一 Modbus协议简介

Modbus诞生于1979年 莫迪康公司 后来被施耐德电气公司收购。Modbus提供通用语言用于彼此通信的设备和设备。
Modbus已经成为工业领域通信协议的业界标准,并且现在是工业电子设备之间常用的连接方式。Modbus作为目前工业领域应用最广泛的协议。

Modbus优点:

  1. Modbus协议标准开放、公开发表且无版权要求;
  2. Modbus协议支持多种电气接口,包括RS232、RS485、TCP/IP等,还可以在各种介质上传输,如双绞线、光纤、红外、无线等;
  3. Modbus协议消息帧格式简单、紧凑、通俗易懂。用户理解和使用简单,厂商容易开发和集成,方便形成工业控制网络。

Modbus通信过程:

  1. Modbus是一主多从的通信协议: Modbus通信中只有一个设备可以发送请求。
  2. 主机在同一时间内只能向一个从机发送请求,总线上每次只有一个数据进行传输,即主机发送,从机应答,主机不发送,总线上就没有数据通信。
  3. 从机不会自己发送消息给主站,只能回复从主机发送的消息请求。
  4. Modbus并没有忙机制判断,需要通过软件的方式来判断是否从机是否正常接收。

Modbus存储区读写

  1. Modbus协议规定了4个存储区 分别是0 1 3 4区 其中0区和4区是可读可写,1区和3区是只读。
  2. 主机向从机获取数据时,只需要告诉从机数据的起始地址,还有获取多少字节的数据,实际上就是对从机设备对应的实际存储空间进行读写。

Modbus协议类型

Modbus协议类型常见的有几下四种:

  1. Modbus-RTU:  只支持串口, 使用紧凑的十六进制表示数据,后续的命令/数据带有循环冗余校验的校验和。RTU模式比较常用。
  2. Modbus-ASCII:只支持串口, 采用Ascii码表示数据,每8Bit 字节作为两个ASCII字符发送,采用纵向冗余校验的校验和;
  3. Modbus-TCP:支持网口,把MODBUS作为应用层协议,TCP/IP作为下层协议。并且不需要从从机地址,而是需要MBAP报文头,因为TCP本身就具有校验差错的能力故该协议不需要差错校验。
  4. ModbusPlus:是一种典型的令牌环网,完整定义了通讯协议、网络结构、连接电缆(或者光缆)以及安装工具等方面的性能指标。

Modbus协议的三种传输模式

Modbus协议是一项应用层报文传输协议,包括ASCII、RTU、TCP三种报文类型。标准的Modbus协议物理层接口有RS232、RS422、RS485和以太网接口,采用master/slave方式通信。

  1. ASCII:  采用LRC校验;
  2. RTU(远程终端控制系统): 采用16 位CRC校验;
  3. TCP/IP:不使用校验,因为TCP协议是一个面向连接的可靠协议;

Modbus的4种操作对象

Modbus的4种操作对象分别是线圈Coils、离散输入DiscreteInputs、输入寄存器InputRegisters、保持寄存器HoldingRegisters。四种操作对象的读写权限如下:
线圈:PLC的输出位,开关量,在MOdbus中可读可写;
离散输入:PLC的输入位,开关量,在Modbus中只读;
输入寄存器:PLC中只能从模拟量输入端改变的寄存器,在MODBUS中只读;
保持寄存器:PLC中用于输出模拟量信号的寄存器,在MODBUS中可读可写;

二 基于ModBus-TCP的Qt案例示范

Modbus协议是一个master/slave架构的协议。有一个节点是master节点,其他使用Modbus协议参与通信的节点是slave节点。每一个slave设备都有一个唯一的地址。在串行和MB+网络中,只有被指定为主节点的节点可以启动一个命令(在以太网上,任何一个设备都能发送一个Modbus命令,但是通常也只有一个主节点设备启动指令)。一般都是上位机做主站,PLC做从站。

Modbus TCP/IP协议格式

modbus4android 发送十六进制 modbus发送接收实例_寄存器

如上图所示,报文主要分为两部分,分别是协议头(MBAP Header)和PDU。PDU 又包含功能码(Function code)和数据(Data)两部分。

接下来我们直接来看看Qt官方的Modbus-tcp实例:实现主从站的通信功能;

