# Modbus unable to read registers. Timeouts and Disconnects

**URL:** <https://forum.inductiveautomation.com/t/modbus-unable-to-read-registers-timeouts-and-disconnects/3989>\
**Category:** Ignition\
**Created:** [February 13, 2012, 2:22pm UTC](https://forum.inductiveautomation.com/t/modbus-unable-to-read-registers-timeouts-and-disconnects/3989 "2012-02-13T14:22:07Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Greg.Buehler](https://avatars.discourse-cdn.com/v4/letter/g/ecc23a/32.png) [@Greg.Buehler](https://forum.inductiveautomation.com/u/Greg.Buehler)\
**Post date:** [February 13, 2012, 2:22pm UTC](https://forum.inductiveautomation.com/t/modbus-unable-to-read-registers-timeouts-and-disconnects/3989/1 "2012-02-13T14:22:07Z")

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For some unknown reason, the Modbus driver seems to be failing to read the holding registers. The quality is displayed as “Unknown”. I am able to read the values using modpoll, so I’m leaning towards the issue residing in the modbus driver.

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**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:** [February 13, 2012, 3:10pm UTC](https://forum.inductiveautomation.com/t/modbus-unable-to-read-registers-timeouts-and-disconnects/3989/2 "2012-02-13T15:10:44Z")

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Give support a call in about an hour. This kind of stuff always turns out to be either:

[ul]A legitimate timeout is occurring. Communication timeout needs to be increased.[/ul]

or

[ul]There’s a problem with the way the tags are addressed.[/ul]