# Ignition 8.1 Siemens UDT via OPC UA trouble

**URL:** <https://forum.inductiveautomation.com/t/ignition-8-1-siemens-udt-via-opc-ua-trouble/54865>\
**Category:** Ignition\
**Tags:** perspective, ignition81\
**Created:** [January 11, 2022, 9:02am UTC](https://forum.inductiveautomation.com/t/ignition-8-1-siemens-udt-via-opc-ua-trouble/54865 "2022-01-11T09:02:09Z")\
**Posts on this page:** 1\
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**Author:** ![Arnaud\_Declerck](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/arnaud_declerck/32/44872_2.png) [@Arnaud\_Declerck](https://forum.inductiveautomation.com/u/Arnaud_Declerck)\
**Post date:** [January 11, 2022, 3:02pm UTC](https://forum.inductiveautomation.com/t/ignition-8-1-siemens-udt-via-opc-ua-trouble/54865/8 "2022-01-11T15:02:33Z")

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i forgot to mention that i use the PLC on board OPC UA Server  
and this is the structure to read a tag in a db  
 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/7/3/73aa116e888b6d8dd03eaafc827a492b02a853d4.png)  
where DB Name is the name gived to the DB in tia and device Name is the name gived to the udt inside the db.  
Then the OPC Server of your tag should point to the OPC UA server defined on the gateway

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