diff --git a/README.md b/README.md
index b8ad999..bca6baf 100644
--- a/README.md
+++ b/README.md
@@ -55,9 +55,13 @@ https://www.wemos.cc/en/latest/ch340_driver.html
 
 The Arduino SW understands the following commands:
 
-* "D11\n", "D21\n"  or "D61\n"  Activate Relais connected to pin D1, D2 or D6
-* "D10\n", "D20\n"  or "D60\n" Deactivate Relais connected to pin D1, D2 or D6
-* "D1T\n", "D2T\n"  or "D6T\n" Trigger Relais connected to pin D1, D2 or D6 for 500ms
+* "R11\n", "R21\n", "R31\n", "R41\n", "R51\n" Activates Relais connected to pin D1, D2, D6, D7 and D8
+* "R10\n", "R20\n", "R30\n", "R40\n", "R50\n" Deactivates Relais connected to pin D1, D2, D6, D7 and D8
+* "R1T\n", "R2T\n", "R3T\n", "R4T\n", "R5T\n" Trigger Relais connected to pin D1, D2, D6, D7 and D8 for 500ms
+
+The Arduino board sends the status of Relais, when it was triggered with the button with the same command.
+
+The Arduino board sends every second a watchdog signal "WD\n".
 
 ## Installation
 
@@ -85,6 +89,15 @@ Github Sponsors:
 
 [:heart: Sponsor](https://github.com/sponsors/alexmucde)
 
+## Changes
+
+v0.0.3:
+
+* Support up to 5 Relais
+* Changed communication protocol with Arduino board
+* Added Watchdog
+* Fixed startup problem with Arduino Flash Mode
+
 ## Copyright
 
 Alexander Wenzel <alex@eli2.de>
diff --git a/dialog.cpp b/dialog.cpp
index 6f38837..4ee758b 100644
--- a/dialog.cpp
+++ b/dialog.cpp
@@ -30,22 +30,26 @@ Dialog::Dialog(QWidget *parent)
 {
     ui->setupUi(this);
 
+    // clear settings
     on_pushButtonDefaultSettings_clicked();
 
+    // set window title with version information
     setWindowTitle(QString("DLTRelais %1").arg(DLT_RELAIS_VERSION));
 
+    // disable stop button at startup
     ui->pushButtonStop->setDisabled(true);
 
+    // connect status slots
     connect(&dltRelais, SIGNAL(status(QString)), this, SLOT(statusRelais(QString)));
     connect(&dltMiniServer, SIGNAL(status(QString)), this, SLOT(statusDlt(QString)));
 
-    /*  load global settings */
+    //  load global settings from registry
     QSettings settings;
     QString filename = settings.value("autoload/filename").toString();
     bool autoload = settings.value("autoload/checked").toBool();
     bool autostart = settings.value("autostart/checked").toBool();
 
-    /* autoload settings */
+    // autoload settings, when activated in global settings
     if(autoload)
     {
         dltRelais.readSettings(filename);
@@ -53,7 +57,7 @@ Dialog::Dialog(QWidget *parent)
         restoreSettings();
     }
 
-    /* autostart */
+    // autostart, when activated in global settings
     if(autostart)
     {
         on_pushButtonStart_clicked();
@@ -62,6 +66,8 @@ Dialog::Dialog(QWidget *parent)
 
 Dialog::~Dialog()
 {
+
+    // disconnect status slots
     disconnect(&dltRelais, SIGNAL(status(QString)), this, SLOT(statusRelais(QString)));
     disconnect(&dltMiniServer, SIGNAL(status(QString)), this, SLOT(statusDlt(QString)));
 
