| Table of RS232 Pin Designations | |
| 1 | Ground |
| 2 | Transmitted data (TD) |
| 3 | Received data (RD) |
| 4 | Request to send (RTS) |
| 5 | Clear to send (CTS) |
| 6 | Data set ready (DSR) |
| 7 | Ground |
| 8 | Data carrier detect (DCD) |
| 9 | Not connected |
| 10 | Not connected |
| 11 | Not connected |
| 12 | Secondary data carrier detect |
| 13 | Secondary clear to send |
| 14 | Secondary transmitted data |
| 15 | Secondary transmitted clock |
| 16 | Secondary received data |
| 17 | Receiver clock (RC) |
| 18 | Divided clock receiver (DCR) |
| 19 | Secondary request to send |
| 20 | Data terminal ready (DTR) |
| 21 | Signal quality detect (SQ) |
| 22 | Ring indicator (RI) |
| 23 | Data rate selector |
| 24 | External transmitter clock |
| 25 | Busy |