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