# Working with KMtronic Relay board

**URL:** <https://community.openems.io/t/working-with-kmtronic-relay-board/1003>\
**Category:** Uncategorized\
**Created:** [June 23, 2022, 4:20pm UTC](https://community.openems.io/t/working-with-kmtronic-relay-board/1003 "2022-06-23T16:20:40Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![ghada](https://community.openems.io/letter_avatar_proxy/v4/letter/g/ac91a4/32.png) [@ghada](https://community.openems.io/u/ghada)\
**Post date:** [June 23, 2022, 4:20pm UTC](https://community.openems.io/t/working-with-kmtronic-relay-board/1003/1 "2022-06-23T16:20:40Z")

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Hello community!

I’m using the KMtronic relay board ([Controller :: Open Energy Management System](https://openems.github.io/openems.io/openems/latest/edge/device_service.html#_kmtronic_modbus_relay_board)) and i have a few questions as to the configuration.

to my understanding the board gets different signals to turn a specific relay on / off, and that is done via the modbus bridge. My question is, if i want to turn a specific relay (for example relay 1) on, how do i do that via OpenEMS, and what signal do i send?

Thank you in advance, and sorry if my question seems too easy, i’m very new at this!

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**Author:** ![stefan.feilmeier](https://community.openems.io/user_avatar/community.openems.io/stefan.feilmeier/32/2585_2.png) [@stefan.feilmeier](https://community.openems.io/u/stefan.feilmeier)\
**Post date:** [June 27, 2022, 8:25am UTC](https://community.openems.io/t/working-with-kmtronic-relay-board/1003/2 "2022-06-27T08:25:35Z")

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Hi Ghada,

to control a KMTronic relay board (like [KMtronic Ltd: RS485 Serial controlled Eight Channel Relay Board - 12V](https://sigma-shop.com/product/103/rs485-relay-controller-eight-channel.html) via RS485 Modbus/RTU or [KMtronic Ltd: LAN Ethernet IP 8 channels WEB Relay board](https://sigma-shop.com/product/128/lan-ethernet-ip-8-channels-modbus-tcp-relay-board.html) via Modbus/TCP), just configure the following components:

- **Bridge Modbus/RTU Serial** (`Bridge.Modbus.Serial`)

- **IO KMtronic 8-Port Relay Board** (`IO.KMtronic`)

Then you should already see the current states of the relays in the DebugLog output. For simple control, add:

- **Controller IO Fix Digital Output** (`Controller.Io.FixDigitalOutput`)
  - `outputChannelAddress`: io0/Relay1
  - `isOn`: true

There are plenty of Controllers available that work on I/Os, like `Controller IO Channel Single Threshold`, `Controller IO Heating Element`, etc.

Regards,  
Stefan