The USB-RS485 is a complete, self powered, USB to RS485 interface working at any baud rate up to 250k baud. It features automatic bus turn-around - any time your not transmitting the module is listening.
Uses the ST485 quarter power tranceiver, so you can have up to 128 devices on the bus.
USB interface uses the FTDI chip which has drivers available for Windows XP64, XP, 2000, ME, 98, CE.NET V4.2, Linux, Mac OS8, OS9, OSX.
The USB-RS485 can also be used to generate a DMX stream, see examples on product page for more info