@@ -70,7 +76,7 @@ Dialog::~Dialog()
 
 void Dialog::restoreSettings()
 {
-    /* DLTRelais */
+    // update names of Relais
     ui->lineEditRelaisName1->setText(dltRelais.getRelaisName(1));
     ui->lineEditRelaisName2->setText(dltRelais.getRelaisName(2));
     ui->lineEditRelaisName3->setText(dltRelais.getRelaisName(3));
@@ -85,11 +91,15 @@ void Dialog::updateSettings()
 
 void Dialog::on_pushButtonStart_clicked()
 {
+    // start communication
     updateSettings();
 
+    // start Relais and DLT communication
     dltRelais.start();
     dltMiniServer.start();
 
+    // disable settings and start button
+    // enable stop button
     ui->pushButtonStart->setDisabled(true);
     ui->pushButtonStop->setDisabled(false);
     ui->pushButtonDefaultSettings->setDisabled(true);
@@ -99,9 +109,14 @@ void Dialog::on_pushButtonStart_clicked()
 
 void Dialog::on_pushButtonStop_clicked()
 {
+    // stop communication
+
+    // stop Relais and DLT communication
     dltRelais.stop();
     dltMiniServer.stop();
 
+    // enable settings and start button
+    // disable stop button
     ui->pushButtonStart->setDisabled(false);
     ui->pushButtonStop->setDisabled(true);
     ui->pushButtonDefaultSettings->setDisabled(false);
@@ -111,6 +126,9 @@ void Dialog::on_pushButtonStop_clicked()
 
 void Dialog::statusRelais(QString text)
 {
+    // status from Relais
+
+    // Relais status changed on Arduino board
     if(text=="R10\r\n")
     {
         ui->checkBoxRelais1->setChecked(false);
@@ -165,6 +183,8 @@ void Dialog::statusRelais(QString text)
         ui->checkBoxRelais5->setChecked(true);
         return;
     }
+
+    // status of Relais communication changed
     else if(text == "" || text == "stopped")
     {
         QPalette palette;
@@ -190,8 +210,10 @@ void Dialog::statusRelais(QString text)
 
 void Dialog::statusDlt(QString text)
 {
+    // status from DLT Mini Server
     ui->lineEditStatusDLT->setText(text);
 
+    // status of DLT communication changed
     if(text == "" || text == "stopped")
     {
         QPalette palette;
@@ -218,6 +240,9 @@ void Dialog::statusDlt(QString text)
     }
 }
 
+// The following functions are called, when the Relais Checkboxes are triggered or the Trigger
+// button is pressed
+
 void Dialog::on_checkBoxRelais1_clicked(bool checked)
 {
     if(checked)
@@ -322,8 +347,10 @@ void Dialog::on_checkBoxRelais5_clicked(bool checked)
         dltMiniServer.sendValue2(dltRelais.getRelaisName(5),"Off");
     }
 }
+
 void Dialog::on_pushButtonDefaultSettings_clicked()
 {
+    // Reset settings to default
     dltRelais.clearSettings();
     dltMiniServer.clearSettings();
 
@@ -332,14 +359,18 @@ void Dialog::on_pushButtonDefaultSettings_clicked()
 
 void Dialog::on_pushButtonLoadSettings_clicked()
 {
+    // Load settings from XML file
+
     QString fileName = QFileDialog::getOpenFileName(this,
         tr("Open Settings"), "", tr("DLTRelais Settings (*.xml);;All files (*.*)"));
 
     if(fileName.isEmpty())
     {
+        // No file was selected or cancel was pressed
         return;
     }
 
+    // read the settings from XML file
     dltRelais.readSettings(fileName);
     dltMiniServer.readSettings(fileName);
 
@@ -348,6 +379,8 @@ void Dialog::on_pushButtonLoadSettings_clicked()
 
 void Dialog::on_pushButtonSaveSettings_clicked()
 {
+    // Save settings into XML file
+
     updateSettings();
 
     QString fileName = QFileDialog::getSaveFileName(this,
@@ -355,15 +388,23 @@ void Dialog::on_pushButtonSaveSettings_clicked()
 
     if(fileName.isEmpty())
     {
+        // No file was selected or cancel was pressed
         return;
     }
 
