Hi,
I am facing the following problem:
In CAS mode I would like to bypass the setpoint of the PID to the out of the PID, this realised the bypass parameter to on. When the PID is placed in MAN normal operations will copy the OUT to the SP, to block the function I set the bypass parameter back to off. This bypass parameter is read-only when PID mode is CAS, I would like to write the bypass parameter when the PID changes from MAN to CAS.
Using a CALC block and checking the actual and target mode doesn't seam to work, in my opinion when the PID is changed from MAN to CAS there should be a state where the PID actual state is MAN and the target state is CAS in this state I should be able to force the bypass parameter back to on.
Maybe I miss a state why this logic doesn't work:
Thanks,
Werner
Are you actually using the PID algortihm at any point in this control strategy? If not,. then you might consider replacing the PID with an Analog output or Manual loader function block to provide the pass-through setpoint function you require without having to toggle bypass on and off. Analog output block option SP-PV track in man can be disabled to ensure when the output is written in Man, the SP does not track.
If you need to use the PID, have you looked into disabling some of the pertinent CONTROL_OPTS for the PID? (Track In Man etc.)
Andre Dicaire