QExtSerialPort - receives data only, after port was first opened in other terminal-like application



  • Hi, i'm rather new to Qt, and started a project which require a serial port connection, so I downloaded the qextserialport library, and compiled It into the project. It properly connects with the device, but there is a problem when It comes to data receiving. When I start the compiled application, and send data from the device It receives only 1 byte which is 7F in hex (device send string: "KeyA pressed").
    The problem disappears when I start other app for serial port communication, open port on which the device is connected in that app and close It.
    Any ideas what is going on ?
    here is my code for opening serial port :
    @
    serialPort = new QextSerialPort("COM3");
    serialPort->setBaudRate(BAUD115200);
    serialPort->setDataBits(DATA_8);
    serialPort->setParity(PAR_NONE);
    serialPort->setFlowControl(FLOW_OFF);
    serialPort->setStopBits(STOP_1);
    serialPort->setTimeout(500);
    serialPort->setQueryMode(QextSerialPort::EventDriven);
    serialPort->open(QIODevice::ReadWrite | QIODevice::Unbuffered);

    if(serialPort->isOpen())
    {
    ui.statusbar->showMessage("succesfull connected with device..");
    connect(serialPort,SIGNAL(readyRead()),this,SLOT(slot_receive()));
    }
    else ui.statusbar->showMessage("unable to connect with device..");
    @

    and here is slot_receive() function:

    @
    void USARTtest::slot_receive()
    {
    char data[1024];
    int numBytes = serialPort->bytesAvailable();
    int readed = serialPort->read(data,1024);
    data[readed] = '\0';
    ui.textEdit->insertPlainText(QString::number(readed)+"\n");
    //ui.textEdit->insertPlainText(QString(data));
    }
    @

    I'm using the 4.7.0 version of Qt, and QT-eclipse integration.



  • Read "this":http://developer.qt.nokia.com/forums/viewreply/67246/
    Perhaps you change your mind and take another library.



  • I didn't hear about that library earlier, I will give it a try :)
    As I see you are one of the developers of that library, so I have a question - does it support the readyRead() signal ? or do I have to manually handle the way I check if there is any incoming data ?



  • Supported.

    Behavior is "almost completely" copies QAbstractSocket, with all methods, etc.
    All I/O is also buffered and non-blocking.
    See examples in /tests directory.
    In the general, try.


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