Milesight nodes support receive downlink command from MQTT broker. For more detail about communication protocol for Milesight nodes, please visit our website document.


1. Check if MQTT server is reachable for gateway and if gateway connects to MQTT server.

2. Check if you entered the right topic path. There are two topic format for downlink:

  • You can leave Downlink data blank, then publish topic format is: application/[applicationID]/device/[devEUI]/tx, for example: application/1/device/24e1612292633821/tx
  • If you want to fill your own topic path, the custom topic path should contain the device EUI, you should use parameter: $deveui like below images. The publish topic format is: kevin_test/uc1114down/24e1612292633821

3. Check if the command format correct. MQTT only support base64 format, you should convert HEX to base64 and use correct jason format. You can use this tool to convert HEX to base64.

Jason format: {“data”: “CQAA/w==”, “confirmed”: true, “fport”: 85 }

Note: the “data” and “fport” parameter are mandatory, the “fport” must match the Application Port on nodes, which default 85. All the punctuation are fixed, you can only use double quotation for parameter and payload, and the “true” for “confirmed” must be lowercase.

Once published, you can navigate to Network Server -> Packets to check if the downlink sent successfully.

You can see there is ACK response packet means senor received downlink properly.

4. Check if the RX2 frequency and data rate are match in both gateway and nodes.


If you need any help for deeper assistance, feel free to contact Milesight Technical Support.