| PIN | TYPE | FUNCTION[/td] |
| DCD | In | "Data carrier detect" |
| RX | In | Asynchronous serial data receive |
| TX | Out | Asynchronous serial data transmit (idle high) |
| DTR | Out | "Data terminal ready" control output (often used with DSR) |
| GND | Power | Ground |
| DSR | In | "Data set ready" control input (often used with DTR) |
| RTS | Out | "Ready to send" control output (often used with CTS) |
| CTS | In | "Clear to send" control input (often used with RTS) |
| RI | In | "Ring indicator" control input |
| VCC | Power | Logic supply voltage (3 – 5.5 V, externally supplied) |
| INV | Out | Serial port detection pin, high if serial port connected |
| TX | Out | Asynchronous serial data transmit, inverted (idle low) |
