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How to use National Instruments M-Series cards with Matlab

2005 legacy content

Who is this for?
For all people wanting to use their M-Series cards (and/or NI-DAQmx drivers) with Matlab.

    Update August 1st, 2006
I was just made aware by Steven that Matlab now supports M-Series cards via the new Data Acquisition Toolbox. This is an easy and very refined way of accessing the new capabilities of the M-Series and can even be used to access the older E-series cards through the newer NI-DAQmx.

    Update April 28th, 2010
I have just received the following info: 
I'm not sure why, but your code seemed to work fine for me until 
I tried any of the create channel commands. 
They all returned a -200088 error. 
I finally figured out a very slight tweak to your code 
that worked for me - not sure why the original didn't work.

I had to pass the initial task handle as empty - uint32([]). 
This is example code that worked for me:

    taskhDO0 = [];
    [err,b,taskhDO0] = calllib('myni','DAQmxCreateTask','DO0',uint32(taskhDO0))
    [err,b,c,d] = calllib('myni','DAQmxCreateDOChan',taskhDO0,'Dev1/port0/line0','',DAQmx_Val_ChanPerLine)

 I am using matlab 7.8.0 (R2009a) on XP.
As I have no way of testing this any more, I have not changed the source code below.
Also, be sure to check the NI forums :)

Content:
Basic introduction into importing NI-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. Matlab did (in February 2005) not support either series directly and the Data Acquisition Toolbox (DAQ) was only compatible with the E-series cards. This has changed now (August 2006). By buying the Matlab Data Acquisition Toolbox you can access both E-Series and M-Series cards (and many cards by other manufacturers) seamlessly from within Matlab. For a full list of supported hardware, see the Matlab list of Supported Hardware Devices and Vendors in DAQ. Furthermore, using the Adaptor Kit that is supplied with the Matlab DAQ Toolbox might make it possible to even connect to your otherwise unsupported card.
I'll leave this page online because it still is a feasible way to access functions of the M-Series cards and furthermore illustrates some very basic steps on how to use Matlab's powerful function of importing dll files.

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)

The following function enables triggered and untriggered, synchronized or unsynchronized AI

function messmatrix=NImess(synchron,trigger,numofchans,samprate,samptime)
% function messmatrix=NImess(synchron,trigger,numofchans,samprate,samptime)
% 2005, written by jens.roesner -at- gmx.de
% version 1.0 as of 20.02.2005
% provides access of NI's NI-DAQmx driver from Matlab
% Analog Input (synchronized or not) with (especially) M-Series cards
% Measures the first numofchans channels.

if ~libisloaded('myni')
    disp('Matlab: Load nicaiu.dll')
    funclist = loadlibrary('nicaiu.dll','nidaqmx.h','alias','myni');
    %if you do NOT have nicaiu.dll and nidaqmx.h
    %in your Matlab path, add full pathnames or copy the files.
    %libfunctions('myni','-full') % use this to show the...
    %libfunctionsview('myni')     % included function
end
disp('Matlab: dll loaded')
disp('')

disp('NI: Define constants')
% Other constants must be searched in the NI installation directory
DAQmx_Val_Volts= 10348; % measure volts
DAQmx_Val_Rising = 10280; % Rising
DAQmx_Val_FiniteSamps = 10178; % Finite Samples

disp('NI: Create Tasks')
taskh1=uint32(1);
[a,b,taskh1] = calllib('myni','DAQmxCreateTask','master',taskh1)
% a will be the error code

if synchron==1
    taskh2=uint32(1);
    [a,b,taskh2] = calllib('myni','DAQmxCreateTask','slave1',taskh2);
    taskh3=uint32(1);
    [a,b,taskh3] = calllib('myni','DAQmxCreateTask','slave2',taskh3);
end

disp('NI: Create AI Channels')
taskchans1=['Dev1/ai0:' num2str(numofchans-1)];
[a,b,c,d] = calllib('myni','DAQmxCreateAIVoltageChan',uint32(taskh1),taskchans1,'',-1,-10,10,DAQmx_Val_Volts,'')
if synchron==1
    taskchans2=['Dev2/ai0:' num2str(numofchans-1)];
    taskchans3=['Dev3/ai0:' num2str(numofchans-1)];
    [a,b,c,d] = calllib('myni','DAQmxCreateAIVoltageChan',uint32(taskh2),taskchans2,'',-1,-10,10,DAQmx_Val_Volts,'');
    [a,b,c,d] = calllib('myni','DAQmxCreateAIVoltageChan',uint32(taskh3),taskchans3,'',-1,-10,10,DAQmx_Val_Volts,'');
end

