Modbus problem, beginner

GhostWolf

Hello,

I new to qt, and to programming at all.
I learned a bit of Basic (PICBasic), and i quite understand the way it works.
Now i want to learn c++ to make a modbus programm.

I already understand a bit of it, but now i encountered a problem.

When i connect my PC to the modbus device, and press connect, it says no device connected. If i use an other programm it workes.

I made a modification on the modbus master example, and thought that was the problem, but when i open master, and try to connect that, i get the same.

Can it be something with me using W8.1 and the MingW32 compiler?

I can not post the code now, because it is on my other pc, but the connection part is the same as on master. And this one is also not working.
I tested the connection with MBreader, and this worked.

Can it also be that QT askes a connection confirmation? And MBreader just starts to poll?

Serial, 9600, no par. 1 stop, 8 data.
This is also set.

Thanks

SGaist

Hi and welcome to devnet,

You should provide more information:

Version of Qt
What type of hardware are you connecting to ?
What kind of device are you trying to connect to ?

GhostWolf

Thanks,
On the laptop that i am using for the connection i have :

Qt Creator 4.4.1
Based on Qt 5.9.2 (MSVC 2015, 32 bit)

The hardware is an alarm/monitoring system.
It is made to monitor some data, like temperatures, and if they exceed a certain point, it will give alarm. The whole system is controlled/checked by a display.
On the system is a modbus connection, so you can add a computer to it, to create your own visualisation of the data.

This all works, if i connect with MBreader. Today i did a check with CASmodbus scanner, and i saw this one also askes for a connection, and got it. But with my QT programm, and with (examples) master it does not connect.

I will add the code. It is made as connection test, so i do have some remarks and old stuff still in there.

Project:

#-------------------------------------------------
#
# Project created by QtCreator 2017-10-17T19:11:13
#
#-------------------------------------------------

QT       += core gui serialport serialbus

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = Noris_test
TEMPLATE = app

# The following define makes your compiler emit warnings if you use
# any feature of Qt which has been marked as deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS

# You can also make your code fail to compile if you use deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0


SOURCES += \
        main.cpp \
        mainwindow.cpp \
    settings.cpp

HEADERS += \
        mainwindow.h \
    settings.h

FORMS += \
        mainwindow.ui \
    settings.ui

Header mainwindow:

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QtSerialPort/QSerialPort>
#include <QtSerialBus/QModbusRtuSerialMaster>
#include <QtSerialBus/QtSerialBus>
#include <QModbusDataUnit>
#include "settings.h"


QT_BEGIN_NAMESPACE

class QModbusClient;
class QModbusReply;

namespace Ui {
class MainWindow;
class Settings;
}

QT_END_NAMESPACE
class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = nullptr);
    ~MainWindow();


private:
    QModbusDataUnit readRequestIR() const;
    QModbusDataUnit readRequestCO() const;
    QModbusDataUnit readRequestHR() const;
    QModbusDataUnit readRequestDI() const;
    Settings *settingswindow;

private slots:

//    void serialReceived();
    void readReadyCO();
    void readReadyDI();
    void readReadyIR();
    void readReadyHR();
    void onStateChanged(int state);



    void on_PB_dis_clicked();

    void on_PB_con_clicked();

    void on_actionExit_triggered();

private slots:

    void updateRPM(const QString);

    void on_actionSettings_triggered();

private:
    Ui::MainWindow *ui;
    QModbusReply *lastRequest;
    QModbusClient *modbusDevice;
    Settings *m_settings;


};

#endif // MAINWINDOW_H

Header Settings

#ifndef SETTINGS_H
#define SETTINGS_H

#include <QMainWindow>
#include <QDialog>
#include <QSerialPort>

namespace Ui {
class Settings;
}

class Settings : public QMainWindow
{
    Q_OBJECT

public:
    struct Startsettings {
        QString port ;
        int parity = QSerialPort::NoParity;
        int baud = QSerialPort::Baud9600;
        int dataBits = QSerialPort::Data8;
        int stopBits = QSerialPort::OneStop;
        int responseTime = 10000;
        int numberOfRetries = 3;

    };

    explicit Settings(QWidget *parent = 0);
    ~Settings();

