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PID Setpoint Restore Parameter Values

Hi, I have several clients who are unhappy with how their setpoints in PID loops restore after a power failure. The setpoint parameter in a PID loop is not available to check the box for restore. Is there a reason why?? this seems silly to me. I realize that setpoints would stay if I put the Controllers on a UPS but thats only good for 20-30 minutes... Things happen and power failures last longer than that in our kneck of the woods.

Any solutions anyone??? These are running systems so I don't want to just start adding extra parameters in their modules (meaning i don't want to have a setpoint input parameter to tie the faceplate to because then automatic limits won't work..)

Why is it designed like this?!?! [:@]

4 Replies

  • I feel your pain.   This solution works for PIDs that are stand alone (not a slave to a master PID) where the operators enter the setpoint.   On a periodic basis I manually go and in DeltaV Explorer, I upload changes.   I am selective (I wish there was a sort option) in that I only upload PID set-points, alarm limits, and tuning changes.   I do not upload modes, bypasses, DC1 set-points, or simulation values.
    Mr. Chris Williams – Controls Technology
    DAK Americas LLC, CA site
  • I believe this is intentional to prevent the PID loop from automatically actuating the final control element as soon as power is restored. You'll notice mode is not preserved either.
    If power is lost to the control system and there is 20-30 minutes of UPS capacity, safely shutting down the process is probably priority. I would imagine the running setpoints would need to be ramped down as part of this activity, anyway.
    Operator driven setpoints shouldn't change much if a steady process is desired. If setpoints are being recalculated or adjusted due to process conditions, an advanced control solution may be worthwhile to re-align the process setpoints rather than relying on human interaction of frequent setpoint changes.
  • In reply to Youssef.El-Bahtimy:

    I understand everyone's points. I do monthly uploads for all my clients. And to my self I wouldn't think it would be important because start up setpoints will probably be different than running setpoints anyways. But you wouldn't image how angry my clients are about this one feature. And everyone likes to shoot the messenger haha
  • A word of caution. The upload values have multiple issues on multiple versions of DeltaV (I have confirmed them on v11.3 and v13). ALWAYS check the values. These issues include both incorrect values being put into the code base and changed values being missed.

    I am currently developing a reporting tool to aid in addressing this type of concern for one of my clients.

    As for operator setpoints etc before a failure, I always point the operator to the historian recorded data. By doing this it prompts them to think about the state of the plant before the failure.