Rockwell Automation Publication 2080-UM002K-EN-E - March 2019 317
Appendix
F
PID Function Blocks
The PID function block has parameter naming similar to RSLogix 500 and is
recommended for users who are already familiar with programming in
RSLogix 500. The IPIDCONTROLLER function block has the advantage of
supporting auto tune.
Comparison Between IPIDCONTROLLER and PID
IPIDCONTROLLER PID Description
Common parameters
Process PV Process Variable feedback
Setpoint SP Set Point input
Output CV CV output
Gains.DirectActing Control Control direction of process (cooling versus
heating).
Gains.ProportionalGain Gains.Kc Controller gain for both P and I
Gains.TimeIntegral Gains.Ti Time integral value for I
Gains.TimeDerivative Gains.Td Time derivative value for D
Gains.DerivativeGain Gains.FC A higher filter constant makes CV output more
responsive to error. Acts like a derivative gain.
AbsoluteError AbsoluteError Absolute value of error
PID specific parameters
– CVMin For limiting CV
CVMax For limiting CV
AutoManual TRUE = Normal operation of PID.
FALSE = Manual operation using CVManual.
CVManual CV when in manual mode
Enable TRUE = Start execution with current input
parameters.
FALSE = CV equals zero.
Active TRUE = PID state is running.
FALSE = PID state is stopped.
Error TRUE = PID has an error.
FALSE = PID has no errors.
ErrorID PID Error ID
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