I have 2 PC's running XP that I need to communicate through serial ports. There is an older software program for inventory control that used to communicate through RS-232. I currently have a PCI to serial card installed with a null modem adapter at each PC and a new CAT5e cable running between the 2. The cable is good as per my tester. All I can get is the error 777 no matter what configuration I use. I cannot get the software program to communicate another way as it wants to set up baud rate and modem and modem attributes internally. The program is called "DSD" Direct Store Distribution, I believe. It is used for our small grocery store inventory/pricing system. We cannot afford an upgrade right now. I really need advice on setting up this direct cable communication.