface Solution Experts
Page S-28
MDS
Supplement
I/O EQUATION STATION
PID Viewer Program
The protocol must be “Modbus-RTU”. Note the Baud
Rate, Parity, Address and Comm Port because they
will be set in the PID Viewer program.
®
The PID Viewer program, MDSPID.EXE, allows you
to view the PID parameters in bar graph and trend
formats using Modbus-RTU protocol. MDSPID also
acts as a DDE source to allow access to PID data
from other Windows programs.
Requirements
MDSPID is a Windows 3.1 program. MDSPID has
the same hardware requirements as MDSCNFG.
(See “Installation—Hardware/Software Requirements” on page 10 of the Manual.)
Although the I/O EQUATION STATION can be programmed to communicate via Profibus, ASCII or
Modbus-RTU, it must be programmed for ModbusRTU to run with MDSPID.
®
Operation
To try out MDSPID, install it from the Setup disk onto
the same computer you use to run MDSCNFG.
Note:
If the MDSPID Setup program does not
install successfully, exit all programs
besides the Windows Program Manager,
and run Setup again.
If all of the hardware (i.e. the comm port, cable, and
RS232-485 converter) is set up and working correctly and MDSCNFG communicates successfully
with the I/O EQUATION STATION ®, then MDSPID
should also communicate successfully.
MDS Communication Settings
Before starting the PID Viewer program, start
MDSCNFG and select “Communication” from the
main menu bar, then “Module Parameters”. The
“Module Selection” window will display serial communication information about the module on your
comm link (If not, try “Search All”).
The Interface Solution Experts
Starting MDSPID
Start the PID Viewer program by clicking on the
MDSPID icon inside the MDSPID program group.
The I/O EQUATION STATION® PID Viewer faceplate
will appear.
Select “Communications” from the main menu bar,
then “Comm Settings”, and fill in the information to
match the comm settings of the MDS module.
(“Data Bits” should be set to 8.) Click “OK”.
Again, select “Communications” from the main menu
bar, then “Device Address”, and move the slide bar
until the correct address appears. Click “OK”.
Click the “Start” button. The green “Communicating”
indicator appears, and the bar graphs and trend display become active.
Note:
The configuration downloaded to the MDS
module must contain at least one PID
Controller (CO) variable, in order for
MDSPID to run.
Trend Options
Select “Trend” from the main menu bar, then “Process Range”. Here you can rescale the trend plots
and bar graphs for the Process Variable and
Setpoint to fit the engineering units of your application. This does not affect the Controller Output displays, since the Controller Output range is always
0-100%.
To modify the time width encompassed by the trend
display, select “Trend” from the main menu bar and
then select “Time Scale”.
Page S-29
MDS
Supplement
Controller Parameters
Dynamic Data Exchange (DDE)
Under “Mode”, the radio buttons labeled “Manual”
and “Auto” switch the controller between Manual and
Auto modes.
The Dynamic Data Exchange (DDE) allows another
Windows program, running on the same PC and at
the same time as MDSPID, to access the PID parameter data on a real time basis. MDSPID acts as
a DDE source, so the other program must be a DDE
destination. Data can be written to MDSPID by the
destination program using a DDE “poke”.
Click on each of the two “Change” buttons in turn.
One allows you to change the controller constants K,
Ti and Td. The other allows you to change Setpoint
and Controller Output. Note that Controller Output
can only be changed if the “Mode” selection is set to
“Manual”.
Note:
From MDSPID, only Controller parameters
that are “Host sourced” within the MDS
configuration can be changed.
A single MDS can have up to two Controller (CO)
variables configured to allow for cascade control.
Under “CO Variable”, you can switch between “CO1”
and “CO2”. When set to “CO1”, the faceplate displays the parameters of the first CO variable in the
configuration (i.e., the CO variable with the lowest
variable number). When set to “CO2”, the faceplate
displays the parameters of the second CO variable.
The destination program must address registers in
MDSPID using DDE’s “application|topic!item” format.
The addresses of accessible data within MDSPID
are listed in Table S-16.
A text value of “A” in the “Mode” register means controller mode is Auto, while “M” means Manual.
Table S-16. Data Addresses within MDSPID
Data
Address
Proportional Gain, K
MDSPID|MDSPID!Gain
Integral Time, Ti
MDSPID|MDSPID!IntTime
Derivative Time, Td
MDSPID|MDSPID!DerivTime
Setpoint
MDSPID|MDSPID!Setpoint
Process Variable
MDSPID|MDSPID!ProcVar
Controller Output
MDSPID|MDSPID!CtrlOut
Mode
MDSPID|MDSPID!Mode
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RETURN PROCEDURES
To return equipment to Moore Industries for repair, follow these four steps:
1. Call Moore Industries and request a Returned Material Authorization (RMA) number.
Warranty Repair –
If you are unsure if your unit is still under warranty, we can use the unit’s serial number
to verify the warranty status for you over the phone. Be sure to include the RMA
number on all documentation.
Non-Warranty Repair –
If your unit is out of warranty, be prepared to give us a Purchase Order number when
you call. In most cases, we will be able to quote you the repair costs at that time.
