Low frequency measurement with digital input

Hello,

I started using LabVIEW recently and I would like to know if it is possible to calculate or measure the frequency of a digital signal (pulse train) using a regular digital input (no counter or analog input available). I have a cDAQ with an NI 9425 module. The characteristics of the pulse train signal that I'm trying to measure are: Frequency = 100 Hz, Duty cycle = 50%.

Any help or example would be appreciated.

Thank you.