Public Class MessModul
    Implements System.ComponentModel.INotifyPropertyChanged
 
    Private _spannung As Double
    Public Property Spannung() As Double
        Set(ByVal value As Double)
            _spannung = value
            RaiseEvent PropertyChanged(Me, _
            New System.ComponentModel.PropertyChangedEventArgs _
            ("Spannung"))
        End Set
        Get
            Return _spannung
        End Get
    End Property
 
    Private _messwert As Double
    Public Property messwert() As Double
        Set(ByVal value As Double)
            _messwert = value
            RaiseEvent PropertyChanged(Me, _
            New System.ComponentModel.PropertyChangedEventArgs _
            ("Messwert"))
        End Set
        Get
            Return _messwert
        End Get
    End Property
 
    Public Event PropertyChanged(ByVal sender As Object, _
     ByVal e As System.ComponentModel.PropertyChangedEventArgs) _
     Implements System.ComponentModel.INotifyPropertyChanged.PropertyChanged
End Class

Public Class frmMain
 
    Dim txtSpannung As New TextBox With _
    {.Parent = Me, .Top = 10, .Left = 10, .Width = 200}
 
    Dim WithEvents btnAbfrage As New Button With _
    {.Parent = Me, .Top = 50, .Left = 10, .Width = 200, .Text = "Abfrage"}
 
    Dim lblMesswert As New Label With _
    {.Parent = Me, .Top = 90, .Left = 10, .Width = 200}
    Dim MeineAbfrage As New frmAbfrage
 
    Dim MeinMessModul As New MessModul
 
    Private Sub frmMain_Load(ByVal sender As System.Object, _
                         ByVal e As System.EventArgs) Handles MyBase.Load
 
        txtSpannung.DataBindings.Add(New Binding_
               ("Text", MeinMessModul, "Spannung"))
        lblMesswert.DataBindings.Add(New Binding _
               ("Text", MeinMessModul, "Messwert"))
 
    End Sub
 
    Private Sub btnAbfrage_Click(ByVal sender As Object, _
            ByVal e As System.EventArgs) Handles btnAbfrage.Click
 
        With MeineAbfrage
            .AbfrageMessModul = MeinMessModul
            .ShowDialog()
        End With
    End Sub
End Class

Public Class frmAbfrage
 
    Private txtMesswert As New TextBox With _
    {.Parent = Me, .Top = 10, .Left = 10, .Width = 200}
 
    Private _abfragemessmodul As MessModul
 
    Private btnOk As New Button With _
        {.Parent = Me, .Top = 50, .Left = 10, .Text = "OK", _
         .DialogResult = Windows.Forms.DialogResult.OK}
 
    Public Property AbfrageMessModul As MessModul
        Set(ByVal value As MessModul)
            _abfragemessmodul = value
        End Set
        Get
            Return _abfragemessmodul
        End Get
    End Property
 
    Private Sub frmAbfrage_FormClosing(ByVal sender As Object, _
        ByVal e As System.Windows.Forms.FormClosingEventArgs) _
        Handles Me.FormClosing
        If e.CloseReason = CloseReason.UserClosing Then
            Me.Hide() : e.Cancel = True
        End If
    End Sub
 
    Private Sub frmAbfrage_Load(ByVal sender As System.Object, _
                   ByVal e As System.EventArgs) Handles MyBase.Load
        If txtMesswert.DataBindings.Count = 0 Then
            txtMesswert.DataBindings.Add(New Binding _
            ("Text", _abfragemessmodul, "Messwert"))
        End If
    End Sub
End Class