I’m presently working on some Cisco certifications and I’m rebuilding my home lab mostly from scratch. My old APC Rack PDU (essentially a network controls power bar) was showing it’s age (it was beige) and not functioning reliably. I bought a used APC AP7901 Metered Rack PDU to take over the job of remotely turning off and on my various Cisco switches, ASAs and routers. I found my new (circa 2010) AP7901 on eBay for $99.99 including shipping, but it didn’t come with the super special serial cable (part number 940-0144) that was originally provided by APC (they never come with them used). I tried the various DE-9 (yes, DE-9, not DB-9) adapters that I had, but none worked in this application.
Why didn’t I use DHCP to issue the unit an address? Well I did, but that didn’t work. My home DHCP server (Sonicwall NSA250M) was giving it an IP address, but no amount of NMAP probing could get anything from the device). A serial cable was the way to get things rolling.
These cables are no longer available from APC, so you’ll need to make your own.
Here’s how to make the 940-0144 serial cable
- Start with a standard Cisco serial cable. This has a Female 9-pin serial port at one end and a RJ-45 connect at the other.
- Cut off the RJ-45 cable connector.
- Identify the two grounds, RX and TX pins.
- Crimp on your own RJ-11 connector with the wires in the correct order.
- Connect your new cable to your APC and get a working serial connection.
Sounds easy right? Well it is, but I’ll give a few additional detailed instructions below in case this is your first time making this type of cable.