Generate high frequency digital waveform - the 2nd

[Helga]

Hi!

I'm using the PCI-6284 DAQ device and I'm trying to send a digital waveform with a frequency of 21440 Hz (and receive an analog signal at the same time). Well the single bits should be send with 21440 Hz.

Nearly the same thing as here: http://forums.ni.com/ni/board/message?board.id=250&message.id=53420

I changed the "Correlated Dig Write With Counter" example to my purposes and tried.  It did run and it did send the digital signal, but not in the right timing. I need it in real time and allways in the same frequency. But measurements show that every circle of waveform needs a different time. Sometimes longer than required, sometimes shorter.

I'd be happy about some advices,

Helga

[Andrea_Perin]

Hi Helga,

thank you for your question.

Can you quantify the observed jitter of your digital generation?

What does it happens if you try the standard LV example (see picture)?

Do you still observe this deviation from the deisired output frequency?

Best regards.

Andrea P.

NI Germany

[Helga]

I think, I misunderstood the example. The last While-Loop doesn't wait for each task to finish one cycle? It just checks whether there was an error? Does that mean that there's no software solution to check whether the digital output is timed right?

Sorry for not answering your questions, but maybe you already helped me ... or you gave me loads of new questions