How do I enable DMA on my PCI-6024E?

[headleypc]

According to this KnowledgeBase article, my PCI-6024E should have one available DMA channel.  However, when I look up the device in the MAX under "Tradition NI-DAQ Devices" (since under "NI-DAQmx Devices > PCI-6024E" there is no mention of DMA) it displays System > Resources > Direct Memory Access 0.  Is DMA actually available on my DAQ device?  If so, how do I enable it?  We use this device with DASYLab 10 on Windows XP, need to write/record at 1000Hz, and are having much trouble without DMA.

Thank you,
Patrick

[Corby_B]

Hello headleypc,

Thanks for your post and questions about DMA!

I believe what you want to do can be done with a property node in DAQmx. When you set up your task do this before you call the DAQmx start.vi and this will allow you to set the DMA channel active. Also take a look at this knowledge base that talks about how to use the DMA channels in different programing environments.

How do I Configure the Data Transfer Mechanism (Interrupt or DMA) in DAQmx and Traditional DAQ?

Also see the picture attached that shows how to do this with the property nodes. Let us know if this information helps you and I wish you the best of luck with your applications.

Cheers!

Corby_B
http://www.ni.com/support

[headleypc]

Corby,

Thank you for replying.  We are actually using DASYLab v.10 as our data acquisition program; it seems from your reply that in LabVIEW and other applications the selection of DMA is done internally.  I cannot find such options in DASYLab - it seems as though everything concerning the A/D conversion is controlled in the Measurement & Automation Explorer.  Is this where I would enable DMA?  As I stated before, I could not find such an option there.

Thank you,

Patrick

[Corby_B]

Hello headleypc,

Thanks for your post back,

DMA is actually handled by the DAQmx driver and unless you specify the DMA channel is on by default. So if you are doing an Analog input task then the transfer for that will be DMA. Using the DAQmx driver you can set weather or not you want to have DMA on or not specifically for the tasks that you are performing. Since this card only has one you would only be able to do this for one task. Are you not able to pull out the data from the card fast enough using the DASYLab software? In labVIEW we have what is called a producer consumer design witch allows you to take data in one programming loop and then process or save data in another. That way you will avoid the problem of buffer overflows and missing data. So the question about how DASYLab handles DMA might need to be addressed to the DASYLab support team. Let us know if this information helps you and please post back if you have any other questions.

Cheers!

Corby_B
http://www.ni.com/support