Why do I get a 'memPageLockError' with the ScanStart function?

[CAS]

I am using PCI-6110 and PCI-6111 boards for high speed data acquisition. I am using triggered acquisition into a preallocated buffer using SCAN_Start() and DAQ_Check() functions amongst others. I find that I get a -10447 memPageLockError status returned from SCAN_Start() when the total number of points I request for a total of 4 channels exceeds 33,533,952 points. This is less than half that which SCAN_Start() is supposed to be able to handle (2^24 * number of channels), and through experimenting, I have found that this is actually a different error to that thrown by SCAN_Start() when its limit is exceeded (> 2^24 throws an error code -10010 for 1 channel).

I would like to know where this limit comes from. If I know what it is I can work around it but I am worried that it may be machine dependent. Could somebody please tell me if this is machine dependent or perhaps if this an error which has a patch in a later NI-DAQ version (something mentioned in a related posting but I'm not sure if it applies here).

Details of my system:

OS: Windows 2000 SP4

Programming Language: Borland C++ Builder 5.0

NI-DAQ: 6.9.1f28

RAM: 512MB

(Update to NI-DAQmx not really an option at this point).

Thanks.

[SachaE]

Hi,

  assuming you're not multi-threading, I think that Windows is stopping the driver allocating that amount of memory in one go - if you're allocating doubles (so 8x33,533,952 = 268MB (and change) then the OS won't allow that amount of memory to be allocated in one go. (Windows tends to page lock to 64MB)

Why do you need a buffer that big? (I know Scan Start is a finite setup, but I'm wondering about going for a continuous setup instead where a much smaller buffer would be required.)

Can you use DAQmx (

Driver here :

https://www.ni.com/en/support/downloads/drivers/download.ni-daq-mx.html

Borland interface here :

https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z000000P9udSAC&l=en-US

)

Hope that helps.

Thanks

Sacha Emery
National Instruments (UK)