The set-up process is very simple, and best understood by referring the wiring diagram. If everything goes right,you should see the burning eye of the red LED when there is no object in the safe-zone ...

Enclosed are the ultrasonic sensor, a temperature sensor and an LED indicating the power status. On the other side of the CAT5 cable can be found an Arduino compatible board with an XBee shield ...

Now, the venerable ultrasonic sensor joins the gallery of classics given a size change treatment, like the 555 timer we’ve seen two different takes on, or perhaps that one Arduino Uno.