S-Functions: ssWriteRTWParamSettings in mdlRTW does not work.

Hey there,

I've got a problem regarding the inlining of some C S-Functions.

My S-Function expects some non tuneable parameters (e.g., "port_number"), which I try to write to the .rtw file in order to access them with my corresponding .tlc file.

My C Code looks as follows:

#define PORT_NUMBER  (( uint8_T )( mxGetPr( ssGetSFcnParam( S , PORT_NUMBER_IDX ) )[ 0 ] ) + (uint8_T)1 )

static void mdlRTW(SimStruct *S)

{
    if(!ssWriteRTWParamSettings (S, 1, SSWRITE_VALUE_NUM, "port_number", PORT_NUMBER))
  {
    return; /* An error occurred. */
  }
}

I tried accessing the parameter with

      %assign port_number = SFcnParamSettings.port_number

in my tlc file, but when building the model, I kept getting "unidentified identifier SFcnParamSettings".

Subsequently I searched the built .rtw file for "SFcnParamSettings", but nothing was found. Shouldn't there be a block with this title in it? For me it looks like the mdlRTW function wasn't executed correctly, but why?

And how can I check if it works?

Answer 1

[Eike]

Note: This seems to be triggered by the same problem I encountered here. I built the model in my own development path using copies of all relevant files/libraries instead of doing so in the original project folder.

I do not know about Matlab's exact problem before, but building in the original folder solved the issue. Again, I find Matlab's error reporting kind of misleading.

With kind regards,

Eike

Answer 2

[Kaustubha Govind]

I wonder if the write is failing becausing SSWRITE_VALUE_NUM requires a real_T value, but you are passing in a uint8_T value. You could try using ssWarning or ssPrintf inside your if condition to detect when ssWriteRTWParamSettings is unsuccessful.

Use SSWRITE_VALUE_DTYPE_NUM to write a SS_UINT8 type value, by passing in a void pointer to the same. See the documentation for more details.

Answer 3

[Eike]

Thank you for your reply!

The issue regarding the data type sounds logical to me, I have corrected that one. I also tried doing some error handling using ssWarning, ssPrintf and fprintf (to create a log file), but none of these produced any output. And I still keep getting the "undefined Identifier SFcnParamSettings". How can I find out if my mdlRTW is used at all?

At the moment, my code looks like this:

    #define MDL_RTW
    static void mdlRTW(SimStruct *S)
      {
          ssWriteRTWParamSettings (S, 1, SSWRITE_VALUE_DTYPE_NUM, "port_number", &PORT_NUMBER, DTINFO(SS_UINT8, 0));
          ssPrintf ("An error occured during .rtw generation!");
      }

And I still don't get any output. I don't have to configure anything to use a mdlRTW function, do I? Just put the c and tlc file of same name in the workspace, and Matlab recognises both?

[Kaustubha Govind]

AFAIK, you only need to define MDL_RTW (as you already are) - nothing else needs to be configured.

However, I'm not sure how this code even compiles because of how you use "&PORT_NUMBER" - you can't get the address of a temporary. You need to define another variable:

#define MDL_RTW

static void mdlRTW(SimStruct *S)

{

uint8_T pn = PORT_NUMBER;

ssWriteRTWParamSettings (S, 1, SSWRITE_VALUE_DTYPE_NUM, "port_number", &pn, DTINFO(SS_UINT8, 0));

ssPrintf ("An error occured during .rtw generation!");

}

[Eike]

That's right, that was probably a flaw, I have corrected that one, too. Thanks!

However, there's still no SFcnParamSettings block in my model.rtw.

Fortunately, while searching, I noticed that the parameter does exist in the rtw-File including its value, just not under that name.

Now I'm using "%assign ::port_number = block.Parameter[1].Value[0] + 1", which works.

I have completely no clue why the SFcnParamSettings thing does not work for me, but I don't care anymore ;-)

[Eike]

Appendix: I realized, that for this solution the mdlRTW function is completely irrelevant. I removed it from my C file and parameter passing still works.

Just if anyone's interested.