Probleme beim öffnen und schließen des mscomm-port in vb6, wenn er eine Schnittstelle mikrocontroller

    '****** paste this in form'*********    
    Option Explicit

        Dim Portnumber As Integer


        Private Sub cmdClose_Click()

            On Error GoTo handler

            MSComm1.PortOpen = False
            Shape1.FillColor = vbRed
            cmdOpen.Enabled = True
            txtRecieve.Text = ""
            Exit Sub

        handler:                                MsgBox Err.Description
        End Sub

        Private Sub cmdOpen_Click()

            On Error GoTo handler

         '   Debug.Print cboComm.ItemData(cboComm.ListIndex)

            portnumber = Mid(cboComm.Text, 4, (Len(cboComm.Text) - 3))

            a = Mid(cboComm.Text, 4, (Len(cboComm.Text) - 3))
        '    If MSComm1.PortOpen = False Then
                MSComm1.CommPort = portnumber
                MSComm1.PortOpen = True
                Shape1.FillColor = vbGreen
                cmdOpen.Enabled = False
        '    End If

            Exit Sub

        handler:                   MsgBox Err.Description
        End Sub

        Private Sub Form_Load()
            cboComm.Clear   '*** cbo is for combobox
            MSComm1.Settings = "9600,n,8,1"
            ListComPorts
        End Sub

        Private Sub ListComPorts()

            Dim i As Integer

            cboComm.Clear

            Static iData As Integer
            iData = -1

            For i = 1 To 16
                If ComAvailable(i) Then
                    cboComm.AddItem (("COM") & i)
                    iData = iData + 1
                    cboComm.ItemData(iData) = i
                End If

            Next

            cboComm.ListIndex = 0
            '    cmdGet.Enabled = False
        End Sub

        Private Sub MSComm1_OnComm()

            Select Case MSComm1.CommEvent

                Case comEvReceive
                    txtRecieve.Text = MSComm1.Input

                Case Else
                    Debug.Print "Event: " & MSComm1.CommEvent
            End Select

        End Sub
        '**************** End of form code **************

       '*********** Now API code******************

        '********** Paste in Module**************

        Option Explicit

        '*** API Declarations
        Public Declare Function CreateFile Lib "kernel32" Alias "CreateFileA" (ByVal lpFileName As String, ByVal dwDesiredAccess As Long, ByVal dwShareMode As Long, lpSecurityAttributes As SECURITY_ATTRIBUTES, ByVal dwCreationDisposition As Long, ByVal dwFlagsAndAttributes As Long, ByVal hTemplateFile As Long) As Long

        Public Declare Function CloseHandle Lib "kernel32" (ByVal hObject As Long) As Long

        '*** API Structures
        Public Type SECURITY_ATTRIBUTES

            nLength As Long
            lpSecurityDescriptor As Long
            bInheritHandle As Long

        End Type

        '***API Constants
        Public Const FILE_SHARE_READ = &H1

        Public Const FILE_SHARE_WRITE = &H2

        Public Const OPEN_EXISTING = 3

        Public Const FILE_ATTRIBUTE_NORMAL = &H80

        '*** Create a Fuction to check whether COM exists or not. If exists return "true" otherwise "false"
        Public Function ComAvailable(comnum As Integer) As Boolean

            Dim hcom As Long

            Dim ret  As Long

            Dim sec  As SECURITY_ATTRIBUTES

            hcom = CreateFile("\.\COM" & comnum & "", 0, FILE_SHARE_READ + FILE_SHARE_WRITE, sec, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0)

            If hcom = -1 Then
                ComAvailable = False
            Else
                ComAvailable = True

                '*** close the CO MPort
                ret = CloseHandle(hcom)
            End If

        End Function

        ''''''''*******End of module code********

I think  this will help you.....