Frequency measurement of digital input

[Evie]

I'm just experimenting with SingalExpress.  I want to measure the frequency of a digital input and record this along with the digital data.

1. Applying 10 Hz sq. wave to port 2.0 of a USB-6501
2. First step:  DAQmx Acquire, digital line input, continuous samples
3. 2nd step:  Convert Digital to Analog (makes analog waveform)
4. 3rd step:  Timing and Transition (put a check mark by frequency)
5. Select run
6. Data view has x-axis as time.
7. Legend says "inf" to the right of "frequency"

[dannnnny]

I guess I should have left a question.  What am I doing wrong?

[Matthew_W]

 Hi Evie,

 
 To measure frequency with SignalExpress using your USB-6501

1. Add a DAQmx Acquire->Analog Input step, put your digital input into the analog input you pick, set the sampling rate to be atleast 2-10x the input signal rate.
   
2.  Add the Timing and Transition step
3. Run the VI
4. Observe the frequency.
   

Best regards,

MatthewW
Applications Engineer
National Instruments

Message Edited by Matthew W on 08-02-2007 05:45 PM