Cannot connect to the system console

[Working on mac.
Pixhawk is connected via FTDI 3.3V Cable.]

I tried to access the system console by typing the following to the terminal:
screen /dev/tty.usbserial-xxxx 57600 8N1

All I got is a blank screen, with no response to hitting the enter key.

Do I have to do the radio calibration first in the QGroundControl?

Thank you for your attention and time.