QT and Libmodbus

**hoan_do_van** · 2nd March 2015, 06:26

hi!
I view the source code of QModMaster and now want to build a Qt GUI application server using libmodbus .
my application is run on raspberry pi.
when i run my application, GUI appears only when there is a connection.
anyone have any examples of this application can send t it? please!

code:
tcp.h:

Qt Code:

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#ifndef TCP_H
#define TCP_H
 
#include <QObject>
#include <modbus/modbus.h>
#include <modbus/modbus-tcp.h>
#include <QDebug>
#include <QEventLoop>
 
QT_BEGIN_NAMESPACE
 
//static int NB_CONNECTION;
 
class TcpPrivate;
 
class Q_NETWORK_EXPORT Tcp : public QObject
{
    Q_OBJECT
public:
    explicit Tcp(QObject *parent = 0);
    ~Tcp();
 
    bool listen(const char* address, int port,int NB);
 
    modbus_t *server;
    int ser;
 
 
Q_SIGNALS:
    void newconnection();
    void accepterror();
 
protected:
    virtual void incomingConnection(int handle);
    void addPendingConnection(int socket);
 
    Tcp(TcpPrivate &dd, QObject *parent = 0);
 
public slots:
 
private:
   Q_DISABLE_COPY(Tcp)
   Q_DECLARE_PRIVATE(Tcp)
};
 
QT_END_NAMESPACE
 
#endif // TCP_H

#ifndef TCP_H
#define TCP_H

#include <QObject>
#include <modbus/modbus.h>
#include <modbus/modbus-tcp.h>
#include <QDebug>
#include <QEventLoop>

QT_BEGIN_NAMESPACE

//static int NB_CONNECTION;

class TcpPrivate;

class Q_NETWORK_EXPORT Tcp : public QObject
{
    Q_OBJECT
public:
    explicit Tcp(QObject *parent = 0);
    ~Tcp();

    bool listen(const char* address, int port,int NB);

    modbus_t *server;
    int ser;


Q_SIGNALS:
    void newconnection();
    void accepterror();

protected:
    virtual void incomingConnection(int handle);
    void addPendingConnection(int socket);

    Tcp(TcpPrivate &dd, QObject *parent = 0);

public slots:

private:
   Q_DISABLE_COPY(Tcp)
   Q_DECLARE_PRIVATE(Tcp)
};

QT_END_NAMESPACE

#endif // TCP_H

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tcp_p.h:

Qt Code:

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#ifndef TCP_P_H
#define TCP_P_H
 
#include "tcp.h"
#include "object_p.h"
#include <QtCore/QList>
#include <QDebug>
//#include <winsock2.h>
#include <sys/socket.h>
#include <netinet/in.h>
 
QT_BEGIN_NAMESPACE
 
class TcpPrivate: public QObjectPrivate
{
    Q_DECLARE_PUBLIC(Tcp)
public:
    TcpPrivate();
    ~TcpPrivate();
 
    QList<int *> pendingConnections;
 
    quint16 port;
    const char* address;
    int maxConnections;
 
    void readNotification();
    void setreadNotification(bool enable);
};
 
QT_END_NAMESPACE
 
#endif // TCP_P_H

#ifndef TCP_P_H
#define TCP_P_H

#include "tcp.h"
#include "object_p.h"
#include <QtCore/QList>
#include <QDebug>
//#include <winsock2.h>
#include <sys/socket.h>
#include <netinet/in.h>

QT_BEGIN_NAMESPACE

class TcpPrivate: public QObjectPrivate
{
    Q_DECLARE_PUBLIC(Tcp)
public:
    TcpPrivate();
    ~TcpPrivate();

    QList<int *> pendingConnections;

    quint16 port;
    const char* address;
    int maxConnections;

    void readNotification();
    void setreadNotification(bool enable);
};

QT_END_NAMESPACE

#endif // TCP_P_H

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tcp.cpp:

Qt Code:

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#include "tcp.h"
#include "tcp_p.h"
#include <qlist.h>
 
QT_BEGIN_NAMESPACE
 
/*! \internal
*/
TcpPrivate::TcpPrivate()
: port(0)
, maxConnections(30)
{
}
 
/*! \internal
*/
 
TcpPrivate::~TcpPrivate()
{
}
 
void TcpPrivate::readNotification()
{
    Q_Q(Tcp);
            qDebug() << "dang o for";
            if(pendingConnections.count() > maxConnections)
            {
                qDebug() << "too many connections";
                return;
            }
 
            socklen_t addrlen;
            struct sockaddr_in clientaddr;
            int descriptor;
 
            qDebug() << "ser" << q->ser;
            descriptor  = accept(q->ser,(struct sockaddr*)&clientaddr,&addrlen);
            qDebug() << "descriptor " << descriptor;
            if(descriptor == -1)
            {
                //q->pauseaccepting();
                qDebug() << "accept connection failed";
                emit q->accepterror();
                return;
 
            }
 
            qDebug("TcpPrivate::processIncomingConnection() accepted socket %i", descriptor);
 
            q->incomingConnection(descriptor);
 
            emit q->newconnection();
 
            qDebug() << "emit newconnection";
            //return;
}
 
/*! \internal
*/
 
void TcpPrivate::setreadNotification(bool enable)
{
    if(enable)
        readNotification();
}
 
