[SOLVED] How to config Modbus 8 relay board

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Hello every one! Begginner here

This is my first question here. I have configured a SDM-630 watt metter and an EP-SOLAR charge controller over paper UI

Now im trying to configure a Modbus Relay board.After 2 days trying to configure it over Paper UI, i stucked at a point of the transformations.

I can read the relays state, i can turn it on by the switch on Paper UI but, it dont turn of in the switch

I have read many tutorials and infos here about modbus binding, but really dont understand. Maybe my english is not enough for that task. I speak portuguese.

My question is: HOW TO CONFIGURE that board to turn on-off with Paper UI ?



Umm, we don’t know. What board, cannot see it from here?

It would be a really good idea to share what you have done so far, especially as it works in part.
It would be an even better idea to share any documentation you have about the relay board, i.e. what is it expecting you to send to turn on relays?

thank you very much for the reply!

that is exactly like your answer on that post:


the relay is the same but it is 8 relays instead of 4.

but works in the SAME way.

i stucked in the part of the transformation of ON OFF and off to on.

How i do that on PAPER UI ?

My goal is to deviate solar panels from my ON GRID inverters to my charging string.

in brazil, they are not paying good for the net metered energy, soo i started a lithium power wall, conected to an EPEVER TRACER AN controller. i want to use NODE-RED LATER to process the inputs from the SDM630 WATTMETER, and them deviate panels from ongrid to charging string using this relay board.

I already started constructing the node-red flow i can compare the wattage passing thru SDM 630 on each phase and then make something. this make something is turning on and off some panels of the ON GRID string.

Okay. So what you want is to have an openHAB Switch type Item, and when that is commanded ON or OFF you want to send 256 or 512 to a modbus holding register?

Create a transformation file myweirdswitch.map


Define a modbus data Thing to include


among your usual writeType and address settings.

1 Like

worked PERFECTLY!!!

Created .MAP file inside transform folder.

no i have a switch that turn on and of relay 1

Man you are great developing openhab.

I do a donation for the project soon i can.


the only thing i see is the lack of documents explaining how to do it over PAPER UI. Maybe i will try to cooperate on that. everything here is using paper UI.


Not me, I’m just a user, but yes they have done a great job.