RS 232 Pinouts for DB25 and DB9 Connectors Last updated; Save as PDF Pins commonly used for RS-232 (serial): Commonly used RS232 Null Modem Pin out for DB25 and DB 9 connectors: RS232 DB25 pinout RS232 DB25 to DB9 converter The original pinout for RS232 was developed for a 25 pins sub D connector. In mixed applications, a 9 to 25 pins converter can be used to connect connectors of different sizes. RS232 port (DB25 serial port). DB25 pinout guide. 3ft DB25 M/M Serial RS232 Cable Connect your printer, modem or other RS-232 serial/parallel device to a switchbox Choose from our selection of DB25 connectors, including computer connectors, computer adapters, and more. In stock and ready to ship. Wiring, pinout and signals for full RS232 connector Since the introduction of the smaller serial port on the IBM-AT, 9 pins RS232 connectors are commonly used. Many audio interfaces, AD/DA converters, digital mixers, and other devices use DB25 connectors to carry eight channels of AES/EBU.Typically these cables “break out” into XLR connectors (four male connectors, four female connectors) to accommodate individual stereo AES/EBU connections.