diff --git a/mainwindow.h b/mainwindow.h
--- a/mainwindow.h
+++ b/mainwindow.h
@@ -3,7 +3,9 @@
 
 #include <QMainWindow>
 #include <QString>
+#include <QVector>
 #include <QSerialPort>
+#include <qwt_plot_curve.h>
 
 namespace Ui {
 class MainWindow;
@@ -21,6 +23,12 @@ private:
     Ui::MainWindow *ui;
     QSerialPort serialPort;
 
+    unsigned int numOfSamples;
+    QwtPlotCurve curve;
+    QVector<double> dataArray;
+    QVector<double> dataX;
+    void addData(double data);
+
 private slots:
     void loadPortList();
     void loadBaudRateList();