How to access the extern declared global variables in a imported C function?

Hi,

I imported C code into Embedded Coder using C caller block.

My C file has extern declarations for variables.

I do not know how I can access this extern variables to pass them values from Simulink application.

I am thinking to create an interface C function that receive lot of arguments and define and assign the values to the externs. But there is a lot of signals (global variables).

Is it any other simpler way of doing this without having to write explicitly new interface C functions?

Regards.