Midea Heating & Cooling
Controls Midea fancoil operation mode, temperature setpoint, and fan speed via Modbus RTU
This template provides read and write access to Midea MKT3-V fancoil units via Modbus RTU. It covers operation mode, temperature setpoint, fan speed, coil temperatures, and error or protection states. The WDC3-86S thermostat is mandatory for proper operation.
- Protocol
- Modbus RTU
- Connection
- RS485, 9600 baud
- Registers
- 18, read and write
- Brand
- Midea - frigicoll
- Key readings
- Operation mode · T1 inside temperature · T2-C coil cooling / T2-H coil heating · Fan speed · Error state · Protection state
- Available commands
- Operation mode · Temperature setpoint · Fan speed · Lock flag
- Compatible models
- MKT3-V1000G12-CL · MKT3-V-----G12-CL · WDC3-86S
- Last updated
Registers (18)
18 read, 13 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| 01 OPERATION MODE | Read and write | ||||
| 02 TS TEMPERATURE SET | °C | Read and write | |||
| 03 FAN SPEED | Read and write | ||||
| 04 RUN TIMER | Read and write | ||||
| 05 STOP TIMER | Read and write | ||||
| 06 T1 INSIDE TEMPERATURE | °C | Read and write | |||
| 07 T2-C COIL-COOLING | °C | Read and write | |||
| 08 T2-H COIL-HEATING | °C | Read and write | |||
| 12 LOCK FLAG | Read and write | ||||
| 13 PUMP STATE | Read and write | ||||
| 14 ERROR STATE | Read and write | ||||
| 15 PROTECTION STATE | Read and write | ||||
| 17 PROTECTION STATE 2 | Read and write | ||||
| 18 INFO COCE Modbus Air FANCOIL 1 | V | Read | |||
| 19 INFO VENT 2 | Read | ||||
| 20 Version INFO | Read | ||||
| 40 BOUD RATE | Read | ||||
| 41 PARITY | Read |
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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
Connect the ModbusCloud Gateway to the fancoil RS-485 bus using P for positive and Q for negative.
Ensure the WDC3-86S thermostat is wired to each Midea MKT3-V fancoil, as it is mandatory for normal operation.
Set a unique Modbus slave address on each fancoil using the wired controller or remote controller, starting from address 1.
Verify the serial port settings on the gateway match the fancoil defaults: 9600 baud, no parity, 8 data bits, 1 stop bit, Modbus RTU.
Import the Midea MKT3-V fancoil template in the ModbusCloud platform and assign each device to its correct slave address.
Confirm live data appears on the dashboard by checking that T1 inside temperature and operation mode values are updating.
Things to watch for
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.
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.
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.
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.
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