# Modbus TCP connected slave tool can't read tag

**URL:** <https://forum.inductiveautomation.com/t/modbus-tcp-connected-slave-tool-cant-read-tag/86077>\
**Category:** Ignition\
**Tags:** ignition81\
**Created:** [February 21, 2024, 5:37am UTC](https://forum.inductiveautomation.com/t/modbus-tcp-connected-slave-tool-cant-read-tag/86077 "2024-02-21T05:37:07Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![taohongyu88](https://avatars.discourse-cdn.com/v4/letter/t/f05b48/32.png) [@taohongyu88](https://forum.inductiveautomation.com/u/taohongyu88)\
**Post date:** [February 21, 2024, 5:37am UTC](https://forum.inductiveautomation.com/t/modbus-tcp-connected-slave-tool-cant-read-tag/86077/1 "2024-02-21T05:37:07Z")

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Version : 8.1.24  
In Gateway ,I add modbus tcp device and connect local Modbus Slave Tool.

OPC UA Modbus Config:

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/4/7/4754e3bf50e3021f07e67555cfa391ef62d66012.png)

Modbus Slave Config:

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/5/8/5814ab2a89df84c94ac728fd4d2b5a3f5715cd54.png)

Then in the OPC Quick Client, I subscribe tag can read its value ; but I read tag ,show bad.

Opc Quick Client:

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/7/8/78a3141f73ff65308dfe505d269d958fcdc9ca39.png)

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<div class="post-metadata">

**Author:** ![taohongyu88](https://avatars.discourse-cdn.com/v4/letter/t/f05b48/32.png) [@taohongyu88](https://forum.inductiveautomation.com/u/taohongyu88)\
**Post date:** [February 28, 2024, 6:44am UTC](https://forum.inductiveautomation.com/t/modbus-tcp-connected-slave-tool-cant-read-tag/86077/2 "2024-02-28T06:44:50Z")

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[Modbus TCP tags switch to bad quality - Ignition - Inductive Automation Forum](https://forum.inductiveautomation.com/t/modbus-tcp-tags-switch-to-bad-quality/75834)

It’s probably the address offset, not the DataType. Try turning the “Span Gaps” setting off.