How to modify a QSerialPort Name while application is running - c++

Question

I successfully read from a serial port with QSerialPort when I setup the instance's parameters in my main window constructor. I want my GUI to enable changing port however, but I can't seem to start reading when changing my com port after starting my application (I do so with a spinBox that sets up the COM port name of my QSerialPort instance). Here is my code (mainwindow.cpp), my problem is that if I do not directly use serial->setPortName(); in my constructor, and I put it in my slot linked to my spinBox signal, I can't read data received from my com port with qDebug anymore.
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QSerialPort>
#include <QSerialPortInfo>
#include <QDebug>
QSerialPort *serial;
MainWindow::MainWindow(QWidget *parent)
: QMainWindow(parent)
, ui(new Ui::MainWindow)
{
ui->setupUi(this); // Here by default. Takes a pointer to mainwindow as argument
serial = new QSerialPort(this);
qDebug() << "nb ports: " << QSerialPortInfo::availablePorts().length();
foreach(const QSerialPortInfo &serialPortInfo, QSerialPortInfo::availablePorts())
{
qDebug() << "name" << serialPortInfo.portName();
}
qDebug() << "is " << serial->open(QSerialPort::ReadOnly);
qDebug() << "err " << serial->error();
// Create the signal and slot for
connect(ui->com_spinBox, SIGNAL(valueChanged(const QString&)),
this, SLOT(setComPort(const QString&)));
// Create the signal and slot for receiving data from device
connect(serial, SIGNAL(readyRead()), this, SLOT(serialReceived()));
}
MainWindow::~MainWindow()
{
delete ui;
serial->close(); // instance is closed when mainwindow destroyed
}
// My 2 custom slots below!!!
void MainWindow::serialReceived()
{
QByteArray ba;
ba = serial->readAll();
ui->label->setText(serial->readAll());
qDebug()<<ba;
}
void MainWindow::setComPort(const QString& com)
{
serial->close();
serial = new QSerialPort(this); // this (mainwindow) is parent
qDebug() << serial->portName();
QString comPort = "COM" + com;
qDebug() << comPort;
serial->setPortName(comPort);
serial->setBaudRate(QSerialPort::Baud9600);
serial->setDataBits(QSerialPort::Data8);
serial->setParity(QSerialPort::NoParity);
serial->setStopBits(QSerialPort::OneStop);
serial->setFlowControl(QSerialPort::NoFlowControl);
serial->open(QSerialPort::ReadOnly);
}
Here I tried moving all my serial instance setup from constructor to my slot, and close and re-open the instance to see if it helps, but I still cannot read anything with serialReceived() slot when tuning to the right COM port.. It does work if I put everything in the constructor and setPortName() with the right port number at the start of the program.
Thanks!

Answer 1

Try to delete and create again your QSerialPort before setPortName()
serial->deletLater();
serial = new QSerialPort(this);
serial->setPortName("COM1");