# Node-Red Modbus write node's not working

**URL:** <https://discourse.nodered.org/t/node-red-modbus-write-nodes-not-working/49143>\
**Category:** General\
**Created:** [31 July 2021 12:52 UTC](https://discourse.nodered.org/t/node-red-modbus-write-nodes-not-working/49143 "2021-07-31T12:52:49Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![rrabbit454](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/rrabbit454/32/74694_2.png) [@rrabbit454](https://discourse.nodered.org/u/rrabbit454)\
**Post date:** [31 July 2021 12:52 UTC](https://discourse.nodered.org/t/node-red-modbus-write-nodes-not-working/49143/1 "2021-07-31T12:52:49Z")

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Hello.  
In my house i have main automation (lights, heating, Hot water) done using Unipi PLC controller and Home Assistant on Raspberry Pi4 for additional task like camera, tracking and some more other things.  
Both controllers are integrated using modbus , on home assistant i have Node red addon to read data from Unipi1.1. I have 16 read nodes for coils, 2 read nodes for holding registers (for temperature) and 2 nodes for writing data to coils controlling heating and hot water. For several months it was everything ok exept sometimes after update core or node red addon i experience some problems with write nodes(not working). Usually restarting helps so overall it was ok. Last week i add 7 more read nodes, also i done core and node red updates, form then all read nodes work perfect but write nodes sometimes work but very slow and then not working at all.  
For few days im trying to solve the promlem but no luck…  
Any help will be helpful.  
Thanks in advance.

 ![Modbus1](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/a/0/a07bef23d3c5fdecdae9e629643ebe2e3828d536.png)

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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:** [31 July 2021 14:13 UTC](https://discourse.nodered.org/t/node-red-modbus-write-nodes-not-working/49143/2 "2021-07-31T14:13:33Z")

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My advice would be to do 1 single read of multiple registers then parse the results using buff-parser e.g...

 ![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/7/c/7c0245ab16e0231909211ed26a48d7688a878efd.png)

That will greatly reduce comms to modbus device & should be more stable.

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**Author:** ![rrabbit454](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/rrabbit454/32/74694_2.png) [@rrabbit454](https://discourse.nodered.org/u/rrabbit454)\
**Post date:** [1 August 2021 12:42 UTC](https://discourse.nodered.org/t/node-red-modbus-write-nodes-not-working/49143/3 "2021-08-01T12:42:45Z")

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Hello Steve.  
Thanks for reply. Your way of configuration makes much more sense, i'm new to node red so i didn't know about it. You mean i'm should not use more then 10 read node's in configuration? As it's advised? You think this may couse the write node's problems?  
I have exactly the same topic on HA forum

> **[Node-Red Modbus write node's not working](https://community.home-assistant.io/t/node-red-modbus-write-nodes-not-working/325913)**
>
> Hello. In my house i have main automation (lights, heating, Hot water) done using Unipi PLC controller and Home Assistant on Raspberry Pi4 for additional task like camera, tracking and some more other things. Both controllers are integrated using...

And another user suggest the problem it's on HA site, and that makes sense as well.  
Regards.

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**Author:** ![rrabbit454](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/rrabbit454/32/74694_2.png) [@rrabbit454](https://discourse.nodered.org/u/rrabbit454)\
**Post date:** [8 August 2021 11:59 UTC](https://discourse.nodered.org/t/node-red-modbus-write-nodes-not-working/49143/4 "2021-08-08T11:59:49Z")

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Hello.  
I was too busy over the week but yesterday i try configuration proposed by Steve and everything works perfect.  
Thank You Steve.

 ![Modbus2](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/3/3/33b0314361041af7401e9932bf0b49500e1525a0.png)  
 ![Modbus5](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/d/0/d073cbcec57a6f2ba9940a7403a5f6d2e221b32c.png)  
 ![Modbus6](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/3/d/3d7afa49a760d6da518777466997096f397852fe.png)  
 ![Modbus3](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/e/3/e3947994e23d20ed5d8eb57af3e969771a189f15.png)  
 ![Modbus4](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/7/d/7d4fc0fb96ae3032f88195fb34d37bde3786e001.png)

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<div class="post-metadata">

**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:** [8 August 2021 12:30 UTC](https://discourse.nodered.org/t/node-red-modbus-write-nodes-not-working/49143/5 "2021-08-08T12:30:43Z")

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> [@rrabbit454](#):
>
> I was too busy over the week but yesterday i try configuration proposed by Steve and everything works perfect.  
> Thank You Steve.

Youre welcome.

> [@rrabbit454](#):
>
> ![Modbus3](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/e/3/e3947994e23d20ed5d8eb57af3e969771a189f15.png)

In case you lose this screenshot, the built-in help contains this info...

 ![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/9/5/951416f36ab344cac728a96480a4bac8cf279fa1.png)

Also, as you probably noticed, the `add` button auto increments the offset to assist you...

![c1QhuKasew](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/0/3/031776407768d25d9fde74d759556af3322a3838.gif)

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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:** [7 October 2021 12:30 UTC](https://discourse.nodered.org/t/node-red-modbus-write-nodes-not-working/49143/6 "2021-10-07T12:30:56Z")

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