Mathematica is a powerful tool when mathematical calculations are needed. It has tons of useful functions for data analysis, calculations and modeling. Arduino is good tool for simple and fast control and data acquisition using analog and digital pins. If you need to do more serious data analysis that you collect from real world then it is best to do this with more appropriate tools like Mathematica.
William shares his short tutorial on how to pass data from Arduino to Mathematica using serial port. Arduino has a handy Serial.write() function that simply sends data over serial channel. Major attention is paid on setting SrialIO package that is called from Mathematica. Once you get it working, reading data requires only few lines of script code.