diff --git a/src/portcontrol.cpp b/src/portcontrol.cpp
--- a/src/portcontrol.cpp
+++ b/src/portcontrol.cpp
@@ -1,5 +1,5 @@
 /*
-  Copyright © 2016 Hasan Yavuz Özderya
+  Copyright © 2017 Hasan Yavuz Özderya
 
   This file is part of serialplot.
 
@@ -130,6 +130,9 @@ PortControl::PortControl(QSerialPort* po
                      SELECT<int>::OVERLOAD_OF(&QButtonGroup::buttonClicked),
                      this, &PortControl::selectFlowControl);
 
+    // test code
+    connect(ui->pbDTR, &QPushButton::clicked, ui->ledDTR, &LedWidget::toggle);
+
     loadPortList();
     loadBaudRateList();
     ui->cbBaudRate->setCurrentIndex(ui->cbBaudRate->findText("9600"));