//Qt中几个常用的串口modbus类

QModbusRtuSerialSlave    //modbus串口通信方式下的服务器类
QModbusRtuSerialMaster   //串口通信方式下的客户端类
QModbusServer            // QModbusServer类接收和处理modbus的请求。
QModbusDataUnit         //存储接收和发送数据的类,数据类型为1bit和16bit
QModbusReply            //客户端访问服务器后得到的回复(如客户端读服务器数据时包含数据信息)

主站关键代码:

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "settingsdialog.h"
#include "writeregistermodel.h"

#include <QModbusTcpClient>
#include <QModbusRtuSerialClient>
#include <QStandardItemModel>
#include <QStatusBar>
#include <QUrl>

enum ModbusConnection {
    Serial,
    Tcp
};

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    //初始化设置对话框类
    m_settingsDialog = new SettingsDialog(this);

    //初始化菜单操作
    initActions();

    //初始化写入寄存器模型
    writeModel = new WriteRegisterModel(this);
    //设置地址起始位置
    writeModel->setStartAddress(ui->writeAddress->value());
    //设置写入的地址位数量
    writeModel->setNumberOfValues(ui->writeSize->currentText());

    //把要写入的数据使用模型的方式,给视图展示出来
    ui->writeValueTable->setModel(writeModel);
    //设置隐藏的列为第二列
    ui->writeValueTable->hideColumn(2);

    //当视图有更新时,同步刷新列表
    connect(writeModel, &WriteRegisterModel::updateViewport,
            ui->writeValueTable->viewport(), QOverload<>::of(&QWidget::update));

    //添加写入数据单元的类型: 主要有五种,分别是 无效、线圈、离散输入、输入寄存器、保持寄存器
    ui->writeTable->addItem(tr("线圈"), QModbusDataUnit::Coils);
    ui->writeTable->addItem(tr("离散输入"), QModbusDataUnit::DiscreteInputs);
    ui->writeTable->addItem(tr("输入寄存器"), QModbusDataUnit::InputRegisters);
    ui->writeTable->addItem(tr("保持寄存器"), QModbusDataUnit::HoldingRegisters);

#if QT_CONFIG(modbus_serialport)
    //设置连接类型,有串口和TCP两种方式
    ui->connectType->setCurrentIndex(0);
    //使用当前选择的连接方式进行与服务器端连接
    onConnectTypeChanged(0);
#else
    // 锁定串行端口选项
    ui->connectType->setCurrentIndex(1);
    //使用当前选择的连接方式进行与服务器端连接
    onConnectTypeChanged(1);
    //禁用选择框
    ui->connectType->setEnabled(false);
#endif

    //创建标准项模型对象,一共10行一列
    auto model = new QStandardItemModel(10, 1, this);
    //循环添加项到标准模型里面
    for (int i = 0; i < 10; ++i)
        model->setItem(i, new QStandardItem(QStringLiteral("%1").arg(i + 1)));
    ui->writeSize->setModel(model);
    ui->writeSize->setCurrentText("10");

    //把写入位变化及时更新至写入注册模型中
    connect(ui->writeSize, &QComboBox::currentTextChanged,
            writeModel, &WriteRegisterModel::setNumberOfValues);

    //把开始地址更新至写入模型中
    connect(ui->writeAddress, &QSpinBox::valueChanged, writeModel, &WriteRegisterModel::setStartAddress);

    //把起始位之前的位选择功能禁用
    connect(ui->writeAddress, &QSpinBox::valueChanged, this, [this, model](int i) {
        int lastPossibleIndex = 0;
        const int currentIndex = ui->writeSize->currentIndex();
        for (int ii = 0; ii < 10; ++ii) {
            if (ii < (10 - i)) {
                lastPossibleIndex = ii;
                model->item(ii)->setEnabled(true);
            } else {
                model->item(ii)->setEnabled(false);
            }
        }
        if (currentIndex > lastPossibleIndex)
            ui->writeSize->setCurrentIndex(lastPossibleIndex);
    });
}

