Serial port Communication with pc through serial Adapter

[sankarapandiyan]

@J-Hilk said in Serial port Communication with pc through serial Adapter:

connect(serial, &QSerialPort::readyRead,this, &MainWindow::serialReceived);

Thanks a lot . I have changed the code
from

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

to

connect(serial, &QSerialPort::readyRead,this, &MainWindow::serialReceived);
but same output is came

[KroMignon]

@sankarapandiyan said in Serial port Communication with pc through serial Adapter:

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

You should prefer using new connect style, so connect validity will be checked at compilation:

connect(serial, &QSerialPort::readyRead,this, &MainWindow::serialReceived);

And then in the slot:

void MainWindow::serialReceived()
{
    QByteArray rawData;
    while(!serial->atEnd())
    {
        rawData.append(serial->readAll());
    }
    if(!rawData.isEmpty())
    {
        QString glen = QString(rawDaa);
       /*QString*/ line = ui->receive->toPlainText();
       ui->receive->setText(ui->receive->toPlainText()+line+"\n");
       ui->receive->setText(line + "\r\n" + glen + "\r\n");
       line = txt3;
    }
    checkAndSendData();
}

Or if you are sure always receiving a '\r' or '\n' from your device, you can do it like this:

void MainWindow::serialReceived()
{
    while(serial->canReadLine())
    {
        QString glen = QString(serial->readLine());
       /*QString*/ line = ui->receive->toPlainText();
       ui->receive->setText(ui->receive->toPlainText()+line+"\n");
       ui->receive->setText(line + "\r\n" + glen + "\r\n");
       line = txt3;
    }
    checkAndSendData();
}

look at documentation ==> https://doc.qt.io/qt-5/qserialport.html#canReadLine

[J.Hilk]

As I don't have a serial dive at hand that returns data I can't debug it for you.

Start the debugger (F5) set a breakpoint in serialReceived and step over/in via F10/F11 and see what happens

That said, I vaguely remember that one should not call write from the slot that is connected to readyRead ( my be wrong here )

So you could try:

void MainWindow::serialReceived()
{
    ....
    QMetaObject::invokeMethod(this, &MainWindow::checkAndSendData, Qt::QueuedConnection);
}

to push the write to the next event loop cycle

[sankarapandiyan]

@KroMignon said in Serial port Communication with pc through serial Adapter:

You should prefer using new connect style, so connect validity will be checked at compilation:
connect(serial, &QSerialPort::readyRead,this, &MainWindow::serialReceived);

I want to change this
from -
-->connect(serial,SIGNAL(readyRead()),this, SLOT (serialReceived()))
to
-->connect(serial, &QSerialPort::readyRead,this, &MainWindow::serialReceived);

Like this you are saying ?

I tried by your words , and i have edited my code , this is my code i have attached below

void MainWindow::on_pushButton_clicked()
{
    serial = new QSerialPort (this) ;
    serial->setPortName(ui->comboBox->currentText());
    serial->setBaudRate (QSerialPort::Baud115200);
    serial->setDataBits(QSerialPort::Data8);
    serial->setParity (QSerialPort::NoParity);
    serial->setStopBits (QSerialPort::OneStop);
    serial->setFlowControl(QSerialPort::NoFlowControl);
    serial->open(QIODevice::ReadWrite);
   // connect(serial,SIGNAL(readyRead()),this, SLOT (serialReceived()));
    connect(serial, &QSerialPort::readyRead,this, &MainWindow::serialReceived);

   ui->progressBar->setValue(100);
//    ui->receive->clear();
}

void MainWindow::checkAndSendData()
{
    if(!m_lines.isEmpty()){
        QByteArray inBytes;
        QByteArray baToSend = m_lines.takeFirst().toUtf8();
        serial->write(baToSend);
        ui->aknowmnt->setText("Sent Message -->" "\n"+ QString(baToSend) + "\n");
    } else {
        ui->aknowmnt->setText("Receiving ");
    }
}

void MainWindow::on_send_clicked()
{
     line   = ui->sender->toPlainText();
    QString txt1 = ui->receive->toPlainText();
    /*QString*/ txt3 = ui->aknowmnt->toPlainText();

     if(m_lines.isEmpty()){
    QFile inputFile(QString("/home/adx-soft1/Shankar/serial/myfile1.txt"));
    inputFile.open(QIODevice::ReadOnly);
    if (!inputFile.isOpen())
        return;

