Mielta M7

Mielta M7 is a functional and reliable GPS tracking device with 2 SIM slots, 4 universal ports, voice support, 16 MB black box and more working over Wialon Combine protocol. The device features RS-485, RS-232, 1-Wire, and CAN interfaces out of the box, built-in Li-Pol battery, and an SD card slot. USB 2.0 and Bluetooth 3.0 make configuration of the tracker quick and convenient. 

Protocol: wialon-combine Manufacturer: Mielta Forum discussion
Properties
Custom command
custom
Send custom command to device
hex: Payload is encoded as HEX string
payload: Text or hex data to send
Send string 1234
{"payload":"1234"}
Send string 1234 in hex
{"hex":true,"payload":"31323334"}