Serial port timeout - Qextserialport

hello.
I want to write a program that will open the port and read data (in continuous mode, loop).

According to the algorithm:

Start ->
1.Try open port
a) if opened then read data
b) if not opened it wait 30 seconds and try to raise open port (jump to 1)

Code:

---

#include "mainwindow.h"
#include "ui_mainwindow.h"
 
 
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    port = new QextSerialPort("/dev/ttyUSB0");
    port->setBaudRate(BAUD9600);
    port->setFlowControl(FLOW_OFF);
    port->setParity(PAR_NONE);
    port->setDataBits(DATA_8);
    port->setStopBits(STOP_1);
 
    port->setTimeout(500);
    reading();
 
}
 
MainWindow::~MainWindow()
{
    delete ui;
}
 
 
 
void MainWindow::reading()
{
 
 
    qDebug() << port->open(QIODevice::ReadWrite);
 
    if (port->isOpen()==false)
    {
        port->flush();
 
        port->startTimer(30000);
        qDebug() << "its it reading";
        //port->waitForReadyRead(1000);
        reading();
    }
    else
    {
        connect(port, SIGNAL(readyRead()), this, SLOT(onDataAvailable()));
    }
}
 
void MainWindow::onDataAvailable()
{
 
    if (port->isOpen())
    {
    QByteArray mdata = port->readAll();
    qDebug() << "\n";
 
    qDebug() << mdata.toHex(); // hex data
    qDebug() << mdata;  //  ascii data
 
 
 
    ui->lineEdit->clear();
    ui->lineEdit->setText(mdata);
    }
    else
    {
 
        reading();
        qDebug() << "error 2 port is not open";
    }
   // port->close();
}

---

First of all in method MainWindow::reading() if port->isOpen == false You have an infinite loop and stack overflow - You are calling reading in reading.
Second this all happens in the MainWindow constructor. By me it should be something like this :

Code:

---

#include "mainwindow.h"
#include "ui_mainwindow.h"
 
 
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    port = new QextSerialPort("/dev/ttyUSB0");
    port->setBaudRate(BAUD9600);
    port->setFlowControl(FLOW_OFF);
    port->setParity(PAR_NONE);
    port->setDataBits(DATA_8);
    port->setStopBits(STOP_1);
 
    port->setTimeout(500);
    QTimer::singleShot(0,this,SLOT(reading()));
 
}
 
MainWindow::~MainWindow()
{
    delete ui;
}
 
 
 
void MainWindow::reading()
{
 
 
    qDebug() << port->open(QIODevice::ReadWrite);
 
    if (port->isOpen()==false)
    {
        port->flush();
 
        qDebug() << "its it reading";
        QTimer::singleShot(30000,this,SLOT(reading()));
    }
    else
    {
        connect(port, SIGNAL(readyRead()), this, SLOT(onDataAvailable()));
    }
}
 
void MainWindow::onDataAvailable()
{
 
    if (port->isOpen())
    {
    QByteArray mdata = port->readAll();
    qDebug() << "\n";
 
    qDebug() << mdata.toHex(); // hex data
    qDebug() << mdata;  //  ascii data
 
 
 
    ui->lineEdit->clear();
    ui->lineEdit->setText(mdata);
    }
    else
    {
 
        reading();
        qDebug() << "error 2 port is not open";
    }
   // port->close();
}
 
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---

Of course raeding() should be declared as SLOT.