# JSON Derived Tags

**URL:** <https://forum.inductiveautomation.com/t/json-derived-tags/51259>\
**Category:** Ignition\
**Created:** [September 23, 2021, 1:10pm UTC](https://forum.inductiveautomation.com/t/json-derived-tags/51259 "2021-09-23T13:10:23Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![jlandwerlen](https://avatars.discourse-cdn.com/v4/letter/j/bc8723/32.png) [@jlandwerlen](https://forum.inductiveautomation.com/u/jlandwerlen)\
**Post date:** [September 23, 2021, 1:10pm UTC](https://forum.inductiveautomation.com/t/json-derived-tags/51259/1 "2021-09-23T13:10:23Z")

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From ICC yesterday, there was a discussion on using JSON derived tags for OPC-UA. Was curious how many actually do this, besides DMC.

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**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:** [September 23, 2021, 1:18pm UTC](https://forum.inductiveautomation.com/t/json-derived-tags/51259/2 "2021-09-23T13:18:43Z")

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Commonly used with the built-in OPC server of modern Siemens PLCs:

> [@OPC UA struct data type?](https://forum.inductiveautomation.com/t/opc-ua-struct-data-type/26905/2):
>
> You can take advantage of reading whole structs in OPC UA servers as of Ignition 7.9.12 and 8.0.0. When you bring the tag in you’ll notice Ignition presents a JSON value. The strategy here is a little involved but it works. For each of the UDTs you’ll be subscribing to in the PLC you make a corresponding UDT in Ignition. It should have a “Source” OPC tag member that will correspond to the Node with the struct value in the server and as a result have a JSON value in Ignition. Then for each memb…