Most storage devices that do not require vision and a brain to read data fall into this category. Electromagnetic data may be stored in either an analog data or digital data format on a variety of media.
Direct Tripwire Alarm - The wire placed across the path is directly connected with the cord, wire or string placed across the particular path. Laser Tripwire Alarm - An invisible laser, typically an infra-red, is used instead of a cord or string.
One of the wires provides a precise 5 volt power supply from the PCM. Another wire provides the ground circuit, grounded only through the PCM. The third is the signal wire, carrying the signal voltage generated by the MAP sensor to the PCM.