There are now devices (or at least more of them) that provide native OS X drivers, so this document is now slightly redundant.
After purchasing the Targus USB to Serial (PA088) Adapter, I found that the driver included was for Windows only. I needed this to work under OS X 10.4. After searching the Targus website, I found out that this device is only compatible with Windows. Hmmm.
This adapter is made for newer hardware that doesn’t come with serial ports. There are several adapters (or converters) on the market, the Targus PA088 Adapter was the only one I could find at a nearby shopping center. It took some trial and error, but here’s how I managed to get it working under OS X.
First I downloaded the Magic Control driver from the MCT website:
It appears this link is no longer valid.
Thanks to Mitch for finding the file, you can download a copy here.
Please note, this probably won’t work with newer Apple hardware, it was originally performed on a PPC PowerBook a few years ago.
Then I edited the plist file installed by the driver:
Then I replaced the following 2 ID’s, by those found in System Profiler (under USB):
I then changed the permissions to 755 on all the files under (I compared this to the other drivers) the driver folder:
Then, I ran kextload, and it worked:
sudo kextload /System/Library/Extensions/USBSerialDriver.kext
kextload: /System/Library/Extensions/USBSerialDriver.kext loaded successfully
You should now see a new serial device appear in /dev:
crw-rw-rw- 1 root wheel 2, 0 Dec 6 21:15 tty
crw-rw-rw- 1 root wheel 9, 8 Dec 6 18:54 tty.Bluetooth-Modem
crw-rw-rw- 1 root wheel 9, 6 Dec 6 18:54 tty.Bluetooth-PDA-Sync
crw-rw-rw- 1 root wheel 9, 2 Dec 6 21:16 tty.USB Serial
crw-rw-rw- 1 root wheel 9, 0 Dec 6 18:54 tty.modem
crw--w---- 1 root tty 4, 0 Dec 6 18:54 ttyp0
crw--w---- 1 root tty 4, 1 Dec 6 21:50 ttyp1
You can now access the serial port via /dev/tty.USB Serial ala UNIX!