Passing Strings as StateFlow Graphical Functions' parameters

Hi, I have developed a library of StateFlow Graphical Functions that act as wrappers for some C functions. In my C functions, I have to pass some String parameters but this is not allowed in StateFlow Graphical Functions. Is there a workaround for this?

PS: I also cannot use

ml.myStr='Say Something';

and then call:

mySFGF(ml.myStr);

Again, not allowed.

Thanks Ramtin