“Pinout” is a term describing how an electrical cable is wired. Some cables do not have pinouts because they only contain a single internal wire, like coax cables. But if a cable has multiple pins on the end of the cable, it will have a pinout.

Each type of multi-pin cable has a standard pinout or two, but these layouts are not set in stone. Some machines will require non-standard pinouts; this will require users to use a custom cable.

Pinouts also come into play when using a cable with two different ends. For example, going from DB9 (9 pins) to DB25 (25 pins) will mean the DB25 side has 16 unused, “dead” pins.

If you need to know what pinout a cable needs, ideally there will be a spec sheet handy showing it. The next best option is contacting the manufacturer of the equipment the cable will be used with to see if they have a spec sheet available. If you have a cable tester available, that can be used to see how the pins line up. As a last resort, a cable can also be cut open to verify the pinout.

In the guide below, we will be highlighting the standard pinout configuration for common types of multi-pin cables.

 

Ethernet Pinouts

 

Ethernet uses two main pinouts, straight and crossover. Straight cables are used to connect computers to other devices, like modems and routers. Crossover cables are used to connect two computers directly. The wires inside ethernet cables are color-coded to industry standards, making it easy to follow the standard pinout options.

Straight pinouts are divided into two different options, T-568A and T-568B. The “B” option is the standard today, although finding the “A” cables still in use in older buildings

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