The APC Master Switch series PDUs have an RJ11 socket for the serial port, if you have a spare Cisco serial cable lying about here is a quick trick to make up a 9 pin D-Type socket to RJ11 plug cable:
| Cisco Pin | Colour | RJ11 Pin | Description |
| 1 | Grey | CTS | |
| 2 | Blue | DSR | |
| 3 | Green | 3 | TX |
| 4 | Yellow | 5 | GND |
| 5 | Orange | 2 | GND |
| 6 | Red | 4 | RX |
| 7 | Brown | DTR | |
| 8 | Black | RTS |
Pins 1 and 6 on the RJ11 are not connected.