# S7-1200 PLC Connection Bug

**URL:** <https://community.factoryio.com/t/s7-1200-plc-connection-bug/2766>\
**Category:** Support\
**Created:** [March 5, 2024, 6:36am UTC](https://community.factoryio.com/t/s7-1200-plc-connection-bug/2766 "2024-03-05T06:36:19Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![abhishek.ramchandran](https://avatars.discourse-cdn.com/v4/letter/a/e19b73/32.png) [@abhishek.ramchandran](https://community.factoryio.com/u/abhishek.ramchandran)\
**Post date:** [March 5, 2024, 6:36am UTC](https://community.factoryio.com/t/s7-1200-plc-connection-bug/2766/1 "2024-03-05T06:36:19Z")

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Hey Team,

Thanks for a great product!

I am currently using Factory I/O v2.5.5 Ultimate Edition

I normally configured a connection to my Siemens S7-1200 PLC (CPU 1212C AC/DC/Rly) via S7 PUT/GET.

I am independently fetching values with a python program connecting to the PLC via OPCUA. During the OPCUA connection, Factory I/O encounters connection issues. Any recommendations?

Please see attached image showcasing the same:

 ![bug-maybe](https://europe1.discourse-cdn.com/flex017/uploads/factoryio/original/1X/27b145e71224512ecb8a8eebb5651a690b56b7ae.jpeg)

BR,  
Abhi

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**Author:** ![abhishek.ramchandran](https://avatars.discourse-cdn.com/v4/letter/a/e19b73/32.png) [@abhishek.ramchandran](https://community.factoryio.com/u/abhishek.ramchandran)\
**Post date:** [March 5, 2024, 6:43am UTC](https://community.factoryio.com/t/s7-1200-plc-connection-bug/2766/2 "2024-03-05T06:43:12Z")

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I have narrowed down the bug to the moment when an OPCUA client connect to the S7 PLC is called. Also confirmed the same bug in v2.5.6

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**Author:** ![janbumer1](https://dub1.discourse-cdn.com/flex017/user_avatar/community.factoryio.com/janbumer1/32/60_2.png) [@janbumer1](https://community.factoryio.com/u/janbumer1)\
**Post date:** [March 5, 2024, 7:18am UTC](https://community.factoryio.com/t/s7-1200-plc-connection-bug/2766/3 "2024-03-05T07:18:37Z")

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To understand your bug correctly, you are connecting to your PLC from Factory I/O with PUT/GET and exchanging data, in the instant you connect to the PLC with OPCUA the connection of Factory I/O is dropped? Could you test if you can still connect to the PLC over PUT/GET using a different device, like maybe another S7-PLC?  
Is there any error messages in the error buffer of the PLC?