You might try using the "Measure Pulse (DAQ-STC).vi" example located in
./Program Files/National Instruments/LabVIEW/examples/daq/counter/daq-stc.llb/*.
Or if you're using a TIO board, try using the "Measure Pulse (NI-TIO).vi" example located in
./Program Files/National Instruments/LabVIEW/examples/daq/counter/ni-tio.llb/*.
gus....