Standard DB-9 pin out is as follows.
Serial Port (DB9)

Pin Signal Description
--- ------ -----------
1   CD     Carrier Detect
2   RD     Receive Data
3   TD     Transmit Data
4   DTR    Data Terminal Ready
5   GND    Ground
6   DSR    Data Set Ready
7   RTS    Request to Send
8   CTS    Clear to Send
9   RI     Ring Indicator