How to set IRQ mode for PCI-6733?

[AHancock]

I am working with a 16 slot rack which is full of mostly National Instruments PCI cards.   The computer is running near 100% CPU.   My investigation has determined that the call to DAQmxWriteAnalogF64 in my code for a PCI-6733 card is taking approximately 30% of the CPU time.  This function is called at approximately 120 Hz.  The card is used to generate a sine wave of up to 14KHz.  The clock speed is 250000 and the buffer size is 2048. 

I have noticed the Data Transfer Mechanism is set to Programmed I/O.  I have attempted to change Transfer mode, but it doesn't seem to be taking it.

Are there any examples of calls to DAQmxSetAODataXferMech for the 6733 card?

Thanks,

Aaron

[samantham]

Hello,

To set the data transfer mechanism, please look to the NI-DAQmx C Reference Help.  The topic titled "Get/Set/Reset AO_DataXferMech" is helpful and has a link for the values for the last parameter of the function.  As far as examples, I do not believe there are any examples specific to changing data transfer mechanism.  However, here are two KnowledgeBases that should help.  One states to set the data transfer mechanism after the timing call to avoid an error.

KnowledgeBase 34FGAFVM: How do I Configure the Data Transfer Mechanism (Interrupt or DMA) in DAQmx a...

KnowledgeBase 2W8CH8HT: Error -200172 When Changing the Data Transfer Mechanism

I am curious to know if you are interating any DAQmx function calls other than DAQmx Read or Writes.  This might be why your processor is railing.