serial cable: The ends are RS232 9 pin. It's the same cable you might use on a thermal printer for UPS, FedEx, DHL, etc. It's a straight through cable. Although it is a 9 pin cable the only connections required are:
pin 2 to pin 2
pin 3 to pin 3
pin 5 to pin 5
null modem cable: Sometimes called a twisted pair cable. The ends are RS232 9 pin. Although it is a 9 pin cable the only connections required are:
pin 2 to pin 3
pin 3 to pin 2
pin 5 to pin 5
Now that you know the wiring configuration, don't forget to order the proper ends. These cables come as female to female, female to male, and male to male.
RS-232
Female
RS-232
Male
I hope this will clear up any confusion and help you in purchasing the correct cable. RS232 cables are available from your DMS International dealer. We supply a high quality cable with molded ends. If you have any problem finding these cables you are welcome to send me a email and I'll point you to the dealers that carry these.