Continuous data acquisition with DAQmx without data acquisition toolbox

[T_alexis]

I'm trying to acquire data continuosly from my DAQ card. However, my data acquisition toolbox doesn't supported RTSI triggering, and "manual" trigger is still not fast enough. 

I found the sample code of JeansDE of using M-series card in Matlab by using ANSI C (http://www.jr-worldwi.de/work/matlab/index.html). Moreover, there's also sample code of continuosly acquiring data in National instruments (for example,  "ContAcq-ExtClk-DigStart.c").

My problem is that  I don't know how to write the CVI Callback function "EveryNCallback" in ANSI C into Matlab. 

[a,b] = calllib('myni', 'DAQmxRegisterEveryNSamplesEvent', uint32(AItaskHandle),  DAQmx_Val_Acquired_Into_Buffer, 1000, 0, EveryNCallback, ' ');

Any suggestions to write this function or another ways to overcome this problem are welcome.

Thanks a lot.

[rpurser]

Hi,

I'm not sure which version of Data Acquisition Toolbox & MATLAB you are using, but we did add RTSI support as part of our R2008b release, which came out in October of 2008.

All the best,

-Rob

---

Rob Purser

Manager, T&M

The MathWorks

[T_alexis]

My Matlab is R2006a, and it doesn't support RTSI.

[Joeri_Wingelinckx_NI]

Hi,

I don't know if you already heard about or had a look at the free "NI-DAQmx Tools for The MathWorks, Inc. MATLAB®"

[poreef]

I am trying to do a similar thing here.  I would use the Data Acquisition Toolbox, but my Matlab R2009b is running on linux.  The NI-DAQmx Tools comes in a Windows installer, so I assume it is also Windows-only.

The ideal would be:

1. Continuous acquisition of several analog inputs.

2. Continous reporting of that data back to the Matlab environment.

3. MATLAB plots what I care about and stores the data to disk.

A  backup plan would be:

1. MEX interface to existing C-code.  (I can run the example ANSI C code from the linux command line)

2. C writes to disk

3. MATLAB reads from disk, plots and re-stores the data.

I'm pretty sure I can implement the backup plan with my existing MEX skills but I would much prefer something along the lines of the first option.  That seems to be available in the tools built by Matlab and NI but only for Windows users.

I know that one can create a variable in a MATLAB workspace from within C MEX so maybe that is an option?

Do either of you have suggestions?

[cmora]

Hi T_alexis,

Could you solve your problem with Matlab?

 I am now trying to implement the same function ('DAQmxRegisterEveryNSamplesEvent') but nothing seems to work. Were you able to implement it in the end?

Thanks and regards,

Cmora