DTECH RS232 to RS485 / RS422 Serial Communication Data Converter Adapter Mini-Size Pro grade RS232 to RS485 / RS422 converter. It easily lets you connect any RS485 or RS422 device directly to COM port. Best solution for the communication between serial port and RS485 or RS422 device. Unique serial charge pump drive technology, no external power supply, the real three-wire communication (TXD,RXD,GND). No need serial port initialization. Supports baud rates up to 115.2 Kbps; Automatic sense serial signal rate. Supports a maximum connection distance of 4000ft (1200m)