Allen-Bradley LOGIX 5000 Reference Manual page 71

Process Control Instructions
CVROCLimit REAL
FF REAL
FFPrevious REAL
FFSetPrevious BOOL
HandFB REAL
HandFBFault BOOL
WindupHIn BOOL
WindupLIn BOOL
ControlAction BOOL
DependIndepend BOOL
PGain REAL
Rockwell Automation Publication 1756-RM006K-EN-P - November 2018
CV rate of change limit, in percent per second. Rate of change limiting is only used
when in Auto or Cascade/Ratio modes or Manual mode if CVManLimiting is true. Enter
0 to disable CV ROC limiting. If CVROCLimit < 0, the instruction sets the appropriate bit
in Status and disables CV ROC limiting.
Valid = 0.0 to maximum positive float
Default = 0.0
Feed forward value. The value of feed forward is summed with CV after the zero-
crossing deadband limiting has been applied to CV. Therefore changes in FF are always
reflected in the final output value of CV. If FF < -100 or > 100, the instruction sets the
appropriate bit in Status and limits the value used for FF.
Valid = -100.0 to 100.0
Default = 0.0
FF value. If FF SetPrevous is set, the instruction sets FF
n-1
valu eof FF from the previous execution. If FFPrevious < -100 or > 100, the instruction
sets the appropriate bit in Status and limits value used for FF
Valid = -100.0 to 100.0
Default - 0.0
Request to use FFPrevious. If true, FFn-1 = FFPrevious.
Default is false.
CV Hand feedback value. CV equals this value when in Hand mode and HandFBFault is
false (good health). This value typically comes from the output of a field mounted
hand/ auto station and is used to generate a bumpless transfer out of hand mode. If
HandFB < 0 or > 100, the instruction sets the appropriate bit in Status and limits the
value used for CV.
Valid = 0.0 to 100.0
Default = 0.0
HandFB value bad health indicator. If the HandFB value is read from an analog input,
then HandFBFault is typically controlled by the status of the analog input channel.
When true, HandFBFault indicates an error on the input module and the instruction sets
the appropriate bit in Status.
Default is false = "good health"
Windup high request. When true, the CV cannot integrate in a positive direction. The
signal is typically obtained from the WindupHOut output from a secondary loop.
Default is false.
Windup low request. When true, the CV cannot integrate in a negative direction. This
signal is typically obtained from the WindupLOut output from a secondary loop.
Default is false.
Control action request. Set to true to calculate error as E = PV - SP; clear to false to
calculate error as E = SP - PV.
Default is false.
Dependent/independent control request. When true, use the dependent form of the
PID equation; when false, use the independent form of the equations.
Default is false.
Proportional gain. When the independent form of the PID algorithm is selected, enter
the unitless proportional gain into this value. When the dependent PID algorithm is
selected, enter the unitless controller gain into this value. Enter 0 to disable the
proportional control. If PGain < 0, the instruction sets the appropriate bit in Status and
uses a value of PGain = 0.
Valid = 0.0 to maximum positive float
Default = 0.0
Chapter 1
= FFPrevious. FF is the
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