Help sending files via COM port

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Hello,

I think, the same example in this article . This article was wrote by another user. But, in my opinion, it is nearest example with serial port for your question on this site.

Thank you for your help. I did it. But I have some problems, this is my code:
I only sent 1 txt file, but when I received it, I received 3 txt files, the first file was divided into 3 files.

void MayInternet::serialReceived()
{
//Tao file nhan
QDateTime local= QDateTime::currentDateTime();
bool checkfile=true;
if (checkfile)
{
    QString filename="TinNhan"+local.date().toString("dd.MM.yyyy")+local.time().toString("hh.mm.ss")+".txt";
    if (Name!=filename)
    {
        Name=filename;
        checkfile=false;
    }
}
QFile file(Name);
if (!file.open(QFile::Append | QFile::Text))
{
    QMessageBox::warning(this, "Canh bao", "Khong tao duoc file / File khong ton tai. " + file.errorString());
    return ;
}
//Kiem tra du lieu tu cong va ghi vao file
if(serialPort->bytesAvailable())
{
    QByteArray datas = serialPort->readAll();
    if(datas.size()>0)
    {
        if(file.isOpen())
        {
             QTextStream in(&file);
             in<<datas;                 
        }
        file.close();
    }
    else {
        QMessageBox::warning(this, "Cảnh báo", "Không có dữ liệu. " + file.errorString());
        return;
    }
    if(serialPort->atEnd())
    {
        checkfile=true;
    }
}

Hello,

I think. It is technology limitation. You can't send big file in one message. Just concatenate this several messages to one file.

I have another question: I use 9-pin COM port, I want PC1 just send only, PC2 only receive. Therefore I connect Tx of COM1 (PC1) to Rx of COM2 (PC2). In my file.txt there is MD5 to check PC2, if the received PC2 file is match with the original file. if the file is not match, how to PC1 be aware and send it again (without the connect Tx of PC2 to Rx of PC1

Sorry, I don't know this moment.

I have another question:I want to read data from the COM port and write to the txt file, after I finish writing, I will open the file and display the screen. The problem I have is, I have not received all the data, they have been displayed on the screen, and the data is not fully received. This is my code:

doc () is the function that displays the screen

    QByteArray datas = serialPort->readAll();
    if(datas.size()>0)
    {
        if(file.isOpen())
        {
             QTextStream in(&file);
             in<<datas;
        }
        file.close();

    }
    else {
        QMessageBox::warning(this, "Cảnh báo", "Không có dữ liệu. " + file.errorString());
        return;
    }
if(serialPort->atEnd())
{
    doc();
}

Do you have all information in txt file if you open this file in standard windows notepad?

Under Windows OS method readAll() works badly.

Try this variant

QFile inputFile(fileName);
if (inputFile.open(QIODevice::ReadOnly))
{
   QTextStream in(&inputFile);
   while (!in.atEnd())
   {
      QString line = in.readLine();
      ...
   }
   inputFile.close();
}