    Startsettings startsettings() const;

private slots:
    void on_closeButton_clicked();

private:
    Startsettings m_settings;
    Ui::Settings *ui;
};

#endif // SETTINGS_H

Source mainwindow:

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QtSerialPort/QSerialPort>
#include <QtSerialPort/QSerialPortInfo>
#include <QtSerialBus>
#include <QModbusRtuSerialMaster>
#include <QStandardItemModel>
#include <QStatusBar>
#include <string>
#include <QDebug>
#include <QMessageBox>
#include "qmessagebox.h"
#include "settings.h"

enum ModbusConnection {
   Serial
};


//QSerialPort *serial;

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
    , lastRequest(nullptr)
    , modbusDevice(nullptr)
{
    ui->setupUi(this);
    m_settings = new Settings(this);
    statusBar()->showMessage("Check Settings before connecting");




//    serial = new QSerialPort(this);
//    serial->setPortName("com1");
//    serial->setBaudRate(QSerialPort::Baud9600);
//    serial->setDataBits(QSerialPort::Data8);
//    serial->setParity(QSerialPort::NoParity);
//    serial->setStopBits(QSerialPort::OneStop);
//    serial->setFlowControl(QSerialPort::NoFlowControl);
//    serial->open(QIODevice::ReadWrite);
//    connect(serial, SIGNAL(readyRead()),this,SLOT(serialReceived()));




    ui->RPM->display("-----");
    ui->HTT->display("-----");
    ui->HTP->display("-----");

//    const auto ports = QSerialPortInfo::availablePorts();
//    for (const QSerialPortInfo &info : ports)
//        ui->serialPortCombo->addItem(info.portName(), false);








}

MainWindow::~MainWindow()
{
    delete ui;
    if (modbusDevice)
        modbusDevice->disconnectDevice();
    delete modbusDevice;
}


//void MainWindow::serialReceived()

//{
//    QByteArray ba;
//    ba=serial->readAll();
//    ui->label_4->setText(ba);
//    qDebug()<<ba;

//}

void MainWindow::on_PB_dis_clicked()
{
    if (modbusDevice)
        modbusDevice->disconnectDevice();
    delete modbusDevice;
    ui->statusBar->showMessage("Disconnecting",5000);
}

void MainWindow::on_PB_con_clicked()
{


    QMessageBox msgBox;
    msgBox.setWindowTitle("CONNECTING");
    msgBox.setText("Please check your settings before connecting");

    QAbstractButton*
            pbuttonyes =
            msgBox.addButton("Settings", QMessageBox::YesRole);
            msgBox.addButton("No", QMessageBox::NoRole);
            msgBox.exec();
if (msgBox.clickedButton()==pbuttonyes){

       settingswindow =new Settings(this);
       settingswindow->setFixedSize(250, 360);
       settingswindow->setWindowTitle("Settings");
       settingswindow->show();
   return;
   }
   else {





    if (!modbusDevice)
        ui->statusBar->showMessage("No device connected");
        return;

    statusBar()->clearMessage();
    if (modbusDevice->state() != QModbusDevice::ConnectedState) {

                modbusDevice->setConnectionParameter(QModbusDevice::SerialPortNameParameter,
                m_settings->startsettings().port);
                modbusDevice->setConnectionParameter(QModbusDevice::SerialParityParameter,
                    m_settings->startsettings().parity);
                modbusDevice->setConnectionParameter(QModbusDevice::SerialBaudRateParameter,
                    m_settings->startsettings().baud);
                modbusDevice->setConnectionParameter(QModbusDevice::SerialDataBitsParameter,
                    m_settings->startsettings().dataBits);
                modbusDevice->setConnectionParameter(QModbusDevice::SerialStopBitsParameter,
                    m_settings->startsettings().stopBits);

}
    modbusDevice->setTimeout(m_settings->startsettings().responseTime);
    modbusDevice->setNumberOfRetries(m_settings->startsettings().numberOfRetries);;
            if (!modbusDevice->connectDevice()) {
                statusBar()->showMessage(tr("Connect failed: ") + modbusDevice->errorString(), 5000);
            }else{ statusBar()->showMessage("Connected");
}


            if (!modbusDevice)
                return;
            statusBar()->clearMessage();


