Abstract: The present invention relates to a system for measuring the frequency of a vibrating wire sensor using a digital counter system, which measures changes in the length of a structure to monitor changes in the structure, comprising: a processor which outputs an excitation signal to an excitation signal interface unit for a vibrating wire sensor, and compares the counted value input from an external source with a consumed time to calculate a resonant frequency; said excitation signal interface unit for a vibrating wire sensor, which receives the excitation signal from the processor, converts the received signal into a form capable of generating an excitation, and outputs the converted signal; said vibrating wire sensor, which outputs an intrinsic vibration signal in response to the excitation signal; a received signal interface unit for the vibrating wire sensor, which receives an intrinsic vibration signal output by the vibrating wire sensor, converts the received signal into a signal recognizable by the process