# Modbus tag connect and disconnect

**URL:** <https://forum.inductiveautomation.com/t/modbus-tag-connect-and-disconnect/10810>\
**Category:** Ignition\
**Created:** [November 19, 2015, 10:27pm UTC](https://forum.inductiveautomation.com/t/modbus-tag-connect-and-disconnect/10810 "2015-11-19T22:27:49Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![idc](https://avatars.discourse-cdn.com/v4/letter/i/43a26b/32.png) [@idc](https://forum.inductiveautomation.com/u/idc)\
**Post date:** [November 19, 2015, 10:27pm UTC](https://forum.inductiveautomation.com/t/modbus-tag-connect-and-disconnect/10810/1 "2015-11-19T22:27:49Z")

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I have 18,000 Modbus tags using a scan class (1 minute). I turn on the history on the diagnostic tag that shows the connection status and in two hours it recorded 7 disconnections. Not sure why we are losing connection to the Modbus PLC.

Any idea?  
Thanks!  
-Ivan

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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:** [November 20, 2015, 1:20am UTC](https://forum.inductiveautomation.com/t/modbus-tag-connect-and-disconnect/10810/2 "2015-11-20T01:20:31Z")

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Most Modbus devices will close incoming connections that are idle for more than 10-15 seconds. If your device is configurable in this manner then you just need to increase it. Otherwise you need to make subscribe at least one tag at a rate below the threshold where the device will close the connection.