In order to run a data analysis program, installed on a Teensy 2.0 microcontroller running arduino, I have to go to the screen by typing
screen -S trans -L /dev/ttyACM0 (the name of the screen is trans).
screen -S trans -X stuff "s$(printf \\r)"
echo "s" > /dev/ttyACM0
What you want is
screen -S trans -X stuff 'command'$(echo -ne '\015')
screen -S trans -X stuff 's'$(echo -ne '\015')
in your case. Let me know if this works for you.