# Problem with switch commutation

**URL:** <https://discourse.nodered.org/t/problem-with-switch-commutation/88038>\
**Category:** General\
**Created:** [16 May 2024 21:22 UTC](https://discourse.nodered.org/t/problem-with-switch-commutation/88038 "2024-05-16T21:22:39Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![LastViking](https://avatars.discourse-cdn.com/v4/letter/l/ba9def/32.png) [@LastViking](https://discourse.nodered.org/u/LastViking)\
**Post date:** [16 May 2024 21:22 UTC](https://discourse.nodered.org/t/problem-with-switch-commutation/88038/1 "2024-05-16T21:22:39Z")

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Hello,  
I use node-red to communicate with Siemens s7-1200 and Alexa. My problem is when I do the command in Alexa to activate one DO in the PLC. The command is for activate light. I do the command to turn lights on in Alexa and I turn off in my HMI. When I see the state of the switch in Alexa he show me ON. Whoever the lights are off because I turn off in hmi. Anyone can help me to resolve this situation?  
Best regards  
Marco Wilson

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<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/1X/d073cd938eafa2e558d7c2cd59003b3ef4963033.png) [@system](https://discourse.nodered.org/u/system)\
**Post date:** [14 August 2024 21:23 UTC](https://discourse.nodered.org/t/problem-with-switch-commutation/88038/2 "2024-08-14T21:23:33Z")

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