Adds one RS-232, RS-422 or RS-485 serial port by connecting to a USB port 2000V DC optical isolation/25KV ESD surge protection No need to open chassis to set operation modes- one external DIP switch for easy RS-232, RS-422, RS-485 mode settings Automatic transmit and receive control for 2-wire RS-485 half-duplex mode OS Compatibility:Windows 98, Me, XP, 2000, 2003, CE, Vista, Windows 7, 8 ,10 and Windows 11 as well as Linux and Mac OS 10.X