//begin lezen CO1
if (auto *replyCO = modbusDevice->sendReadRequest(readRequestCO(), 1)) {
if (!replyCO->isFinished())
connect(replyCO, &QModbusReply::finished, this, &MainWindow::readReadyCO);
else
delete replyCO; // broadcast replies return immediately
} else {
statusBar()->showMessage(tr("Read CO error: ") + modbusDevice->errorString(), 5000);
}

//einde lezen CO1

//begin lezen DI1
if (auto *replyDI = modbusDevice->sendReadRequest(readRequestDI(), 1)) {
if (!replyDI->isFinished())
connect(replyDI, &QModbusReply::finished, this, &MainWindow::readReadyDI);
else
delete replyDI; // broadcast replies return immediately
} else {
statusBar()->showMessage(tr("Read DI error: ") + modbusDevice->errorString(), 5000);
}

//einde lezen DI1

//begin lezen IR1
if (auto *replyIR = modbusDevice->sendReadRequest(readRequestIR(), 1)) {
if (!replyIR->isFinished())
connect(replyIR, &QModbusReply::finished, this, &MainWindow::readReadyIR);
else
delete replyIR; // broadcast replies return immediately
} else {
statusBar()->showMessage(tr("Read IR error: ") + modbusDevice->errorString(), 5000);
}

//einde lezen IR1

//begin lezen HR1
if (auto *replyHR = modbusDevice->sendReadRequest(readRequestHR(), 1)) {
if (!replyHR->isFinished())
connect(replyHR, &QModbusReply::finished, this, &MainWindow::readReadyHR);
else
delete replyHR; // broadcast replies return immediately
} else {
statusBar()->showMessage(tr("Read HR error: ") + modbusDevice->errorString(), 5000);
}

//einde lezen HR1




   }}




//readrequest 1
QModbusDataUnit MainWindow::readRequestCO() const
{
   const auto table =
        static_cast<QModbusDataUnit::RegisterType> (QModbusDataUnit::Coils);

    int startAddress1 = (100);
    int numberOfEntries1 = (5);
   return QModbusDataUnit(table, startAddress1, numberOfEntries1);
}

QModbusDataUnit MainWindow::readRequestDI() const
{
   const auto table =
        static_cast<QModbusDataUnit::RegisterType> (QModbusDataUnit::DiscreteInputs);

    int startAddress1 = (100);
    int numberOfEntries1 = (5);
   return QModbusDataUnit(table, startAddress1, numberOfEntries1);
}

QModbusDataUnit MainWindow::readRequestIR() const
{
   const auto table =
        static_cast<QModbusDataUnit::RegisterType> (QModbusDataUnit::InputRegisters);

    int startAddress1 = (100);
    int numberOfEntries1 = (5);
   return QModbusDataUnit(table, startAddress1, numberOfEntries1);
}

QModbusDataUnit MainWindow::readRequestHR() const
{
   const auto table =
        static_cast<QModbusDataUnit::RegisterType> (QModbusDataUnit::HoldingRegisters);

    int startAddress1 = (100);
    int numberOfEntries1 = (5);
   return QModbusDataUnit(table, startAddress1, numberOfEntries1);
}




//readrequest einde

void MainWindow::readReadyCO()
{
{
auto replyCO = qobject_cast<QModbusReply *>(sender());
if (!replyCO)
return;

if (replyCO->error() == QModbusDevice::NoError) {
const QModbusDataUnit unit = replyCO->result();
for (uint i = 0; i < unit.valueCount(); i++) {
    const QString entry = tr("Address: %1, Value: %2").arg(unit.startAddress() + i)
                             .arg(QString::number(unit.value(i),
                                  unit.registerType() <= QModbusDataUnit::Coils ? 10 : 16));
//    ui->label_4->setText(entry);
}
} else if (replyCO->error() == QModbusDevice::ProtocolError) {
statusBar()->showMessage(tr("Read response error: %1 (Mobus exception: 0x%2)").
                            arg(replyCO->errorString()).
                            arg(replyCO->rawResult().exceptionCode(), -1, 16), 5000);
} else {
statusBar()->showMessage(tr("Read response error: %1 (code: 0x%2)").
                            arg(replyCO->errorString()).
                            arg(replyCO->error(), -1, 16), 5000);
}

