I searched for similar questions on this issue but found none related to Mac OSX.
Situation:
Trying to test android apps on a Galaxy S (D
Well I tried all kind of stuff for a phone that was working yesterday but not today. Finally replacing the cable between the phone and my mac solved the issue.
Go to
Connect Storage To PC
Source: Galaxy S II Forums - Help, Mac won't recognize my galaxy S 2
This happens all the time with lots of phones. Two things that have worked for me are (1) type "adb kill-server" at the command line, or (2) try another cable.
I know it is ridiculous but do make sure your phone's got a SIM card!
To activate the USB debugging on Samsung Galaxy S go to Menu -> Settings -> Applications -> Development -> Check "USB debugging".
make sure that you plugin your device in the usb ports on the mac itself, not on the keyboard usb-ports.