Using PID_3Step
5.3 PID_3Step V1
PID control
156 Function Manual, 03/2017, A5E35300227-AC
Simulating PID_3Step V1 with PLCSIM
Note
Simulation with PLCSIM
For the simulation with PLCSIM, the time behavior of the simulated PLC is not exactly
identical to that of a "real" PLC. The actual cycle clock of a cyclic interrupt OB can have
larger fl
uctuations with a simulated PLC than with "real" PLCs.
In the standard configuration, PID_3Step determines the time between calls automatically
and monitors them for fluctuations.
For a simulation of PID_3Step with PLCSIM, for example, a sampling time erro
r (ErrorBits =
DW#16#00000800) can therefore be detected.
This results in ongoing tuning being aborted.
The response in automatic mode depends on the value of the ActivateRecoverMode tag.
To prevent this from happening, you should configure PID_3Step for simulation with PLCSIM
as follows:
CycleTime.EnEstimation = FALSE
CycleTime.EnMonitoring = FALSE
CycleTime.Value: Assign the cycle clock of the calling cyclic interrupt OB in seconds to
this tag.
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