How do I use the FOPEN function in Embedded MATLAB when running in Rapid Accelerator mode in Simulink 7.7 (R2008b)?

I am using the Embedded MATLAB Function block in my model to perform some calculations. I am writing some intermediate data to a text file using the FOPEN, FPRINTF and FCLOSE commands. Since these commands are not inherently supported with EML, I am using the eml.extrinsic construct to use these functions. The model runs fine in Normal and Accelerator modes but gives the following error message when run in Rapid Accelerator mode:

 Failed to eliminate a use of the MATLAB function 'fopen'. For non-simulation builds, uses of unsupported MATLAB functions are eliminated if they do not effect the function outputs.

 Function 'Embedded MATLAB Function' (#39.225.256), line 12, column 10:

 "fopen('pointScorefile.txt','w')"

A sample model (trial_fopen.mdl) is attached.

Answer 1

[MathWorks Support Team]

The error occurs because the FOPEN function is not supported for code generation. The Rapid Accelerator mode works only with those models containing blocks that support code generation of a standalone executable.

To work around the issue, you can use eml.ceval to evaluate an external C function (which performs the file handling operations).

The demo ("Embeddable C-Code Generation Using Embedded MATLAB Coder") illustrates how this can be accomplished. In R2008b, this demo can be found by executing the following at the MATLAB command prompt:

web([matlabroot '/toolbox/rtw/rtwdemos/html/rtwdemo_emlcbasicdemo.html'], '-helpbrowser')

A working model (trial_fopen_c.mdl) can be found in the attachments.