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CHARMS Logic Solver Download Issues

We are adding a new CHARMS logic solver SIS system into our existing DeltaV DCS control system.  We are reading the SIS I/O into modules which are assigned to the CSLS.  We have DCS modules which reference the logic solver I/O via external references.  When we do a download of the CSLS, the status of the external reference in the DCS module goes to BadNoCommUV.  This status stays bad for periods of up to 15 seconds.  We are looking for a way to eliminate this issue without putting in custom logic to delay a bad status alarm in each module.  Our assumptions were that by using a DeltaV SIS system, we wouldn't have this issue because they are  on the same communication bus.

• CHARMS logic solver

boykindj

• 17 Oct 2015 5:28 PM
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5 Replies

• Ben Bishop

  

  • 20 Oct 2015 9:00 PM

  I see that you have opened a ticket with our Global Service Center on this matter. Please update the community when it is resolved.

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• boykindj

  

  • 22 Oct 2015 2:33 PM

  The global service center suggested wiring from the LSAI block to an output parameter in the SIS module. Then referencing the output parameter from the DCS module. It was also suggested to change the download behavior of the DCS module to "Preserve user defined and critical block values". We tried this, but got the same results. The references between systems go bad for periods of 10-15 seconds during a download.

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• Tadeu Batista

  

  • 23 Oct 2015 1:55 PM

  In reply to boykindj:

  First question I have is, where is this DCS modules been assigned? to the Local SZ Controller or to a remote DeltaV controller?
  One suggestion would be, instead of driving the variable using parameter, you should try to assign the Input to an AI block within the DCS module.

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• boykindj

  

  • 11 Nov 2015 12:59 AM

  In reply to Tadeu Batista:

  We have tried moving the modules from the BPCS controller to the SZ controller, but the result is still the same. All communication is lost between the CSLS and anything outside of it's processor. Also, moving modules to the SZ controller would not necessarily work in cases when non-safety I/O is also tied to that module. (ie. PID loop). Our current solution is to delay the status of the referenced signal by 20 seconds which is slightly longer than the time required to download and re-establish communications. I'm hoping a solution for this is released in the future.

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• Andre Dicaire

  

  • 2 Dec 2015 12:15 AM

  In reply to boykindj:

  Did the GSC confirm how long the IO channel status is supposed to go BAD during and following the CSLS download? I would expect the status to go BAD in this situation.
  
  What I find interesting is that you are downloading a logic solver and expect the BPCS to maintain communication to the Logic Solver IO. The Logic solver does not support partial downloads, by design, in line with IEC 61508 certified functionality. During a download, the CSLS clears its configuration for all its IO and the SIF's. It then loads the new configuration and re-establishes all communications with the SZ controller.
  
  I'm curious to know if you are now looking for a work around or are you still thinking this is abnormal behavior.

  Andre Dicaire

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