QSerialPort::readyRead not responding

[PradeepCK]

Hello,

I am trying to implement Serial COM port program.
The program is not responding to readyread event (I hope my understanding is not wrong).

Here is the code:

/* in .h */
QSerialPort *serialData = nullptr;

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow),
    serialData(new QSerialPort(this))
{
    connect(ui->button_connect, &QPushButton::clicked, this, &MainWindow::openSerialPort);
    connect(serialData, &QSerialPort::errorOccurred, this, &MainWindow::handleCOMError);
    connect(serialData, &QSerialPort::readyRead, this, &MainWindow::readSerialData);
}

Open Serial port:

void MainWindow::openSerialPort()
{
    serialData = new QSerialPort();
    serialData->setPortName(ui->combo_commPort->currentText());
    serialData->setBaudRate(static_cast<QSerialPort::BaudRate>(baudRates[ui->combo_BaudRate->currentIndex()].baudRate));
    serialData->setDataBits(static_cast<QSerialPort::DataBits>(dataBits[ui->combo_DataBits->currentIndex()].dataBits));
    serialData->setParity(static_cast<QSerialPort::Parity>(parity[ui->combo_Parity->currentIndex()].Parity));
    serialData->setStopBits(static_cast<QSerialPort::StopBits>(stopBits[ui->combo_StopBits->currentIndex()].StopBits));
    serialData->setFlowControl(static_cast<QSerialPort::FlowControl>(flowControl[ui->combo_FlowControl->currentIndex()].FlowControl));

    if (serialData->open(QIODevice::ReadWrite)) {
        ui->button_connect->setDisabled(true);
        ui->tabWidget->setEnabled(true);
    } else {
        QMessageBox::critical(this, tr("Error"), serialData->errorString());
    }
}

This code is not triggered:

void MainWindow::readSerialData()
{
    const QByteArray data = serialData->readAll();
    ui->textEdit_recv->append(data);
}

To write data on COM :

void MainWindow::on_button_send_clicked()
{
    QByteArray str = ui->textEdit_send->toPlainText().toUtf8();
    serialData->write(str, str.length());
}

Please let me know a way to resolve this problem. Any pointers would be appreciated.

-- CKP

Note: I wrote most of this program by copying it from an example program - "Terminal Example"

[Christian Ehrlicher]

Where do you open the port?

[PradeepCK]

I have updated the question with the code snippet that opens the COM port

[jsulm]

@PradeepCK You connect signals/slots before you create the QSerialPort instance?!
This can't work...

[PradeepCK]

Lo and behold - the code works now.

Silly me,
Thank you for pointing this out. You are a genius.

-- CKP