| Pin | Signal | Notes |
| 1 | o/c | Not connected |
| 2 | RxD | Data coming from device and entering Mux for onward transmission to Host. |
| 3 | TxD | Optional return data path from Mux to device. Not connected unless jumper link is fitted. Default is not fitted |
| 4 | DTR | Connected to pin 9- this is compatible with a regular (asserted) DTR output |
| 5 | GND | Common data ground |
| 6 | DSR | Not connected |
| 7 | RTS | RS232 handshake line output. Permanently enabled (Wired to +12v via 1k resistor) |
| 8 | CTS | Not connected |
| 9 | Power out | Provides + 5v DC at up to 300mA to power devices |