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

    delete ui;
}

//完成每个菜单的响应处理,即绑定菜单的信号与槽,最终在槽函数里面完成菜单的响应逻辑
void MainWindow::initActions()
{
    ui->actionConnect->setEnabled(true);

    ui->actionDisconnect->setEnabled(false);
    ui->actionExit->setEnabled(true);
    ui->actionOptions->setEnabled(true);


    connect(ui->connectButton, &QPushButton::clicked,
            this, &MainWindow::onConnectButtonClicked);
    connect(ui->actionConnect, &QAction::triggered,
            this, &MainWindow::onConnectButtonClicked);
    connect(ui->actionDisconnect, &QAction::triggered,
            this, &MainWindow::onConnectButtonClicked);
    connect(ui->readButton, &QPushButton::clicked,
            this, &MainWindow::onReadButtonClicked);
    connect(ui->writeButton, &QPushButton::clicked,
            this, &MainWindow::onWriteButtonClicked);
    connect(ui->readWriteButton, &QPushButton::clicked,
            this, &MainWindow::onReadWriteButtonClicked);
    connect(ui->connectType, &QComboBox::currentIndexChanged,
            this, &MainWindow::onConnectTypeChanged);
    connect(ui->writeTable, &QComboBox::currentIndexChanged,
            this, &MainWindow::onWriteTableChanged);

    connect(ui->actionExit, &QAction::triggered, this, &QMainWindow::close);
    connect(ui->actionOptions, &QAction::triggered, m_settingsDialog, &QDialog::show);
}


//检测连接类型
void MainWindow::onConnectTypeChanged(int index)
{
    //如果客户端已连接,则断开
    if (modbusDevice) {
        modbusDevice->disconnectDevice();
        delete modbusDevice;
        modbusDevice = nullptr;
    }

    //转换连接类型的数字为当前定义的枚举,即Serial或Tcp
    auto type = static_cast<ModbusConnection>(index);
    //如果是串口
    if (type == Serial) {
#if QT_CONFIG(modbus_serialport)
        //初始化QModbusRtuSerialClient类,它表示Modbus客户端,并且使用串行总线与Modbus服务器进行通信
        modbusDevice = new QModbusRtuSerialClient(this);
#endif
    }
    //如果是TCP
    else if (type == Tcp) {
        //初始化QModbusTcpClient类,它是Modbus-TCP客户端设备的接口类
        modbusDevice = new QModbusTcpClient(this);

        //如果端口设置没有设置,则把默认值设置为127.0.0.1:502
        if (ui->portEdit->text().isEmpty())
            ui->portEdit->setText(QLatin1String("127.0.0.1:502"));
    }

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

    if (!modbusDevice) {
        ui->connectButton->setDisabled(true);
        statusBar()->showMessage(tr("无法创建Modbus客户端."), 5000);
    } else {
        connect(modbusDevice, &QModbusClient::stateChanged,
                this, &MainWindow::onModbusStateChanged);
    }
}

//配置一些主站相关的参数
void MainWindow::onConnectButtonClicked()
{
    if (!modbusDevice)
        return;

    statusBar()->clearMessage();
    if (modbusDevice->state() != QModbusDevice::ConnectedState) {
        if (static_cast<ModbusConnection>(ui->connectType->currentIndex()) == Serial) {
            modbusDevice->setConnectionParameter(QModbusDevice::SerialPortNameParameter,
                ui->portEdit->text());
#if QT_CONFIG(modbus_serialport)
            //设置串口的几个关键参数:parity,baud,dataBits,stopBits
            modbusDevice->setConnectionParameter(QModbusDevice::SerialParityParameter,
                m_settingsDialog->settings().parity);
            modbusDevice->setConnectionParameter(QModbusDevice::SerialBaudRateParameter,
                m_settingsDialog->settings().baud);
            modbusDevice->setConnectionParameter(QModbusDevice::SerialDataBitsParameter,
                m_settingsDialog->settings().dataBits);
            modbusDevice->setConnectionParameter(QModbusDevice::SerialStopBitsParameter,
                m_settingsDialog->settings().stopBits);
#endif
        } else {
            //设置连接的IP和端口
            const QUrl url = QUrl::fromUserInput(ui->portEdit->text());
            modbusDevice->setConnectionParameter(QModbusDevice::NetworkPortParameter, url.port());
            modbusDevice->setConnectionParameter(QModbusDevice::NetworkAddressParameter, url.host());
        }
        modbusDevice->setTimeout(m_settingsDialog->settings().responseTime);
        modbusDevice->setNumberOfRetries(m_settingsDialog->settings().numberOfRetries);
        if (!modbusDevice->connectDevice()) {
            statusBar()->showMessage(tr("连接失败: ") + modbusDevice->errorString(), 5000);
        } else {
            ui->actionConnect->setEnabled(false);
            ui->actionDisconnect->setEnabled(true);
        }
    } else {
        modbusDevice->disconnectDevice();
        ui->actionConnect->setEnabled(true);
        ui->actionDisconnect->setEnabled(false);
    }
}



