Qt/C++ communication with CMMO-ST-C5-1-LKP Festo c

Question

I am trying to commicate with a motor controller via modbus with Qt/C++.

I connect to it using this code that I took mainly from Qt SerialBus adueditor example:

    void Stepper::connect_device(){
    if (ui.pb_connect->text() == "Connect"){
    m_device = device;device->setParameters(0, 0x0000, 0x0000, 0x000F, 0x0000);   
    m_device->setConnectionParameter(QModbusDevice::NetworkAddressParameter, ui.tcpAddressEdit->text());
    m_device->setConnectionParameter(QModbusDevice::NetworkPortParameter, ui.tcpPortEdit->text());
    m_device->setTimeout(1000);
    m_device->setNumberOfRetries(3);connect(m_device, &QModbusDevice::errorOccurred, this, [this](QModbusDevice::Error) {
        qDebug().noquote() << QStringLiteral("Error: %1").arg(m_device->errorString());
        reset();
        /*QMessageBox msgBox;
        msgBox.setWindowTitle("Modbus TCP Client");
        msgBox.setText("Connection error !");
        msgBox.exec();
        emit ui.pb_connect->clicked();*/
        return;
    }, Qt::QueuedConnection);

    connect(m_device, &QModbusDevice::stateChanged, [this](QModbusDevice::State state) {
        switch (state) {
        case QModbusDevice::UnconnectedState:
            qDebug().noquote() << QStringLiteral("State: Entered unconnected state.");
            ui.pb_connect->setEnabled(true);
            ui.pb_connect->setText("Connect");
            break;
        case QModbusDevice::ConnectingState:
            qDebug().noquote() << QStringLiteral("State: Entered connecting state.");
            ui.pb_connect->setEnabled(false);
            ui.pb_connect->setText("Trying to connect..");
            break;
        case QModbusDevice::ConnectedState:
            qDebug().noquote() << QStringLiteral("State: Entered connected state.");
            ui.pb_connect->setText("Disconnect");
            ui.pb_connect->setEnabled(true);
            break;
        case QModbusDevice::ClosingState:
            qDebug().noquote() << QStringLiteral("State: Entered closing state.");
            ui.pb_connect->setEnabled(true);
            ui.pb_connect->setText("Connect");
            break;
        case QModbusDevice::TimeoutError:
            qDebug().noquote() << QStringLiteral("State: Time out error.");
            QMessageBox msgBox;
            msgBox.setWindowTitle("Modbus TCP Client");
            msgBox.setText("Time out !");
            msgBox.exec();
        }
    });
    m_device->connectDevice();
}
else
{
    disconnectAndDelete();
}}

Once the connection is established, I commission the drive using this tcp pdu = "00000004084301000000000000", the device is commissionned and an error with code "E047" occurs because the communication was interrupted. The problem is when I try to make a reset (which is a rising edge on the reset bit) I send these two consecutive frames, but it doesn't work, the error still remains.

void Stepper::reset(){ 
QModbusReply *reply = nullptr;
Data = "00000004084301000000000000";
QByteArray pduData = QByteArray::fromHex(Data.toLatin1());
reply = m_device->sendRawRequest(QModbusRequest(QModbusRequest::FunctionCode(0x0010), pduData), 0x01);  

connect(reply, &QModbusReply::finished, [reply, this]() {
    qDebug() << "Receive: Asynchronous response PDU: " << reply->rawResult() << endl;
    Data = "00000004084B01000000000000";
    QByteArray pduData = QByteArray::fromHex(Data.toLatin1());
    QModbusReply *reply = nullptr;
    while (reply)
        reply = m_device >sendRawRequest(QModbusRequest(QModbusRequest::FunctionCode(0x0010), pduData), 0x01);
});}

I took a look at this simulator "Modbus TCP Client V1.0.0.12" https://www.festo.com/net/cs_cz/SupportPortal/default.aspx?q=modbus&tab=4 that festo offers, when I click "Start" button, the frame is sent permanently, then I can click on the reset bit and the error is eliminated. The communication is interrupted and the error occurs only when I click "Stop". When the communication is running I can do other things like clicking stop button or changing function code, is it using multithreading? In this case, how can I provide a continuous communication with the controller like this simulator interface?

click here to see modbus tcp simulator images

Answer 1

It finally worked, here is the code:

void Stepper::reset(){
QTimer *timer1 = new QTimer(this);
timer1->setSingleShot(false);
timer1->start(100);
connect(timer1, &QTimer::timeout, [this]() {
    send_packet("00000004084301000000000000");
});
QTimer *timer2 = new QTimer(this);
timer2->setSingleShot(false);
timer2->start(100);
connect(timer2, &QTimer::timeout, [this]() {
send_packet("00000004084B01000000000000");
});}

The send_packet function is simply this function :

void Stepper::send_packet(QString Data){
QModbusReply *reply = nullptr;
QByteArray pduData = QByteArray::fromHex(Data.toLatin1());
reply = m_device->sendRawRequest(QModbusRequest(QModbusRequest::FunctionCode(0x0010), pduData), 0x01);  
if (reply)
    return;}