using a FTDI USB to Serial chip adapter and trying to find a good serial emu. for Mac OS X I found this great tip to find out the device which gets installed when you plug your USB-Serial adapter in your Mac and how to use the built in program screen with it:
First, open Terminal (Applications/Utilities/Terminal). Next, type
to get a list of your serial lines. Pick the one that you want to open. For example, my list looks like this:
gf:dev gf$ ls -al tty.*
crw-rw-rw- 1 root wheel 18, 4 Jan 25 07:32 tty.Bluetooth-Modem
crw-rw-rw- 1 root wheel 18, 8 Jan 25 07:32 tty.Bluetooth-PDA-Sync
crw-rw-rw- 1 root wheel 18, 10 Jan 25 09:20 tty.PL2303-0000103D
crw-rw-rw- 1 root wheel 18, 0 Jan 25 07:32 tty.SerialPort-1
And I know /dev/tty.PL2303-0000103D is the USB-to-serial adaptor becuase it’s connected, if you unplug it the tty.PL2303-0000103D stops being listed.
Knowing the serial port, you can just type screen portname datarate to show the serial data on the screen. In my case, it was:
screen /dev/tty.PL2303-0000103D 9600
To quit the screen app, type control-A, then control-\.
from a post by Greg Ferro