    QTextStream stream(&inputFile);
    while (!stream.atEnd()){
            line = stream.readLine();
            m_lines.append(line+QString("\r\n"));
    }

     }
     checkAndSendData();

}
void MainWindow::serialReceived()
{
    QByteArray rawData;
    while(!serial->atEnd())
    {
        rawData.append(serial->readAll());
    }
    if(!rawData.isEmpty())
    {
        QString glen = QString(rawData);
       /*QString*/ line = ui->receive->toPlainText();
       ui->receive->setText(ui->receive->toPlainText()+line+"\n");
       ui->receive->setText(line + "\r\n" + glen + "\r\n");
       line = txt3;
    }
    checkAndSendData();
}

and my output is sended like this ,

I Dont know what is the Exact problem is

[small_bird]

@sankarapandiyan
You need to set a timer to delay some time after each serial write.

[sankarapandiyan]

@small_bird ok fine , But is it possible to send the all data with in just a one click with ack ..! that is my exact problem

[sankarapandiyan]

@J-Hilk You are saying like this ?

void MainWindow::serialReceived()

{
    QMetaObject::invokeMethod(this, &MainWindow::checkAndSendData, Qt::QueuedConnection);
    
    QString glen = serial->readAll();
    if (glen.length()>0){
    /*QString*/ line = ui->receive->toPlainText();
    ui->receive->setText(ui->receive->toPlainText()+line+"\n");
    ui->receive->setText(line + "\r\n" + glen + "\r\n");
    line = txt3;
    }
   checkAndSendData();
}

[J.Hilk]

@sankarapandiyan

void MainWindow::serialReceived()
{
    ....
    QMetaObject::invokeMethod(this, &MainWindow::checkAndSendData, Qt::QueuedConnection);
}

void MainWindow::serialReceived()

{
    QString glen = serial->readAll();
    if (glen.length()>0){
    /*QString*/ line = ui->receive->toPlainText();
    ui->receive->setText(ui->receive->toPlainText()+line+"\n");
    ui->receive->setText(line + "\r\n" + glen + "\r\n");
    line = txt3;
    }
   QMetaObject::invokeMethod(this, &MainWindow::checkAndSendData, Qt::QueuedConnection);
}

[small_bird]

@sankarapandiyan
of course you can, define a queue and then put every line into the queue. every time ,get one from the queue and then put it into the serial port.

[sankarapandiyan]

@J-Hilk said in Serial port Communication with pc through serial Adapter:

void MainWindow::serialReceived()

{
QString glen = serial->readAll();
if (glen.length()>0){
/QString/ line = ui->receive->toPlainText();
ui->receive->setText(ui->receive->toPlainText()+line+"\n");
ui->receive->setText(line + "\r\n" + glen + "\r\n");
line = txt3;
}
QMetaObject::invokeMethod(this, &MainWindow::checkAndSendData, Qt::QueuedConnection);
}

I Have tried this my output is same like this

this is my code is there is any problem in my code

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QList>
#include <QComboBox>
#include <QString>
#include <QTextEdit>
#include <QTime>
#include <QDebug>
#include <QtSerialPort/QSerialPortInfo>
#include <QtSerialPort>
#include <QFile>
#include <QList>

  QString line ;
  QString txt3;
QSerialPort *serial;
QStringList m_lines;
//QByteArray rawData;


MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{

    ui->setupUi(this);

    QString filename1="/home/adx-soft1/Shankar/serial/myfile1.txt";
      QFile file(filename1);
      if(!file.exists()){
          qDebug() << "NO FILE "<<filename1;
      }else{
          qDebug() << filename1<<" ...";
      }
      QString line1;
      ui->sender->clear();
      if (file.open(QIODevice::ReadOnly | QIODevice::Text)){ ui->sender->setText(file.readAll()); }

    QList<QSerialPortInfo> list;
    list = QSerialPortInfo::availablePorts();

    for (int i= 0; i < list.length(); i++)
    {
        ui->comboBox->addItem(list[i].portName());

