Thankfully as time has passed, those have gotten a lot more standardized. It’s rare to find anything these days that isn’t the Cisco pinout. Most new stuff is just USB which is even better. But vendors who use USB connectors without putting USB on the port annoy the crap out of me. More on reddit.com

This pinout worked for me: RJ45 -> DB9 RTS 1 -> 8 CTS DTR 2 -> 6 DSR TXD 3 -> 2 RXD GND 4 -> 5 GND GND 5 -> 5 GND RXD 6 -> 3 TXD DSR 7 -> 4 DTR CTS 8 -> 7 RTS IIRC, I had to leave one of the ground pins unplugged. http://i.imgur.com/O3RRKQC.jpg *Edit: Here's another picture for clarity. Also, you can push the pins back out with something like a small flathead screwdriver (~1mm). http://i.imgur.com/7hWniXb.jpg More on reddit.com

Just make sure whatever you get has an FTDI chip. More on reddit.com

You have to configure most RJ45-to-DE9 adapters yourself, so you should be able to get it working. You need to know the RJ45 pinout of your USB-to-RJ45 adapter, as well as the pinout of the DE9 connector on your switch, so you know how to configure the adapter. Do the work on paper, so you know what pin is supposed to connect to what. Before you push the terminals into the DE9 socket (which is rather permanent, unless you have the re-pinning tool) you might try temporarily connecting the loose pin connectors directly to the switch, to see if you get communication. Then plug them into the DE9 socket, and close it up. If you have multiple switches with multiple DE9s and you find that it doesn't work on one of them, then get a second adapter and wire it up for that switch. Then, mark each adapter, so that you know which one works with each switch. More on reddit.com