+    // read the settings from XML file
     QFile file(fileName);
     if (!file.open(QFile::WriteOnly | QFile::Text))
-             return;
+    {
+        // Cannot open the file for writing
+        return;
+    }
 
     QXmlStreamWriter xml(&file);
     xml.setAutoFormatting(true);
+
+    // FIXME: Cannot read data from XML file, which contains a start document
+    // So currently do not call StartDocument
     //xml.writeStartDocument();
 
     xml.writeStartElement("DLTRelaisSettings");
@@ -371,6 +412,8 @@ void Dialog::on_pushButtonSaveSettings_clicked()
         dltMiniServer.writeSettings(xml);
     xml.writeEndElement(); // DLTRelaisSettings
 
+    // FIXME: Cannot read data from XML file, which contains a end document
+    // So currently do not call EndDocument
     //xml.writeEndDocument();
     file.close();
 
@@ -378,10 +421,10 @@ void Dialog::on_pushButtonSaveSettings_clicked()
 
 void Dialog::on_pushButtonSettings_clicked()
 {
+    // Open settings dialog
     SettingsDialog dlg(this);
 
     dlg.restoreSettings(&dltRelais, &dltMiniServer);
-
     if(dlg.exec()==QDialog::Accepted)
     {
         dlg.backupSettings(&dltRelais, &dltMiniServer);
@@ -391,6 +434,7 @@ void Dialog::on_pushButtonSettings_clicked()
 
 void Dialog::on_pushButtonInfo_clicked()
 {
+    // Open information window
     QMessageBox msgBox(this);
 
     msgBox.setWindowTitle("Info DLTRelais");
diff --git a/dialog.h b/dialog.h
index 4f2950e..ad733cb 100644
--- a/dialog.h
+++ b/dialog.h
@@ -38,39 +38,40 @@ class Dialog : public QDialog
 
 private slots:
 
+    // Relais control
     void on_checkBoxRelais1_clicked(bool checked);
     void on_pushButtonRelais1Trigger_clicked();
     void on_checkBoxRelais2_clicked(bool checked);
     void on_pushButtonRelais2Trigger_clicked();
     void on_checkBoxRelais3_clicked(bool checked);
     void on_pushButtonRelais3Trigger_clicked();
+    void on_checkBoxRelais4_clicked(bool checked);
+    void on_pushButtonRelais4Trigger_clicked();
+    void on_checkBoxRelais5_clicked(bool checked);
+    void on_pushButtonRelais5Trigger_clicked();
 
+    // Status of Relais and DLT connection
     void statusRelais(QString text);
     void statusDlt(QString text);
 
+    // Settings and Info
     void on_pushButtonSettings_clicked();
     void on_pushButtonDefaultSettings_clicked();
     void on_pushButtonLoadSettings_clicked();
     void on_pushButtonSaveSettings_clicked();
     void on_pushButtonInfo_clicked();
 
+    // Start and stop communication
     void on_pushButtonStart_clicked();
     void on_pushButtonStop_clicked();
 
-    void on_pushButtonRelais4Trigger_clicked();
-
-    void on_pushButtonRelais5Trigger_clicked();
-
-    void on_checkBoxRelais4_clicked(bool checked);
-
-    void on_checkBoxRelais5_clicked(bool checked);
-
 private:
     Ui::Dialog *ui;
 
     DLTRelais dltRelais;
     DLTMiniServer dltMiniServer;
 
+    // Settings
     void restoreSettings();
     void updateSettings();
 };
diff --git a/dltrelais.cpp b/dltrelais.cpp
index c0c6d01..405cd5a 100644
--- a/dltrelais.cpp
+++ b/dltrelais.cpp
@@ -29,6 +29,9 @@ DLTRelais::~DLTRelais()
 
 void DLTRelais::start()
 {
+    // start communication
+
+    // set serial port parameters
     serialPort.setBaudRate(QSerialPort::Baud115200);
     serialPort.setDataBits(QSerialPort::Data8);
     serialPort.setParity(QSerialPort::NoParity);
@@ -36,19 +39,29 @@ void DLTRelais::start()
     serialPort.setFlowControl(QSerialPort::NoFlowControl);
     serialPort.setPortName(interface);
 