    }
}

MainWindow::~MainWindow()
{
    delete ui;
    serial->close();
}


void MainWindow::on_pushButton_clicked()
{
    serial = new QSerialPort (this) ;
    serial->setPortName(ui->comboBox->currentText());
    serial->setBaudRate (QSerialPort::Baud115200);
    serial->setDataBits(QSerialPort::Data8);
    serial->setParity (QSerialPort::NoParity);
    serial->setStopBits (QSerialPort::OneStop);
    serial->setFlowControl(QSerialPort::NoFlowControl);
    serial->open(QIODevice::ReadWrite);
    connect(serial,SIGNAL(readyRead()),this, SLOT (serialReceived()));
//    connect(serial, &QSerialPort::readyRead,this, &MainWindow::serialReceived);

   ui->progressBar->setValue(100);
//    ui->receive->clear();
}

void MainWindow::checkAndSendData()
{
    if(!m_lines.isEmpty()){
        QByteArray inBytes;
        QByteArray baToSend = m_lines.takeFirst().toUtf8();
        serial->write(baToSend);
        ui->aknowmnt->setText("Sent Message -->" "\n"+ QString(baToSend) + "\n");
    } else {
        ui->aknowmnt->setText("Receiving ");
    }
}

void MainWindow::on_send_clicked()
{
     line   = ui->sender->toPlainText();
    QString txt1 = ui->receive->toPlainText();
    /*QString*/ txt3 = ui->aknowmnt->toPlainText();

     if(m_lines.isEmpty()){
    QFile inputFile(QString("/home/adx-soft1/Shankar/serial/myfile1.txt"));
    inputFile.open(QIODevice::ReadOnly);
    if (!inputFile.isOpen())
        return;

    QTextStream stream(&inputFile);
    while (!stream.atEnd()){
            line = stream.readLine();
            m_lines.append(line+QString("\r\n"));
    }

     }
     checkAndSendData();

}
void MainWindow::serialReceived()

{

    QString glen = serial->readAll();
    if (glen.length()>0){
    /*QString*/ line = ui->receive->toPlainText();
    ui->receive->setText(ui->receive->toPlainText()+line+"\n");
    ui->receive->setText(line + "\r\n" + glen + "\r\n");
    line = txt3;
    }
   checkAndSendData();
   QMetaObject::invokeMethod(this, &MainWindow::checkAndSendData, Qt::QueuedConnection);

}

But I have not get the correct output @J-Hilk

[small_bird]

@sankarapandiyan check your encode function

[sankarapandiyan]

@small_bird Encode function means What you mean ? i didnt get you

[J.Hilk]

@sankarapandiyan
ok, lets simplify your code, I assume receive and aknowmntare QTextEdits or QTextBrowser, since they have a toPlainTextfunction

void MainWindow::checkAndSendData()
{
    if(!m_lines.isEmpty()){
        QByteArray baToSend = m_lines.takeFirst().toUtf8();
        serial->write(baToSend);
        ui->aknowmnt->append("Sent Message --> "+ QString(baToSend));
    } else {
        ui->aknowmnt->append("All are send ");
    }
}

void MainWindow::serialReceived()

{
    QString glen = serial->readAll();
    if (glen.length()>0){
         ui->receive->append( "Received -->" + QString(glen));
    }
   QMetaObject::invokeMethod(this, &MainWindow::checkAndSendData, Qt::QueuedConnection);

}

[sankarapandiyan]

@J-Hilk

Yes i have tried this method , the correct data is not shown in the receiver side ..

