Process Control Instructions
90 Rockwell Automation Publication 1756-RM006K-EN-P - November 2018
Hand While in Hand mode the PID algorithm does not compute the change in CV.
CV = HandFB, regardless of the control mode. Hand mode is typically used to indicate that control of the
final control element was taken over by a field hand/auto station.
Select Hand mode using ProgHandReq:
Set ProgHandReq to request hand mode. This value is usually read as a digital input from a hand/auto
station.
The Cascade/Ratio, Auto, and Manual modes can be controlled by a user program
when in Program control or by an operator interface when in Operator control.
The Override and Hand modes have a mode request input that can only be
controlled by a user program; these inputs operate in both Program and Operator
control.
Selecting the Setpoint
Once the instruction determines program or operator control and the PID mode,
the instruction can obtain the proper SP value. You can select the cascade/ratio SP
or the current SP.
Cascade/Ratio SP
The cascade/ratio SP is based on the UseRatio and ProgOper values.
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