Getting Error -200279: Unable to Keep Up with Acquisition in DAQmx

[Kevin_Price]

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@PaulOfElora wrote:

Looking at articles like at:  https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z000000PAraSAG&l=en-US

They talk about the circular "PC Buffer".  Is that the "DAQmx driver's" memory? 

Yes, the circular buffer mentioned in that article is referring to the PC memory managed by the DAQmx driver.

Note: that article has mostly good info, but there are a few details where the terminology isn't careful or precise enough, and is thus at least a bit misleading and maybe wrong.   Among the nits:

- "Decrease the samples per channel rate with the DAQmx Timing function" -- should say 'sample rate'

- "Samples that are written to the circular PC buffer are overwritten before they are read into Application Development Environment (ADE) memory."  -- Actually, a task error is thrown when the overwrite would have occurred.  After that, the DAQmx driver *prevents* you from reading them into ADE memory.   Whether or not the overwriting actually happens is a moot point -- there's an error and you lose access to your data regardless.

    (Technically, there's a DAQmx property you can set to "allow overwrite", but that's not the default behavior nor is it commonly used.)

I also noticed the careful distinction between the terms over-WRITE and over-FLOW.  I don't know if that's a new-ish distinction as I've had a long-time (and seemingly incorrect) habit of using the term over-FLOW when referring to the DAQmx circular buffer.  Maybe I haven't been careful enough in my terminology all these years either.

-Kevin P