Opis złącza RS232, czyli popularnie zwany COM.
| Pin | Sygnał |
| 1 | DCD (Data Carrier Detect) |
| 2 | RD (Receive Data [RxD]) |
| 3 | TD (Transmit Data [RxD]) |
| 4 | DTR (Data Terminal Ready) |
| 5 | GND |
| 6 | DST (Data Terminal Ready) |
| 7 | RTS (Request To Send) |
| 8 | CTS (Clear To Send) |
| 9 | RI (Ring Indicator) |