# Write a Coil in Modbus

**URL:** <https://discourse.nodered.org/t/write-a-coil-in-modbus/29042>\
**Category:** General\
**Created:** [26 June 2020 19:33 UTC](https://discourse.nodered.org/t/write-a-coil-in-modbus/29042 "2020-06-26T19:33:57Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![jrahumadag](https://avatars.discourse-cdn.com/v4/letter/j/c68b51/32.png) [@jrahumadag](https://discourse.nodered.org/u/jrahumadag)\
**Post date:** [26 June 2020 19:33 UTC](https://discourse.nodered.org/t/write-a-coil-in-modbus/29042/1 "2020-06-26T19:33:57Z")

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Hi,

A few words before: I new in Node-Red (and in the world of programming).  
I'm, doing a little project that consist in to read a Moxa Iologik with AI (4-20mA), DI and DO; then i'm connecting the signals to ubidots.

In the AI channels i have a sensor of moisture and temperature. All ok with this in the flow and ubidots.

But in ubidots i created a switch (on/off) because i want to change the DO in the same way to activate a fan, but i have two problems:

1. The ubidots\_in node doesn't received the signal of my dashboard
2. I put in the flow (like alternative in the mean time i resolved the issue with "ubidots\_in") a modbus write node with a inject node, but only i can turn on the DO; when i push the inject node again i can't turn off.

thanks

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**Author:** ![system](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/1X/d073cd938eafa2e558d7c2cd59003b3ef4963033.png) [@system](https://discourse.nodered.org/u/system)\
**Post date:** [25 August 2020 19:34 UTC](https://discourse.nodered.org/t/write-a-coil-in-modbus/29042/2 "2020-08-25T19:34:08Z")

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