In Rx3i PLCs (at least) when you create an instance UDT in the PLC code, the components of the UDT are separated from name of the instance via a period EG .
When I browse my Rx3i PLC via the Ignition (or other) OPC UA browser I see the OpcItemPath of the element with the expected period in the overall string. However when I drag the item into the tag list, the period of the name gets replaced with an underscore (but the OpcItemPath remains the same/correct with the period in it)
Can someone confirm that this is expected behavior of Ignition, and that nothing can be done about it?
Expected and nothing can be done about it.
Ignition tag paths have all kinds of restrictions and legacy baggage that prevents perfectly reasonable characters from being used in them.
edit: suppose I should have said tag names, not tag paths, but the names become part of the path which is where all the restrictions come into play.
I work with a bunch of people that think section_value and section.value are two perfectly good and distinct variable names in a PLC! I’m just trying to understand what the implications of that are with Ignition.
It isn’t really a surprise–dots are punctuation separating the udt name from the element name, in the same way that slashes in tag paths are punctuation. This is pretty universal across many namespaces. (Like pretty much any programming language.) I would argue dots are not perfectly reasonable characters for tag names.
Yeah I agree with that. When I was talking about perfectly reasonable I had “[” and “]” in mind… you know, like for array syntax like
Foo which is turned into the insane
Foo_0_ in Ignition