One approach to cabling is to have several types of cables around and when an interfacing situation arises, try them all out and see if one will work. This is not such a bad approach, so we present several common cable diagrams below.
The documentation for the device you wish to communicate with may contain cable diagrams for hooking up the device to common computers. All but the "Straight Through" cable could be considered "Null Modem" cables because they attempt to make another non-modem device look like a modem. A phone call to the device manufacturer can also save a lot of time in determining what cable to use.
