'typedef void(AppCallbackT)( ReqCntrlT*,
    '                            CallBkAppDataT*,
    '                            AppCntxtDataT*,
    '                            StatusDataT* );
 
    Public Delegate Sub CallbackFunction(ByRef vbReqCntrlT As ReqCntrlT, _
                                       ByRef vbCallBkAppDataT As _
                                       CallBkAppDataT, _
                                       ByRef vbAppCntxtDataT As AppCntxtDataT, _
                                       ByRef vbStatusDataT As StatusDataT)
 
    'void VCI_Connect( ReqCntrlT     *reqControl,
    '                  CnctReqDataT  *reqData,
    '                  AppCallbackT  *callbackFunc,
    '                  AppCntxtDataT *callbackCntxtData,
    '                  CnctRespDataT *respData,
    '                  StatusDataT   *statusDataGlobal );
 
    <DllImport("VALUES.dll", CharSet:=CharSet.Ansi, _
      CallingConvention:=CallingConvention.Cdecl)> _
        Public Shared Sub VCI_Connect(ByRef reqControl As ReqCntrlT, _
                                    ByRef reqData As CnctReqDataT, _
                                    ByRef callbackFunc As CallbackFunction, _
                                    ByRef callbackCntxtData As AppCntxtDataT, _
                                    ByRef respData As CnctRespDataT, _
                                    ByRef statusDataGlobal As StatusDataT)
    End Sub

        Dim cb As CallbackFunction
        cb = AddressOf myCallBackFunction
 
        VCI_Connect(reqControl, reqData, cb, callbackCntxtData, respData, _
          statusDataGlobal)

    Private Sub myCallBackFunction(ByRef vbReqCntrlT As ReqCntrlT, _
                                ByRef vbCallBkAppDataT As CallBkAppDataT, _
                                ByRef vbAppCntxtDataT As AppCntxtDataT, _
                                ByRef vbStatusDataT As StatusDataT)
                   '
                   '
                   '  do something
                   '
                   '
     End Sub