replyCO->deleteLater();
}

}
void MainWindow::readReadyDI()
{
{
auto replyDI = qobject_cast<QModbusReply *>(sender());
if (!replyDI)
return;

if (replyDI->error() == QModbusDevice::NoError) {
const QModbusDataUnit unit = replyDI->result();
for (uint i = 0; i < unit.valueCount(); i++) {
    const QString entry = tr("Address: %1, Value: %2").arg(unit.startAddress() + i)
                             .arg(QString::number(unit.value(i),
                                  unit.registerType() <= QModbusDataUnit::DiscreteInputs ? 10 : 16));
//    ui->label_4->setText(entry);
}
} else if (replyDI->error() == QModbusDevice::ProtocolError) {
statusBar()->showMessage(tr("Read response error: %1 (Mobus exception: 0x%2)").
                            arg(replyDI->errorString()).
                            arg(replyDI->rawResult().exceptionCode(), -1, 16), 5000);
} else {
statusBar()->showMessage(tr("Read response error: %1 (code: 0x%2)").
                            arg(replyDI->errorString()).
                            arg(replyDI->error(), -1, 16), 5000);
}

replyDI->deleteLater();
}

}
void MainWindow::readReadyIR()
            {
    {
        auto replyIR = qobject_cast<QModbusReply *>(sender());
        if (!replyIR)
            return;

        if (replyIR->error() == QModbusDevice::NoError) {
            const QModbusDataUnit unit = replyIR->result();
            for (uint i = 0; i < unit.valueCount(); i++) {
                const QString entry = tr("Address: %1, Value: %2").arg(unit.startAddress() + i)
                                         .arg(QString::number(unit.value(i),
                                              unit.registerType() <= QModbusDataUnit::InputRegisters ? 10 : 16));
                MainWindow::updateRPM(entry[8]);
                ui->label_4->setText(entry);

            }
        } else if (replyIR->error() == QModbusDevice::ProtocolError) {
            statusBar()->showMessage(tr("Read response error: %1 (Mobus exception: 0x%2)").
                                        arg(replyIR->errorString()).
                                        arg(replyIR->rawResult().exceptionCode(), -1, 16), 5000);
        } else {
            statusBar()->showMessage(tr("Read response error: %1 (code: 0x%2)").
                                        arg(replyIR->errorString()).
                                        arg(replyIR->error(), -1, 16), 5000);
        }

        replyIR->deleteLater();
    }

}

void MainWindow::updateRPM(const QString RPMreading)

{
ui->RPM->display(RPMreading);
}

void MainWindow::readReadyHR()
{
{
auto replyHR = qobject_cast<QModbusReply *>(sender());
if (!replyHR)
return;

if (replyHR->error() == QModbusDevice::NoError) {
const QModbusDataUnit unit = replyHR->result();
for (uint i = 0; i < unit.valueCount(); i++) {
    const QString entry = tr("Address: %1, Value: %2").arg(unit.startAddress() + i)
                             .arg(QString::number(unit.value(i),
                                  unit.registerType() <= QModbusDataUnit::HoldingRegisters ? 10 : 16));
//    ui->label_4->setText(entry);
}
} else if (replyHR->error() == QModbusDevice::ProtocolError) {
statusBar()->showMessage(tr("Read response error: %1 (Mobus exception: 0x%2)").
                            arg(replyHR->errorString()).
                            arg(replyHR->rawResult().exceptionCode(), -1, 16), 5000);
} else {
statusBar()->showMessage(tr("Read response error: %1 (code: 0x%2)").
                            arg(replyHR->errorString()).
                            arg(replyHR->error(), -1, 16), 5000);
}

replyHR->deleteLater();
}

}

void MainWindow::onStateChanged(int state)
{

    if (state == QModbusDevice::UnconnectedState)
        statusBar()->showMessage("Disconnected");
    else if (state == QModbusDevice::ConnectedState)
        statusBar()->showMessage("Connected");
}

void MainWindow::on_actionExit_triggered()
{
    MainWindow::close();
}



void MainWindow::on_actionSettings_triggered()
{
    settingswindow =new Settings(this);
    settingswindow->setFixedSize(250, 360);
    settingswindow->setWindowTitle("Settings");
    settingswindow->show();
}

