# Node-red-contrib-modbus Help?

**URL:** <https://discourse.nodered.org/t/node-red-contrib-modbus-help/93716>\
**Category:** General\
**Created:** [5 December 2024 23:05 UTC](https://discourse.nodered.org/t/node-red-contrib-modbus-help/93716 "2024-12-05T23:05:49Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Buzzylogic](https://avatars.discourse-cdn.com/v4/letter/b/f17d59/32.png) [@Buzzylogic](https://discourse.nodered.org/u/Buzzylogic)\
**Post date:** [5 December 2024 23:05 UTC](https://discourse.nodered.org/t/node-red-contrib-modbus-help/93716/1 "2024-12-05T23:05:49Z")

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I'm using node-red-contrib-modbus to set speed and turn on/off a VFD drive over ethernet. I have a manual for the drive, but when I try to write a value to the address, it says "Error: Modbus exception 2: Illegal data address (register not supported by device)"

 ![modbus address](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/a/3/a33a441887fd1589eb981540a58841debd9c714f.jpeg)  
Not that I know what value I need to write out anyway.

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**Author:** ![Buzzylogic](https://avatars.discourse-cdn.com/v4/letter/b/f17d59/32.png) [@Buzzylogic](https://discourse.nodered.org/u/Buzzylogic)\
**Post date:** [6 December 2024 17:10 UTC](https://discourse.nodered.org/t/node-red-contrib-modbus-help/93716/3 "2024-12-06T17:10:24Z")

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I figured it out

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**Author:** ![Steve-Mcl](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/steve-mcl/32/4826_2.png) [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)\
**Post date:** [7 December 2024 03:46 UTC](https://discourse.nodered.org/t/node-red-contrib-modbus-help/93716/4 "2024-12-07T03:46:21Z")

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Hey @Buzzylogic I am pleased you've got your issue solved.

As for why you got no responses, it's probably related to not specifying exactly which vfd or potential helpers with your type of vfd have not encountered the same issue or they did not spot this thread. Sorry about that.

What would be great is if you could explain how you resolved the situation for any future readers. I would probably also include the make and model of your vfd so that it can be searched and found.

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**Author:** ![Buzzylogic](https://avatars.discourse-cdn.com/v4/letter/b/f17d59/32.png) [@Buzzylogic](https://discourse.nodered.org/u/Buzzylogic)\
**Post date:** [7 December 2024 12:03 UTC](https://discourse.nodered.org/t/node-red-contrib-modbus-help/93716/5 "2024-12-07T12:03:53Z")

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I gave the solution, but for some reason it didn't post. The VFC is an Ironhorse ACG-40P5 from automation direct. I found that I can't used the full address 40898 for on/off and 40896 for frequency, but have get rid of the 4, so 898 and 896. It works now.

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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:** [21 December 2024 12:04 UTC](https://discourse.nodered.org/t/node-red-contrib-modbus-help/93716/6 "2024-12-21T12:04:17Z")

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