D-Sub DB9 9-Pin Female Terminal Block Adapter, Can connect any serial device. It is used for computers, control units, digital cameras, set-top boxes, barcode devices, industrial instruments and other communication equipment.
| Foot Position | Logogram | Significance |
| Pin 1 | CD | Carrier Detect |
| Pin 2 | RXD | Receive |
| Pin 3 | TXD | Transmit |
| Pin 4 | DTR | Data Terminal Ready |
| Pin 5 | GND | Ground |
| Pin 6 | DSR | Data Set Ready |
| Pin 7 | RTS | Request To Send |
| Pin 8 | CTS | Clear To Send |
| Pin 9 | RI | Ring Indicator |