//监听连接状态
void MainWindow::onModbusStateChanged(int state)
{
    bool connected = (state != QModbusDevice::UnconnectedState);
    ui->actionConnect->setEnabled(!connected);
    ui->actionDisconnect->setEnabled(connected);

    if (state == QModbusDevice::UnconnectedState)
        ui->connectButton->setText(tr("连接"));
    else if (state == QModbusDevice::ConnectedState)
        ui->connectButton->setText(tr("断开"));
}

//读取从站(服务器端)的数据
void MainWindow::onReadButtonClicked()
{
    if (!modbusDevice)
        return;

    ui->readValue->clear();
    statusBar()->clearMessage();

    //向服务器请求读取数据,参数含义为:数据单元和服务器地址
    if (auto *reply = modbusDevice->sendReadRequest(readRequest(), ui->serverEdit->value())) {
        //判断答复状态,若还没结束则读取请求过来的数据
        if (!reply->isFinished())
            //开始读取数据
            connect(reply, &QModbusReply::finished, this, &MainWindow::onReadReady);
        else
            delete reply; // 广播回复立即返回
    } else {
        statusBar()->showMessage(tr("读取错误: ") + modbusDevice->errorString(), 5000);
    }
}


//读取数据
void MainWindow::onReadReady()
{
    auto reply = qobject_cast<QModbusReply *>(sender());
    if (!reply)
        return;

    //没有错误则开始读取数据
    if (reply->error() == QModbusDevice::NoError) {
        //记录读取的数据
        const QModbusDataUnit unit = reply->result();
        //依次取出各个位的数据
        for (qsizetype i = 0, total = unit.valueCount(); i < total; ++i) {
            const QString entry = tr("地址: %1, 值: %2").
                    arg(unit.startAddress() + i).
                    arg(QString::number(unit.value(i),unit.registerType() <= QModbusDataUnit::Coils ? 10 : 16));
            //把每一个位的数据放入列表中显示出来,包括地址和值
            ui->readValue->addItem(entry);
        }
        //若通信异常,则显示对应的错误信息
    } else if (reply->error() == QModbusDevice::ProtocolError) {
        statusBar()->showMessage(tr("读取响应错误: %1 (Modbus异常: 0x%2)").
                                    arg(reply->errorString()).
                                    arg(reply->rawResult().exceptionCode(), -1, 16), 5000);
    } else {
        statusBar()->showMessage(tr("读取响应错误: %1 (编码: 0x%2)").
                                    arg(reply->errorString()).
                                    arg(reply->error(), -1, 16), 5000);
    }

    reply->deleteLater();
}


//写数据
void MainWindow::onWriteButtonClicked()
{
    if (!modbusDevice)
        return;
    statusBar()->clearMessage();

    //获取写入数据的包装类型
    QModbusDataUnit writeUnit = writeRequest();
    //获取需要写入的区域:线圈、保持寄存器
    QModbusDataUnit::RegisterType table = writeUnit.registerType();
    //writeUnit.valueCount()返回寄存器中数据单元的起始地址。
    for (qsizetype i = 0, total = writeUnit.valueCount(); i < total; ++i) {
        //如果写入的区域是线圈,则可以写入
        if (table == QModbusDataUnit::Coils)
            //写入线圈的0至结束地址
            writeUnit.setValue(i, writeModel->m_coils[i + writeUnit.startAddress()]);
        else
            //写入保持寄存器0至结束地址
            writeUnit.setValue(i, writeModel->m_holdingRegisters[i + writeUnit.startAddress()]);
    }

    //开始写入数据,参数为要写入的封装数据和服务器地址
    if (auto *reply = modbusDevice->sendWriteRequest(writeUnit, ui->serverEdit->value())) {
        //检测写入状态
        if (!reply->isFinished()) {
            connect(reply, &QModbusReply::finished, this, [this, reply]() {
                if (reply->error() == QModbusDevice::ProtocolError) {
                    statusBar()->showMessage(tr("写入响应错误: %1 (Modbus异常: 0x%2)")
                        .arg(reply->errorString()).arg(reply->rawResult().exceptionCode(), -1, 16),
                        5000);
                } else if (reply->error() != QModbusDevice::NoError) {
                    statusBar()->showMessage(tr("写入响应错误: %1 (编码: 0x%2)").
                        arg(reply->errorString()).arg(reply->error(), -1, 16), 5000);
                }
                reply->deleteLater();
            });
        } else {
            // broadcast replies return immediately
            reply->deleteLater();
        }
    } else {
        statusBar()->showMessage(tr("写错误: ") + modbusDevice->errorString(), 5000);
    }
}

