C# Signature:

[DllImport(@"setupapi.dll", CharSet=CharSet.Auto, SetLastError = true)]
public static extern Boolean SetupDiEnumDeviceInterfaces(
   IntPtr hDevInfo,
   ref SP_DEVINFO_DATA devInfo,
   ref Guid interfaceClassGuid,
   UInt32 memberIndex,
   ref SP_DEVICE_INTERFACE_DATA deviceInterfaceData
);

// Alternate signature if you do not care about SP_DEVINFO_DATA and wish to pass NULL (IntPtr.Zero). Note example below uses this signature.
[DllImport(@"setupapi.dll", CharSet = CharSet.Auto, SetLastError = true)]
public static extern Boolean SetupDiEnumDeviceInterfaces(
   IntPtr hDevInfo,
   IntPtr devInfo,
   ref Guid interfaceClassGuid,
   UInt32 memberIndex,
   ref SP_DEVICE_INTERFACE_DATA deviceInterfaceData
);

VB Signature:

  <DllImport("setupapi.dll", CharSet:=CharSet.Auto, SetLastError:=True)> _
  Public Shared Function SetupDiEnumDeviceInterfaces(ByVal hDevInfo As IntPtr, _
    ByRef devInfo As SP_DEVICE_INTERFACE_DATA, ByRef interfaceClassGuid As Guid, _
    ByVal memberIndex As UInt32, ByRef deviceInterfaceData As SP_DEVICE_INTERFACE_DATA) As Boolean
  End Function

VB 9 Syntax

Public Declare Auto Function SetupDiEnumDeviceInterfaces Lib "setupapi.dll" ( _
    ByVal DeviceInfoSet As IntPtr, _
    ByVal DeviceInfoData As UInteger, _
    ByRef InterfaceClassGuid As Guid, _
    ByVal MemberIndex As UInteger, _
    ByRef DeviceInterfaceData As SP_DEVICE_INTERFACE_DATA) As Boolean

User-Defined Types:

None.

VB User-Defined Types:

<StructLayout(LayoutKind.Sequential)> _
Public Structure SP_DEVICE_INTERFACE_DATA
    Public cbSize As UInteger
    Public InterfaceClassGuid As Guid
    Public Flags As UInteger
    Public Reserved As IntPtr
End Structure

Notes:

A call to SetupDiEnumDeviceInterfaces retrieves a pointer to a structure that identifies a specific device interface in the previously retrieved DeviceInfoSet array. The call specifies a device interface by passing an array index. To retrieve information about all of the device interfaces, an application can loop through the array, incrementing the array index until the function returns zero, indicating that there are no more interfaces. The GetLastError API function then returns No more data is available.

Tips & Tricks:

    [StructLayout(LayoutKind.Sequential)]
    public struct SP_DEVINFO_DATA
    {
        public uint cbSize;
        public Guid ClassGuid;
        public uint DevInst;
        public IntPtr Reserved;
    }

//You need to create a structure for the deviceInterfaceData like this....

    [StructLayout(LayoutKind.Sequential)]
    public struct SP_DEVICE_INTERFACE_DATA
    {
        public uint cbSize;
        public Guid InterfaceClassGuid;
        public uint Flags;
        public IntPtr Reserved;    
    }

//Then initialize the cbSize value like this in your calling method

SP_DEVICE_INTERFACE_DATA devData = new SP_DEVICE_INTERFACE_DATA();

devData.cbSize = System.Runtime.InteropServices.Marshal.SizeOf(devData);

// failure to do so will always return false (which is the value you'll also get if the device is not connected)

// Here's what the call looks like...

bool result = Win32Calls.SetupDiEnumDeviceInterfaces(ipDeviceHndl, iLU, ref DeviceGUID, 0, ref devData);

// The DeviceGUID parameter will be device dependant. Look in the Manufacturer's sdk or api for the correct guid for your device

Sample Code:

class Win32Calls
    {
    [DllImport(@"setupapi.dll", CharSet = CharSet.Auto, SetLastError = true)]
    public static extern IntPtr SetupDiGetClassDevs(ref Guid classGuid, IntPtr enumerator, IntPtr hwndParent, UInt32 flags);
    [DllImport(@"setupapi.dll", CharSet = CharSet.Auto, SetLastError = true)]
    public static extern Boolean SetupDiEnumDeviceInterfaces(IntPtr hDevInfo, IntPtr devInfo, ref Guid interfaceClassGuid, UInt32 memberIndex, ref SP_DEVICE_INTERFACE_DATA deviceInterfaceData);

    }

Additional Sample:

Guid DiskGUID = new Guid(GUID_DEVINTERFACE_DISK);

// We start at the "root" of the device tree and look for all
// devices that match the interface GUID of a disk
IntPtr h = SetupDiGetClassDevs(ref DiskGUID, 0, IntPtr.Zero, DIGCF_PRESENT | DIGCF_DEVICEINTERFACE);
if (h.ToInt32() != INVALID_HANDLE_VALUE)
{
   bool Success = true;
   int i = 0;            //To author: Could you, please, check it once again? My compiler tells me, it suppose to be uint instead of int.
                 //Thank you.
   while (Success)
   {
     // create a Device Interface Data structure
     SP_DEVICE_INTERFACE_DATA dia = new SP_DEVICE_INTERFACE_DATA();
     dia.cbSize = Marshal.SizeOf(dia);

     // start the enumeration
     Success = SetupDiEnumDeviceInterfaces(h, IntPtr.Zero, ref DiskGUID, i, ref dia);
     if (Success)
     {
       // build a DevInfo Data structure
       SP_DEVINFO_DATA da = new SP_DEVINFO_DATA();
       da.cbSize = Marshal.SizeOf(da);

       // build a Device Interface Detail Data structure
       SP_DEVICE_INTERFACE_DETAIL_DATA didd = new SP_DEVICE_INTERFACE_DETAIL_DATA();
       didd.cbSize = 4 + Marshal.SystemDefaultCharSize; // trust me :)

       // now we can get some more detailed information
       int nRequiredSize = 0;
       int nBytes = BUFFER_SIZE;
       if (SetupDiGetDeviceInterfaceDetail(h, ref dia, ref didd, nBytes, ref nRequiredSize, ref da))
       {
       // current InstanceID is at the "USBSTOR" level, so we
       // need up "move up" one level to get to the "USB" level
       IntPtr ptrPrevious;
       CM_Get_Parent(out ptrPrevious, da.DevInst, 0);

       // Now we get the InstanceID of the USB level device
       IntPtr ptrInstanceBuf = Marshal.AllocHGlobal(nBytes);
       CM_Get_Device_ID(ptrPrevious, ptrInstanceBuf, nBytes, 0);
       string InstanceID = Marshal.PtrToStringAuto(ptrInstanceBuf);

       Marshal.FreeHGlobal(ptrInstanceBuf);
       }
       i++;
     }
   }
}
SetupDiDestroyDeviceInfoList(h);