Watlow CLS200 - Ratio Control; Setup Loop Ratio Control Menu; Figure 5.7 - Relationship between the Master Loops Process Variable and the Ratio Loops Setpoint

CLS200 Series User’s Guide
Chapter 5: Enhanced Features
108
Ratio Control
Ratio control allows the process variable of one loop (master loop), multiplied by a ratio, to be the
setpoint of another loop (ratio loop). You can assign any process variable to determine the setpoint
of a ratio loop.
By adjusting the ratio control parameters, you can adjust the influence that the master loop process
variable has on the setpoint of the ratio loop.
Maximum SP
Minimum SP
Minimum
Maximum
Master PV * Control Ratio + SP Differential
Ratio Loop Setpoint
Master Loop Process Variable
SP Differential
SP: Setpoint
PV: Process Variable
PV
PV
Figure 5.7 — Relationship Between the Master Loop’s Process Variable and the Ratio Loop’s Setpoint
NOTE! Ratio control cannot be used on the same control loop as cascade control.
However, both features may be used in the same multiloop controller.
Setup Loop Ratio Control Menu
The ratio control parameters appear in the SETUP LOOP RATIO CONTROL menu.
ALARM
SETUP LOOP 02
RATIO CONTROL?
Press YES to set up the ratio control parameters with loop number 2 as the ratio loop.