To fully understand the concept of magnetic mapping an understanding of the basic function of a reed sensor is required. The reed sensor is an ideal method of sensing and detecting movement of any kind. Typically a permanent magnet is mounted to a moving member. This can be a piston, a float, a rotating disk, or anything else. The reed sensor houses a hermetically sealed reed switch that is generally mounted to a printed circuit board (PCB) or hard wired to an electrical circuit. The reed switch senses the physical movement of the magnet and the reed contacts will close or open depending upon whether the magnet is moving toward the reed sensor or away from it.