Measuring a 32Mhz Frequency output using NI PXI 6614

[_nirolf]

Hello,

I am trying to measure a 32Mhz frequency output from a micro using an NI6614 PXI FCU, but I keep getting errors in the measurement and there seems to be a great deal of instability.

The odd issue is that some of the measurements seem to be more of an error value like 33333333.333333 or other similar values that cycle each time I try to repeat.

My questions in regards to this would be:

1. Have I been mistaken and the NI6614 is not something I should try to use for this?

2. If it is a usable and stable device for this type of measurement, what am I doing wrong?

The VI I am using was adapted from a 32Khz one.

[ZYOng]

You are using Low Frequency with 1 Counter method to measure a high frequency of 32 MHz.

According to page 3-15 of NI 6614 User Manual, the error is 32/(100-32) = 47%

You should use the High Frequency with 2 Counters method, which gives you an error of 0.003125% per milliseconds of measurement.

[_nirolf]

Hello,

I have allready tried to generate a sample clock using a second counter as suggested in the documentation, but the results are the same. Or have I misunderstood the documentation?

[ZYOng]

You did not wire anything to the Method input of the Create Counter Input Task VI. The task will use the default Low Frequency with 1 counter.

Refer to Method 2 in Making Accurate Frequency Measurements in LabVIEW