D-sub connectors, also known as D-subminiature connectors, are a type of electrical connector with two or more parallel rows of contacts. The metal shell, shaped in a D, ensures the connector is in the proper orientation when plugged in. The shell also may protect against electromagnetic interference. The circuitry is connected to the contacts by crimp, PCB solder, solder cup, PCB press fit and wire wrap connections.
When they were first developed, they were the smallest connectors used in computer hardware. Smaller and less expensive connectors have been developed so their use in consumer products is waning. They are still used in non-consumer products where their form, density, size and cost are still valuable to the user.
The shell of the female socket fits tightly inside the plug’s shell. Dsub connectors often have screws on the plug end which allow the connectors to be locked together. This relieves mechanical strain on the much thinner pins.
Pins have a ‘normal density’, meaning the pins are 0.109 inches apart and rows are 0.112 inches apart. Each row is offset from the one above it by 0.0545 inches. The most common pin counts are 9, 15, 25, 37 and 50.
The most common use of D-sub connectors is for serial communications. Uninterruptable power supplies also use them, but rather than for communications, they use them to determine power conditions. Nine pin connectors are used in token ring networks, the controller area network and other computer networks.
Video game consoles also use D-sub connectors, but often used a molded plastic body with no fastening screws. The same size connector is used for many systems, although they are not all interchangeable.