Configure tag history binding expression syntax

I’m trying to create tag history bindings with parameters. As a first step I’m trying to understand how this works by creating a simple tag history query expression:

I’m getting “Error configuration” at the bottom of the binding dialog.

I’m missing some understanding here. Can anyone give me some guidance?

Expressions don’t support collection literals like [] and {}. The ‘Expression’ is probably best as a direct or indirect (property()) reference to a custom property somewhere with the correct formatting.

Thank you, Paul, but isn’t that just moving the problem over to the binding on the property() reference?

Let’s say I’m creating a Perspective XY Chart to be used on a dashboard for a group of machines.

Machine 1
> Ambient temp
> Compressor1 motor amps (ns=1;s=[Simulator1]_Meta:Refrigeration/Compressor1/motorAmps)
Machine 2
> Ambient temp
> Compressor1 motor amps (ns=1;s=[Simulator2]_Meta:Refrigeration/Compressor1/motorAmps)

How would I generate the custom property to allow me to feed the Machine 1 or Machine 2 tags into the chart history binding?

Thank you for your patience.

If it’s a binary one or the other, you could use an expression structure binding, right? The aggregate and alias would be fixed keys, and the path would use an expression to pull in whichever is appropriate.

Anything more dynamic than that and I would just use a script transform.

To be totally honest, I’ve never completely understood the ‘why’ of how expression mode works on Perspective history bindings.

Can you show an example of how this is done? I realy need the tag history binding path to be dynamic or else the whole function is useless.

You have to point to a custom property which contains an array of object. In the first object, add a value "path" and enter your tag path. To make it dynamic, bind the tag path.

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I created a custom property on the view level with the correct syntax. and then bound that custom property in the expression of the tag query history