I believe that your rangefinder is the same design as the Daventech SRF04 model and works with WPILib as described here:
http://wpilib.screenstepslive.com/s/...asonic-sensors
Be careful, it has two connections:
- Echo pulse output: Causes the sensor to send an ultrasonic "ping"
- Trigger pulse input: listens for the echo to return
Be sure to connect it as described in the documentation.