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Import warning for module with DCC block with custom named sets

We are creating a module based on the DCC and EDC blocks.

The module is designed with the intent that only certain states can be selected for interlock states (e.g. only Stop is allowed for a motor). We have a custom named set for DCC1/I_STATEx with a subset of states. This seemed to be the only way to prevent an invalid value from appearing as an option during configuration of an instance of the module.

When we import the CLASS we get an import warning for each I_STATEx parameter:

WARNING: The values in the named set '<custom named set>' are a subset of those in the defining set '$interlock_states' for parameter <module>/DCC1/I_STATE1'

Is there any real concern with this warning?

• DeltaV #DCS
• configuration
• DCC

Brian Hrankowsky

• 22 Jul 2021 12:26 PM
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3 Replies

• Matt Stoner

  

  • 22 Jul 2021 12:48 PM

  No, there is no concern with this as long as you have all of the available selections for interlock states that are require for the instance(s).
  
  Although by doing this if there ever is a case that needs to Interlock to an active state (assuming you are removing all the active states) then you will have to change and depending on how the class I_STATEx parameters are setup (i.e. Allow named set changes for new instances option) then this might be simple Named set change (option Checked) or a lot of work to class/new class development (option unchecked). Interlocks to non Fail Positions are rare but they do come up occasionally. We typically just leave the available SPs as available Interlock States and some just leave I_STATEx set to Passive so they go to defined Fail Position (defined Passive state). Some don't like the graphic showing interlock state as Passive and prefer to see the state but again there is no concern with what you have done and import warning received.

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• Brian Hrankowsky

  

  • 22 Jul 2021 2:19 PM

  In reply to Matt Stoner:

  Thanks Matt Stoner !
  
  we certainly see the active state interlocks on valves.
  
  Our objectives were to reduce configuration errors by taking away invalid selections.
  
  Do others just sort of "live with it"?

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• Matt Stoner

  

  • 22 Jul 2021 2:50 PM

  In reply to Brian Hrankowsky:

  Yeah I think I've only done this to test it was possible before the DCC and EDC blocks were to be released in v13 as I knew someone might want to do this but I definitely see the merits of limiting config errors when possible. The problem is that when you need to do it and it isn't available, it is 2 am on a weekend and someone wants to do it right then. Those are the balances you have to weight and I always lean to not having to be called at 2 am on the weekend to support :)

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