Hanh,
To measure the height of a pulse with your DAQ device, you will need to acquire the pulse signal with an analog input channel and analyze the waveform in software. LabVIEW includes a VI that makes this analysis simple. Amplitude and Level.vi outputs a waveform's amplitude, high state level, and low state level. This VI is available from the following location:
Functions >> Waveform >> Waveform Measurements
I have also created a quick example that acquires a signal and determines its amplitude and high state level. I have attached it below.
Good luck with your application.
Spencer S.