Watlow CLS200 - Remote Analog Setpoint; Remote Analog Setpoint Example: Setting a Setpoint with a PLC; Table 5.4 - Application Example: Setting up Remote Setpoint

CLS200 Series User’s Guide
Chapter 5: Enhanced Features
112
Remote Analog Setpoint
The remote analog setpoint is set up identically to ratio control. To provide a setpoint remotely,
typically a voltage or current source is connected to an analog input on the controller. This input is
configured as a linear input type and the master loop for ratio control. All other input types are also
usable as remote analog setpoint inputs.
Specify the loop to which the analog input is connected as the master loop and setup the rest of the
ratio control parameters as outlined in Setup Loop Ratio Control Menu on page 108.
Remote Analog Setpoint Example: Setting a Setpoint with a PLC
Remote analog setpoint allows external equipment, such as a PLC or other control system, to
change the setpoint of a loop.
Both the remote analog setpoint feature and the process variable retransmit feature can be used
with PLC systems as the link between multiloop PID control systems and PLC systems.
For example, a 0 to 5VDC signal representing 0 to 300°F will be used as a remote setpoint input to
the CLS200. The input signal will be received on loop 1 with the control being performed on loop 2.
Note that proper scaling resistors must be installed on the input of loop 1 to allow it to accept a
0 to 5VDC input.
To set up this application, you would do the following:
1. In the loop 1 SETUP LOOP INPUT menu, set the INPUT TYPE to LINEAR, set HI PV to
300, set LO PV to 0, set HI RDG to 100.0% and set LO RDG to 0.0%.
2. Change the display to loop 2, and then enter the setup parameters. Go to the first screen in
Table 5.4.
3. Follow the steps in Table 5.4 to configure the process variable retransmit option.
Table 5.4 — Application Example: Setting Up Remote Setpoint
DISPLAY USER INPUT
ALARM
SETUP LOOP 02
RATIO CONTROL?
Press YES to set up the cascade parameters with loop 2.
ALARM
02 RATIO CONTROL
MSTR LOOP? 01
Assign loop 01 to be the master loop. Press ENTER.
ALARM
02 RATIO CONTROL
MIN SP? 0
Enter the minimum ratio loop setpoint. For this example, we
will use 0˚ F. Press ENTER.