QIODevice::write (QSerialPort): device not open

[deleted286]

When i debug, it says command aborted. I couldnt find my mistake

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QSerialPort>
#include <QDebug>

QSerialPort *serial;

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    serial = new QSerialPort(this);
    serial->setPortName("com4");
    serial->setBaudRate(QSerialPort::Baud9600);
    serial->setDataBits(QSerialPort::Data8);
    serial->setParity(QSerialPort::NoParity);
    serial->setStopBits(QSerialPort::OneStop);
    serial->setFlowControl(QSerialPort::NoFlowControl);
    serial->open(QIODevice::ReadWrite);
    serial->write("its working");
    connect(serial, SIGNAL(readyRead()), this, SLOT(serialReceived()));

}

MainWindow::~MainWindow()
{
    delete ui;
    serial->close();
}

void MainWindow::serialReceived()
{
    QByteArray ba;
    ba=serial->readAll();
    ui->label->setText(ba);
    qDebug() << ba;
}

[jsulm]

@suslucoder said in QIODevice::write (QSerialPort): device not open:

serial->open(QIODevice::ReadWrite);

Check whether open() succeeded.

[deleted286]

@jsulm I checked. Its not working. It returns false. Why should it be?

[SGaist]

Hi,

Port already opened in another application.
Not enough user rights to access it.

There's an error method that will give you more information.

[J.Hilk]

@suslucoder are you sure com4 is the correct name ? something seems of, I would suggest using https://doc.qt.io/qt-5/qserialportinfo.html
to query for the correct port and port name