if synchron==1
    [a,b]=calllib('myni','DAQmxSetRefClkSrc',taskh1,'/Dev1/10MHzRefclock');
    [a,b]=calllib('myni','DAQmxSetRefClkSrc',taskh2,'/Dev1/10MHzRefclock');
    [a,b]=calllib('myni','DAQmxSetRefClkSrc',taskh3,'/Dev1/10MHzRefclock');
    [a]=calllib('myni','DAQmxSetRefClkRate',taskh1,10000000);
    [a]=calllib('myni','DAQmxSetRefClkRate',taskh2,10000000);
    [a]=calllib('myni','DAQmxSetRefClkRate',taskh3,10000000);
end

nsample=samprate*samptime; %

disp('NI: Config Sample Clock')
[a,b]=calllib('myni','DAQmxCfgSampClkTiming',taskh1,'',samprate,DAQmx_Val_Rising,...
     DAQmx_Val_FiniteSamps,nsample)
if synchron==1
   [a,b]=calllib('myni','DAQmxCfgSampClkTiming',taskh2,'',samprate,DAQmx_Val_Rising,...
        DAQmx_Val_FiniteSamps,nsample)
   [a,b]=calllib('myni','DAQmxCfgSampClkTiming',taskh3,'',samprate,DAQmx_Val_Rising,...
        DAQmx_Val_FiniteSamps,nsample)
end

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
if synchron==1
    [a,b]=calllib('myni','DAQmxCfgDigEdgeStartTrig',taskh2,'/Dev1/ai/StartTrigger',DAQmx_Val_Rising )
    [a,b]=calllib('myni','DAQmxCfgDigEdgeStartTrig',taskh3,'/Dev1/ai/StartTrigger',DAQmx_Val_Rising )
end

disp('NI: Start task(s)')
if synchron==1
    [a]=calllib('myni','DAQmxStartTask',taskh3)
    [a]=calllib('myni','DAQmxStartTask',taskh2)
    [a]=calllib('myni','DAQmxStartTask',taskh1)
else
    [a]=calllib('myni','DAQmxStartTask',taskh1)
end


DAQmx_Val_GroupByScanNumber = 1;
readarray1=ones(numofchans,nsample);
readarray1_ptr=libpointer('doublePtr',readarray1);
if synchron==1
    readarray2=ones(numofchans,nsample);
    readarray3=ones(numofchans,nsample);
    readarray2_ptr=libpointer('doublePtr',readarray2);
    readarray3_ptr=libpointer('doublePtr',readarray3);
end
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);
if synchron==1
    [a,readarray2,sampread,empty]=calllib('myni','DAQmxReadAnalogF64',taskh2,-1,-1,...
         DAQmx_Val_GroupByScanNumber,readarray2_ptr,arraylength,sampread_ptr,empty_ptr);
    [a,readarray3,sampread,empty]=calllib('myni','DAQmxReadAnalogF64',taskh3,-1,-1,...
         DAQmx_Val_GroupByScanNumber,readarray3_ptr,arraylength,sampread_ptr,empty_ptr);
end

disp('NI: Stop task')
[a] = calllib('myni','DAQmxStopTask',taskh1);
if synchron==1
    [a] = calllib('myni','DAQmxStopTask',taskh2);
    [a] = calllib('myni','DAQmxStopTask',taskh3);
end

disp('NI: Clear task(s)')
[a] = calllib('myni','DAQmxClearTask',taskh1);
if synchron==1
    [a] = calllib('myni','DAQmxClearTask',taskh2);
    [a] = calllib('myni','DAQmxClearTask',taskh3);
end

if synchron==1
    messmatrix=[readarray1' readarray2' readarray3'];
else
    messmatrix=[readarray1'];
end

disp('NImess finished')

Simple AO

function AOtaskhandle=NIsetAO(tasknum,outputchan,voltage)
% function messmatrix=NIsetAO(tasknum,outputchan,voltage)
% tasknum=0 for a new task or task-handle for existing chan
% only single-channel DC out
% 2005, written by jens.roesner -at- gmx.de
% version 1.0 as of 20.02.2005
% provides access of NI's NI-DAQmx driver from Matlab
% Analog Output with (especially) M-Series cards

if ~libisloaded('myni')
    disp('Matlab: Load nicaiu.dll')
    funclist = loadlibrary('nicaiu.dll','nidaqmx.h','alias','myni');
    %funclist = libfunctions('myni','-full')
    %libfunctionsview('myni')
end
disp('Matlab: dll loaded')
disp('')

disp('NI: Define constants')
DAQmx_Val_Volts= 10348; % measure volts
DAQmx_Val_Rising = 10280; % Rising
DAQmx_Val_FiniteSamps = 10178; % Finite Samples