//读写数据: 只有保持寄存器支持同时读写
void MainWindow::onReadWriteButtonClicked()
{
    if (!modbusDevice)
        return;
    ui->readValue->clear();
    statusBar()->clearMessage();

    //写请求
    QModbusDataUnit writeUnit = writeRequest();
    QModbusDataUnit::RegisterType table = writeUnit.registerType();
    for (qsizetype i = 0, total = writeUnit.valueCount(); i < total; ++i) {
        if (table == QModbusDataUnit::Coils)
            writeUnit.setValue(i, writeModel->m_coils[i + writeUnit.startAddress()]);
        else
            writeUnit.setValue(i, writeModel->m_holdingRegisters[i + writeUnit.startAddress()]);
    }

    //读写请求
    if (auto *reply = modbusDevice->sendReadWriteRequest(readRequest(), writeUnit,
        ui->serverEdit->value())) {
        if (!reply->isFinished())
            connect(reply, &QModbusReply::finished, this, &MainWindow::onReadReady);
        else
            delete reply; // broadcast replies return immediately
    } else {
        statusBar()->showMessage(tr("读错误: ") + modbusDevice->errorString(), 5000);
    }
}


//检测写入区域的选择: 线圈、离散输入、输入寄存器、保持寄存器
void MainWindow::onWriteTableChanged(int index)
{
    //判断是线圈还是保持寄存器
    const bool coilsOrHolding = index == 0 || index == 3;
    //如果选择的是线圈或保持寄存器
    if (coilsOrHolding) {
        //隐藏第2、3列
        ui->writeValueTable->setColumnHidden(1, index != 0);
        ui->writeValueTable->setColumnHidden(2, index != 3);
        //根据列内容的大小调整第一列的大小。
        ui->writeValueTable->resizeColumnToContents(0);
    }

    //若写入区域为保持寄存器,则启用读写按钮
    ui->readWriteButton->setEnabled(index == 3);
    //若写入区域为线圈或保持寄存器,则启用读写按钮
    ui->writeButton->setEnabled(coilsOrHolding);
    //若写入区域为保持寄存器,则启用写入区域的所有字节输入框
    ui->writeGroupBox->setEnabled(coilsOrHolding);
}



//包装需要读取的数据
QModbusDataUnit MainWindow::readRequest() const
{
    //获取当前需要读取的区域:线圈、离散输入、输入寄存器、保持寄存器
    const auto table =
        static_cast<QModbusDataUnit::RegisterType>(ui->writeTable->currentData().toInt());

    int startAddress = ui->readAddress->value();
    Q_ASSERT(startAddress >= 0 && startAddress < 10);

    // 不要超过10个条目,在需要读取的字节数与有效数据的字节数之间获取较小的值
    quint16 numberOfEntries = qMin(ui->readSize->currentText().toUShort(), quint16(10 - startAddress));
    //返回需要读取的数据单元,参数的含义分别是要读取的区域、开始地址、读取的字节数
    return QModbusDataUnit(table, startAddress, numberOfEntries);
}




//包装写入的数据
QModbusDataUnit MainWindow::writeRequest() const
{
    //获取写入数据的区域类型:线圈、离散输入、输入寄存器、保持寄存器
    const auto table =
        static_cast<QModbusDataUnit::RegisterType>(ui->writeTable->currentData().toInt());
     //开始地址
    int startAddress = ui->writeAddress->value();
    Q_ASSERT(startAddress >= 0 && startAddress < 10);

    //  不要超过10个条目,在需要读取的字节数与有效数据的字节数之间获取较小的值
    quint16 numberOfEntries = qMin(ui->writeSize->currentText().toUShort(), quint16(10 - startAddress));
    //返回需要读取的数据单元,参数的含义分别是要读取的区域、开始地址、读取的字节数
    return QModbusDataUnit(table, startAddress, numberOfEntries);
}

从站关键代码:

