Note that you will need to connect to the same device that you connect to from within the Arduino development environment. I created a symlink between the longer-winded device name and /dev/tty.usbserial to cut down on keystrokes.
I am running into a bunch of other problems as well, but I don't really know too much about programming, so I am starting here.
Can anyone explain what exactly the author means by that and how to find the device name of my arduino?
The device name is what your OS will need to talk to the Arduino. You want to use the same virtual serial port as you do when loading a sketch on the Arduino.
Check the Tools/Serial port entry in the Arduino IDE, and see what is there as options. If you know the one you normally use to load sketches, it will be that one. Should be something like COM1 COM2 or what ever in Windows I think, and something else in OSX/Linux. For me on Linux, it's "/dev/ttyUSB0" And as you saw in the page you linked to, the OSX user who wrote it had a different name.
If that doesn't work, there are a few little python programs that should list the serial ports on your OS here. http://pyserial.sourceforge.net/examples.html
Look under "finding serial ports". And you will need to have your Arduino plugged into the USB while you are running it.
Symlinks as far as I vaguely understand are kind of like short cuts in Linux and OSX, but a bit more complicated. Not sure if they are available in Windows. Hopefully someone who actually knows what they are talking about will be along to explain it properly to both of us.
When it comes to running the python code, make sure you have already installed the pySerial libraries, and don't call your serial communications test program "serial.py". It's embarrassing when you spend ages trying to figure out why the example doesn't work,and you finally realise you have been calling a program called serial.py with the import serial command instead of the serial function in the library. :-[
hey thanks. I figured it out as well. I was just confused, because on windows (as you suggested) I just use com3...
i had some driver issues which prevented communication ... the code was fine ... but as I had no idea what he was talking about there I thought that might be the problem...