Analog signal period measurement using analog trigger

[Torfins]

LV7.1
DAQmx
DAQCard-6062E (PCMCIA)
Windows XP

Greetings.
I am trying to measure the period between rising edges from an envelope-detector in order to demodulate a signal. The time between the edges will vary from 2ms and up to 4 to 5 sec.

I have found a possible start in the DAQ-STC-example 'Measure_AI_Frequency.vi', but I'd like to use DAQmx if possible. In addition, this example does not seem to deal with periods yielding counter overflow.

My question is twofold: How do I route the internal analog trigger to a counter, and how do I set up a continous period measurement which accurately supports the above-mentioned periods?

I'm new to DAQmx and period measurements, and am grateful for any advice.

Regards,
Torfinn

[reddog]

Here is a similar post which I think should answer your question. If you still have questions, please reply back.

[Torfins]

Thanks for the tip, the property node with the 'CI.Freq.Term' property was the trick I'd been looking for. However, it does not work. I have tried both ai0 as trigger input as well as PFI0, but I do not get any readings. Using the PFI0 input, I get the error "Data was overwritten before it could be read by the system.". Using ai0, I simply get a timeout: ("Some or all of the samples requested have not yet been acquired."). It seems like PFI0 triggers, but not ai0. I've tried varying values for 'Sample per Read', but it does not change the behaviour.

I get the old DAQ-STC example "ATCOUT Viewer.vi" to work, (not for counting, it just displays the ATCOUT trigger and the ai0 signal.) I might have to rearrange this vi to get a solution. I am amazed that the DAQmx is so hard to configure for this simple task. The ATCOUT (or AnalogComparisonEvent) is internally availible, so why have to route it out..?

Still hoping for a solution with DAQmx..

Regards,
Torfinn