Emerson Exchange 365

Fail state behavior of Charm DO 's

We're implementing and testing Charm DO's with Relay Output terminals and I'd like to undertstand the normal expected behavior during failure states.  If both IO networks are disconnected the DO charm goes to configured fail state (as per our requirements), this is also true for removing both CIOC's, but on restoration of the comms/CIOC's we seem to have to toggle the DO (through DC block) to get the DO to energise again.  Is this normal behavior?

• CHARMS
• Behaviour

AdrianOffield

• 9 Jun 2015 12:22 PM
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7 Replies

• Aaron Crews

  

  • 12 Jun 2015 4:11 PM

  Adrian - I would guess that some of this is expected behavior, and some might be in your Device Control block configuration. When you pull the CIOC, does the motor module fail? You should have your SP go back to stop. The intent here would be to avoid automatically running motors when a CIOC comes back online (which sounds like a bad idea).

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• AdrianOffield

  

  • 12 Jun 2015 7:38 PM

  In reply to Aaron Crews:

  Appreciate the concept but motors have two outputs one start, one stop, so no chance of motor starting. DC block fails, but my issue is with the stop DO when motor already stopped. This means I have to toggle to start, then fail, then reenergize stop DO. This should be a configurable option if I wish.

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• mastermadhawa

  

  • 12 Jun 2015 8:20 PM

  In reply to AdrianOffield:

  I believe the option "Passive on Active Timeout" on Device_Opts on a DC dlock is what you may need.

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• AdrianOffield

  

  • 13 Jun 2015 3:33 AM

  In reply to mastermadhawa:

  Thanks mastermadhawa, but the issue is with the STOP digital output (Charm). I'm not trying to start motors, the motor is already STOPPED, but if the charm fails with the STOP DO energized, then the output is de-energized....if the charm is re-inserted, the DO does NOT come back on. It is not a DC block issue.....it is a CHARM issue I am trying to answer.

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• Michael Moody

  

  • 13 Jun 2015 3:37 PM

  In reply to AdrianOffield:

  Are you looking at the failure of an individual CHARM or the entire CIOC or both?
  When the DO CHARM is reinserted, what value is the DC block passing to the CHARM address? Does the output from the CHARM agree with the value sent from the DC Block?
  Is your installation requiring a "RUN" DO (constantly on) to run the motor and "STOP" DO (constantly on) to stop the motor? Or do they Pulse? Or does the "STOP" output release once the motor is confirmed stopped?
  What is the expected behavior while the CHARM is failed or the CIOC has failed?

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• AdrianOffield

  

  • 14 Jun 2015 5:18 AM

  In reply to Michael Moody:

  Both scenarios are valid, so either CHARM failing or CIOC.
  
  This is my problem, the STOP DO with DC block in passive state, after CHARM reinsertion the DO does not energize. The DO block is showing a 1 with bad status (red x).
  The motor starter interface is just traditional pulsed START and maintained STOP signals. STOP DO to low to break control circuit.
  
  Obviously if the motor was running and the CHARM failed, then the DO will drop and the DC will also transition to passive. The issue is when the DC block is already passive (Stopped), how do I programmatically restore a failed STOP DO? Looks like I need to incorporate the DO status into the signal coming form the DC block????

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• Matt Stoner

  

  • 15 Jun 2015 12:49 PM

  In reply to AdrianOffield:

  I believe that the I/O on the DC block (All the output function blocks most likely) is sent on change of state and only when status is good and not when the bad status has become good (not sure why this is but the reason for bus configuration below).
  
  What you are describing seem to be acting just like Asi/Devicenet/Profibus and it is suggested within Books Online to use external references is these cases.
  
  Try using External References to the CHARM START and STOP signals that are wired from the DC1/F_OUT_D1 and DC1/F_OUT_D2 (You have to show these as outputs on the DC block).
  
  I believe this is the only way to get your config to work as you would expect.

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