Why does the waveform chart doesn't work at low sample rate and with few channels?

[Will.D]

From what I can tell, this is a timing/sampling issue.  I think the fact that your timed loop is running at 1kHz, and that you are requesting multiple samples, sampled at 100Hz in your loop is causing the problem.  Try leaving your sampling as "single sample" and then changing the loop frequency.

Edited for clarity

Message Edited by Will.D on 11-24-2006 02:29 PM

[molo511]

hi

[TCPlomp]

Hi,

I think I know the issue.
The 6024 is a PC-card right?
In that case daqmx has an issue with slow rates.
On PCI systems DMA is used to transfer the data, and daqmx get notified when the number of samples are acquired. Now on PC-card that doesn't work, and the data is transfered when the on-board buffer is full (after 2 kbyte of data) at 2 channels 10 Hz this can take a while.
There is a work around, there is a property where you can set de transfer mechanism (I don't have daqmx on this PC), or the polling mechanism of daqmx. Try these.

Found a KB document

Let me know if this works!!

Ton

[molo511]

Hi TonP,

thanks a lot! I modified the program according what you said, and it works perfect now!

I attached my code here too, in case anyone gets the same problem as me.