Midea Heating & Cooling

Use cases

• Monitor T1 inside temperature and coil temperatures on a live dashboard for each fancoil zone.
• Adjust temperature setpoints and fan speed remotely without visiting the installation site.
• Create an alert when the fancoil reports an error or protection state to reduce response time.
• Track operation mode changes over time to verify scheduled heating and cooling programs.
• Lock fancoil controls via the lock flag to prevent unauthorized adjustments by building occupants.

Installation

1. 1Connect the ModbusCloud gateway (MCG or MLP series) to the fancoil RS-485 bus using P for positive and Q for negative.
2. 2Ensure the WDC3-86S thermostat is wired to each Midea MKT3-V fancoil, as it is mandatory for normal operation.
3. 3Set a unique Modbus slave address on each fancoil using the wired controller or remote controller, starting from address 1.
4. 4Verify the serial port settings on the gateway match the fancoil defaults: 9600 baud, no parity, 8 data bits, 1 stop bit, Modbus RTU.
5. 5Import the Midea MKT3-V fancoil template in the ModbusCloud platform and assign each device to its correct slave address.
6. 6Confirm live data appears on the dashboard by checking that T1 inside temperature and operation mode values are updating.

Things to watch for

01

The fancoil shows an error and does not respond to commands. What is wrong?

The WDC3-86S thermostat is most likely not connected. The fancoil firmware requires the T1 inside temperature from this thermostat. Without it, the unit enters an error state and rejects operation mode and fan speed commands.

02

Two fancoils on the same bus are not communicating properly. How do I fix this?

Each fancoil must have a unique slave address. If two units share the same address, communication will fail. Reassign addresses so no duplicates exist on the bus.

03

I changed the baud rate and now communication is lost. What should I do?

Power cycle the fancoil to restore communication. The default serial configuration is 9600 baud, no parity, 8 data bits, 1 stop bit. Avoid changing these parameters unless you are certain the gateway matches the new settings.

04

Can I use Modbus ASCII instead of Modbus RTU?

No. The Midea MKT3-V fancoil only supports Modbus RTU. Modbus ASCII is not available on these units.

Registers (18)

18 read / 13 write

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