DB-9 Connector Pinout
Author: Stephen Stebbing
The DB-9 connector is a member of the D-subminiature or D-sub family of connectors and is officially known as the DE-9 connector. It is commonly used for RS232 serial ports.
1. Diagram
Note that the DTE device (eg the PC) uses the male plug and the DCE peripheral (eg the modem) uses the female socket.
2. Pinout
| Pin | Symbol | Name |
|---|---|---|
| 1 | DCD | Data Carrier Detect |
| 2 | RXD | Receive Data |
| 3 | TXD | Transmit Data |
| 4 | DTR | Data Terminal Ready |
| 5 | GND | Signal Ground |
| 6 | DSR | Data Set Ready |
| 7 | RTS | Request to Send |
| 8 | CTS | Clear to Send |
| 9 | RI | Ring Indicator |
- The DCE peripheral receives data on the TXD line and transmits on the RXD line.
- For a null-modem connection, DTR is connected to DSR and RTS is connected to CTS.