Damn, I posted the wrong Fortran code... It´s too early in the morning and I haven´t had any coffee yet ;-)

globaleVariablen is a module where username is declared as character*4. In the C# part you have to name the length of the character, so you write get_username(stringBuilderValue, 4), although the Fortran function doesn´t have a second parameter. 

 

 

	subroutine put_username(value)
		use globaleVariablen
		implicit none
		character*4 username
		username = value
	end subroutine put_username
!
	character*4 function get_username()
		use globaleVariablen
		implicit none
		getusername = username
	end function get_username

Markus