Hi Ron, thanks for your reply. Here is what I intend to do; the motor will be driving a conveyor with boxes on it. A worker will be standing in the middle of the conveyor to pick up the boxes. The sensor will be placed at the end of the conveyor to detect any boxes missed out by the worker. When the sensor senses a box, it will signal the motor to stop immediately. When the box is removed, the motor resumes. The purpose of this project is to avoid boxes from falling off at the end of the conveyor.