How do I change the Modbus slave address on the ONOKOM MH-2-MB-B?

Write the desired address to Modbus register 128 using a Modbus master tool or through the ModbusCloud write function. After writing, power cycle the gateway and update the slave address in your ModbusCloud project to match.

The vane position registers seem to conflict between reading and writing. Is that normal?

Yes. Registers at address 9 (horizontal vanes) and address 11 (vertical vanes) are dual-purpose. Reading returns the current position, and writing sets a new position. The template handles both directions automatically.

I see no data coming from the ONOKOM gateway. What should I check first?

Verify RS-485 wiring polarity (A to A, B to B), confirm the baud rate is set to 9600 on both sides, and ensure the slave address configured in ModbusCloud matches the address on the gateway. Also check that the AC connected status register returns a valid value.

Can I connect multiple ONOKOM MH-2-MB-B gateways on one RS-485 bus?

Yes. Assign each gateway a unique Modbus slave address via register 128. Then add a separate template instance in ModbusCloud for each address. All units can share the same RS-485 bus and serial port.

Free Modbus template: ONOKOM AIR MH-2-MB-B

Name: ONOKOM AIR MH-2-MB-B
Brand: Onokom
SKU: e227f739-28b0-4d25-a660-a1df590c96f1

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Free Modbus template: ONOKOM AIR MH-2-MB-B | ModbusCloud

Registers (11)

5 read / 8 write

Name	Address	Function	Type	Unit	Access
Indoor air temperature	3	FC03	uint16	°C	R
Outdoor air temperature	4	FC03	int16	°C	R
AC connected (Status)	20	FC01	uint16		R
Vertical vanes (Status)	11	FC03	uint16		R/W
Horizontal vanes	9	FC03	uint16		R/W
Active (Control)	1	FC05	uint16		W
Loxone modes (Control)	15	FC06	uint16		W
Smart fan speed	8	FC06	uint16		W
Target temperature	5	FC06	int16	°C	W
Modbus address (Service)	128	FC06	uint16		W
Vertical vanes (Control)	10	FC06	uint16		W

ONOKOM AIR MH-2-MB-B

Overview

Key readings

Available commands

Use cases

Installation

Things to watch for

Registers (11)

Working with Modbus in your projects?

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