+    // open serial port
     if(serialPort.open(QIODevice::ReadWrite)==true)
     {
+        // open with success
+
+        // prevent flash mode of Wemos D1 mini
         serialPort.setDataTerminalReady(false);
-        status(QString("started"));
+
+        // connect slot to receive data from serial port
         connect(&serialPort, SIGNAL(readyRead()), this, SLOT(readyRead()));
+
+        status(QString("started"));
         qDebug() << "DLTRelais: started" << interface;
     }
     else
     {
+        // open failed
+
         qDebug() << "DLTRelais: Failed to open interface" << interface;
         status(QString("error"));
     }
 
+    // connect slot watchdog timer and start watchdog timer
     connect(&timer, SIGNAL(timeout()), this, SLOT(timeout()));
     timer.start(3000);
     watchDogCounter = 0;
@@ -57,79 +70,108 @@ void DLTRelais::start()
 
 void DLTRelais::stop()
 {
+    // stop communication
+    status(QString("stopped"));
+    qDebug() << "DLTRelais: stopped" << interface;
 
+    // close serial port, if it is open
     if(serialPort.isOpen())
     {
         serialPort.close();
+
+        // disconnect slot to receive data from serial port
         disconnect(&serialPort, SIGNAL(readyRead()), this, SLOT(readyRead()));
     }
 
+    // stop watchdog timer
     timer.stop();
     disconnect(&timer, SIGNAL(timeout()), this, SLOT(timeout()));
 
-    status(QString("stopped"));
-    qDebug() << "DLTRelais: stopped" << interface;
 }
 
 void DLTRelais::readyRead()
 {
+    // data on serial port was received
+
+    // loop as long as data is available
     while(serialPort.bytesAvailable())
     {
         char data[256];
+
+        // read one line form serial port
         qint64 size = serialPort.readLine(data,sizeof(data));
 
         if(size>0)
+        {
+            // line is not empty
             qDebug() << "DLTRelais: readLine" << data;
 
-
-        if(QString(data) == "WD\r\n")
-        {
-            watchDogCounter++;
-        }
-        else
-        {
-            status(QString(data));
+            if(QString(data) == "WD\r\n")
+            {
+                // watchdog message received
+                watchDogCounter++;
+            }
+            else
+            {
+                // all other messages forward to status signal
+                status(QString(data));
+            }
         }
     }
 }
 
 void DLTRelais::timeout()
 {
+    // watchdog timeout
+
+    // check if watchdog was triggered between last call
     if(watchDogCounter==watchDogCounterLast)
     {
-        qDebug() << "DLTRelais: Watchdog expired try reconnect" ;
+        // no watchdog was received
+        qDebug() << "DLTRelais: Watchdog expired try to reconnect" ;
 
+        // if serial port is open close serial port
         if(serialPort.isOpen())
         {
             serialPort.close();
             disconnect(&serialPort, SIGNAL(readyRead()), this, SLOT(readyRead()));
         }
 
+        // try to reopen serial port
         if(serialPort.open(QIODevice::ReadWrite)==true)
         {
+            // retry was succesful
+
+            // prevent flash mode of Wemos D1 mini
             serialPort.setDataTerminalReady(false);
+
+            // connect slot to receive data from serial port
             connect(&serialPort, SIGNAL(readyRead()), this, SLOT(readyRead()));
+
             status(QString("started"));
             qDebug() << "DLTRelais: started" << interface;
         }
         else
         {
+            // retry failed
+
             qDebug() << "DLTRelais: Failed to open interface" << interface;
             status(QString("error"));
         }
+        watchDogCounterLast = watchDogCounter;
     }
-    watchDogCounterLast = watchDogCounter;
 }
 
