Process Control Instructions
64 Rockwell Automation Publication 1756-RM006K-EN-P - November 2018
Output Parameter Data Type Description
EnableOut BOOL Enable output.
Out REAL The calculated output of the algorithm. Math status flags are
used for this output.
DeltaT REAL Elapsed time between updates. This is the elapsed time in
seconds used by the control algorithm to calculate the process
output.
Status DINT Status of the function block.
InstructFault (Status.0) BOOL The instruction detected one of the following execution errors.
This is not a minor or major controller error. Check the
remaining status bits to determine what occurred.
LeadInv (Status.1) BOOL Lead < minimum value or Lead > maximum value.
LagInv (Status.2) BOOL Lag < minimum value or Lag > maximum value.
TimingModeInv (Status.27) BOOL Invalid TimingMode value.
For more information about timing modes, see Function Block
Attributes.
RTSMissed (Status.28) BOOL Only used in real time sampling mode. Set when
ABS | DeltaT - RTSTime | > 1 (.001 second).
RTSTimeInv (Status.29) BOOL Invalid RTSTime value.
RTSTimeStampInv
(Status.30)
BOOL Invalid RTSTimeStamp value.
DeltaTInv (Status.31) BOOL Invalid DeltaT value.
Description
The LDLG instruction supports one lead and lag in series. The instruction also
allows configurable gain and bias factors. The LDLG instruction is designed to
execute in a task where the scan rate remains constant.
The LDLG instruction uses this equation:
with these parameter limits:
Parameter Limitations
Lead LowLimit = 0.0
HighLimit = maximum positive float
Lag LowLimit = DeltaT/2 (DeltaT is in seconds)
HighLimit = maximum positive float
Whenever the value computed for the output is invalid, NAN, or INF, the
instruction sets Out = the invalid value and sets the Math overflow status flag.
To Next Page
Loading...
Need help?
General