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

#include <QModbusRtuSerialServer>
#include <QModbusTcpServer>
#include <QRegularExpression>
#include <QRegularExpressionValidator>
#include <QStatusBar>
#include <QUrl>

//枚举连接类型
enum ModbusConnection {
    Serial,
    Tcp
};

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    setupWidgetContainers();

    //设置默认连接类型
#if QT_CONFIG(modbus_serialport)
    ui->connectType->setCurrentIndex(0);
    onCurrentConnectTypeChanged(0);
#else
    // 锁定串行端口选项,设置连接类型
    ui->connectType->setCurrentIndex(1);
    onCurrentConnectTypeChanged(1);
    ui->connectType->setEnabled(false);
#endif

    m_settingsDialog = new SettingsDialog(this);
    initActions();
}

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

    delete ui;
}

//初始化菜单
void MainWindow::initActions()
{
    ui->actionConnect->setEnabled(true);
    ui->actionDisconnect->setEnabled(false);
    ui->actionExit->setEnabled(true);
    ui->actionOptions->setEnabled(true);

    connect(ui->connectButton, &QPushButton::clicked,
            this, &MainWindow::onConnectButtonClicked);
    connect(ui->actionConnect, &QAction::triggered,
            this, &MainWindow::onConnectButtonClicked);
    connect(ui->actionDisconnect, &QAction::triggered,
            this, &MainWindow::onConnectButtonClicked);
    connect(ui->connectType, &QComboBox::currentIndexChanged,
            this, &MainWindow::onCurrentConnectTypeChanged);

    connect(ui->actionExit, &QAction::triggered, this, &QMainWindow::close);
    connect(ui->actionOptions, &QAction::triggered, m_settingsDialog, &QDialog::show);
}

//类型变化检测,根据选中的不同连接类型创建不同的对象
void MainWindow::onCurrentConnectTypeChanged(int index)
{
    if (modbusDevice) {
        modbusDevice->disconnect();
        delete modbusDevice;
        modbusDevice = nullptr;
    }

    //获取连接类型并强制转换为枚举
    auto type = static_cast<ModbusConnection>(index);
    //串口连接方式
    if (type == Serial) {
#if QT_CONFIG(modbus_serialport)
        modbusDevice = new QModbusRtuSerialServer(this);
#endif
    }
    //TCP连接方式
    else if (type == Tcp) {
        modbusDevice = new QModbusTcpServer(this);
        if (ui->portEdit->text().isEmpty())
            ui->portEdit->setText(QLatin1String("127.0.0.1:502"));
    }
    //若类型为serial时,启用仅监听按钮,否则禁用
    ui->listenOnlyBox->setEnabled(type == Serial);

    //如果对象为空,则提示错误信息
    if (!modbusDevice) {
        ui->connectButton->setDisabled(true);
        statusBar()->showMessage(tr("Could not create Modbus server."), 5000);
    } else {
        //对象创建成功后,初始化各个数据区的参数设置
        QModbusDataUnitMap reg;
        reg.insert(QModbusDataUnit::Coils, { QModbusDataUnit::Coils, 0, 10 });
        reg.insert(QModbusDataUnit::DiscreteInputs, { QModbusDataUnit::DiscreteInputs, 0, 10 });
        reg.insert(QModbusDataUnit::InputRegisters, { QModbusDataUnit::InputRegisters, 0, 10 });
        reg.insert(QModbusDataUnit::HoldingRegisters, { QModbusDataUnit::HoldingRegisters, 0, 10 });

        modbusDevice->setMap(reg);

        connect(modbusDevice, &QModbusServer::dataWritten,
                this, &MainWindow::updateWidgets);
        connect(modbusDevice, &QModbusServer::stateChanged,
                this, &MainWindow::onStateChanged);
        connect(modbusDevice, &QModbusServer::errorOccurred,
                this, &MainWindow::handleDeviceError);

        connect(ui->listenOnlyBox, &QCheckBox::toggled, this, [this](bool toggled) {
            if (modbusDevice)
                modbusDevice->setValue(QModbusServer::ListenOnlyMode, toggled);
        });
        emit ui->listenOnlyBox->toggled(ui->listenOnlyBox->isChecked());
        connect(ui->setBusyBox, &QCheckBox::toggled, this, [this](bool toggled) {
            if (modbusDevice)
                modbusDevice->setValue(QModbusServer::DeviceBusy, toggled ? 0xffff : 0x0000);
        });
        emit ui->setBusyBox->toggled(ui->setBusyBox->isChecked());

