There isn't a standard (to our knowledge) on which cat5 wires go to which RS232 lines, so we just wire them in sequence like this:
|RS232 via Cat 5|
|8P8C Modular Jack Lead Color (Pin #)||DB9 Pin #||Signal Name||Source|
|Blue (1)||1||CD - Carrier Detect||Modem|
|Orange (2)||2||RXD - Receive Data||Modem|
|Black (3)||3||TXD - Transmit Data||Terminal|
|Red (4)||4||DTR - Data Terminal Ready||Terminal|
|Green (5)||5||Signal Ground|
|Yellow (6)||6||DSR - Data Set Ready||Modem|
|Brown (7)||7||RTS - Request To Send||Terminal|
|White (8)||8||CTS - Clear To Send||Modem|
Pin 9 is Frame Ground and is not required.
Note that with a few of these adapters in your toolkit, along with the usual supply of modular plugs, flat cable, and crimp-tool, you can make up your own RS232 cables as needed, always the perfect length!