Why am I getting a linking error about the function defined in the S-function wrapper C file when building my model?

I used a S-function Builder block to generate the S-function source code, TLC, and mex file for me. Then, I replace this S-function Builder block with a S-function block, giving it the name of the generated S-function.

Now, when I build the model, I got an error saying [mdl_name].obj : error LNK2019: unresolved external symbol [sfcnname]_Outputs_wrapper referenced in function [mdl_name]_step.

Answer 1

[MathWorks Support Team]

The issue is caused by the fact that when the S-function Builder block is taken out, the model is losing information about what source files other than the [s-function name].c would be associated with the MEX file that is given to the S-function block.

In order to the S-function block to know where to look for the _wrapper.c, you need to explicitly tell it in the *S-function modules field of the S-function block. More information about this field can be found here:

https://www.mathworks.com/help/rtw/ug/build-integrated-code-within-the-simulink-environment.html#bp67s_y-3