Here you see Mathematica steering Arduino. A random sample function chooses an integer within a range between 1 and 180 and sends it to the Arduino Uno via serial. A driver compiled on the Arduino composes the integer from a series of ASCII values and drives the servo. Servo is steered by Servo class (s. Arduino documentation). To set up your mac Mathematica please have a look at the guide written by William J Turkel. His blog page was very helpful to make Mathematica communicate via serial with Arduino.