Two DB9 male connectors & two 6-pin terminal block connectors for optimal flexibility of serial connection 2000V DC optical isolation. 25KV ESD surge protection No need to open chassis to set operation modes-two external DIP switches for easy RS-422, RS-485 mode settings. Installed as standard Windows COM port Automatic transmit and receive control for 2-wire RS-485 half-duplex mode High speed serial port with the baud rate up to 921.6K bps