Use M-Series cards with DAQmx in Matlab!

Question

Hi DAQers!
Who is this message for?
For all people wanting to use their M-Series cards (and/or NI_CAQmx drivers) with Matlab.
Content:
Basic introduction into importing DAQmx into Matlab. Simple AI (analog input), advanced AI (synchronous)
and simple AO solutions are displayed with Matlab source code.
Motivation:
There's probably little disagreement that the new M-Series cards are superior to the old E-Series cards.
However, Matlab does (as of February 2005) not support either directly.
By buying the Data Acquisition Toolbox you can access most of the E-Series' functions from within Matlab.
But this will not help you with your new M-Series card! But it is possible to use M-Series cards with Matlab.
First step
Start by loading the NI dll:
funclist = loadlibrary('nicaiu.dll','nidaqmx.h','alias','myni')
(You can choose any alias as long as it is a legal variable name.)
If your version of Matlab is too old to provide the "loadlibrary" function directly, download it here:
http://www.codeproject.com/dll/MatlabGenericDll.asp?df=100&forumid=26247&exp=0&select=972623
After importing, you see the list of available functions.
You can also display them by
libfunctionsview('myni')
That's basically it. By using the National Instruments NI-DAQmx C Reference manual and libfunctionsview('myni')
you have access to those functions. One special thing you need to keep in mind is the fact that pointers
work differently in Matlab than in C. This problem can be solved by using the Matlab function "libpointer".
Sometimes Matlab does not require a pointer when C would. But I found that it does not hurt to
specify a pointer in this case. Whether Matlab expects a pointer can be seen in the output
created by libfunctionsview('myni')
The general syntax for calling DAQmx functions is:
[outputarguments]=calllib(alias,NIDAQmx_functionname,inputarguments)
My next message will show a function I wrote that enables basic and advanced analoginput.
Jens

Answer 1

Hi!
As promised, my Matlab function to use the M-Series card with Matlab.
I have the bad habit of programming in German and English at the same time.
I tried to correct that for this posting. I hope I succeeded!
I wrote this function to suit my needs -which it does.
Feel free to modify it to suit yours.
Jens
Edit: I just saw that my m-File is longer than 5000 characters! #duh#
Sorry!
I'll see if I can get a download up!
Here's the abbreviated m-file without synchronous AI:
function messmatrix=NImess(synchron,trigger,numofchans,samprate,samptime)
funclist = loadlibrary('nicaiu.dll','nidaqmx.h','alias','myni');
disp('NI: Create Tasks')
taskh1=uint32(1);
[a,b,taskh1] = calllib('myni','DAQmxCreateTask','master',taskh1)
taskchans1=['Dev1/ai0:' num2str(numofchans-1)];
[a,b,c,d] = calllib('myni','DAQmxCreateAIVoltageChan',uint32(taskh1),taskchans1,'',-1,-10,10,DAQmx_Val_Volts,'')
nsample=samprate*samptime; %
disp('NI: Config Sample Clock')
[a,b]=calllib('myni','DAQmxCfgSampClkTiming',taskh1,'',samprate,DAQmx_Val_Rising,...
DAQmx_Val_FiniteSamps,nsample)
disp('NI: Config Digital edge start trigger')
if trigger==1
[a,b]=calllib('myni','DAQmxCfgDigEdgeStartTrig',taskh1,'/Dev1/PFI0',DAQmx_Val_Rising );
else
[a]=calllib('myni','DAQmxDisableStartTrig',taskh1)
end
disp('NI: Start task(s)')
[a]=calllib('myni','DAQmxStartTask',taskh1)
DAQmx_Val_GroupByScanNumber = 1;
readarray1=ones(numofchans,nsample);
readarray1_ptr=libpointer('doublePtr',readarray1);
sampread=0;
sampread_ptr=libpointer('int32Ptr',sampread);
empty=[];
empty_ptr=libpointer('uint32Ptr',empty);
arraylength=nsample*numofchans; % more like "buffersize",
disp('NI: Reading Data!')
[a,readarray1,sampread,empty]=calllib('myni','DAQmxReadAnalogF64',taskh1,-1,-1,...
DAQmx_Val_GroupByScanNumber,readarray1_ptr,arraylength,sampread_ptr,empty_ptr);
disp('NI: Stop task')
[a] = calllib('myni','DAQmxStopTask',taskh1);
disp('NI: Clear task(s)')
[a] = calllib('myni','DAQmxClearTask',taskh1);
messmatrix=[readarray1'];
disp('NImess finished')