Weird PID Behavior

  • So,

    I try to do some heater controlling and no matter what I do the DFactor stays zero. The only thing which brings some action is to use a negative D value which brings dampening but on the ramp-up and not when reaching the target value. Long story short: Can't for the live of me damp the overshoot the PI Part is producing and I need an "overdampend" setup because the customer is sort of intolerant concerning overshoot. Also the underlying Formula is sort of weird.

    Has anybody any advise or has implemented a working PID with anti windup for Mervis?

    Thanks, Andi

  • I've also been frustrated with the built-in PID logic, both with the D-term and how the min and max are implemented. I'm planning to just write my own so that it behaves as I'd expect it to.

  • Yeah, I'll dump the unipis from my project, this and (after updating the ide) "Your project has been created with (old version), please stick to that version forever to avoid errors" did it for me. Yes, S7 or Wago PFC are more expensive but concerning the hours I dumped into troubleshooting the are the better deal.

  • Hi guys,
    I know this is a Mervis section, but if PID control is what you are after, consider switching to REXYGEN. Works like charm.

  • @Matt Did you manage to write a better PID implementation in Mervis that you could share? When using the built-in PID logic for controlling hydronic underfloor heating valves (huge time delay), it only acts as a pure PI controller.

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