7 Replies Latest reply on Aug 30, 2018 1:49 PM by vkaufmann

Set Attribute Default UOM as PI Point

Abu.Salam Aug 29, 2018 5:45 PM

Hello,

For a PI point we expect to have two types of UOM / EU which are (psi or in H2O), how can we setup the Default UOM for that element attribute with what we have from PI point dynamically rather than hard code it in the template?

Re: Set Attribute Default UOM as PI Point

vkaufmann Aug 29, 2018 6:49 PM (in response to Abu.Salam)

Hi Abu,

I moved this thread to a more appropriate space. Am I to understand that you want to set the UOM of an attribute to dynamically change depending on the value of a PIPoint? This is not generally how UOM's are handled. If the UOMs are part of the same class, then it is up to the client to query the attribute with the desired UOM and will be converted as needed. Can you explain what you are querying these attributes with?

--Vince
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- Re: Set Attribute Default UOM as PI Point
  
  Abu.Salam Aug 29, 2018 7:34 PM (in response to vkaufmann)
  
  Thank you!
  
  So, we have 2 types of VRUs, High Pressure (HP) and Low Pressure (LP). For the HP VRUs, the Suction pressure is psi and for the LP VRUs, the same suction pressure is in H2O.
  
  I was trying to use the same element template (VRU) and change the UOM in AF based on the PI tag UOM / EU. Because, when we create those tags, we put appropriate UOM based on the VRU types.
  
  Can i do this or i have to have a Derived template for HP & LP and keep the Suction pressure separately?
  
  Thanks again!
  
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  - Re: Set Attribute Default UOM as PI Point
    
    vkaufmann Aug 29, 2018 8:45 PM (in response to Abu.Salam)
    
    Rather than have logic to switch between the UOMs, you should have the different equipment types leverage separate (derived) templates which define the correct unit for the high pressure and low pressure variations.
    
    --Vince
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    - Re: Set Attribute Default UOM as PI Point
      
      Abu.Salam Aug 29, 2018 8:50 PM (in response to vkaufmann)
      
      Got it, thank you so much.
      
      On the other note, i believe it is not possible to inherit UOM from PI tags to AF attributes, correct? This will be a good feature so that we wont have to double trouble, same UOM enter twice.
      
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      - Re: Set Attribute Default UOM as PI Point
        
        vkaufmann Aug 29, 2018 8:57 PM (in response to Abu.Salam)
        
        PI Point UOMs defined in the Data Archive never had any function other than to be a visual indicator. UOMs in AF are much more functional and are completely separate from whats stored in the Data Archive. Because of this, I don't think there would ever be a way to directly link them.
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      - Re: Set Attribute Default UOM as PI Point
        
        vkaufmann Aug 30, 2018 1:49 PM (in response to Abu.Salam)
        
        Hi Abu,
        
        If you are satisfied with my answer above, would you mind marking it as correct to close out the thread?
        
        --Vince
        
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Re: Set Attribute Default UOM as PI Point

sraposo Aug 29, 2018 7:19 PM (in response to Abu.Salam)

Hi Abu,

In addition to Vince's comment, unless I'm misunderstanding here, how does an application (client) know whether the UOM in the PI Point is of one of psi or H20 ? How should AF know if it's PSI or H20?

Thanks,
Seb
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