Hi Christian, I am getting a handle to a device set which seems to work fine. Once I have that handle, I need to step through the set and pass each item to setupdienumdeviceinterfaces(). Below is the code I am currently working with for trying to figure this out:

*--below is a valid guid which I can get a handle to
cguid = [{36FC9E60-C465-11CF-8056-444553540000}]
? cguid

*!*	DIGCF_ALLCLASSES 
*!*	Return a list of installed devices for all device setup classes or all device interface classes. 
*!*	DIGCF_DEVICEINTERFACE 
*!*	Return devices that support device interfaces for the specified device interface classes. 
*!*	DIGCF_DEFAULT 
*!*	Return only the device that is associated with the system default device interface, if one is set, for the specified device interface classes. 
*!*	DIGCF_PRESENT 
*!*	Return only devices that are currently present in a system. 
*!*	DIGCF_PROFILE 
*!*	Return only devices that are a part of the current hardware profile. 
#DEFINE ERROR_NO_MORE_ITEMS        259
#DEFINE ERROR_INVALID_PARAMETER     87
#DEFINE ERROR_INVALID_FLAGS       1004
#DEFINE ERROR_INSUFFICIENT_BUFFER  122
#DEFINE DIGCF_INTERFACEDEVICE       16           && 0x00000010
#DEFINE DIGCF_PRESENT                2           && 0x00000002
#define DIGCF_ALLCLASSES             4
*!*	#define DIGCF_DEFAULT           0x00000001  // only valid with DIGCF_DEVICEINTERFACE
*!*	#define DIGCF_PRESENT           0x00000002
*!*	#define DIGCF_ALLCLASSES        0x00000004
*!*	#define DIGCF_PROFILE           0x00000008
*!*	#define DIGCF_DEVICEINTERFACE   0x00000010

DECLARE SHORT StrToIntEx IN Shlwapi; 
	STRING pszString, INTEGER dwFlags, INTEGER @pllRet 

DECLARE INTEGER GetLastError IN kernel32

DECLARE INTEGER SetupDiGetClassDevs IN setupapi.dll ;
    STRING @cGuid, ;
    STRING Enumerator, ;
    INTEGER hwndParent, ;
    INTEGER nFlags
    
 nflags = 0   
 Enumerator = []
 hwndParent = 0
   
DECLARE INTEGER SetupDiEnumDeviceInterfaces IN setupapi;
	INTEGER DeviceInfoSet,;
	STRING @ DeviceInfoData,;
	STRING @ ByRefterfaceClassGuid,;
	INTEGER MemberIndex,;
	STRING @ DeviceInterfaceData
	
sizeof = REPLICATE(' ',2048)+CHR(0)
i = 1
nInfo = REPLICATE(' ',2048)+CHR(0)
PSP_DEVINFO_DATA = []
	
lnpointer = 0
DO WHILE .T.
	lnpointer =  SetupDiGetClassDevs(@cGuid,null,0,DIGCF_INTERFACEDEVICE)
	IF TYPE('lnpointer') = "N" .and. lnpointer > 0
		lldestroy = .t.
		? '        Handle to Device Set: '
		?? ALLTRIM(STR(lnpointer))
		DeviceInfoSet = lnpointer
		i = 1
                *--I have a handle to the device set (DeviceInfoSet)
		*--Now I need to step through the set and pass each item to the below function	

*!*			IF !SetupDiEnumDeviceInterfaces(DeviceInfoSet, @nInfo , @cGuid, 0, @sizeof)
*!*				IF GetLastError() = ERROR_NO_MORE_ITEMS
*!*					EXIT
*!*				ELSE
*!*					EXIT
*!*				ENDIF
*!*			ELSE
*!*				EXIT
*!*			ENDIF
			
	ELSE
		EXIT
	ENDIF
ENDDO
IF lldestroy
	*--Cleanup
	?'=================================================='
	?'Cleaning Up...'
	DECLARE INTEGER SetupDiDestroyDeviceInfoList IN setupapi;
	    INTEGER DeviceInfoSet
	llokay = SetupDiDestroyDeviceInfoList(lnpointer)
	?'        Releasing the handle - SetupDiDestroyDeviceInfoList Result: '
	?? llokay
	?'        Last Error: '
	?? GetLastError()
	
ENDIF
RETURN

FUNCTION hex2dec (lcHex)
#DEFINE STIF_SUPPORT_HEX           1 
LOCAL lnRet 
lnRet = 0 
IF StrToIntEx (lcHex, STIF_SUPPORT_HEX, @lnRet) = 1
	RETURN lnRet
ELSE
	RETURN 0
ENDIF

RETURN



*************************************************************************

//
// Device information structure (references a device instance
// that is a member of a device information set)
//
typedef struct _SP_DEVINFO_DATA {
    DWORD cbSize;
    GUID  ClassGuid;
    DWORD DevInst;    // DEVINST handle
    DWORD Reserved;
} SP_DEVINFO_DATA, *PSP_DEVINFO_DATA;

//
// Device interface information structure (references a device
// interface that is associated with the device information
// element that owns it).
//
typedef struct _SP_DEVICE_INTERFACE_DATA {
    DWORD cbSize;
    GUID  InterfaceClassGuid;
    DWORD Flags;
    DWORD Reserved;
} SP_DEVICE_INTERFACE_DATA, *PSP_DEVICE_INTERFACE_DATA;

//
// Flags for SP_DEVICE_INTERFACE_DATA.Flags field.
//
#define SPINT_ACTIVE  0x00000001
#define SPINT_DEFAULT 0x00000002
#define SPINT_REMOVED 0x00000004

//

>Hello Tracy,
>
>"how would you access the properties of the result if the result is a set?"
>
>i don't quite understand what you mean.
>Do you mean a function that returns a pointer to an array of C style strings?
>
>e.g.
>

>DECLARE INTEGER SomeFunc IN somedll.dll INTEGER @ nArraySize
>LOCAL lnSize
>lnSize = 0
>lnPointer = SomeFunc(@lnSize)
>FOR xj = 1 TO lnSize
> ? "Item", xj, SYS(2600,lnPointer)
> lnPointer = lnPointer + 4 && + sizeof(char*)
>ENDFOR
>

>
>if this is not what you meant, you may point me to the API function that you wanna use so i can have a look at it and give you a more precise answer.
>
>Christian