PCMCIA acquisition problem (indicator refresh)

[andrej]

Hi!

I use LV 8.2 and DAQmx 8.3 drivers on laptop with NI DAQCard-6036E (PCMCIA). As a demostration I eclose acquisition.vi as attachment. Everything works fine if samples per channel is set to 500 or more (sampling rate is 1000 all the time), but when samples per channel is set to 100, indicators are refreshd every fifth iteration of while loop (if you run acquisition.vi you will noticed thah while watching loop index indicator whitch is increasing by 5). I also run this VI with other cards like USB or PCI and it works fine (indicators are refresh everyiteration of loop). I have this problem only with PCMCIA card.
I hope that somebody can help me because it is crucial for the project that I developed.

Thank you in advance!

Andrej

[Ed W]

Hi Andrej,

Thank you for posting to the NI forums.  This is the expected default behavior for your device, and in general, all of our PCMCIA devices.  Unlike our PCI devices, PCMCIA devices do not support DMA – they are interrupt driven.  The default interrupt to trigger the onboard data fetch into RAM is setup to occur when the onboard memory is more than half full.  You can change this setting to fetch the data when the onboard memory is simply “not empty”. 

This is described in the following Knowledge Base article.

Data Updates Very Slowly at Low Sample Rates in NI-DAQmx With PCMCIA DAQCards

I hope this helps!  Please post back if you have further questions. 

Ed W.

Applications Engineer

National Instruments