This RS232 to RS485 converter is compatible with the RS232C and RS485 standard. It is able to convert RS232 signals to RS485 balanced differential signals and extend the communication distance to 1.2 km. It is a passive converter and doesn\'t require a external power supply. It uses a particular pump to gain power from the RS232 signals (RTS, DTR, TXD) without initializing the RS232 interface