Wierd behavior with QSerialPort: readLine()

[Reudi]

Hello,
I hope i'm not making a fool of myself for asking a stupid Question.

I'm using the QSerialPort in a Class to control a little robot via USB.
The communication between robot and PC is simple.
After receiving a command the robot, the robot executes the command.
After that the robot sends a line with some data
and an other line with an "OK" back.

I wrote a little method which send a command and waits for an OK of the robot.
I Init the serial port with

m_serial->setPortName("ttyUSB0");
if (!m_serial->open(QIODevice::ReadWrite))
{

    cout << "ERROR: Could not open serial port." << endl;
    return 0;
}
m_serial->setBaudRate(m_serial->Baud115200);
m_serial->setStopBits(m_serial->OneStop);
m_serial->setFlowControl(m_serial->NoFlowControl);
m_serial->setParity(m_serial->NoParity);
m_serial->setDataBits(m_serial->Data8);
m_serial->setReadBufferSize(0);
m_serial->flush();

string executeAndWait()
{

string answer;
QString temp = QString::fromStdString("M10");
QByteArray command = temp.toLocal8Bit();
m_serial->write( command);
m_serial->waitForReadyRead(100000000);
data = m_serial->readAll();
if i use readLine or readAll doesnt change he result

string check = data.toStdString() ;
cout<<check<<endl;

//check if end of answer reached, i knwo i know its not pretty...
while(check.find("OK") == string::npos){
m_serial->waitForReadyRead(100000000);
data = m_serial->readAll();
check = data.toStdString() ;

}

I'm getting the output :
M10 XY 300 380 0.00 0.00 A0 B0 H
0 S95 U15 D60

and i'm expecting
M10 XY 300 380 0.00 0.00 A0 B0 H0 S95 U15 D60
OK

i did some testing and found out, there is always a cut after 32 Characters.
I used other libraries for the communication before and had no issues what so ever.

Im cluesless
Please help

PS:
If i haven't given you all the information you need please tell me

[VRonin]

The problem is here:

m_serial->waitForReadyRead(100000000);
data = m_serial->readAll();

ready read is emitted when some data can be read but that does not imply that all data can be read.

see https://forum.qt.io/topic/70123/server-is-losing-bytes/3 , it's the same problem

[Reudi]

Thank you for your answer, i tried to work with the Datastreams mentioned in the Example. It didn't work for me.
In the end i wrote a little method which works.

while(data.size() == avaiableBytes)
{

is pretty much all i do.
But I got one question left.

Sometimes the '\n' is removed by readLine and sometimes it isnt. How does this happen.

Cheers for the help much appreciation