MATLAB: No MEX file gets created when calling “accelbuild” in MATLAB R2016b

accelbuildacceleratorjitmex filesmodesimulink

To develop a simulation tool for our customer, we use "accelbuild" so as to create a compiled model to accelerate simulation. In R2011b, calling "accelbuild" creates a mexw32/mexw64 file, but in R2016b, I noticed that nothing is created.

I would like to know if there is a way to get a compiled mexw64 file in R2016b? Is there a configuration setting that I should change to set it on?

Best Answer

As of MATLAB R2016a, the accelerator mode simulation for Simulink models uses Just-In-Time acceleration by default instead of generating accelerator mode MEX-files for the models. The reason for this is because JIT acceleration is inherently faster than running MEX-files. You can find more information on this in the following link:

https://www.mathworks.com/help/simulink/ug/how-the-acceleration-modes-work.html?#brcp5hx-1

In order to be able to generate accelerator mode MEX-files for your model, you would need to switch to the classic accelerator mode. Please run the following command to do so:

set_param(0, 'GlobalUseClassicAccelMode', 'on');

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MATLAB: Is MATLAB R2017a unable to locate build file with a “NMAKE : fatal error U1052: file ‘MODELNAME.mk’ not found” error when using Visual Studio 2017

Microsoft recently changed Visual Studio 2017 behavior to set the current folder to a default directory when any Developer tools are run.

When 'model.bat' calls 'vcvarsall.bat', it will change the current folder to the default directory which is not the 'model_grt_rtw' directory. Thus, 'nmake' will not be able to find 'model.mk' file.

Refer to Bug Report 1649009 for additional information.

As discussed in the above Bug Report, the temporary fix is to set an environment variable in MATLAB by executing the command below at MATLAB Command Window:

>> setenv('VSCMD_START_DIR','%CD%')

Add this to matlabrc to ensure it is set at startup. This will result in successful builds. However, this may cause a harmless 'project path cannot be found' message during build.

This bug was fixed as of <https://www.mathworks.com/downloads/web_downloads/download_update?release=R2017b&s_tid=ebrg_R2017b_1_1649009 R2017b Update 1>.

If you have a current subscription to MathWorks Software Maintenance Service (SMS), you can download the product updates. If not, learn more about <https://www.mathworks.com/services/maintenance/ MathWorks SMS>.

MATLAB: Does clear mex command in StopFcn specified in Simulink Model Properties’ not unlock the MEX files and unload DLLs

The reason for this behavior, as the "clear mex" document points out, is that 'clear mex does not clear locked MEX functions or functions that are currently in use'. In Simulink, the MEX files are not unlocked until the model and all it's callbacks are done.

To achieve your workflow, you can explicitly force the MEX to unlock using "munlock" and then use "clear mex". Here is the example script that you can use it in the "StopFcn" of your model.

% Initially, the MEX is locked
isLocked = mislocked('mexTest.mexw64')
clear mex;
% MEX should be locked even after clearing it
isLocked = mislocked('mexTest.mexw64')
% Unlock MEX explicitly
munlock('mexTest.mexw64')
% Check if locked and then clear
isLocked = mislocked('mexTest.mexw64')
clear mex

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MATLAB: Is MATLAB R2017a unable to locate build file with a “NMAKE : fatal error U1052: file ‘MODELNAME.mk’ not found” error when using Visual Studio 2017

MATLAB: Does clear mex command in StopFcn specified in Simulink Model Properties’ not unlock the MEX files and unload DLLs

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