RS232

Pinout

Rx/Tx RTS/CTS/DTR/DSR

Signal Level converts

MAX 232 is from an RS-232 serial port to signals suitable for use in TTL circuit.

• http://en.wikipedia.org/wiki/MAX232

USB to COM chip

PL-2303:

http://www.prolific.com.tw/eng/products.asp?id=59

about/overview

http://www.prolific.com.tw/eng/downloads.asp?ID=23

datasheet download page

http://www.prolific.com.tw/eng/downloads.asp?id=31

driver download page