StarTech RS-232 to RS485/422 Serial Converter (IC485S) Converts RS232C to either RS-485 or RS-422 with cable length up to 4000 ft! Suitable for a broad range of operating environments, this adapter includes an optional 9V power adapter or can draw power on its own. Supports point-to-point multidrop configuration and full or half duplex operation Can be used to monitor RS-485/422 signal