AYA 3Ft (3 Feet) USB 2.0 to RS485 Serial Converter Adapter for WinXP/7, Linux, MAC Modems, smart card readers, terminal, POS (point of sale) devices, industrial control devices and RS232 peripheral upgrades No need external power, powered by USB port Support auto-handshaking agreement Transmission speed up to 57.6kbps in the distance of 1200m Support remote waking up and power management Support communication of multiple ends up to 32 RS485 equipment Regular voltage range of RS-485 port:-7V~+12V