ONOKOM AIR MH-2-MB-B
Controls Mitsubishi Heavy air conditioners via the ONOKOM MH-2-MB-B Modbus gateway.
This template integrates Mitsubishi Heavy air conditioners via the ONOKOM MH-2-MB-B Modbus RTU gateway into the ModbusCloud platform. It reads indoor and outdoor temperatures, AC connection status, and vane positions, while offering control over on/off state, target temperature, fan speed, and operating mode.
- Protocol
- Modbus RTU
- Connection
- RS485, 9600 baud
- Registers
- 11, read and write
- Brand
- Onokom
- Key readings
- Indoor air temperature · Outdoor air temperature · AC connected status · Vertical vanes status · Horizontal vanes status
- Available commands
- Active on/off · Target temperature · Smart fan speed · Operating mode
- Compatible models
- ONOKOM MH-2-MB-B
- Last updated
Registers (11)
5 read, 8 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| Indoor air temperature | °C | Read | |||
| Outdoor air temperature | °C | Read | |||
| AC connected (Status) | Read | ||||
| Vertical vanes (Status) | Read and write | ||||
| Horizontal vanes | Read and write | ||||
| Active (Control) | Write | ||||
| Loxone modes (Control) | Write | ||||
| Smart fan speed | Write | ||||
| Target temperature | °C | Write | |||
| Modbus address (Service) | Write | ||||
| Vertical vanes (Control) | Write |
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Use cases
- Monitor indoor and outdoor air temperatures on a live dashboard for remote comfort verification.
- Switch Mitsubishi Heavy AC units on or off remotely to reduce energy waste outside occupied hours.
- Create an alert when the AC connected status drops, indicating a communication fault between gateway and indoor unit.
- Adjust target temperature setpoints from the cloud to respond to changing occupancy or weather conditions.
- Log operating mode and fan speed changes over time to support energy audits and maintenance planning.
Installation
Connect the ONOKOM MH-2-MB-B gateway to the Mitsubishi Heavy indoor unit using the proprietary AC bus cable as described in the ONOKOM installation manual.
Wire the RS-485 A and B terminals of the ONOKOM gateway to the corresponding terminals on your ModbusCloud Gateway, observing correct polarity.
Set the baud rate on the ModbusCloud gateway serial port to 9600, matching the ONOKOM default.
Verify or change the Modbus slave address on the ONOKOM gateway via service register at address 128, ensuring each unit on the bus has a unique address.
Import the ONOKOM MH-2-MB-B template in the ModbusCloud platform and assign the correct slave address and serial port.
Confirm communication by checking that indoor air temperature and AC connected status appear with valid values on the dashboard.
Things to watch for
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.
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