Creating Dynamic Nested UDT

Ignition
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1

Hi all,

I have a question about the scope of nested UDTs.

My setup looks like this:

  • I have a Line UDT

  • Inside the Line UDT, I have a nested Machine UDT (under a “Sub Systems” folder)

  • The Machine UDT has OPC tags (e.g. RawString) where the OPC Item Path depends on parameters like:

    • Site

    • Line

    • OPCServer

    • Model

Originally, those parameters were in the Machine UDT, and the OPC item paths worked fine.

I then tried to move those parameters up to the Line UDT level.

But by doing this, I realized that the nested Machine UDT cannot directly read or use parameters defined on the parent Line UDT in its OPC Item Path bindings.

My questions are:

  1. Is there a way for nested UDT to access parent UDT parameters directly?

  2. Or is there a better method for this case as I plan to expand and add new site with a large number of lines. what’s a good structure to avoid excessive manual parameter setup while still keeping OPC paths clean and maintainable?

I’m mainly trying to sanity‑check whether my original approach (parameters inside the machine UDT) was actually the right one, or if there’s a better way for this.

Thanks!

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2

You can access the parent's UDT params with the usual {param1} format. Just set the nested UDT's param values to the parent's params