How to use DAQmxGet/Set/ResetBufOutputBufSize with Matlab

[JasonW]

Hello,

I'm using Matlab and the nicaiu.dll to make calls to the NI-PCI6534.  I'm just a novice with using this DLL and I'm confused by how to use the DAQmxGet/Set/ResetBufOutputBufSize command.

In the chm file, this is all I get on how to use the command:

int32 __CFUNC DAQmxGetBufOutputBufSize(TaskHandle taskHandle, uInt32 *data);

int32 __CFUNC DAQmxSetBufOutputBufSize(TaskHandle taskHandle, uInt32 data);

int32 __CFUNC DAQmxResetBufOutputBufSize(TaskHandle taskHandle);

I'm not a programmer by training and am a bit confused about pointers in general.  If I want to set the buffer size to 128 and then retrieve the buffer size, I would think I would send the following calls:

calllib(Lib,'DAQmxSetBufOutputBufSize',hTask,uint32(128))

To retrieve the command, I'm confused on what I put for the uInt32 *data

calllib(Lib,'DAQmxGetBufOutputBufSize',hTask,???)

Any help is grateful,

Jason

[Benjamin38]

Jason, you would want to reference the uint32 by pointer call (which is what the * before the data is for).  Your code would look something like this:  

uint32 bufSize = uint32(128);

DAQmxSetBufOutputBufSize(TaskHandle taskHandle, bufSize);

DAQmxGetBufOutputBufSize(TaskHandle taskHandle, *bufSize);

Hope this helps, good luck with your programming!  

[JasonW]

Hi Ben,

Thank you for your reply.

Let's see if I understand your answer...I should do the following:

Buffer = uint32(128);

pBuffer = libpointer('uint32Ptr',Buffer);

Err = calllib(Lib,'DAQmxSetBufOutputBufSize',hTask,Buffer);  % Set the buffer size

[Err, Y] = calllib(Lib,'DAQmxGetBufOutputBufSize',hTask,pBuffer); % Retrive the buffer size

When I run the 'DAQmxGetBufOutputBufSize', Err = 0 and I would expect Y to give me a value of 128 but I receive a pointer of type uint32Ptr with an empty value.

What am I missing?

Thanks,

Jason