D-sub connector, as a major category of connector types, is mainly used in computer communication ports. In addition, D connector also has two or more parallel contact rows, and is surrounded by D metal frame. The standard specification of type D connector is defined by the international standard IEC 60807-3 / DIN 41652. According to the IEC standard, four different types of standard connectors are defined. These connectors differ in case size and number of pins, which are named DA, DB, DC, DD, and DE connectors, followed by their number of pins.