How to use a string tag in UDT, as the tagpath for another instance?

Hi All, not sure if the topic sentence is clear enough.
I have a tagpath: Plant/Analog/Tag1/Value, value of 5.
I have a UDT, which contains:

  1. string tag, containing the tagpath for another instance tag to use
  2. a reference/expression/derived tag/memory (whichever feasible), the source tag path should refer to the string tag’s content, so that it will read from that path and give the value of 5.

I understand that if i make use of parameters, and incorporate into a expression, i can make it work. but i am hoping not to involve parameters, as i have lots of tags to refer to, i need to manually key in all of them…

Any help is appreciated, many thanks in advance!

To further elaborate more, i have a edge system, and data are sent throught the MQTT modules to a server.
Since alarm properties are not included, i wanna reference those analog tags from my server, and from there, i will configure the alarms accordingly.

Example edge tag as displayed on server side:
[MQTT Engine]Edge Nodes/Plant/Area1/Tag1/Value"

My UDT source tag path will be something like:
[MQTT Engine]Edge Nodes/Plant/{Area}/{InstanceName}/Value

So that if i can auto generate the {Area} (which is already done), i would be able to retrieve the value directly.

If I am understanding what you need correctly, you should be able to accomplish this with an Expression Tag that is setup in the following way:

Presumption: A tag name tagPath exists that contains a string value of the path to the tag you want to get the value for. New expression tag is being created as a sibling to tagPath.

Expression: tag({[.]tagPath})


Hi Garth, thank you very much, that is the function i was looking for!! :blush: