# Scan Class read Mode error

**URL:** <https://forum.inductiveautomation.com/t/scan-class-read-mode-error/6581>\
**Category:** Ignition\
**Created:** [May 25, 2013, 1:16pm UTC](https://forum.inductiveautomation.com/t/scan-class-read-mode-error/6581 "2013-05-25T13:16:00Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![gadgetguru69](https://avatars.discourse-cdn.com/v4/letter/g/e274bd/32.png) [@gadgetguru69](https://forum.inductiveautomation.com/u/gadgetguru69)\
**Post date:** [May 25, 2013, 1:16pm UTC](https://forum.inductiveautomation.com/t/scan-class-read-mode-error/6581/1 "2013-05-25T13:16:00Z")

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We have found that in our system we are seeing a scan class error on start up of the gateway. This appears to be because we have one scan class that is set to read instead of subscribe. In the last restart of the system we set this scan class back to subscribe with no other changes and the error was gone.

Running 7.6 rc5  
[logs.bin.gz](https://us1.discourse-cdn.com/inductiveautomation/original/2X/f/f60232969dc1f00be6220e1dd54ecb7c9dd3c232.gz) (533 KB)

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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:** [May 25, 2013, 2:12pm UTC](https://forum.inductiveautomation.com/t/scan-class-read-mode-error/6581/2 "2013-05-25T14:12:57Z")

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So what you’re seeing is that the SQLBridge module gets started and starts executing its scan class in read mode before the OPC-UA module starts and the client can finish making its connection to the server.

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**Author:** ![gadgetguru69](https://avatars.discourse-cdn.com/v4/letter/g/e274bd/32.png) [@gadgetguru69](https://forum.inductiveautomation.com/u/gadgetguru69)\
**Post date:** [May 25, 2013, 2:54pm UTC](https://forum.inductiveautomation.com/t/scan-class-read-mode-error/6581/3 "2013-05-25T14:54:36Z")

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So this is also harmless error once system is up and stabilized?

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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:** [May 25, 2013, 3:28pm UTC](https://forum.inductiveautomation.com/t/scan-class-read-mode-error/6581/4 "2013-05-25T15:28:00Z")

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Yeah… I think it’s always been this way, but more recently the UA client logs an error message when a read happens while it’s not connected.

I’ll take a look at this on Tuesday and see what we can do about it.

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**Author:** ![gadgetguru69](https://avatars.discourse-cdn.com/v4/letter/g/e274bd/32.png) [@gadgetguru69](https://forum.inductiveautomation.com/u/gadgetguru69)\
**Post date:** [May 25, 2013, 3:40pm UTC](https://forum.inductiveautomation.com/t/scan-class-read-mode-error/6581/5 "2013-05-25T15:40:10Z")

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Great thanks for the info.