COM interfaces

[jjgermis]

This topic relates to the Microsoft Component Object Model: I used the Fortran Module Wizard in VS2005 to generatea module for the COM interfaces. The COM object is created successfully. Here is the code:

[cpp]	  CALL COMINITIALIZE(status)
	  write(*,*) 'Opens the Maxwell script interface'
	  CALL COMCREATEOBJECT ("AnsoftMaxwell.MaxwellScriptInterface", maxwellapp, status)
	  write(*,*) 'Perform some FEA calculations'
	  desktop = IMaxwellAppComInterface_GetAppDesktop(maxwellapp, pVal)[/cpp]

When I try to get the desktop information, I get the following error: Unhandled exception at 0x00000000 in maxwell.exe: 0xC0000005: Access violation reading location 0x00000000.
The automatically generated COM module for the GetAppDesk functionis as follows:

[cpp]		INTERFACE
			!method GetAppDesktop
  			INTEGER(4) FUNCTION IMaxwellAppComInterface_GetAppDesktop($OBJECT, pVal)
				INTEGER(INT_PTR_KIND()), INTENT(IN)	:: $OBJECT	 ! Object Pointer
				!DEC$ ATTRIBUTES VALUE	:: $OBJECT
				INTEGER(INT_PTR_KIND()), INTENT(OUT)	:: pVal	! IDispatch
				!DEC$ ATTRIBUTES REFERENCE	:: pVal
			!DEC$ ATTRIBUTES STDCALL :: IMaxwellAppComInterface_GetAppDesktop
			END FUNCTION IMaxwellAppComInterface_GetAppDesktop
		END INTERFACE

  			INTEGER(4) FUNCTION $IMaxwellAppComInterface_GetAppDesktop($OBJECT, pVal)
				IMPLICIT NONE
	
				INTEGER(INT_PTR_KIND()), INTENT(IN)	:: $OBJECT	 ! Object Pointer
				!DEC$ ATTRIBUTES VALUE	:: $OBJECT
				INTEGER(INT_PTR_KIND()), INTENT(OUT)	:: pVal	! IDispatch
				!DEC$ ATTRIBUTES REFERENCE	:: pVal
				INTEGER(4) $RETURN
				INTEGER(INT_PTR_KIND()) $VTBL			! Interface Function Table
				POINTER($VPTR, $VTBL)
				$VPTR = $OBJECT			! Interface Function Table
				$VPTR = $VTBL + 28	! Add routine table offset
				IMaxwellAppComInterface_GetAppDesktop_PTR = $VTBL
				$RETURN = IMaxwellAppComInterface_GetAppDesktop($OBJECT, pVal)
				$IMaxwellAppComInterface_GetAppDesktop = $RETURN
			END FUNCTION $IMaxwellAppComInterface_GetAppDesktop
[/cpp]

I have no experience with COM and do not know where to find information or help on this topic. I will glad for advice on how to solve this issue.