NI PCI 6534 - DAQmx Error - locking physical memory on WinXP

[cjoseph]

Hello Folks,

The DAQmx v8.5 software on WinXP with the NI PCI 6534 board works with my program for small data sets.
When I try sending  22 million samples of 32 bits each I get the following error for the DAQmx software.

"DAQmx Error: One or more memory pages in the specified logical buffer could not be locked into physical memory.

The operation could not be completed as specified. Task Name: _unnamedTask<0>".

I am guessing that either the National driver or XP is having a hard time locking the required memory (>64Mbytes).

Is there a setting in the national software that is needed in order to avoid this?
Or is there some WinXP registry setting that can me modified so the driver can allocate large physical blocks.

Thanks for your help in advance,
Carlton.

ps my code is attached below

[Abhinav T]

Hi,

There isn't an XP registry key that you can modify to increase the block size. However is there any reason why you are trying to output 22 million samples all at the same time? You could try to stagger it so that you send the data in bursts instead.

I am testing you code right now and will let you know how that goes.

[cjoseph]

Hi Abhinav T.,

I used the first National example I found. I never got to bursts. Attached is an example input file for my program.

Thanks,

Carlton.

[cjoseph]

Hi Abhinav T.,

I used the first National example I found. I never got to bursts. Attached is an example input file for my program.

Thanks,

Carlton.

[Abhinav T]

Carlton,

You will need to modify the example so that you perform multiple writes instead of just one. If you chunck up your data into smaller pieces you will use less bandwidth in the data transfer.

If you call DAQmxWriteDigitalU32 with your data in chuncks you should be able to get rid of this error.

[cjoseph]

Hello Abhinav T.,

I will try the data chunk method.

Do you have any hint on the maximum data chunk size?
I can try a number of sizes but is there any official word on the recommended data chunk size?

Thanks,
Carlton.