Problem of script

//  turn data string into a number (float.Parse（datastring)).
// if distance is greater than X -> melt iceberg
// else rebuild iceberg.

After completing the ultrasonic sensor to send a signal to the computer, I found that I did not know how to combine this script with the key signal in unity. So I found some related tutorials on the website.
http://www.me.lhu.edu.tw/~tin/arduino/U3_Arduino_Unity3d.pdf
https://code.google.com/archive/p/unity-arduino-serial-connection/downloads