WIRE LENGTH MEASURING INSTRUMENT, SENSOR IDENTIFICATION DEVICE, AND SENSOR POSITION CHECKING DEVICE

摘要

PROBLEM TO BE SOLVED: To provide an instrument for measuring the wire length of a signal line and a novel device for identifying a sensor issuing a signal by measuring the wire length. SOLUTION: This wire length measuring instrument comprises an alternating current launching means 21 for launching into the signal line an AC signal of a frequency allowing the signal line to be regarded as a lumped constant circuit, an alternating current receiving means 22 for receiving the AC signal from the signal line, a calculation means 23 for calculating the imaginary part of complex impedance from the launched and received signals, and a conversion means 24 for converting the imaginary part of the complex impedance into a wire length. This instrument can be applied to a sensor identifying device in a mechanical security system having a plurality of sensors connected to a controller via a signal line.