The repair price you are quoted will be a “Not To Exceed” price, which means that the
actual repair costs may be less than the quote. Be sure to include the RMA number on
all documentation.
2. Provide us with the following documentation:
a) A note listing the symptoms that indicate the unit needs repair
b) Complete shipping information for return of the equipment after repair
c) The name and phone number of the person to contact if questions arise at the factory
3. Use sufficient packing material and carefully pack the equipment in a sturdy shipping
container.
4. Ship the equipment to the Moore Industries location nearest you.
The returned equipment will be inspected and tested at the factory. A Moore Industries
representative will contact the person designated on your documentation if more information is
needed. The repaired equipment, or its replacement, will be returned to you in accordance with
the shipping instructions furnished in your documentation.
WARRANTY DISCLAIMER
THE COMPANY MAKES NO EXPRESS, IMPLIED OR STATUTORY WARRANTIES (INCLUDING ANY WARRANTY OF MERCHANTABILITY OR OF FITNESS
FOR A PARTICULAR PURPOSE) WITH RESPECT TO ANY GOODS OR SERVICES SOLD BY THE COMPANY. THE COMPANY DISCLAIMS ALL WARRANTIES ARISING FROM ANY COURSE OF DEALING OR TRADE USAGE, AND
ANY BUYER OF GOODS OR SERVICES FROM THE COMPANY ACKNOWLEDGES THAT THERE ARE NO WARRANTIES IMPLIED BY CUSTOM OR
USAGE IN THE TRADE OF THE BUYER AND OF THE COMPANY, AND THAT
ANY PRIOR DEALINGS OF THE BUYER WITH THE COMPANY DO NOT IMPLY THAT THE COMPANY WARRANTS THE GOODS OR SERVICES IN ANY
WAY.
ANY BUYER OF GOODS OR SERVICES FROM THE COMPANY AGREES
WITH THE COMPANY THAT THE SOLE AND EXCLUSIVE REMEDIES FOR
BREACH OF ANY WARRANTY CONCERNING THE GOODS OR SERVICES
SHALL BE FOR THE COMPANY, AT ITS OPTION, TO REPAIR OR REPLACE
THE GOODS OR SERVICES OR REFUND THE PURCHASE PRICE. THE
COMPANY SHALL IN NO EVENT BE LIABLE FOR ANY CONSEQUENTIAL OR
INCIDENTAL DAMAGES EVEN IF THE COMPANY FAILS IN ANY ATTEMPT
TO REMEDY DEFECTS IN THE GOODS OR SERVICES , BUT IN SUCH CASE
THE BUYER SHALL BE ENTITLED TO NO MORE THAN A REFUND OF ALL
MONIES PAID TO THE COMPANY BY THE BUYER FOR PURCHASE OF THE
GOODS OR SERVICES.
ANY CAUSE OF ACTION FOR BREACH OF ANY WARRANTY BY THE
COMPANY SHALL BE BARRED UNLESS THE COMPANY RECEIVES
FROM THE BUYER A WRITTEN NOTICE OF THE ALLEGED DEFECT OR
BREACH WITHIN TEN DAYS FROM THE EARLIEST DATE ON WHICH THE
BUYER COULD REASONABLY HAVE DISCOVERED THE ALLEGED DEFECT OR BREACH, AND NO ACTION FOR THE BREACH OF ANY WARRANTY SHALL BE COMMENCED BY THE BUYER ANY LATER THAN
TWELVE MONTHS FROM THE EARLIEST DATE ON WHICH THE BUYER
COULD REASONABLY HAVE DISCOVERED THE ALLEGED DEFECT OR
BREACH.
RETURN POLICY
For a period of thirty-six (36) months from the date of shipment, and under
normal conditions of use and service, Moore Industries ("The Company") will
at its option replace, repair or refund the purchase price for any of its manufactured products found, upon return to the Company (transportation charges
prepaid and otherwise in accordance with the return procedures established
by The Company), to be defective in material or workmanship. This policy
extends to the original Buyer only and not to Buyer's customers or the users
of Buyer's products, unless Buyer is an engineering contractor in which case
the policy shall extend to Buyer's immediate customer only. This policy shall
not apply if the product has been subject to alteration, misuse, accident, neglect or improper application, installation, or operation. THE COMPANY
SHALL IN NO EVENT BE LIABLE FOR ANY INCIDENTAL OR CONSEQUENTIAL DAMAGES.
United States • info@miinet.com
Tel: (818) 894-7111 • FAX: (818) 891-2816
Australia • sales@mooreind.com.au
Tel: (02) 8536-7200 • FAX: (02) 9525-7296
© 2006 Moore Industries-International, Inc.
Belgium • info@mooreind.be
Tel: 03/448.10.18 • FAX: 03/440.17.97
The Netherlands • sales@mooreind.nl
Tel: (0)344-617971 • FAX: (0)344-615920
China • sales@mooreind.sh.cn
Tel: 86-21-62491499 • FAX: 86-21-62490635
United Kingdom • sales@mooreind.com
Tel: 01293 514488 • FAX: 01293 536852
Specifications and Information subject to change without notice.
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