# Causes of tag not matching plc

**URL:** <https://forum.inductiveautomation.com/t/causes-of-tag-not-matching-plc/62140>\
**Category:** Ignition\
**Created:** [July 20, 2022, 6:37pm UTC](https://forum.inductiveautomation.com/t/causes-of-tag-not-matching-plc/62140 "2022-07-20T18:37:34Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![zacharyw.larson](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/zacharyw.larson/32/23749_2.png) [@zacharyw.larson](https://forum.inductiveautomation.com/u/zacharyw.larson)\
**Post date:** [July 20, 2022, 6:37pm UTC](https://forum.inductiveautomation.com/t/causes-of-tag-not-matching-plc/62140/1 "2022-07-20T18:37:34Z")

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PLC says one number  
Ignition says a different number  
Tag claims it is good quality  
Published date is days ago

The infeed value is updating in both PLC and Ignition  
The outfeed value is not updating in ignition or hasn’t since a few days ago.  
The outfeed value is updating in the PLC.

CPU reads 69%, which I think might be the culprit, but it seems odd to impact this tag and not many others.

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<div class="post-metadata">

**Author:** ![Matrix\_Engineering](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/matrix_engineering/32/19781_2.png) [@Matrix\_Engineering](https://forum.inductiveautomation.com/u/Matrix_Engineering)\
**Post date:** [July 20, 2022, 6:43pm UTC](https://forum.inductiveautomation.com/t/causes-of-tag-not-matching-plc/62140/2 "2022-07-20T18:43:20Z")

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What PLC brand and series?  
What firmware?  
What driver?  
Can you show screenshots of the PLC tags with values and the Ignition tag OPC path?

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<div class="post-metadata">

**Author:** ![zacharyw.larson](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/zacharyw.larson/32/23749_2.png) [@zacharyw.larson](https://forum.inductiveautomation.com/u/zacharyw.larson)\
**Post date:** [July 20, 2022, 6:51pm UTC](https://forum.inductiveautomation.com/t/causes-of-tag-not-matching-plc/62140/3 "2022-07-20T18:51:20Z")

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Rockwell RS logix 16  
not sure

I setup a new tag, and set it the same  
It says last published value is uncertain with a date of June 30th 2022.  
Thought that was odd.

I was able to write to the tag in the plc.  
I could take some limited screenshots.  
Is the fact it wrote to the plc adequate though?

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<div class="post-metadata">

**Author:** ![Matrix\_Engineering](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/matrix_engineering/32/19781_2.png) [@Matrix\_Engineering](https://forum.inductiveautomation.com/u/Matrix_Engineering)\
**Post date:** [July 20, 2022, 6:55pm UTC](https://forum.inductiveautomation.com/t/causes-of-tag-not-matching-plc/62140/4 "2022-07-20T18:55:29Z")

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I’ve stopped using rockwell.

Does RS logix 16 mean;  
Ver 16 firmware? In which case you should be using the legacy driver

or

e.g. an L16ER compactlogix?

Or other?

Is this part of a UDT? Is external access (in the PLC) enabled on one tag and not the other?

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<div class="post-metadata">

**Author:** ![Matrix\_Engineering](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/matrix_engineering/32/19781_2.png) [@Matrix\_Engineering](https://forum.inductiveautomation.com/u/Matrix_Engineering)\
**Post date:** [July 20, 2022, 6:56pm UTC](https://forum.inductiveautomation.com/t/causes-of-tag-not-matching-plc/62140/5 "2022-07-20T18:56:04Z")

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Did it use to work and suddenly stopped or has never worked?

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<div class="post-metadata">

**Author:** ![zacharyw.larson](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/zacharyw.larson/32/23749_2.png) [@zacharyw.larson](https://forum.inductiveautomation.com/u/zacharyw.larson)\
**Post date:** [July 20, 2022, 7:18pm UTC](https://forum.inductiveautomation.com/t/causes-of-tag-not-matching-plc/62140/6 "2022-07-20T19:18:53Z")

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Someone with access to config on the gateway webpage reset the communication to the device and that tag is working now.

Thanks for helping me Matrix.  
Sorry didn’t have answers faster.