Emerson Exchange 365

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Displaying a Condition expression in graphics

I have a library object with a configurable condition.  I would like to show the condition string just like you would see it in expression editor, but on a detail faceplate.  I can't see it as an option when configuring a text field, does a parameter exist to be able to see it in the graphics?  I'm trying to avoid having to open control studio just to see what that expression is.

bmross

• 19 May 2017 2:35 PM
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2 Replies

• Matt Stoner

  

  • 19 May 2017 3:52 PM

  Brian,
  
  The expression isn't a runtime parameter that can be referenced from a graphic, just a configured 'parameter'.
  
  You will need to use the description parameter (DESC for Condition block) to 'replicate' the expression (it is runtime and can also be changed during runtime if needed but you will need logic 'somewhere' to do this) and have the graphic link to this.
  
  We typically remove the "code syntax" stuff for these:
  
  Expression = ('//XV101/EDC1/PV_D.CV' != 'edc_states_vlv:Open') or ('//FIC102/PID1/PV.CV' < 30)
  Description = XV101 <> Open or FIC102 < 30 GPM
  
  Regards,
  Matt

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• Andre Dicaire

  

  • 19 May 2017 7:41 PM

  You could use a string parameter in the module to hold the expression logic, leaving the descriptor to provide a user friendly text as to the purpose of the CND block.
  
  I've seen users place a Text field in the sheet to expose the logic expression so one does not need to drill into the block to see the logic expression. But you still have to launch Control Studio to see the Expression.
  
  Although the T_EXPRESSION is treated as a parameter in the engineering tools (you can bulk edit the expression), on line the CND1/T_EXPRESSION returns a numeric value. In reality, the expression is sent to the controller in a Tokenized fashion that is not meaningful to humans. The only place the expression exists in readable text format is in the database, and any export.
  
  If you create a String parameter named something like CND1_EXP, for CND1, and so on, your Detail could show this. The CND1/DESC.cv would remain available for its primary purpose of description. Either way, you have to reproduce the text in a string in order to display it.

  Andre Dicaire

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