AO memory underflow - Daqmx/6229, system speed

[Mark_BFN]

I'm doing some mixed data acquisition and specifically having problems with some analog outputs.

We've switched our computer system from a Pentium 4 3ghz/800fsb to a Core Duo 2 mobile processor 2ghz/667fsb and I've developed onboard device memory underflow problems. I can only guess that the slower bus isn't fast enough to keep up with the PCI 6229 DAQ.

In reasearchign this problem I have a few questions... By default do all PCI DAQ tasks use DMA? If not, is there a way to specifically configure this in DAQ MX? Are there any driver settings to tweak here?

Second,  I have only 1000 points to write to the card at any given time. Is there a way to send this data over to the daq's fifo before the analog output start? Any examples?

Thanks,

Mark

[Sandra_T]

Hello Mark_BFN,

Direct Memory Access (DMA) is the default method of data transfer for DAQ devices that support it. Each acquistion circuit ( ie AI, AO etc. ) have a dedicated DMA channel. In most applications all data transfers use DMA.

What is the exact error you got? What is the error code?

I see that you want to be able to write 1000 points of data to the card. The AO FIFO buffer allows you to download points fo a waveform to your M series card without host computer interaction. I would take a look at the following shipping examples. You can locate them in NI Example Finder. Read the description to see what each of these examples do.

Cont Gen Voltage Wfm-Int Clk-On-Board Regeneration.vi

Cont Gen Voltage Wfm-Int Clk-Non Regeneration.vi

Take a look at these to get you started.

Regards,
  Sandra T.

Applications Engineer | National Instruments