In order to facilitate with different standard serial interface of computer, external device or intelligent instrument for remote data communication, mutual conversion to standard serial interface. The converter is compatible with RS-232, RS-485 standard, can convert the RS-232 signal single end balanced differential RS-485 signal, transient voltage built rapidly inhibit protector, the protector is designed to protect the RS-485 interface, using today's advanced TVS (TRANSIENT VOLTAGE SUPPRESSOR) converter converts the communication distance of RS-485 is extended to 1.2 km, no external power required by the unique "RS-232 charge pump" drive, don't need to initialize the RS-232 serial port can get power, with zero delay automatic transceiver inside conversion, automatic control data flow direction of I/O circuit is unique, without any handshake signals (such as RTS, DTR etc.), which is written in RS-232 mode under the program running in RS-232 mode without changes, ensure appropriate existing software and hardware interface, converter transmission rate of 300-115.2Kbps. can be applied in between, the main control machine main control and single chip computer or peripheral constitute a point-to-point, point to multipoint remote multi computer communication network, realize multi machine response communication. Widely used in industrial automation control system, smart card, access control system, consumption system, attendance system, parking lot system, Self-service banking system, bus toll system, toll station system etc..