Regarding Projector Programming using QT - c++

Question

I am connecting the projector to Quectel QCOM application. Now I want to skip that application and create my customized application to control the projector.
I wrote a program based on the guidelines of Quectel to switch off the projector. Following is the code. Even I used the QSerialPort code. But the projector couldn't switch off. However using the command prompt of the Quectel QCOM application, I could control the projector.
Please help me in this guys! I am stuck in this since a month.
main.cpp
#include "mainwindow.h"
#include <QApplication>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow w;
w.show();
return a.exec(); //
}
mainwindow.cpp
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QDebug>
#include<QSerialPort>
#include<string>
#include<QtGui>
#include <QMessageBox>
using namespace std;
QSerialPort *serial;
MainWindow::MainWindow(QWidget *parent)
: QMainWindow(parent)
, ui(new Ui::MainWindow)
{
ui->setupUi(this);
}
MainWindow::~MainWindow() //
{
delete ui;
}
void MainWindow::on_pushButton_clicked()
{
QMessageBox::information(this,"Title here","Hello World");
serial = new QSerialPort(this);
serial->setPortName("COM3");
serial->setBaudRate(QSerialPort::Baud115200,QSerialPort::AllDirections);
serial->setDataBits(QSerialPort::Data8);
serial->setFlowControl(QSerialPort::NoFlowControl);
serial->setStopBits(QSerialPort::OneStop);
serial->setParity(QSerialPort::NoParity);
if(!serial->open(QIODevice::ReadWrite))
{
qDebug()<<"error: can't open com port";
}
QString command = "WT+LEDE=0\n";
QByteArray x = command.toLocal8Bit();
serial->write(x);
}
mainwindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
MainWindow(QWidget *parent = nullptr);
~MainWindow();
private slots:
void on_pushButton_clicked();
private:
Ui::MainWindow *ui;
};
#endif // MAINWINDOW_H
QMake project file:
#-------------------------------------------------
Project created by QtCreator 2019-11-02T10:55:21
#-------------------------------------------------
QT += core gui serialport
greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
TARGET = GUISerialPort
TEMPLATE = app
SOURCES += main.cpp
mainwindow.cpp
HEADERS += mainwindow.h
FORMS += mainwindow.ui