# Quality code Unknown for OPC connection. What does it mean?

**URL:** <https://forum.inductiveautomation.com/t/quality-code-unknown-for-opc-connection-what-does-it-mean/106242>\
**Category:** Ignition\
**Tags:** ignition81\
**Created:** [May 14, 2025, 8:45am UTC](https://forum.inductiveautomation.com/t/quality-code-unknown-for-opc-connection-what-does-it-mean/106242 "2025-05-14T08:45:08Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![danielps1818](https://avatars.discourse-cdn.com/v4/letter/d/ecae2f/32.png) [@danielps1818](https://forum.inductiveautomation.com/u/danielps1818)\
**Post date:** [May 14, 2025, 8:45am UTC](https://forum.inductiveautomation.com/t/quality-code-unknown-for-opc-connection-what-does-it-mean/106242/1 "2025-05-14T08:45:08Z")

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Hi!

I downloaded the internal historian. Here is a representation of what is happening:

tagid | numvalue | strvalue | quality | t\_stamp | syncid

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/2/5/25d23960dbd226c26a33198ce2f6adf3b8d7802b.png)  
As you can see, for some reason the value connected via OPC it goes from 3 to 0 and back to 3 (this should not happend).  
This occurs always whenever the quality is shown as UNKNOWN. Any idea what this could mean? Also, what exactly means quality unknown?

The tag is connected via opc directly and is a counter for a machine that goes up whenever they are doing something and reset back to 0 when the finish (that is why it shouldn't go to 0 in the middle of doing something).

Thanks in advance!

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**Author:** ![patrixmith](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/patrixmith/32/75926_2.png) [@patrixmith](https://forum.inductiveautomation.com/u/patrixmith)\
**Post date:** [May 14, 2025, 5:03pm UTC](https://forum.inductiveautomation.com/t/quality-code-unknown-for-opc-connection-what-does-it-mean/106242/2 "2025-05-14T17:03:23Z")

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Can you include headers for the columns? Hard to know what we are looking at.

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<div class="post-metadata">

**Author:** ![danielps1818](https://avatars.discourse-cdn.com/v4/letter/d/ecae2f/32.png) [@danielps1818](https://forum.inductiveautomation.com/u/danielps1818)\
**Post date:** [May 19, 2025, 9:53am UTC](https://forum.inductiveautomation.com/t/quality-code-unknown-for-opc-connection-what-does-it-mean/106242/3 "2025-05-19T09:53:03Z")

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Done.

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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:** [May 19, 2025, 11:53am UTC](https://forum.inductiveautomation.com/t/quality-code-unknown-for-opc-connection-what-does-it-mean/106242/4 "2025-05-19T11:53:36Z")

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Unknown typically means the connection was briefly broken. You may need wireshark captures to show the problem, if not visible directly within Ignition.