DAQmx examples

Examples of talking to a National Instruments (NI) DAQ card without the data acquisition toolbox.

Description

Examples of using matlab to talk to a National Instruments (NI)
DAQ card _without_ the 'data acquisition toolbox'

I have mainly used code and examples from Jens Roesner here:
http://www.jr-worldwi.de/work/matlab/index.html
However, I had to make a few slight tweaks to get it to work for me. I have only tested this on Matlab 7.8.0 (R2009a) on WinXP with a NI PCI 6220 board, so no guarantees.

Using Jens' code, I got an error -200088 whenever I tried to create a channel. To get it working, I had to change the initial task handles to uint32([]) which then returned a pointer for taskhandle

I also had trouble with creating tasks, then losing the taskhandle, and not being able to create the same task because of a name conflict. The solution is to not name any of the tasks - names don't seem to be useful anyway. So all my functions pass an empty string as a name.

Other changes are just cosmetic -
made functions for common tasks to simplify my main code
put all task handles in structure so easy to clear

• MATLAB release: MATLAB 7.8 (R2009a)

[Dustin]

Does not seem to work for R2009b (32-bit) on Windows 7 (32-bit) w/ NI-DAQmx 9.1.0.

??? Error using ==> DAQmxCheckError at 24
DAQmx error - NULL pointer was passed for a required parameter.

Error in ==> DAQmxCreateDOChan at 28
DAQmxCheckError(lib,err);

[Dustin]

Found a fix for R2009b:
taskh = libpointer('voidPtrPtr',0);
muxHandle = taskh;

[result, ~, muxHandle] = calllib('nidaqmx','DAQmxCreateTask','',muxHandle);
muxHandle.setdatatype('voidPtrPtr');
[result, a, b] = calllib('nidaqmx','DAQmxGetTaskName',muxHandle,charBuffer,length(charBuffer));
[result,~,~,~] = calllib('nidaqmx','DAQmxCreateDOChan',muxHandle,'/Moo/port0/line0:3','MUXlines',0);

[Daniel Arellano]

Are you by chance using this code as S- Function? If so how did you implement it

[Nathan Tomlin]

No, I've never used simulink.