ONOKOM AIR MD-3-MB-B

Use cases

• Monitor indoor air temperature and heat exchanger temperatures on a live cloud dashboard for each customer site.
• Set target temperature and operating mode remotely without visiting the installation location.
• Create an alert when the error count increases or a specific error code appears on the Midea unit.
• Track outdoor heat exchanger temperature trends to detect refrigerant issues or performance degradation.
• Manage multiple Midea air conditioners across different sites from a single ModbusCloud account.
• Adjust fan speed and vane swing settings remotely to optimize occupant comfort.

Installation

1. 1Connect the ONOKOM MD-3-MB-B gateway to the Midea air conditioner's communication bus following the wiring diagram in the ONOKOM manual.
2. 2Wire the RS-485 A and B terminals of the ONOKOM gateway to the corresponding terminals on your ModbusCloud gateway (MCG or MLP series).
3. 3Set the Modbus address of the ONOKOM gateway using service register 128 if multiple gateways share the same RS-485 bus.
4. 4Configure the ModbusCloud gateway serial port to Modbus RTU at 9600 baud, 8 data bits, no parity, 1 stop bit.
5. 5Import the ONOKOM AIR MD-3-MB-B template from the ModbusCloud template library and assign it to the correct Modbus address.
6. 6Verify communication by checking that indoor air temperature and AC connected status appear correctly on the ModbusCloud dashboard.

Things to watch for

01

The gateway does not respond on the RS-485 bus. What should I check?

Verify that the A and B wires are not swapped between the ONOKOM gateway and the ModbusCloud gateway. Confirm the baud rate is set to 9600 on both sides. Ensure the Modbus address configured in register 128 matches the address set in the ModbusCloud template.

02

I see an error count but the first error code register shows zero. Is this normal?

The error count register appears duplicated at address 0, which can cause unexpected readings. Check the actual error code register to confirm whether a real fault is present on the Midea unit.

03

Can I connect multiple ONOKOM gateways on the same RS-485 bus?

Yes. Each ONOKOM MD-3-MB-B must have a unique Modbus address. Change the address via service register 128 on each gateway before connecting them to the shared bus.

04

Eco mode and horizontal vanes do not seem to respond to write commands. What could be wrong?

Not all Midea indoor unit models support eco mode or horizontal vane control. Check the Midea unit specifications to confirm these features are available on your specific model.

Registers (15)

9 read / 8 write

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