Mac OS mountain lion Not detect Arduino Serial Port

Using Arduino IDE 1.x
10

What worked for me when the USBmodem port stopped showing was pretty simple, but easy to overlook since the steps are specific. It requires getting the Arduino to reset by removing all power and allowing the Arduino port to reset when the IDE restarts:

  1. unplug from the Arduino the power cable (if being used) and USB cable; all power needs to be removed from the Arduino
  2. quit the IDE if it's running
  3. re-attach the USB cable to the Arduino (but don't attach the Arduino power cable yet)
  4. restart the IDE

Check the USBmodem port is now showing up as a menu option. If it is, now you can re-attach the power cable to the Arduino.

Hope this works for others... I thought this would work because my Mega had the problem. When I plugged in my Uno (after restarting the IDE) the USBmodem port appeared, however, when plugging the Mega in, the port disappeared. That's when I realized the problem was with the Mega and not my Mac drivers.