# OPC tags desync from siemens PLC

**URL:** <https://forum.inductiveautomation.com/t/opc-tags-desync-from-siemens-plc/116554>\
**Category:** Ignition\
**Tags:** opcua, ignition83\
**Created:** [July 28, 2026, 1:15pm UTC](https://forum.inductiveautomation.com/t/opc-tags-desync-from-siemens-plc/116554 "2026-07-28T13:15:23Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Daniel\_Vestol](https://avatars.discourse-cdn.com/v4/letter/d/6f9a4e/32.png) [@Daniel\_Vestol](https://forum.inductiveautomation.com/u/Daniel_Vestol)\
**Post date:** [July 28, 2026, 1:15pm UTC](https://forum.inductiveautomation.com/t/opc-tags-desync-from-siemens-plc/116554/1 "2026-07-28T13:15:24Z")

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We have some tags bound directly to a boolean in a symbolic siemens DB. Their configuration is about as simple as it gets:

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/3/5/35f0d9bceb43e967143113e839af79974353e076.png)

We are now experiencing an issue where they at times randomly change state in ignition, without showing up in the audit log. These tags are never written by scripts either.

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/7/4/74e5637cb657e29b304bd98f0d5346ecdc379cda.png)  
enable alarms and enable\_innblander\_1 went from true to false at 13:19

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/e/b/eb549763be3252c9e3cddb00d855be4ebec6659b.png)  
They now show as false in the tag browser

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/e/d/ed0c3db5b413d4ae420934919164951c6ab0013b.png)  
They show as True in the tia portal monitoring  
They read as True in the OPC quick client:

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/1/9/19bf195ebdb387c9fb6fe870c0b821f9e3601104.png)  
Here is our tag group config:

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/e/3/e38a507bc2bd250e57f2b520f3f49e2e13481741.png)

The gateway is running ignition 8.3.4 b2026030309  
Is this something anyone has experienced before? What can we do to fix this? It has happened a few times now. We first assumed it had something to do with restarting the gateway or changing the structure of the DB, but it doesn't seem like it.

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<div class="post-metadata">

**Author:** ![lane.duncan](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/lane.duncan/32/83700_2.png) [@lane.duncan](https://forum.inductiveautomation.com/u/lane.duncan)\
**Post date:** [July 29, 2026, 4:14am UTC](https://forum.inductiveautomation.com/t/opc-tags-desync-from-siemens-plc/116554/2 "2026-07-29T04:14:55Z")

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> [@Daniel\_Vestol](#):
>
> They read as True in the OPC quick client:

Looks like an issue with a Siemens OPC server delivering bad data to Ignition.

You should use another OPC quick client to confirm if the issue is Ignition dependent or not.