Measure Frequency On 6025e With PFI

[Mic_Scale]

Hello,

I'm using the 6025e board and I would like to measure or even calculate the frequency on two of my PFI's. (PFI6 and PFI5 for this matter).

I would not like to use my counters, as the goal is to quickly measure the frequency on two incoming triggers, which is why they are connected to the PFI's lines in the first place. Obviously connecting them to counters for a mere test would be very inconvenient and not practical.

Their frequency is very low, one at about 50-200 Hz and the other at about 0.2-2 Hz, that is why a very high accuracy is not that important.

I've tried some methods of using those signals as triggers, getting  a waveform, then getting the time lapsed between the first measurement and the last, but I got wrong readings. Perhaps that's because I'm not very well familiar with the waveforms.

Can anyone help me on this ? an example would help very much.

Thanks.

[lrallen]

For the 50-200Hz signal, you should be able to use the Extract Single Tone Measurement.vi.  However, this vi does not work very well for frequencies below 10Hz.  For the other signal, you may have to implement your own algorithm for calculating this.  Perhaps you could use the Basic Level Trigger Detection.vi and calculate the frequency from the time difference between peaks.  Take a look at these options and let me know if you have any questions. 

Regards,

L Allen