Get on Amazon.com : http://www.amazon.com/gp/product/B005CPI0JQ?tag=clothingattes-20
GearMo? Mini USB to RS485 / RS422 Converter FTDI CHIP with Screw Terminals
FTDI CHIP
USB to RS422 or RS485
LED for RX TX and Power
Screw Terminal
Works with Windows 73264bit Vista 2008 XP 2003 OSX 10x Linux etc