So I went to rebuild a Cisco router the other day, but didn’t have a freaking serial port anywhere to drop the config! So I ran down to Fry’s to get a USB-to-Serial adapter. Looking online there are several options, at the actual store I only had two/three to choose from. So I ended up with that ugly thing up above, mostly because even though I will PROBABLY never need dual rs232 ports, there might be that day that I need two (and it was only $1 more!). So that ugly thing up above is the USB-2925 from Cables Unlimited. The BIG problem is that according to their website (which contradicts the package) is that it only works on Mac OS 10.0-10.3! OUCH! But we can find a way around this, cause if not this write up would be worthless 😉
The USB-2925 uses the Moschip MCS7720, which has drivers for OS X. The only problem is the drivers are for 10.4, but they worked for me just fine in 10.6.2 (Snow Leopard). You do have to do the install followed by the restart, but after that take a look:
$ ls /dev/tty.* /dev/tty.Bluetooth-Modem /dev/tty.USB-Serial0.0 /dev/tty.Bluetooth-PDA-Sync /dev/tty.USB-Serial1.1
After that you can use the screen command to work with the connection as found in this guide.
Here is a copy of the drivers if you need them: MCS7720DRV_MAC10.X.zip
**UPDATE**  The website for Moschip changed and the drivers seemed to have vanished. Here is a working one.