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 Diff
erential
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.