 void DLTRelais::clearSettings()
 {
+    // clear settings
     for(int num=0;num<5;num++)
         relaisName[num] = QString("Relais%1").arg(num+1);
 }
 
 void DLTRelais::writeSettings(QXmlStreamWriter &xml)
 {
-    /* Write project settings */
+    // Write project settings to XML file
     xml.writeStartElement("DLTRelais");
         xml.writeTextElement("relaisName1",relaisName[0]);
         xml.writeTextElement("relaisName2",relaisName[1]);
@@ -142,6 +184,7 @@ void DLTRelais::writeSettings(QXmlStreamWriter &xml)
 
 void DLTRelais::readSettings(const QString &filename)
 {
+    // read settings from XML file
     bool isDLTRelais = false;
 
     QFile file(filename);
@@ -208,6 +251,9 @@ void DLTRelais::readSettings(const QString &filename)
 
 void DLTRelais::trigger(int num)
 {
+    // trigger a Relais for 500ms
+    qDebug() << "DLTRelais: trigger" << num;
+
     if(num==1)
         serialPort.write("R1T\n");
     else if(num==2)
@@ -218,12 +264,13 @@ void DLTRelais::trigger(int num)
         serialPort.write("R4T\n");
     else if(num==5)
         serialPort.write("R5T\n");
-
-    qDebug() << "DLTRelais: trigger" << num;
 }
 
 void DLTRelais::on(int num)
 {
+    // set Relais to on
+    qDebug() << "DLTRelais: on" << num;
+
     if(num==1)
         serialPort.write("R11\n");
     else if(num==2)
@@ -234,12 +281,13 @@ void DLTRelais::on(int num)
         serialPort.write("R41\n");
     else if(num==5)
         serialPort.write("R51\n");
-
-    qDebug() << "DLTRelais: on" << num;
 }
 
 void DLTRelais::off(int num)
 {
+    // set Relais to off
+    qDebug() << "DLTRelais: off" << num;
+
     if(num==1)
         serialPort.write("R10\n");
     else if(num==2)
@@ -250,6 +298,4 @@ void DLTRelais::off(int num)
         serialPort.write("R40\n");
     else if(num==5)
         serialPort.write("R50\n");
-
-    qDebug() << "DLTRelais: off" << num;
 }
diff --git a/dltrelais.h b/dltrelais.h
index 20b24fe..03e73d1 100644
--- a/dltrelais.h
+++ b/dltrelais.h
@@ -28,43 +28,51 @@ class DLTRelais : public QObject
     explicit DLTRelais(QObject *parent = nullptr);
     ~DLTRelais();
 
+    // Start and stop connection
     void start();
     void stop();
 
+    // Trigger Relais
     void trigger(int num);
     void on(int num);
     void off(int num);
 
+    // Interface name
     QString getInterface() { return interface; }
     void setInterface(QString interface) { this->interface = interface; }
 
+    // Relais names
     QString getRelaisName(int num) { if(num>0 && num<6) return relaisName[num-1]; else return QString(); }
     void setRelaisName(int num,const QString &name) { if(num>0 && num<6) this->relaisName[num-1] = name; }
 
+    // Settings
     void clearSettings();
     void writeSettings(QXmlStreamWriter &xml);
     void readSettings(const QString &filename);
 
 signals:
 
+    // Called when status changed
     void status(QString text);
 
 private slots:
 
+    // Serial data available
     void readyRead();
 
+    // Watchdog Timeout
     void timeout();
 
 private:
 
+    // Temporary variables
     QSerialPort serialPort;
+    QTimer timer;
+    unsigned int watchDogCounter,watchDogCounterLast;
 
+    // Settings
     QString interface;
     QString relaisName[5];
-
-    unsigned int watchDogCounter,watchDogCounterLast;
-
-    QTimer timer;
 };
 
 #endif // DLT_RELAIS_H