Now I try to study using of QSerialPort with QThread. And during the study I got some strange thing: I get 2 readyRead() signals => 2 readyRead() slots, and I can't to construct response data as one.

What I have:

• I have the class for QSerialPort, there are some slots for open port, for write to port, for read from port. Slot for reading from port s connected to readyRead() signal in constructor of the class:

connect(serialPort, &QSerialPort::readyRead, this, &SerialPort_Class::slot_ReadInPort);

Slot for writing to port:

void SerialPort_Class::slot_WriteToPort(QByteArray writeData)
{
    qDebug() << "SLOT WriteToPort" << endl;
    if (serialPort->isOpen())
    {
        QByteArray readData = serialPort->readAll();

        qDebug() << "Write Request = " << writeData << endl;

        serialPort->write(writeData);

        if (serialPort->waitForBytesWritten(1000))
        {}
        else
        {
            qDebug() << "Write request TIMEOUT" << endl;
        }
    }
}

Slot for readyRead:

void SerialPort_Class::slot_ReadInPort()
{
    QThread::msleep(1000);

    qDebug() << "EMIT SendReadData" << endl;
    emit signal_SendReadData("");
}

• I have the Thread for emitting of signal for writing to port after opening the port and after slot for readyRead() for processing of response data.

And what I get in the Debug log (only 1 write command per opening the port):

"No error" 
checkDevices_slot
SLOT WriteToPort 
Write Request =  "\xA5\x01""c0000\xC9" 
EMIT SendReadData 

This is a normal situation: one request - one response (EMIT SendReadData message).
But often I see the next situation for one cycle:

"No error" 
checkDevices_slot
SLOT WriteToPort 
Write Request =  "\xA5\x01""c0000\xC9" 
EMIT SendReadData 
EMIT SendReadData 

This is a unnormal situation: one request - two responses (2 EMIT SendReadData messages).

And I can't to fix it! I used waitForReadyRead() method even with 1sec delay - and the same problem. I even removed all reading functions in slot (like now) - and the same problem. Maybe, it exists because of baudrate = 9600... I don't know.

Hope for your help! Thank you in advance!