Normally Closed Charm DO?

Can a Charm discrete output be configured as a Normally Closed contact so that it can be utilized in the STOP circuitry of the motor control?

Out client has a 2 output motor control wiring for DCS. The motor control circuit has normally open DO Momentary for Start command in parallel with local start PB and holding contact once motor is pulled in. 

Motor also has a normally closed DO momentary STOP in series with local NC stop PB.

How can this be done in DeltaV using Charms I/O? 

  • The relay terminal block does this. This uses a 24V DO CHARM to drive a SPDT relay integrated into the CHARM terminal block. Pages 4 & 21 in the product data sheet have more information www2.emersonprocess.com/.../PDS_S-series_Electronic_Marshalling.pdf
  • In reply to Mike Link:

    Apparently this can be done with the SPDT relay output.
    This answers my question! Thank you
  • You can set the charm to momentary and/or you can invert it as well to accomplish this. Another alternative is to do a time pulse block between the DC block & the DO block to open the contacts long enough to drop out the seal in circuit.