Owner manual

158
Appendix B: Enhanced Process Control
Remote Setpoint
Remote Setpoint can be used to allow external equipment, such as a
PLC or other control system, to provide an analog output (4-20 mA, 0-5
Vdc, etc.) used to change the setpoint of a loop. The method of
configuring the Remote Setpoint is the same as Ratio Control. In the
previous example, loop 1 would be the remote analog value and loop 2
would be the PID control loop.
Both the remote setpoint feature and the PV retransmit feature can be
used with PLC systems as the link between multi-loop PID control
systems and PLC systems.
For example, a 0-5 Vdc signal representing 0-300 ºF will be used as a
remote SP input to the CLS. The input signal will be received on Loop 1
with the control being performed on Loop 2. Note that proper scaling
resisters must be installed on the input of Loop 1 to allow it to accept a
0-5Vdc input.
From the loop 1 input channel, select the Linear Input Type. Set HiPV =
300, LoPV =0, HiRDG = 100.0%, and LoRDG = 0.0%.
Next go to loop 2 and enter the programming menus. Go to the Ratio
Option Menu and press the YES key to select the Ratio Menu.
Display User Input
Press
Ye s
to setup the Ratio parameters
for loop 02.
Assign loop 01 to be the master loop.
Press
Enter
.
Enter the minimum Ratio loop SP. For
this example, we will use 0 ºF.
Press
Enter
.
LOOP PROCESS UNITS
ALARM SETPOINT STATUS OUT%
SETUP LOOP 02
RATIO CONTROL?
LOOP PROCESS UNITS
ALARM SETPOINT STATUS OUT%
02 RATIO CONTROL
MSTR LOOP? 01
LOOP PROCESS UNITS
ALARM SETPOINT STATUS OUT%
02 RATIO CONTROL
MIN SP? 0