Visual Basic

Private Sub SerialPort1_DataReceived(ByVal sender As Object, ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) Handles SerialPort1.DataReceived
        '' Threading.Thread.Sleep(500)
        Try

            txtResults.Invoke(New myDelegate(AddressOf updateTextBox), New Object() {})

        Catch ex As Exception
            MsgBox(ex.ToString)
        End Try

    End Sub

 Public Delegate Sub myDelegate()

Public Sub updateTextBox()
        With txtResults
            .Font = New Font("Arial", 10.0, FontStyle.Bold)


           SerialPort1.ReadExisting())
            .AppendText(SerialPort1.ReadExisting())

            .ScrollToCaret()


        End With
        'THIS WILL ONLY WORK WHEN CONNECTED  SerialPort1.Close()
    End Sub

#Region "SMS"
    Public Sub openModem()
        Try
            Modem.Open()
        Catch ex As Exception

        End Try

        Thread.Sleep(7000)

        ModemWrite(" ", False)
        MsgBox(ModemWrite("AT+COPS?", True))
    End Sub
    Public Function ModemWrite(ByVal WriteString As String, ByVal ExpectReturn As Boolean) As String
        Dim ReturnString As String = ""
        Modem.DiscardOutBuffer()
        Modem.DiscardInBuffer()


        Try
            Modem.Write(WriteString)
            Application.DoEvents()
        Catch ex As Exception

        End Try
        Thread.Sleep(1000)
        If ExpectReturn = True Then
            While ReturnStringTXT.Text = ""
                Application.DoEvents()
            End While
            While Not ReturnStringTXT.Text = ""
                ReturnString = ReturnStringTXT.Text
            End While

        End If

        Return ReturnString
    End Function
    Private Sub ModemDataReceived(ByVal sender As Object, ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) Handles Modem.DataReceived
        Try
            ReturnStringTXT.Invoke(New smsDelegate(AddressOf updateTextBox), New Object() {})
        Catch ex As Exception
            MsgBox(ex.ToString)
        End Try

    End Sub
    Public Delegate Sub smsDelegate()
    Public Sub updateTextBox()
        ReturnStringTXT.Text = Modem.ReadExisting()
    End Sub
#End Region

System.InvalidOperationException: Invoke or BeginInvoke cannot be called on a control until the window handle has been created.<br />
  at System.Windows.Forms.Control.MarshaledInvoke(Control caller, Delegate method, Objects[] args, Boolean synchronous)<br />
  at System.Windows.Forms.Control.Invoke(Delegate method, Object[] args)<br />
  at Application.GUI.ModemDataReceived(Objects sender, SerialDataReceivedExentArgs e) in C:\Application\Server

private void button1_Click(object sender, EventArgs e)
{
    foreach (Control cntl in this.Controls)
        lockControls(cntl);
}
		
private void lockControls(Control ctrl)
{
    ctrl.Enabled = false;
    foreach (Control childControl in ctrl.Controls)
        lockControls(childControl);
}

Eduard Keilholz wrote:

But why would you also disable all child controls, parent controls do disable child controls once disabled...