how to call external function with a pointer argument in legacy_code

There is a function can_transmit(long ID,usigned char DataArray) used as a MSCAN driver of my device. I want to generate a S-Function by legacy_code and call this function in the generated code. However, I don't know how to pass the address of my data into can_transmit function. I tried the array, however the generated code will use real_T type, and it's reported impossible to convert the real_T* to usigned char.