How to synchronize a pulse group with arbitrary analog signal

[lyonco]

Hi, I have a question about the application of DAQmx program.

Device I have:

NI Device: PCI 6731

Other Devices: function generator, time delayer

I’ve generated a pulse group (500 pulses, 60kHz), which was controlled by an external trigger. I need an arbitrary analog output signal which has 125 periods during the time of 500 pulses.  Bother signals are trigger by one external trigger and can be re-triggered.

I attached the signal I expected, although there is not 500 pulses and 125 analog signal periods.

Thank you!

[Ben]

If you have extra counters available on that board I would set-up a freq devider and route the over-flow as a clock for the analog signal.

Ben

[lyonco]

Thank you Ben for replying!

I am not sure if the AO of PCI 6731 can be triggered and responsed that rapidly, because the pulse group may worked at 140kHz. I cannot get the information about how fast the AO can response.

In my early work, I triggered a triangle wave (50Hz) output with an external trigger, but it often missed some periods. I doubted about the response time of AO at hundreds of kHz frequency. Do you know how to solve this problem?

[lyonco]

BTW, continous AO output has no problem. The miss of signal period only happened in external trigger mode. It means some time, the trigger didn't evoke out the AO output. 

[lyonco]

Can any one give me a tip about AO output delay after receive the trigger?

[Michael G]

Hi lyonco.

This is not something we typically provide in our specifications for devices as with many of our products the slew rate and settling time are the dominant factors.  However, according to the KB linked below (which should still be valid for this case even though the article is written for multifunction DAQ cards), for most devices the delay is about 2-4 clock ticks.  This device should fall on the 2 clock tick side.  Since the clock on the 6731 is 20 MHz, 2 clock ticks should correspond to a delay of about 100 ns.

Delay Between Trigger and First Sample on M Series, X Series, and E Series Multifunction DAQ

Hope this helps.

Regards,

Michael G.