/*! \internal
*/
 
Tcp::Tcp(TcpPrivate &dd, QObject *parent)
    : QObject(dd, parent)
{
}
 
Tcp::Tcp(QObject *parent) : QObject(*new TcpPrivate, parent)
{
}
 
Tcp::~Tcp()
{
 
}
 
bool Tcp::listen(const char* address, int port,int NB)
{
    Q_D(Tcp);
    modbus_t *mb_tcp;
    mb_tcp = modbus_new_tcp(address,port);
    ser = modbus_tcp_listen(mb_tcp,NB);
    if(ser == -1)
    {
        qDebug() << "listen fail";
        return false;
    }
 
    qDebug() << "listenning on socket "<<ser;
 
    d->setreadNotification(true);
}
 
void Tcp::incomingConnection(int handler)
{
    qDebug("QTcpServer::incomingConnection(%i)", handler);
 
    int socket;
    socket = handler;
 //   socket->setSocketDescriptor(handler);
    addPendingConnection(socket);
}
 
void Tcp::addPendingConnection(int socket)
{
    d_func()->pendingConnections.append(&socket);
}

#include "tcp.h"
#include "tcp_p.h"
#include <qlist.h>

QT_BEGIN_NAMESPACE

/*! \internal
*/
TcpPrivate::TcpPrivate()
: port(0)
, maxConnections(30)
{
}

/*! \internal
*/

TcpPrivate::~TcpPrivate()
{
}

void TcpPrivate::readNotification()
{
    Q_Q(Tcp);
            qDebug() << "dang o for";
            if(pendingConnections.count() > maxConnections)
            {
                qDebug() << "too many connections";
                return;
            }

            socklen_t addrlen;
            struct sockaddr_in clientaddr;
            int descriptor;

            qDebug() << "ser" << q->ser;
            descriptor  = accept(q->ser,(struct sockaddr*)&clientaddr,&addrlen);
            qDebug() << "descriptor " << descriptor;
            if(descriptor == -1)
            {
                //q->pauseaccepting();
                qDebug() << "accept connection failed";
                emit q->accepterror();
                return;

            }

            qDebug("TcpPrivate::processIncomingConnection() accepted socket %i", descriptor);

            q->incomingConnection(descriptor);

            emit q->newconnection();

            qDebug() << "emit newconnection";
            //return;
}

/*! \internal
*/

void TcpPrivate::setreadNotification(bool enable)
{
    if(enable)
        readNotification();
}

/*! \internal
*/

Tcp::Tcp(TcpPrivate &dd, QObject *parent)
    : QObject(dd, parent)
{
}

Tcp::Tcp(QObject *parent) : QObject(*new TcpPrivate, parent)
{
}

Tcp::~Tcp()
{

}

bool Tcp::listen(const char* address, int port,int NB)
{
    Q_D(Tcp);
    modbus_t *mb_tcp;
    mb_tcp = modbus_new_tcp(address,port);
    ser = modbus_tcp_listen(mb_tcp,NB);
    if(ser == -1)
    {
        qDebug() << "listen fail";
        return false;
    }

    qDebug() << "listenning on socket "<<ser;

    d->setreadNotification(true);
}

void Tcp::incomingConnection(int handler)
{
    qDebug("QTcpServer::incomingConnection(%i)", handler);

    int socket;
    socket = handler;
 //   socket->setSocketDescriptor(handler);
    addPendingConnection(socket);
}

void Tcp::addPendingConnection(int socket)
{
    d_func()->pendingConnections.append(&socket);
}

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mainwindow.cpp:

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#include "mainwindow.h"
#include "ui_mainwindow.h"
 
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    const char * host = "192.168.0.140";
    int port = 1502;
    ui->setupUi(this);
    new_tcp = new Tcp(this);
    connect(new_tcp,SIGNAL(newconnection()),this,SLOT(newconnection()));
 
    //connect(this,SIGNAL(newconnection()),&loop,SLOT(quit()));
    connect(new_tcp,SIGNAL(accepterror()),this,SLOT(accepterror()));
    new_tcp->listen(host,port,5);
    //loop.exec();
 
}

#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    const char * host = "192.168.0.140";
    int port = 1502;
    ui->setupUi(this);
    new_tcp = new Tcp(this);
    connect(new_tcp,SIGNAL(newconnection()),this,SLOT(newconnection()));

    //connect(this,SIGNAL(newconnection()),&loop,SLOT(quit()));
    connect(new_tcp,SIGNAL(accepterror()),this,SLOT(accepterror()));
    new_tcp->listen(host,port,5);
    //loop.exec();

}

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**anda_skoa** · 2nd March 2015, 12:22

Maybe Tcp::listen() blocks?

Cheers,
_

**hoan_do_van** · 2nd March 2015, 13:39

thank for reply!
I tried to non block non listen socket created by the command deposits,
fcntl ( socket , F_SETFL , 0 ) However it is still not effective , you have examples of this application does not , sent me ? please!

**anda_skoa** · 2nd March 2015, 20:05

I've not used modbus or its Qt wrapper before so I don't have any examples.
If you can't make the listen call non-blocking like e.g. QTcpServer's, then you'll have to use a separate thread.

Cheers,
_