PC Hardware in a Nutshell, 3rd Edition

Making Cables

You’ll probably never need to make a cable, but these guidelines will serve you well if you do:

• Create a grab bag of patch boxes, male-male and female-female 9- and 25-pin gender changers, 9-to-25 adapters, and so forth. You can get these things from Global, DataComm Warehouse, and similar places. They cost only a few dollars and occupy little space. Buy two of each, and add a straight-through 25-wire DB25-to-DB25 cable to the bag. The next time you desperately need a cable and all the stores are closed, you can use these parts to cobble together any cable you need.

• Use these parts to make a jerry-built cable that works, record the pinouts, order a custom cable made to those specifications, and leave the jerry-built cable in place until the new cable arrives to replace it.

• If you’re running cables through walls to wall jacks, make those cables straight-through and label both ends accordingly. No one will remember the cable pinouts later, and testing pinouts on a cable when only one end at a time is accessible is almost impossible. Do the custom pinouts in the drop cable that connects the wall jack to the equipment, and label both ends of that cable, too. Note that a plain cable is a lot easier to run through walls and floors than one that already has connectors attached.

• To make semipermanent quick-and-dirty cables, keep a supply of RJ-to-DB connectors on hand. They are available from Global and other vendors in DB9 and DB25 male and female versions, and have a standard ...