Some more information that could be useful for anyone would help me.
The command: ls /dev/tty.* in Terminal answers: /dev/tty.usbmodem5D11, but that port doesn't appear in the list of ports in Arduino IDE, where I can find only: /dev/cu.usbmodem5D11.
The Mac System Profiler in hardware USB shows Arduino connected to a USB port.
Could it be a problem of baud rate?
Thanks!