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DC Function block motor control having external non wired DeltaV start / stop locations

Hi All,

My question is regarding the DC-Device Control function block for motor control (3-wire VFD with non DeltaV integrated start / stop controls), I understand the DC operation but I am trying to figure out a special case where our operators who are not using a DeltaV workstation will turn on the motor in the field using start/stop push buttons. We do have feedback on if motor is running or not and that signal is put into the DeltaV as DC1 -> IN_1 (motor starter N.O. contact closure) .

 What happens is from the faceplate (FP) side it shows a DeltaV motor status of “Stop” from DC1->SP_D (motor is actually running) and just below that the next box shows “Running” from the DC1->FV_D (Field devices) & OUT_D = 0.

 Is there a way to momentarily pulse the FP start button in software when the IN_1=1 so as to update the DC1 module which then would put DC1->SP_D into "Running" mode and then allow the DeltaV operator to then stop the motor from DeltaV? Or should I have used a different DC motor function block or template?

ShaneG
  • ShaneG
    I will try to use the INPUT from the aux contact to be Cascade_IN and IO_IN1 and mode to be Cascade. This should let SP_D follow the cascade_in and I think this will work will give it a go tomorrow.
  • Matt Stoner

    In reply to ShaneG:

    Your best method will probably be to set the DC/TRK_IN_D to True for a one module scan when the Run Status changes (actual DST value != DC/F_IN_D1 determined before DC block executes) and then set DC/TRK_IN_D back to false the next scan. Using CAS_IN will probably cause other issues as it will only work in CAS mode.

    You will never have a "failure" of the motor because it trips out unless you get some signal(s) about the field pushbuttons either directly or using Hand Off Auto (HOA) type signal to trigger the TRK_IN_D when field buttons "could" be pressed (HOA is not in AUTO).
  • ShaneG

    In reply to Matt Stoner:

    Thank you for your response and for your time Matt S. as this worked and the only thing I needed to do was to also make sure the state changed during a field shutdown so I had to NOT TIMED PULSE to output again using an OR gate for both situations.

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