Rockwell Automation Publication 1756-RM006K-EN-P - November 2018 271
Structured Text
Operand Type Format Description
PI tag PROP_INT structure PI structure
See Structured Text Syntax for more information on the syntax of expressions
within structured text.
PROP_INT Structure
Input
Parameter
Data Type Description
EnableIn BOOL Enable input. If cleared, the instruction does not execute and outputs are not updated.
Default is set.
In REAL The process error signal input. This is the difference between setpoint and feedback.
Valid = any float
Default = 0.0
Initialize BOOL The instruction initialization command. When set, Out and internal integrator are set equal
to the value of InitialValue.
Default is cleared.
InitialValue REAL The initial value input. When Initialize is set, Out and integrator are set to the value of
InitialValue. The value of InitialValue is limited using HighLimit and LowLimit.
Valid = any float
Default = 0
Kp REAL The proportional gain. This affects the calculated value for both the proportional and
integral control algorithms. If invalid, the instruction clamps Kp at the limits and sets the
appropriate bit in Status.
Valid = any float > 0.0
Default = minimum positive float
Wld REAL The lead frequency in radians/second. This affects the calculated value of the integral
control algorithm. If invalid, the instruction clamps Wld at the limits and sets the
appropriate bit in Status.
Valid = see the Description section below for valid ranges
Default = 0.0
HighLimit REAL The high limit value. This is the maximum value for Out. If HighLimit LowLimit, the
instruction sets HighAlarm and LowAlarm, sets the appropriate bit in Status, and sets Out =
LowLimit.
Valid = LowLimit < HighLimit maximum positive float
Default = maximum positive float
LowLimit REAL The low limit value. This is the minimum value for Out. If HighLimit LowLimit, the
instruction sets HighAlarm and LowAlarm, sets the appropriate bit in Status, and sets Out =
LowLimit.
Valid = maximum negative float LowLimit < HighLimit
Default = maximum negative float
HoldHigh BOOL The hold high command. When set, the value of the internal integrator is not allowed to
increase in value.
Default is cleared.
HoldLow BOOL The hold low command. When set, the value of the internal integrator is not allowed to
decrease in value.
Default is cleared.