# Siemens, UDTs & OPC-UA

**URL:** <https://forum.inductiveautomation.com/t/siemens-udts-opc-ua/88189>\
**Category:** Ignition\
**Tags:** perspective, siemens, ignition81, scripting\
**Created:** [April 1, 2024, 11:05pm UTC](https://forum.inductiveautomation.com/t/siemens-udts-opc-ua/88189 "2024-04-01T23:05:53Z")\
**Posts on this page:** 1\
**Showing post:** 4

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**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\
**Post date:** [April 1, 2024, 11:35pm UTC](https://forum.inductiveautomation.com/t/siemens-udts-opc-ua/88189/4 "2024-04-01T23:35:13Z")

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Well, the bottom line is that the Siemens server will perform drastically better if you read only the top level structures and use the derived tags with jsonGet/jsonSet strategy (described [here](https://forum.inductiveautomation.com/t/opc-ua-struct-data-type/26905/2) and elsewhere) to read/write the tags. Unless the structures contain some kind of system type that results in a "swiss cheese" structure that can't be written to, writing should generally work.

The problem with this strategy is it's a real pain in the ass to set up and work with.

I've seen others do an end-run around the Monitored Item limitations in the Siemens server by just using dedicated Tag Groups set to OPC polled/read mode instead of subscribe mode.

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