How to connect a Parallax PING Ultrasonic sensor
Wiring up the Sensor
The Parallax Ping Sensor is very easy to connect. You will need three jumper wires. We recommend that you have one red, one black, and one of another color (preferably white or yellow for the signal wire).
The Ping sensor uses one pin for both sending the start signal to the sensor, and reading the distance from the sensor. This means that the wiring for the sensor is very simple.
All we need to do is connect the 5V pin to the 5V rail, connect the GND pin to GND, and connect the Signal pin to the Arduino digital pin 3.