Reading from SerialPort and convert it to QString?!

Mucip

Hi,
I want to read data from serial port which is connected to incidcator. The indicator sends 8 bits.

Letter like "A" or "B"
2-7 numbers
Carriage return.

I read the serial port without problem. like below code;

serial = new QSerialPort(this);
    serial->setPortName("com6");
    serial->setBaudRate(QSerialPort::Baud9600);
    serial->setDataBits(QSerialPort::Data8);
    serial->setParity(QSerialPort::NoParity);
    serial->setStopBits(QSerialPort::OneStop);
    serial->setFlowControl(QSerialPort::NoFlowControl);

    serial->open(QIODevice::ReadOnly);

    connect(serial,SIGNAL(readyRead()),this,SLOT(serialReceived()));

And serialReceived function is:

void MainWindow::serialReceived()
{
    QByteArray ba;
    ba= serial->readAll();
    ui->label_2->setText(QString(ba));
   ui->plainTextEdit->insertPlainText(QString(ba));

}

It's very strange I can see the data in PlainText like "A 720" but I can not see this value in Label or lineEdit?!

And I can not get the first letter of data like below command

QString aValue = QString(ba).
aValue.mid(0,1)

Normally it must return with "A" letter but nothing?!
What is the problem with QByteArray and QString?!...

Regards,
Mucip:)

SGaist

Hi,

Are you sure there's no null character in the data you send ?

Mucip

Hi,
Thanks for fast return. :)

May be?! I don't know. It can be "A 123456" or "A 123". Depends on Indicator. It can send 123 value or 123456?!
The indicator sends 6 long int value.

But I see it in Plain text. No problem?!... :(

Regards,
Mucip:)

VRonin

@Mucip said in Reading from SerialPort and convert it to QString?!:

But I see it in Plain text.

How do you see it? in debug mode?

Mucip

Hi,
No. I already add the plaintextEditor on the form. and below code:

ui->plainTextEdit->insertPlainText(QString(ba));

I can see the results in the editor. No problem!... :(
Like below;

A 720
A 720
A 720

Regards,
Mucip:)

J.Hilk

@Mucip if you enter a Text via Qt-Designer, can you see that, whan the program is running?
Can you highlight the Label/LineEdit and copy paste the text into a text document?

Mucip

Hi,
I didn't understand? Please could you explain little bit more?...
Regards,
Mucip:)

Mucip

Hi,
I checked.
When I highlight and copy from PlainTextEditor I can paste it on the TextEditor of windows.
But when I highlight and copy it from LineEdit I can not paste it on the TextEditor of windows.

I think between 2th and 7th bits contain NULL when the value less then 6 digits like "200".

So what happend if the ByteArray has NULL and why PlainTextEditor shows the value (like A 720) well and Why LineEdit NOT?!...

Regards,
Mucip:)

J.Hilk

@Mucip Well I just wanted to see, what is actually in that QByteArray

You could use this function to "see" the content of your data:

for(int i(0); i < ba.size();i++)
        qDebug() <<  i << QChar(ba[i]) << static_cast<int>(ba[i]);

Mucip

@J.Hilk said in Reading from SerialPort and convert it to QString?!:

for(int i(0); i < ba.size();i++)
qDebug() << i << QChar(ba[i]) << static_cast<int>(ba[i]);

Hi,
I used it and result:
0 'A' 65
0 ' ' 32
0 ' ' 32
1 '1' 49
0 '4' 52
1 '5' 53
2 '0' 48
0 '\xd' 13

And Idicator shows 1450... This is correct! :)
But How can I get the complate output like "A1450"???

Regards,
Mucip:)

aha_1980

@J.Hilk said in Reading from SerialPort and convert it to QString?!:

@Mucip Well I just wanted to see, what is actually in that QByteArray
You could use this function to "see" the content of your data:
for(int i(0); i < ba.size();i++)
qDebug() << i << QChar(ba[i]) << static_cast<int>(ba[i]);

Easier would be to just convert the byte array to hex:

qDebug() << ba.toHex();

J.Hilk

@Mucip said in Reading from SerialPort and convert it to QString?!:

0 '\xd' 13

I believe thats the culprit a carriage Return ist difficult to display in a QLabel and/or QLineEdit

Also, seeing your index starting from 0 multiple times the text of the QLabel and QLineEdit are constantly overwritten. You'll need to construct a String out of your different received QByteArrays.
I suggest something like this. If it always end with QChar(0x0D)

//Member String
QString str;

void MainWindow::serialReceived()
{
    QByteArray ba;
    bool finished(false);
    ba= serial->readAll();
    for(int i(0); i < ba.size();i++){
         if(ba[i] != 0x0D)
             str.append(ba[i]);
         else finished = true;
   }

    if(finished){
       ui->label_2->setText(str);
       ui->plainTextEdit->insertPlainText(str);
       str.clear();
    }
}

VRonin

can you try:

void MainWindow::serialReceived()
{
QTextStream stream(serial);
const QString receivedStr = stream.readAll();

    ui->label_2->setText(receivedStr );
   ui->plainTextEdit->insertPlainText(receivedStr );

}

Of course there is nothing here assuring you all data was received when the slot gets called

Mucip

Hi,
No. Unfotunatelly same thing. I can see the data in plainTextEdit but not in lineEdit.

Regards,
Mucip:)

VRonin

@Mucip said in Reading from SerialPort and convert it to QString?!:

I can see the data in plainTextEdit but not in lineEdit

You are not setting the data in the lineedit, you are setting the string in a label and a plainTextEdit

Mucip

@J.Hilk said in Reading from SerialPort and convert it to QString?!:

void MainWindow::serialReceived()
{
QByteArray ba;
bool finished(false);
ba= serial->readAll();
for(int i(0); i < ba.size();i++){
if(ba[i] != 0x0D)
str.append(ba[i]);
else finished = true;
}

Hi,
I solved the problem above like solution...
I checked the data one by one and add to QString.
Thanks.