Private Sub Text1_Change()
 
    If Len(Text1.Text) > 6 Then
        Dim iLastPos As Integer
        iLastPos = Text1.SelStart
        Text1.Text = Mid(Text1.Text, 1, 6)
        Text1.SelStart = iLastPos
    End If
 
End Sub
 
Private Sub Text1_KeyPress(KeyAscii As Integer)
 
    If Len(Text1.Text) = 6 And Not KeyAscii = 127 And Not KeyAscii = 8 And _
      Text1.SelLength = 0 Then
        KeyAscii = 0
    End If
 
End Sub

Mit freundlichen Gr??en,
Andy G.