# OPC UA Modbus bad quality tag

**URL:** <https://forum.inductiveautomation.com/t/opc-ua-modbus-bad-quality-tag/57419>\
**Category:** Ignition\
**Created:** [March 21, 2022, 3:19pm UTC](https://forum.inductiveautomation.com/t/opc-ua-modbus-bad-quality-tag/57419 "2022-03-21T15:19:22Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![Antoine\_Rvl](https://avatars.discourse-cdn.com/v4/letter/a/8491ac/32.png) [@Antoine\_Rvl](https://forum.inductiveautomation.com/u/Antoine_Rvl)\
**Post date:** [March 21, 2022, 3:19pm UTC](https://forum.inductiveautomation.com/t/opc-ua-modbus-bad-quality-tag/57419/1 "2022-03-21T15:19:23Z")

</div>

Hello i am having a problem,  
i just add some tag for my modbus connection.  
But quality is BAD,  
what is unusual if i use OPC quick client, i can read the tag(see top of screenshot) but not suscribe (see lower par of screenshot).  
i have many other tag on this same connection working fine.  
but all what i need to add seems not working…  
any idea what should i do ?

 ![bad quality tag](https://us1.discourse-cdn.com/inductiveautomation/original/3X/c/4/c47b3cd76c131de527efefc445bd560c3eae88c1.png)

---

<div class="post-metadata">

**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:** [March 21, 2022, 3:24pm UTC](https://forum.inductiveautomation.com/t/opc-ua-modbus-bad-quality-tag/57419/2 "2022-03-21T15:24:43Z")

</div>

If you disable the “Span Gaps” advanced setting for that Modbus device in the Ignition Gateway does the subscribe for that tag start working?

---

<div class="post-metadata">

**Author:** ![Antoine\_Rvl](https://avatars.discourse-cdn.com/v4/letter/a/8491ac/32.png) [@Antoine\_Rvl](https://forum.inductiveautomation.com/u/Antoine_Rvl)\
**Post date:** [March 23, 2022, 12:30pm UTC](https://forum.inductiveautomation.com/t/opc-ua-modbus-bad-quality-tag/57419/3 "2022-03-23T12:30:37Z")

</div>

Yes it solves the problem.  
Thank you for quick answer.

---

<div class="post-metadata">

**Author:** ![ram](https://avatars.discourse-cdn.com/v4/letter/r/b9bd4f/32.png) [@ram](https://forum.inductiveautomation.com/u/ram)\
**Post date:** [November 29, 2022, 3:50pm UTC](https://forum.inductiveautomation.com/t/opc-ua-modbus-bad-quality-tag/57419/4 "2022-11-29T15:50:48Z")

</div>

Hello Kevin,

I have identical issue and the span gaps setting didn't fix it.Also I have an similar modbus device and that works but this one doesn't when subscribed.Ignition Version 8.1.22  
Any Insights?

---

<div class="post-metadata">

**Author:** ![Syed\_Najam\_ul\_arfeen](https://avatars.discourse-cdn.com/v4/letter/s/41988e/32.png) [@Syed\_Najam\_ul\_arfeen](https://forum.inductiveautomation.com/u/Syed_Najam_ul_arfeen)\
**Post date:** [September 4, 2024, 9:57am UTC](https://forum.inductiveautomation.com/t/opc-ua-modbus-bad-quality-tag/57419/5 "2024-09-04T09:57:50Z")

</div>

I want to thank you, @Kevin.Herron . I was experiencing the same issue with a Modbus tag showing bad quality, and your advice helped me resolve it