Watlow CLS - Manual (Page 168)

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Appendix B: Enhanced Process Control
The loops using the IR sensor as an input is assigned to the Master Loop
in the Ratio Control Option Menu. The secondary loop is the
Differential control loop. By setting the setpoint differential "SP DIFF."
to the desired offset, this will produce the desired offset between the
secondary and master loop setpoints for differential control.
For example setpoints, the Master Loop can be controlled at 325 ºF and
the secondary loop at 375 ºF by using a differential of 50 ºF.
Channel 1 must be set up for PID control of the SP at 325 ºF.
Go to Channel 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 Yes to setup the Ratio parameters
for loop 02.
Assign loop 01 to be the master loop.
Press Enter.
Enter the maximum Ratio loop SP. For
this example, we will use 400 ºF as a
maximum
Press Enter.
Enter the minimum Ratio loop SP. For
this example, we will use 300 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
MAX SP? 400
LOOP PROCESS UNITS
ALARM SETPOINT STATUS OUT%
02 RATIO CONTROL
MIN SP? 300