in Hardware

building a custom serial cable with no soldering

This isn’t the most intellectually stimulating post, but I recently needed to build a custom serial cable to hack into an APC AP9606 Web/SNMP Management Card. (I bought one off eBay for $35.00 installed in a MasterSwitch Plus remote power strip, and the default password had been changed.

Now, I hate soldering. The last time I had to solder a serial cable was to build an RS-422 so a friend and I could get onto the console of a salvaged Challenge L, but that was a real pain. This time, I just needed a one-off to emulate an APC 940-0024 UPS communications cable.

I ended up just going to Above All Electronics and picking up a pair of RJ45-to-DB9 adapter kits — one female, and one male — and wiring the correct pins together. For the purposes of serial communications with the MasterSwitch, you really only need the following connections:

  • Pin #2 Female to Pin #2 Male
  • Pin #3 Female to Pin #1 Male
  • Pin #5 Female to Pin #9 Male

Everything else I just wired randomly to make it neat and clean.

Then, just take a regular Cat5e network cable and connect the two adapters you built and presto, a custom serial cable!

Thanks to the folks on that provided instructions for how to reset the admin password on the card.