if tasknum==0
    disp('NI: Create AO Task')
    if outputchan==0
        taskhAO0=uint32(1);
        [a,b,AOtaskhandle] = calllib('myni','DAQmxCreateTask','AO_0',taskhAO0)
    else
        taskhAO1=uint32(1);
        [a,b,AOtaskhandle] = calllib('myni','DAQmxCreateTask','AO_1',taskhAO1)
    end

    disp('NI: Create AO Channel')
    taskchans=['Dev1/ao' num2str(outputchan)];
    [a,b,c,d] = calllib('myni','DAQmxCreateAOVoltageChan',uint32(AOtaskhandle),taskchans,'',-10,10,DAQmx_Val_Volts,'')
else
    AOtaskhandle=tasknum
end

disp('NI: Set&Start task')
[a,b]=calllib('myni','DAQmxWriteAnalogScalarF64',AOtaskhandle,1,0,voltage,[])

Wave Output AO

function AOtaskhandle=NIsetAOwave2(tasknum,spannungsvektor1,spannungsvektor2,samprate)
% function AOtaskhandle=NIsetAOwave2(tasknum,spannungsvektor1,spannungsvektor2,samprate)
% tasknum=0 for new task, or task-handle for existing
% spannungsvektor is german for "vector of voltages"

if length(spannungsvektor1)~=length(spannungsvektor2)
    disp('Voltage vectors have to be of the same size! Truncating!')
    beep
    beep
    beep
    if length(spannungsvektor1)>length(spannungsvektor2)
        spannungsvektor1=spannungsvektor1(1:length(spannungsvektor2));
    else
        spannungsvektor2=spannungsvektor2(1:length(spannungsvektor1));
    end
end

if ~libisloaded('myni')
    disp('Matlab: Load nicaiu.dll')
    funclist = loadlibrary('nicaiu.dll','nidaqmx.h','alias','myni');
    %funclist = libfunctions('myni','-full')
    %libfunctionsview('myni')
end
disp('Matlab: dll loaded')
disp('')

disp('NI: Define constants')
DAQmx_Val_Volts= 10348; % measure volts
DAQmx_Val_Rising = 10280; % Rising
DAQmx_Val_FiniteSamps = 10178; % Finite Samples
DAQmx_Val_CountUp =10128; % Count Up
DAQmx_Val_CountDown =10124; % Count Down
DAQmx_Val_GroupByChannel = 0; % Group per channel

if tasknum==0
    disp('NI: Create AO Task')
    taskhAO1=uint32(1);
    [a,b,AOtaskhandle] = calllib('myni','DAQmxCreateTask','AO_1',taskhAO1)
    disp('NI: Create AO Channel')
    taskchans=['Dev1/ao0:1'];
    [a,b,c,d] = calllib('myni','DAQmxCreateAOVoltageChan',uint32(AOtaskhandle),taskchans,'',-10,10,DAQmx_Val_Volts,'')
else
    AOtaskhandle=tasknum
end

disp('NI: Config Sample Clock')
%int32 DAQmxCfgSampClkTiming (TaskHandle taskHandle, const char source[],
%float64 rate, int32 activeEdge, int32 sampleMode, uInt64
%sampsPerChanToAcquire);
[a,b]=calllib('myni','DAQmxCfgSampClkTiming',uint32(AOtaskhandle),'',samprate,DAQmx_Val_Rising,...
    DAQmx_Val_FiniteSamps,length(spannungsvektor1))


disp('NI: Set AO task')
%[a,b]=calllib('myni','DAQmxWriteAnalogScalarF64',AOtaskhandle,1,0,spannung,[])
%DAQmxWriteAnalogF64 (TaskHandle taskHandle, int32 numSampsPerChan, bool32 autoStart, float64 timeout, bool32 dataLayout, float64 writeArray[], int32 *sampsPerChanWritten, bool32 *reserved);
%[int32, doublePtr, int32Ptr, uint32Ptr] DAQmxWriteAnalogF64(uint32, int32, uint32, double, uint32, doublePtr, int32Ptr, uint32Ptr)
empty_ptr=libpointer('doublePtr',[]);
zero_ptr=libpointer('int32Ptr',0);
[a,b,c]=calllib('myni','DAQmxWriteAnalogF64',AOtaskhandle, uint32(length(spannungsvektor1)), 0, 10, DAQmx_Val_GroupByChannel, [spannungsvektor1, spannungsvektor2], zero_ptr, []);
disp(['a= ' num2str(a) ' c= ' num2str(c)])

disp('NI: Start AO task')
[a]=calllib('myni','DAQmxStartTask',AOtaskhandle)
if a==0
    disp('NI: AO wave started')
else
    disp('NI: AO wave failed.')
end

disp(' ')
% disp('NI: Stop task')
% [a] = calllib('myni','DAQmxStopTask',AOtaskhandle);
%

Download

NI_2_Matlab.zip (functions described above)
NIconstants.zip (NI constants and error codes)