Serial port connector
The two serial port connectors are identical and are 9-pin, D-SUB male connectors.
| Pin | Signal | I/O | Description |
| 1 | CD | I | Carrier Detect |
| 2 | RXD | I | Receive Data |
| 3 | TXD | O | Transmit Data |
| 4 | DTR | O | Data Terminal Ready |
| 5 | GND | - | Ground |
| 6 | DSR | I | Data Set Ready |
| 7 | RTS | O | Request to Send |
| 8 | CTS | I | Clear to Send |
| 9 | RI | I | Ring Indicator |