Allen-Bradley LOGIX 5000 Reference Manual page 186

Chapter 1 Process Control Instructions
186
Important: Whenever an APC block detects a change in Delta Time (DeltaT), a ModelInit will be performed. For
this reason the blocks should only be run in one of the TimingModes in which DeltaT will be
constant.
• TimingMode = 0 (Periodic) while executing these function blocks in a Periodic Task
• TimingMode = 1 (Oversample)
In either case, if the Periodic Task time is dynamically changed, or the OversampleDT is dynamically
changed, the block will perform a ModelInit.
The following TimingMode setting are not recommended due to jitter in DeltaT:
• TimingMode = 0 (Periodic) while executing these function blocks in a Continuous or Event Task
• TimingMode = 2 (RealTimeSample)
Structure
Input Parameters Data Type
EnableIn BOOL
PV REAL
PVFault BOOL
PVUEMax REAL
PVUEMin REAL
SPProg REAL
SPOper REAL
SPCascade REAL
Rockwell Automation Publication 1756-RM006K-EN-P - November 2018
Description
Enable Input. If False, the function block
will not execute and outputs are not
updated.
Scaled process variable input. This value is
typically read from an analog input
module.
PV bad health indicator. If PV is read from
an analog input, then PVFault will
normally be controlled by the analog input
fault status.
If PVFault is TRUE, it indicates an error on
the input module, set bit in Status.
Maximum scaled value for PV. The value of
PV and SP that corresponds to 100% span
of the Process Variable. If PVEUMax ≤
PVEUMin, set bit in Status.
Minimum scaled value for PV. The value of
PV and SP that corresponds to 0% span of
the Process Variable. If PVEUMax ≤
PVEUMin, set bit in Status.
SP Program value, scaled in PV units. SP is
set to this value when in Program control.
If value of SPProg or SPOper < SPLLimit or
> SPHLimit, set bit in Status and limit
value used for SP.
SP Operator value, scaled in PV units. SP set
to this value when in Operator control.
If value of SPProg or SPOper < SPLLimit or
> SPHLimit, set bit in Status and limit
value used for SP.
SP Cascade value, scaled in PV units. If
CascadeRatio mode and UseRatio is FALSE,
then SP is set to this value, typically this
will be CVEU of a primary loop. If
CascadeRatio mode and UseRatio is TRUE,
then SP is set to this value times Ratio.
If value of SPCascade < SPLLimit or >
SPHLimit, set bit in Status and limit value
used for SP.
Valid and Default Values
Default=TRUE
Valid = any float
Default = 0.0
Default = FALSE
FALSE = Good Health
Valid = PVEUMin < PVEUMax
≤ maximum positive float
Default = 100.0
Valid = maximum negative
float ≤ PVEUMin < PVEUMax
Default = 0.0
Valid = SPLLimit to SPHLimit
Default = 0.0
Valid = SPLLimit to SPHLimit
Default = 0.0
Valid = SPLLimit to SPHLimit
Default = 0.0