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Building a PI Vision display using indirection

Question asked by ian.d.gore on Nov 17, 2017
Latest reply on Dec 5, 2017 by ian.d.gore

Hi Everyone,

 

I have a complex display I want to build in PI Vision.  To support the display I have created an element that gets it's data from other elements depending on the configuration in the display element. I'm using substitution syntax to get the indirection I need.

 

I have this basically working fine in PI System Explorer.  I use a PI Point data reference that uses subsitution to create the attribute path I need to get the data from - like this

AttributeConfig.PNG

 

So when the name of the product changes in NAME, the STOCK attribute automatically updates to point at the new path and picks up the data I want.   Works fine - exactly what I wanted.

 

Then in a classic "bang my head on the table" moment, I built a value symbol on my display in PI Vision - and it didn't work.  Because PI Vision treats my attribute path as a PI Tag name and fails to find it:

 

VisionError.PNG

 

I've had a similar problem in the past and managed to use StringBuilder to get round it.  But in this case StringBuilder doesn't seem to handle the two level indirection (first to build the path and then to follow the path) needed to get at the value.

 

I haven't tried using analytics yet to see if I can get round the problem.

 

Has any one else tried to do this?  Is there a trick I'm missing?

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