QT signal-slot not received - c++

Question

I am trying to connect a signal from a second QMainWindow to the mainwindow. It doesn't say anything about a problem connection when the program is launched, but It doesn't work. I am not very familiar with C++ and Qt so maybe is something simple.
My code consists on a Mainwindow used as a SCADA with Start, stop, On, off buttons. In the second qmainwindow I created a terminal where you can type, start,stop... There, I would like to emit a signal to my MainWindow which is in charge of controlling the multiple threads and windows. The problem is that I cannot connect to my slot. I present here a simple overview of this two pieces of code.
Terminal. h
#ifndef TERMINAL__H
#define TERMINAL__H
#include <QMainWindow>
#include <QTextEdit>
#include <QLineEdit>
#include <QObject>
namespace Ui {
class Terminal_;
}
class Terminal_ : public QMainWindow
{
Q_OBJECT
public:
explicit Terminal_(QWidget *parent = 0);
~Terminal_();
signals:
void turnonPLC_terminal();
public slots:
void newline();
private:
Ui::Terminal_ *ui;
QTextEdit* mTerminal;
QLineEdit* mInput;
};
#endif // TERMINAL__H
mainwindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include "terminal_.h"
#include "terminal_help.h"
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
Terminal_ *terminal;
public slots:
void turnon_terminal();
private:
Ui::MainWindow *ui;
};
#endif // MAINWINDOW_H
Mainwindow.cpp
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "terminal_.h"
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
terminal = new Terminal_(this);
connect(terminal, SIGNAL(turnonPLC_terminal()), this, SLOT(turnon_terminal()));
}
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::turnon_terminal(){
turnonPLC=1;
}
terminal_.cpp
#include "terminal_.h"
#include "ui_terminal_.h"
#include <QDockWidget>
#include <QWidget>
#include <QLineEdit>
QString on=("on");
Terminal_::Terminal_(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::Terminal_)
{
ui->setupUi(this);
mTerminal = new QTextEdit();
setCentralWidget(mTerminal);
mInput = new QLineEdit();
QDockWidget* qdw = new QDockWidget;
qdw->setWidget(mInput);
addDockWidget(Qt::BottomDockWidgetArea, qdw);
connect (mInput, SIGNAL(returnPressed()),
this, SLOT(newline()));
}
Terminal_::~Terminal_()
{
delete ui;
}
void Terminal_::newline(){
QString command = mInput->text();
if (command==on){
emit turnonPLC_terminal();
}
}
Thanks

Answer 1

The signal-slots part in the code works perfectly. (compiled and tested with some small modifications)
After entering "on" (not On as written in question)
Terminal_::newline() slot called, turnonPLC_terminal() is fired and finally
void MainWindow::turnon_terminal() is called.
However, there are some small details the header file is called terminal_.h, not Terminal.h turnonPLC is not defined. terminal is created by not displayed (no show-call).
I guess, there are simply some many small logic errors. Try to use debugger or trace the chain of expected calls with qDebug.