# Dynamically build source tag path for Reference Tag from other tag value **URL:** \ **Category:** Ignition\ **Tags:** ignition81\ **Created:** [January 3, 2024, 7:57am UTC](https://forum.inductiveautomation.com/t/dynamically-build-source-tag-path-for-reference-tag-from-other-tag-value/83724 "2024-01-03T07:57:56Z")\ **Posts on this page:** 1\ **Showing post:** 6
**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\ **Post date:** [January 4, 2024, 1:44pm UTC](https://forum.inductiveautomation.com/t/dynamically-build-source-tag-path-for-reference-tag-from-other-tag-value/83724/6 "2024-01-04T13:44:05Z")
You should make all your Data tags as OPC tags in the UDT. If a particular instance doesn't have one or more of them, **override** the `.valueSource` to "memory". (You can use a simple `system.tag.writeBlocking()` for that.) No config required. No funky, unsupported expressions. Tag configuration bindings don't behave the same as other bindings, so your approach is broken. See this related topic: > [@Tag folder ability to have parameters](https://forum.inductiveautomation.com/t/tag-folder-ability-to-have-parameters/83147/7): > > Of course it would be nice. If the implementation doesn't crush your gateway hardware. The fundamental difference between the configuration bindings in UDT members and the bindings in expression tags and query tags, is that the latter subscribe to changes in the tags they reference, when in event driven mode, so they can re-execute to stay up to date. General tag configuration bindings only execute at tag startup or restart, which is triggered by UDT parameter writes. Alarm configuration pr… --- _[View the full topic](https://forum.inductiveautomation.com/t/dynamically-build-source-tag-path-for-reference-tag-from-other-tag-value/83724)._