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How far is a PID block allowed to wind up when HighLimited on BKCAL_IN

I have two PID loops (FIC and PIC) whos output goes to Control Selector Block (set to minimum select), which goes to an Analog Output block.  The majority of time the FIC has control (lowest output).  The Control Selector Block is doing its job by sending back "Good Cascade NotSelected Highlimited" to the BKCAL_IN of the PIC.  The PIC is doing its job by not winding up too far, because it is HighLimited.  What I don't know, or can't find any information on, is how far is the output of the PIC allowed to wind up?  Any feedback is appreciated.  Thanks!

Lance Dusing
  • gamella
    The not selected PID in a Control Selector scheme has it's integral action disabled (the NotSelected sub status tells the PID to do that). So when not selected the PID acts as a PURE Proportional PID (plus derivative if configured). In that situation the output will be (SP - PV) * Gain.
  • GeloCortez

    In reply to gamella:

    Dynamic Reset Windup should be enabled for this?
  • Andre Dicaire

    In reply to gamella:

    When not selected, the integral term of that PID is replaced by the Back Cal_in value, which is the current output. This PID cannot wind up. When it's PV equals SP, Its out value will equal the current out of CNTRLSEL and a bump less transfer.

    Dynamic reset is for Cascade control, not control select.

    Andre Dicaire

  • GeloCortez

    In reply to Andre Dicaire:

    Thanks for the reply Andre. I did simulated this before with and without Dynamic Reset. the Not selected PID still winds up when Dynamic Reset is disabled. I'll try to simulate it again next year.

    btw, Happy New Year to all.
  • Andre Dicaire

    In reply to GeloCortez:

    Windup is due to integral action. When status is Not selected. . Integral tracking is setting integral term. The PID out will still move due to Proportional action on Error. Check that PID/OUT = gain*error + bkcal_in value.

    Andre Dicaire

  • GeloCortez

    In reply to Andre Dicaire:

    Hi Andre, i did simulated it again and the not selected PID still winds up to 100%. but when i Enabled the Dynamic Reset, PID/OUT = gain*error + bkcal_in value. when no error, PID/OUT = Bkcal_IN

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