Qt and codesys

2022-03-04T12:00:33.560000Z

OK, thank you :)

Qt and codesys

2022-03-04T10:50:14.266000Z

If I'd were in your footsteps, I'd implemented a socket interface instead of a shared memory one.

Qt and codesys

2022-03-04T10:31:23.075000Z

Ok thank you so much.

Qt and codesys

2022-03-04T10:19:10.258000Z

It's only an Example!
You can extract the code you need.
Included parts are only to integrate shm in our framework.

Look at private methods. You can take that methods and modify a little bit.

Qt and codesys

2022-03-04T10:09:34.871000Z

include "advabstractmemorymanager.h"

include "advmemorymanager_global.h"

These are not found. I can't compile them.

Qt and codesys

2022-03-04T09:54:40.018000Z

Shared memory is a right way, but...

In Windows RTE you can use QSharedMemory, you must run application as administrator and use only GLOBAL shared memory. Shared memory should instantiated by OS application and not from CODESYS due visibility problems.

In Windows not RTE you can use local memory, you can run app as same user of runtime. Shared memory should instantiated by OS application and not from CODESYS due visibility problems.

In Linux QSharedMemory has some problem with codesys, you can run OS application from any user. Shared memory should instantiated by OS application and not from CODESYS due visibility problems.

There is a sample of code, we are using in many field applications.
This work in Windows and Linux.

# License CLOSED
# copyright ADV Integration Srl

#ifndef ADVSAHREDMEMORYMANAGER_H
#define ADVSAHREDMEMORYMANAGER_H

#include "advabstractmemorymanager.h"
#include "advmemorymanager_global.h"
#include <QSharedMemory>
#include <QDebug>
#ifdef Q_OS_LINUX
#include <fcntl.h>
#include <sys/shm.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <unistd.h>
#endif

template <class T>
class ADVSahredMemoryManager : public ADVAbstractMemoryManager<T>
{
public:
    explicit ADVSahredMemoryManager(const QString &key) : ADVAbstractMemoryManager<T>(), m_key(key), shm(new QSharedMemory) { instantiateMemory(); }
    virtual ~ADVSahredMemoryManager() { freeMemory(); }

    bool isValid() {return m_valid;};

protected:
    void instantiateMemory()
    {
        dataPtr = nullptr;
        shm->setNativeKey(m_key);
        if (attach()) {
            qWarning()<<QObject::tr("Shm exists, attached")<<m_key<<"!";
            m_valid = true;
        } else {
            if (create())
            {
#ifndef Q_OS_LINUX
                dataPtr = shm->data();
#endif
                memset(dataPtr, 0, sizeof(T));

                qWarning()<<QObject::tr("Shm created")<<m_key;
                m_valid = true;
            } else {
                qWarning()<<QObject::tr("Cannot create shm")<<m_key<<"!!!";
                m_valid = false;
                return;
            }
        }
        ADVAbstractMemoryManager<T>::setDataPointer(reinterpret_cast<T *>(dataPtr));
    }

    void freeMemory()
    {
        if (isAttached()) {
            qDebug()<<"Detach"<<m_key;
            detach();
        }
        delete shm;
    }

private:
    QString m_key;
    QSharedMemory *shm;
    void *dataPtr;

    bool m_valid;

    bool attach() {
#ifndef Q_OS_LINUX
        if (shm->attach()) {
            dataPtr = shm->data();
            return true;
        }
        return false;
#endif
#ifdef Q_OS_LINUX
        int shm_fd = shm_open(shm->nativeKey().toUtf8().toStdString().c_str(), O_RDWR, 0666);
        if (shm_fd >= 0) {
            dataPtr = mmap(nullptr, sizeof(T), PROT_READ | PROT_WRITE, MAP_SHARED, shm_fd, 0);
            if (dataPtr)
                return true;
        }
        return false;
#endif
    }
    void detach() {
#ifndef Q_OS_LINUX
        shm->detach();
#endif
#ifdef Q_OS_LINUX
        shm_unlink(shm->nativeKey().toUtf8().toStdString().c_str());
#endif
    }
    bool create() {
#ifndef Q_OS_LINUX
        return shm->create(sizeof(T));
#endif
#ifdef Q_OS_LINUX
        int shm_fd = shm_open(shm->nativeKey().toUtf8().toStdString().c_str(), O_RDWR | O_CREAT | O_EXCL, 0666);
        if (shm_fd >= 0) {
            int ret = ftruncate(shm_fd, sizeof(T));
            if (ret == 0)
                dataPtr = mmap(nullptr, sizeof(T), PROT_READ | PROT_WRITE, MAP_SHARED, shm_fd, 0);
            else {
                qDebug()<<"Error code ftruncate : "<<errno;
                detach();
            }
            if (dataPtr)
                return true;
            else
                detach();
        }
        return false;
#endif
    }
    bool isAttached() {
#ifndef Q_OS_LINUX
        return shm->isAttached();
#endif
#ifdef Q_OS_LINUX
        return dataPtr != nullptr;
#endif
    }
};

#endif // ADVSAHREDMEMORYMANAGER_H

Qt and codesys

2022-03-04T08:57:58.993000Z

Did you do this? If you can, can you share your files or code?

Qt and codesys

2020-12-16T16:44:00.419000Z

do something like that in Qt to read and map the shared memory
// Setup the shared memory

ifndef WINDOWS32

shmid = 0;
wSize = 256;
wOffset = 0;
strncpy(szName, "Mem1", 4);
shmid = shm_open(szName, O_RDWR, 0777);

#ifndef DEBUG
// Set up shared memory
wSize = 256;
shmidl9 = getshmid();
if(shmidl9 >= 0L)
    test = (TEST*) mmap(NULL, wSize, PROT_READ | PROT_WRITE, MAP_SHARED, shmidl9, 0);

endif

Qt and codesys

2020-12-14T16:11:04.619000Z

For anyone that is looking for how to do this here is a sample project on shared memory communication.

Qt and codesys

2020-12-14T14:50:21.314000Z

Hi
it is easy to share variables using shared memory with Qt, i think

Recent posts to Qt and codesys

Qt and codesys

Qt and codesys

Qt and codesys

Qt and codesys

Qt and codesys

include "advabstractmemorymanager.h"

include "advmemorymanager_global.h"

Qt and codesys

Qt and codesys

Qt and codesys

ifndef WINDOWS32

endif

Qt and codesys

Qt and codesys