How to use an analog trigger to determine single sample acquisition rate

[Orensag]

Hi all,

I have the NI PXIe 6124 on a NI PXIe 1062 Q controller.

I would like to use an analog signal to determine a single sample acquisition rate.

For example: if I enter a sine wave with an unknown frequency, I would like to acquire a single (1) sample across my 4 channels each time the sine wave value is zero.

Is this possible with my devices? And if so how do I do it?

Thanks,

Oren.

[Anthony_F]

Hello Orensag

The different types of triggers supported can be found in the PXIe - 6124 Manual on pages 135-138.  You should be able to set a very small window trigger with around 0 volts so that you trigger on both the rising and the falling edges of the sinewave as it crosses 0 volts.

Do you know the frequency of the input sinewave?  This information would be very beneficial to know to set the correct rate for the DAQmx task.

What you really are looking for is change detection, which is an option in DAQmx Timing VI, but is only supported by certain cards.  Again your sine wave would need to meet the same sample clock timing requirements in the 6124 Specifications.