Source main:

#include "mainwindow.h"

#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.setFixedSize(280, 500);
    w.setWindowTitle("Noris Test");
    w.show();


    return a.exec();
}

source settings:

#include "settings.h"
#include "ui_settings.h"
#include <QSerialPortInfo>
#include <QtSerialBus>
#include "mainwindow.h"

Settings::Settings(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::Settings)
{
    ui->setupUi(this);
    const auto ports = QSerialPortInfo::availablePorts();
    for (const QSerialPortInfo &info : ports)

    ui->comCombo2->addItem(info.portName(), false);
    ui->comCombo2->setCurrentIndex(1);
    ui->parityCombo->setCurrentIndex(0);
    ui->baudCombo->setCurrentText(QString::number(m_settings.baud));
    ui->dataBitsCombo->setCurrentText(QString::number(m_settings.dataBits));
    ui->stopBitsCombo->setCurrentText(QString::number(m_settings.stopBits));
    ui->timeoutSpinner->setValue(m_settings.responseTime);
    ui->retriesSpinner->setValue(m_settings.numberOfRetries);









    connect(ui->applyButton, &QPushButton::clicked, [this]() {
        m_settings.port = ui->comCombo2->currentText();
        m_settings.parity = ui->parityCombo->currentIndex();
        if (m_settings.parity > 0)
            m_settings.parity++;
        m_settings.baud = ui->baudCombo->currentText().toInt();
        m_settings.dataBits = ui->dataBitsCombo->currentText().toInt();
        m_settings.stopBits = ui->stopBitsCombo->currentText().toInt();
        m_settings.responseTime = ui->timeoutSpinner->value();
        m_settings.numberOfRetries = ui->retriesSpinner->value();

        ui->statusbar->showMessage("Settings saved, press close.");
    });
}

Settings::~Settings()
{
    delete ui;
}


Settings::Startsettings Settings::startsettings() const
{
    return m_settings;
}

void Settings::on_closeButton_clicked()
{
    hide();
}

SGaist

Can you give the name of the device ?

GhostWolf

I only have the maker of the device, Thats Noris Automation, this is all I have, the system was build and running before I got to know it. And this is written on the display.

SGaist

You didn't get any documentation for that device ?

GhostWolf

No, not that i am aware of. But the strange thing in my opinion is that the other programms do work.

SGaist

It is indeed. What exact error message are you getting ?

J.Hilk

@GhostWolf just a question on my side, did you check the Modbus-Settings of the ModbusMaster example? For whatever reason, its default Baud Rate is, IIRC 19200, and not the 9600 your device is supposed to have.

GhostWolf

Thanks for the answers, I found the connection problem. I added the part:

void MainWindow::on_connectType_currentIndexChanged(int index)
{
if (modbusDevice) {
modbusDevice->disconnectDevice();
delete modbusDevice;
modbusDevice = nullptr;
}

auto type = static_cast<ModbusConnection> (index);
if (type == Serial) {
    modbusDevice = new QModbusRtuSerialMaster(this);
} else if (type == Tcp) {
    modbusDevice = new QModbusTcpClient(this);
    if (ui->portEdit->text().isEmpty())
        ui->portEdit->setText(QLatin1Literal("127.0.0.1:502"));
}

connect(modbusDevice, &QModbusClient::errorOccurred, [this](QModbusDevice::Error) {
    statusBar()->showMessage(modbusDevice->errorString(), 5000);
});

if (!modbusDevice) {
    ui->connectButton->setDisabled(true);
    if (type == Serial)
        statusBar()->showMessage(tr("Could not create Modbus master."), 5000);
    else
        statusBar()->showMessage(tr("Could not create Modbus client."), 5000);
} else {
    connect(modbusDevice, &QModbusClient::stateChanged,
            this, &MainWindow::onStateChanged);
}

}

And now I can make a connection.

Now I have to test it on the device, but i can't access it for a while, to be continued

Update: Forum Guidelines & Code of Conduct

Qt World Summit: Early-Bird Tickets

Solved Modbus problem, beginner