Below is the pinout of a typical 9 pin RS-232 connector, this connector type is also referred to as a DB-9 connector.
A computer's COM port (DTE) is usually male, and any peripheral devices you connect to this port usually have a female connector (DCE).
| Pin | Signal | DTE Signal Direction | Description |
|---|---|---|---|
| 1 | DCD | IN | Carrier Detect |
| 2 | RXD | IN | Receive Data |
| 3 | TXD | OUT | Transmit Data |
| 4 | DTR | OUT | Data Terminal Ready |
| 5 | GND | - | Signal Ground |
| 6 | DSR | IN | Data Set Ready |
| 7 | RTS | OUT | Request To Send |
| 8 | CTS | IN | Clear To Send |
| 9 | RI | IN | Ring Indicator |