private void Start_btn_Click(object sender, RoutedEventArgs e) { mqttconnection = new MqttConnection(this); mqttconnection.Host = URL_Box.Text; mqttconnection.Port = Convert.ToInt32(Port_Box.Text); mqttconnection.Topic = TopicBox.Text; mqttconnection.MessageText = MessageBox.Text; mqttconnection.Intervaltime = (float)IntervalNr.Value; mqttconnection.Device_Nr = Convert.ToUInt32(DeviceNr.Value); StartSpinner.Visibility = Visibility.Visible; Start_btn.IsEnabled = false; Stop_btn.IsEnabled = true; Label_error.Content = ""; Label_Status.Content = "Connecting "; mqttconnection.MQTTConnection_start(); }