When connecting a webbrick to  9 Pin D connector for a PC use the following connections:

Webbrick A connects to Pin3 of a female DB9 

Webbrick B connects to Pin2 of a female DB9

Ground connects to Pin 5 of a DB9

The webbrick does not support any flow control, and for RS232 it is 8 Bits 1 Stop bit No parity. Main speeds (9600,19200,38400) can be set on the Advanced page. Further speeds (300 up to 250000 need a manual command)

Requires Webbrick firmware 6.5 and Hardware Revision 4 or Later. 

Pin A --  WebBrick TX

Pin B -- WebBrick RX

Note that the WebBrick uses the proper RS232 levels, so you can check that RS232 has been configured because -6V should be on the A terminal and approximately 0V should be on the B terminal.

 RS232 is an unbalanced single ended signalling.

The cable used should be screened and dedictated to the one task. Carrying other signals in the same cable can cause noise pick up making the signal hard to pick up or eroneous data picked up.

The cable length should be limited to 50 feet, ideally shorter. http://en.wikipedia.org/wiki/Rs232