I am trying to make QT automatically connect to my ST32 MCU by serial. MCU is keep sending data for each second. So I thought I can read all the available COM Ports and when the line is not null, I will detect that COM Port is MCU. But All COM Ports are null. Here is related piece of code I am using in QT:
Qt Code: 
  1. #include "mainwindow.h"
  2. #include "ui_mainwindow.h"
  3. #include <QtSerialPort>
  4. #include <QDebug>
  5. QSerialPort *serial;
  6. MainWindow::MainWindow(QWidget *parent)
  7.     : QMainWindow(parent)
  8.     , ui(new Ui::MainWindow)
  9. {
  10.     ui->setupUi(this);
  11.     serial = new QSerialPort(this);
  12.     foreach(QSerialPortInfo port, QSerialPortInfo::availablePorts())
  13.     {
  14.             serial->setPortName(port.portName());
  15.             serial->setBaudRate(QSerialPort::Baud115200);
  16.             serial->setDataBits(QSerialPort::Data8);
  17.             serial->setParity(QSerialPort::NoParity);
  18.             serial->setStopBits(QSerialPort::OneStop);
  19.             serial->setFlowControl(QSerialPort::NoFlowControl);
  20.             serial->open(QIODevice::ReadOnly);
  21.  
  22.             if(!(serial->readLine().isNull()))
  23.             {
  24.                 qDebug()<<port.portName()<<"is opened";
  25.             }
  26.  
  27.     }
  28. }
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I believe 1 second is not enough for QT to detect that. Maybe I should use timeout in QT. Any idea how can I solve this problem?