Allen-Bradley LOGIX 5000 Reference Manual page 101

Process Control Instructions
(4) During instruction first scan, the instruction clears the windup outputs. The
instruction also clears the windup outputs and disables the CV windup algorithm
when CVInitializing is set or if either CVFaulted or CVEUSpanInv is set.
(5) The instruction sets WindupHOut when SPHAlarm is set, or when
ControlAction is cleared and CVHAlarm is set, or when ControlAction is set and
CVLAlarm is set.
The SP and CV limits operate independently. A SP high limit does not prevent
CV from increasing in value. Likewise, a CV high or low limit does not prevent SP
from increasing in value.
(6) The instruction clears WindupHOut when SPHAlarm is cleared, and not
(ControlAction is cleared and CVHAlarm is set), and not (ControlAction is set
and CVLAlarm is set).
(7) The instruction sets WindupLOut when SPLAlarm is set, or when
ControlAction is cleared and CVLAlarm is set, or when ControlAction is set and
CVHAlarm is set.
The SP and CV limits operate independently. A SP low limit does not prevent CV
from increasing in value. likewise a CV low or high limit does not prevent SP from
increasing in value.
(8) The instruction clears WindupLOut when SPLAlarm is cleared and not
(ControlAction is cleared and CVLAlarm is set) and not (ControlAction is set
and CVHAlarm is set).
Processing Faults
The following table describes how the instruction handles execution faults:
Fault Condition Action
CVFaulted is true or Instruction is not initialized, CVInitializing is cleared to false
CVEUSpanInv is true
Compute PV and SP percent, calculate error, update internal parameters for EPercent and
PVPIDPercent
PID control algorithm is not executed
Disable the Auto and Cascade/Ratio modes. If Override or Hand is not the current mode, set to
Manual mode.
Set CV to value determined by Program or Operator control and mode (Manual, Override, or
Hand).
PVFaulted is true Disable the Auto and Cascade/Ratio modes. If Override or Hand is not the current mode, set to
Manual mode
PV high-low, PV rate-of-change, and deviation high-low alarm outputs are cleared to false
PID control algorithm is not executed
Set CV to value by determined by Program or Operator control and mode (Manual, Override, or
Hand).
Rockwell Automation Publication 1756-RM006K-EN-P - November 2018
Chapter 1
101