# Modbus TCP tags switch to bad quality

**URL:** <https://forum.inductiveautomation.com/t/modbus-tcp-tags-switch-to-bad-quality/75834>\
**Category:** Ignition\
**Created:** [July 3, 2023, 9:26am UTC](https://forum.inductiveautomation.com/t/modbus-tcp-tags-switch-to-bad-quality/75834 "2023-07-03T09:26:29Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![joel.golinucci](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/joel.golinucci/32/9927_2.png) [@joel.golinucci](https://forum.inductiveautomation.com/u/joel.golinucci)\
**Post date:** [July 3, 2023, 9:26am UTC](https://forum.inductiveautomation.com/t/modbus-tcp-tags-switch-to-bad-quality/75834/1 "2023-07-03T09:26:29Z")

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When I add only HRFxxxx tags, they are read with a good quality. But as soon as I add a tag with an HRI address, all the tags switch to quality bad.

Only HRF tags:

 ![Only HRF tags](https://us1.discourse-cdn.com/inductiveautomation/original/3X/3/5/357287a139a15627ae62c644289f227f8f95abfe.png)

With a new HRI tag:

 ![with a HRI tag](https://us1.discourse-cdn.com/inductiveautomation/original/3X/0/f/0f8dec3677cf6cff4005f3c920c811e3ca2cc917.png)

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<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:** [July 3, 2023, 12:36pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-tags-switch-to-bad-quality/75834/2 "2023-07-03T12:36:55Z")

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It’s probably the address offset, not the DataType.

Try turning the “Span Gaps” setting off.

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<div class="post-metadata">

**Author:** ![joel.golinucci](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/joel.golinucci/32/9927_2.png) [@joel.golinucci](https://forum.inductiveautomation.com/u/joel.golinucci)\
**Post date:** [July 3, 2023, 12:43pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-tags-switch-to-bad-quality/75834/3 "2023-07-03T12:43:57Z")

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Thank you, you are absolutely right.

In the Modubs TCP device, click Show advanced properties and uncheck the Span gaps checkbox

 ![span gap setting](https://us1.discourse-cdn.com/inductiveautomation/original/3X/1/3/135c223b1b825d6cb1f2f580c551ef62dccc1a81.png)

It works instantanely

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<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:** [July 3, 2023, 12:46pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-tags-switch-to-bad-quality/75834/4 "2023-07-03T12:46:06Z")

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So, what’s happening is in between the old registers you had configured and this new one there are some registers the device does not have defined, and instead of returning 0 or some other default value when they are read, the device is either returning an error code or just ignoring the request.

Disabling Span Gaps prevents these intermediate unaddressed registers from being read, at the cost of there being more requests in total needed to get the registers you are subscribed to.