Serial port reading with QSerialPort : No such slot QObject...

Quintinius

Hello everyone,

I'm trying to read data sent on a serial port using the QSerialPort library. The data are values that come from an Arduino card. After some research, I did the following blockcode which sets the serial port to read and then a signal connected to a slot to acquire the data. The'PortListener' function is then called in the main.

PortListener::PortListener(const QString &portName)
{
    this->port = new QSerialPort();
    port->open(QIODevice::ReadWrite);
    port->setPortName(portName);
    port->setBaudRate(QSerialPort::Baud9600);
    port->setDataBits(QSerialPort::Data8);
    port->setParity(QSerialPort::NoParity);
    port->setStopBits(QSerialPort::OneStop);
    port->setFlowControl(QSerialPort::NoFlowControl);

    connect(port, SIGNAL(readyRead()), this, SLOT(readyReadSlot()));
}

void PortListener::readyReadSlot()
{
    while(!port->atEnd()){
        QByteArray data = port->readAll();
        qDebug() << "message :" << data;
    }
}

After running the program, I get an error message like "QObject::connect: No such slot QObject::readyReadSlot()" which seems to mean that no data is sent on the serial port. However, I did some tests with the examples provided by the QextSerialPort library and I am receiving the data well so the error will not come from there. I would still like to use QSerialPort.

Does anyone have any idea where the problem might come from?

J.Hilk

hi @Quintinius said in Serial port reading with QSerialPort : No such slot QObject...:
you're using the olf (Qt4) syntax,

connect(port, SIGNAL(readyRead()), this, SLOT(readyReadSlot()));

using that synatx, you must mark functions that are slots, with the slots macro in the header file. Or it won't work at all

public slots:
     void readyReadSlot();

ODБOï

@Quintinius said in Serial port reading with QSerialPort : No such slot QObject...:

"QObject::connect: No such slot QObject::readyReadSlot()"

Error is saying that the class QObject has no ~~method~~ public slot called readyReadSlot

I still don't know why you have this error, but please try to use the new Signal/Slot syntax

connect(port, &QSerialPort::readyRead, this, &PortListener::readyReadSlot);