Reciving data from barcode scanner

[Damian7546]

@JonB and what do you think about below solution ?

void ScannerSerialWorker::initSerialPort(QString port)
{
    // Serial Port Initialization
    m_Serial = new QSerialPort(this);
    m_Serial->setPortName(port);
    m_Serial->setBaudRate(QSerialPort::Baud115200);
    m_Serial->setDataBits(QSerialPort::Data8);
    m_Serial->setParity(QSerialPort::NoParity);
    m_Serial->setStopBits(QSerialPort::OneStop);
    m_Serial->setFlowControl(QSerialPort::NoFlowControl);

    if ( m_Serial->open(QIODevice::ReadOnly)){

        QObject::connect(m_Serial, &QSerialPort::readyRead, this, [&]() {
            const QByteArray scannedData = m_Serial->readAll();
            qDebug() << "Scanned data by scanner: " << scannedData;

            receivedData.append(scannedData);
            if(receivedData.endsWith("\r\n")) {
                parseRecivedData();
             }
        });
    }
    qDebug() << "SerialPort for Barcode reader status: " << m_Serial->isOpen();
}

void ScannerSerialWorker::parseRecivedData()
{
    ScannerFrame *m_inFrame = nullptr;
    if (m_inFrame == nullptr)
        m_inFrame = new ScannerFrame();

    else{
        m_inFrame->Clear();
    }

    receivedFrame = receivedData.remove(receivedData.count()-2,2);
    receivedData.clear();

    for (int i=receivedFrame.indexOf("IR01"); i< receivedFrame.count(); i++)
        m_inFrame->AddByte(receivedFrame[i]);

    receivedData.clear();

    emit this->frameReceived(m_inFrame);
    delete m_inFrame;
}

[JonB]

@Damian7546
This look about right.

Personally I would do the receivedFrame = receivedData.remove(receivedData.count()-2,2); in the readyRead() slot next to where you look for the terminating \r\n as they are linked.

Your code assumes you will only get one "line" any time readyRead() is signalled. I don't know if that is guaranteed: in terms of readyRead() itself it could be fired just once when multiple "lines" arrive. If you care about this possibility you would need to handle it.

[Christian Ehrlicher]

@JonB said in Reciving data from barcode scanner:

if that is guaranteed

No, it's not - it's a stream like any other stream too.

[Damian7546]

I gave up with :

 receivedFrame = receivedData.remove(receivedData.count()-2,2);

Now is my code:

void ScannerSerialWorker::initSerialPort(QString port)
{
    // Serial Port Initialization
    m_Serial = new QSerialPort(this);
    m_Serial->setPortName(port);
    m_Serial->setBaudRate(QSerialPort::Baud115200);
    m_Serial->setDataBits(QSerialPort::Data8);
    m_Serial->setParity(QSerialPort::NoParity);
    m_Serial->setStopBits(QSerialPort::OneStop);
    m_Serial->setFlowControl(QSerialPort::NoFlowControl);

    if ( m_Serial->open(QIODevice::ReadOnly)) {
        QObject::connect(m_Serial, &QSerialPort::readyRead, this, [&]() {
            const QByteArray scannedData = m_Serial->readAll();
            qDebug() << "Scanned data by scanner (RAW): " << scannedData;

            receivedData.append(scannedData);
            if(receivedData.contains("\r\n")) {
                parseRecivedData();
                qDebug() << "Scanned data by scanner: " << receivedData;
             }
        });
    }
    qDebug() << "SerialPort for Barcode reader status: " << m_Serial->isOpen();
}

void ScannerSerialWorker::parseRecivedData()
{
    ScannerFrame *m_inFrame = nullptr;
    if (m_inFrame == nullptr)
        m_inFrame = new ScannerFrame();

    else{
        m_inFrame->Clear();
    }

    for (int i=receivedData.indexOf("IR01"); i < receivedData.indexOf("\r\n", 3) ; i++)
        m_inFrame->AddByte(receivedFrame[i]);

    receivedData.clear();

    emit this->frameReceived(m_inFrame);
    delete m_inFrame;
}

@JonB said in Reciving data from barcode scanner:

Your code assumes you will only get one "line" any time readyRead() is signalled.

..so how do i fix my code?

[Christian Ehrlicher]

Why not simply use QIODevice::canReadLine() / readLine()? Your approach only reads the first line, ignores if there one more line or a part of it is available since it throws it away.

[Damian7546]

@Christian-Ehrlicher so it's enough if I only change one line in my code:

const QByteArray scannedData = m_Serial->readAll();

to

const QByteArray scannedData = m_Serial->readLine();

?
Using readLine() I will have \r\n in recived buffor ?

[JonB]

@Damian7546 said in Reciving data from barcode scanner:

Using readLine() I will have \r\n in recived buffor ?

Try it and see?

[Christian Ehrlicher]

@Damian7546 said in Reciving data from barcode scanner:

to
const QByteArray scannedData = m_Serial->readLine();

?

No, since there can be more than one line in your buffer. Wrap it in a canReadLine() call.

[Damian7546]

@Christian-Ehrlicher Like below ?

void ScannerSerialWorker::initSerialPort(QString port)
{
    // Serial Port Initialization
    m_Serial = new QSerialPort(this);
    m_Serial->setPortName(port);
    m_Serial->setBaudRate(QSerialPort::Baud9600);
    m_Serial->setDataBits(QSerialPort::Data8);
    m_Serial->setParity(QSerialPort::NoParity);
    m_Serial->setStopBits(QSerialPort::OneStop);
    m_Serial->setFlowControl(QSerialPort::NoFlowControl);

    if ( m_Serial->open(QIODevice::ReadOnly)) {
        QObject::connect(m_Serial, &QSerialPort::readyRead, this, [&]() {

            while (m_Serial->canReadLine()){
                const QByteArray scannedData = m_Serial->readLine();
                qDebug() << "Scanned data by scanner (RAW): " << scannedData;

                receivedData.append(scannedData);
                if(receivedData.contains("\r\n"))
                    parseRecivedData();
            }
        });
    }
    qDebug() << "SerialPort for Barcode reader status: " << m_Serial->isOpen();
}

[Christian Ehrlicher]

@Damian7546 said in Reciving data from barcode scanner:

            receivedData.append(scannedData);
            if(receivedData.contains("\r\n"))
                parseRecivedData();

Why do you read it line by line just to append it to a QByteArray and split it again afterwards?