External device extension method of vehicle-mounted terminal

The invention provides an external device extension method of a vehicle-mounted terminal. The external device extension method of the vehicle-mounted terminal comprises the steps that firstly, the vehicle-mounted terminal is connected with the input end of a serial port box, and the output end of the serial port box is connected with an external device; secondly, a connecting object of a serial port and the external device connected with the output end of the serial port box are arranged; thirdly, when the vehicle-mounted terminal sends a first data package, packaging is carried out according to the communication protocol of the serial port box to obtain a first package, then the first package is sent to the serial port box, the serial port box carries out analysis according to the communication protocol, and then the first data package is sent to the external device according to the extension ID; when the external device sends a second data package to the vehicle-mounted terminal, the serial port box receives the second data package and then carries out packaging according to the communication protocol to obtain a second package, and the vehicle-mounted terminal carries out analysis according to the communication protocol to obtain the second data package. According to the external device extension method of the vehicle-mounted terminal, diversification of external devices is achieved, and one serial port can be connected with multiple external devices at the same time.