One end of the cable is a stereo 3.5 mm jack and the other end is a DB9 female serial port. DB9 female to DC3.5mm serial cable is primarily used to transfer serial data back and forth from small devices. Fully molded DB9 and 2.5 mm connectors provide strain relief. Wiring Diagram Pin 1 open Pin 6 open Pin 7 open Pin 8 open Pin 2 Tip Left Pin 3 Ring Right Pin 4 open Pin 5 Shield Ground Pin 9 open Key Benefits Enables bidirectional serial data transfer between devices that use a DB9 serial port and a 3.5 mm stereo interface. Robust, plug and play connection with fully molded DB9 and 2.5 mm connectors for reliable use in the field or workshop. Compact design suitable for small devices and tight spaces, reducing wear on connectors and cables. Simple wiring configuration that maps a stereo 3.5 mm jack to a DB9 serial port for straightforward integration. Specifications and compatibility Connectors: DB9 female on one end, 2.5 mm connector on the other end Cable type: DB9 female to DC3.5mm serial cable Wiring: As per the wiring diagram above Use with devices that have a DB9 female serial port and a 3.5 mm stereo interface for serial data transfer Applications Debugging and programming small embedded devices that expose a DB9 serial port and use a 3.5 mm connection for data transfer Exchanging configuration data or logs between portable instruments with DB9 ports and devices using a 3.5 mm serial interface Field service data transfer between equipment that provides a DB9 serial port and a compact device with a 3.5 mm jack