void MainWindow::on_pushButton_clicked()
{
    serial = new QSerialPort (this) ;
    serial->setPortName(ui->comboBox->currentText());
    serial->setBaudRate (QSerialPort::Baud115200);
    serial->setDataBits(QSerialPort::Data8);
    serial->setParity (QSerialPort::NoParity);
    serial->setStopBits (QSerialPort::OneStop);
    serial->setFlowControl(QSerialPort::NoFlowControl);
    serial->open(QIODevice::ReadWrite);
//    connect(serial,SIGNAL(readyRead()),this, SLOT (serialReceived()));
    connect(serial, &QSerialPort::readyRead,this, &MainWindow::serialReceived);

   ui->progressBar->setValue(100);
//    ui->receive->clear();
}

void MainWindow::checkAndSendData()
{
    if(!m_lines.isEmpty()){
        QByteArray baToSend = m_lines.takeFirst().toUtf8();
        serial->write(baToSend);
        ui->aknowmnt->append("Sent Message --> "+ QString(baToSend));
    } else {
        ui->aknowmnt->append("All are send ");
    }
}

void MainWindow::on_send_clicked()
{
     line   = ui->sender->toPlainText();
    QString txt1 = ui->receive->toPlainText();
    /*QString*/ txt3 = ui->aknowmnt->toPlainText();

     if(m_lines.isEmpty()){
    QFile inputFile(QString("/home/adx-soft1/Shankar/serial/myfile1.txt"));
    inputFile.open(QIODevice::ReadOnly);
    if (!inputFile.isOpen())
        return;

    QTextStream stream(&inputFile);
    while (!stream.atEnd()){
            line = stream.readLine();
            m_lines.append(line+QString("\r\n"));
    }

     }
     checkAndSendData();

}

void MainWindow::serialReceived()

{
    QString glen = serial->readAll();
    if (glen.length()>0){
         ui->receive->append( "Received -->" + QString(glen));
    }
   QMetaObject::invokeMethod(this, &MainWindow::checkAndSendData, Qt::QueuedConnection);
}

[sankarapandiyan]

@J-Hilk said in Serial port Communication with pc through serial Adapter:

ok, lets simplify your code, I assume receive and aknowmntare QTextEdits or QTextBrowser, since they have a toPlainTextfunction

Yes Its a QTextEdits

[J.Hilk]

@sankarapandiyan
you're obviously receiving non ascii bytes

void MainWindow::serialReceived()

{
    QByteArray glen = serial->readAll();
    if (glen.length()>0){
         ui->receive->append( QString("Received --> %1").arg(QString(glen.toHex(' ')));
    }
   QMetaObject::invokeMethod(this, &MainWindow::checkAndSendData, Qt::QueuedConnection);

}

[sankarapandiyan]

@J-Hilk said in Serial port Communication with pc through serial Adapter:

void MainWindow::serialReceived()

{
QByteArray glen = serial->readAll();
if (glen.length()>0){
ui->receive->append( QString("Received --> %1").arg(QString(glen.toHex(' ')));
}
QMetaObject::invokeMethod(this, &MainWindow::checkAndSendData, Qt::QueuedConnection);

}

this out put is what i receive from another pc

And the next below image is shown as a data send as some thing different

Even Now also i did not get the exact output sir what should i do i am stuck here .. @J-Hilk

[KroMignon]

@sankarapandiyan Maybe it is a silly question, but are you sure the serial settings your are using, are correct?

• 115200 bauds?
• 8 bits?

Are you using a crossed/null modem serial cable? ==> cf https://en.wikipedia.org/wiki/Null_modem.

[sankarapandiyan]

@KroMignon I am Using hl-340 usb-serial adapter . so here , what i want to give as a baud rate.

void MainWindow::on_pushButton_clicked()
{
    serial = new QSerialPort (this) ;
    serial->setPortName(ui->comboBox->currentText());
    serial->setBaudRate (QSerialPort::Baud115200);
    serial->setDataBits(QSerialPort::Data8);
    serial->setParity (QSerialPort::NoParity);
    serial->setStopBits (QSerialPort::OneStop);
    serial->setFlowControl(QSerialPort::NoFlowControl);
    serial->open(QIODevice::ReadWrite);
    connect(serial,SIGNAL(readyRead()),this, SLOT (serialReceived()));
    ui->progressBar->setValue(100);
//    ui->receive->clear();
}

[KroMignon]

@sankarapandiyan said in Serial port Communication with pc through serial Adapter:

I am Using hl-340 usb-serial adapter

Okay, that's for having a RS232 port on you PC, but to connect two PC you need a "null modem" cable (to cross Tx and Rx signal between the 2 serial ports).
Have you something like this?