Why the Qt(4.8) serial port(qextserialport) readind data from device in 2 part?

Question

this is my code : (I used qextserialport)

SerialPort::SerialPort(QString port)
{
    sp=new QextSerialPort;
    sp->setPortName(port);
    /*port->setBaudRate(BAUD9600);
    port->setFlowControl(FLOW_OFF);
    port->setParity(PAR_NONE);
    port->setDataBits(DATA_8);
    port->setStopBits(STOP_2);*/
    sp->setBaudRate(BAUD115200);
    sp->setDataBits(DATA_8);
    sp->setFlowControl(FLOW_OFF);
    sp->setParity(PAR_NONE);
    sp->setStopBits(STOP_1);
    sp->open(QIODevice::ReadWrite);
    connect(sp,SIGNAL(readyRead()),this,SLOT(ReadData()));

}

void SerialPort::ReadData()
{
    QByteArray ba;
    ba.resize(512);
    ba=sp->readAll();
    emit DataRecieve(ba);
}

this code run on Ubuntu at first and show all the bytes which receive from device, but when I tested it in linux embedded device this code read data from serial device in 2 part. () there is no \n in my bytes. I change the code to this code :

void SerialPort::ReadData()
{
    QByteArray ba;
    ba.resize(512);
    if(sp->bytesAvailable()>0 || sp->waitForReadyRead(20000))
    {
    qDebug()<<sp->bytesAvailable();
    ba=sp->readAll();
    qDebug()<<ba.toHex();
    emit DataRecieve(ba);
    }
}

but again my output is :

4 "aa5524010400000000000000"   
12 "000000000000000000002801"

but it should be :

"aa5524010400000000000000000000000000000000002801"

My output size is maybe 48 bytes or 512 bytes

Answer 1

It depends on serial port driver buffer. You can got readyRead() signal on one ready byte, for example. You should save received bytes to intermediate buffer and process it after all.