        setupDeviceData();
    }
}

//处理设备错误
void MainWindow::handleDeviceError(QModbusDevice::Error newError)
{
    if (newError == QModbusDevice::NoError || !modbusDevice)
        return;

    statusBar()->showMessage(modbusDevice->errorString(), 5000);
}


//连接客户端
void MainWindow::onConnectButtonClicked()
{
    //是否处于未连接状态
    bool intendToConnect = (modbusDevice->state() == QModbusDevice::UnconnectedState);

    statusBar()->clearMessage();

    //按照不同的连接方式创建不同的对象
    if (intendToConnect) {
        //若为serial连接方式,则设置相关参数
        if (static_cast<ModbusConnection>(ui->connectType->currentIndex()) == Serial) {
            modbusDevice->setConnectionParameter(QModbusDevice::SerialPortNameParameter,
                ui->portEdit->text());
#if QT_CONFIG(modbus_serialport)
            modbusDevice->setConnectionParameter(QModbusDevice::SerialParityParameter,
                m_settingsDialog->settings().parity);
            modbusDevice->setConnectionParameter(QModbusDevice::SerialBaudRateParameter,
                m_settingsDialog->settings().baud);
            modbusDevice->setConnectionParameter(QModbusDevice::SerialDataBitsParameter,
                m_settingsDialog->settings().dataBits);
            modbusDevice->setConnectionParameter(QModbusDevice::SerialStopBitsParameter,
                m_settingsDialog->settings().stopBits);
#endif
        }
        //拖尾TCP方式,则设置其IP和端口
        else {
            const QUrl url = QUrl::fromUserInput(ui->portEdit->text());
            modbusDevice->setConnectionParameter(QModbusDevice::NetworkPortParameter, url.port());
            modbusDevice->setConnectionParameter(QModbusDevice::NetworkAddressParameter, url.host());
        }
        //设置服务器地址
        modbusDevice->setServerAddress(ui->serverEdit->text().toInt());
        if (!modbusDevice->connectDevice()) {
            statusBar()->showMessage(tr("Connect failed: ") + modbusDevice->errorString(), 5000);
        } else {
            ui->actionConnect->setEnabled(false);
            ui->actionDisconnect->setEnabled(true);
        }
    } else {
        modbusDevice->disconnectDevice();
        ui->actionConnect->setEnabled(true);
        ui->actionDisconnect->setEnabled(false);
    }
}

//连接状态检测
void MainWindow::onStateChanged(int state)
{
    bool connected = (state != QModbusDevice::UnconnectedState);
    ui->actionConnect->setEnabled(!connected);
    ui->actionDisconnect->setEnabled(connected);

    if (state == QModbusDevice::UnconnectedState)
        ui->connectButton->setText(tr("Connect"));
    else if (state == QModbusDevice::ConnectedState)
        ui->connectButton->setText(tr("Disconnect"));
}

//线圈变化处理函数
void MainWindow::coilChanged(int id)
{
    QAbstractButton *button = coilButtons.button(id);
    bitChanged(id, QModbusDataUnit::Coils, button->isChecked());
}

//离散输入量处理函数
void MainWindow::discreteInputChanged(int id)
{
    QAbstractButton *button = discreteButtons.button(id);
    bitChanged(id, QModbusDataUnit::DiscreteInputs, button->isChecked());
}

//bit位处理函数
void MainWindow::bitChanged(int id, QModbusDataUnit::RegisterType table, bool value)
{
    if (!modbusDevice)
        return;

    if (!modbusDevice->setData(table, quint16(id), value))
        statusBar()->showMessage(tr("Could not set data: ") + modbusDevice->errorString(), 5000);
}

//设置寄存器
void MainWindow::setRegister(const QString &value)
{
    if (!modbusDevice)
        return;

    const QString objectName = QObject::sender()->objectName();
    if (registers.contains(objectName)) {
        bool ok = true;
        const quint16 id = quint16(QObject::sender()->property("ID").toUInt());
        if (objectName.startsWith(QStringLiteral("inReg")))
            ok = modbusDevice->setData(QModbusDataUnit::InputRegisters, id, value.toUShort(&ok, 16));
        else if (objectName.startsWith(QStringLiteral("holdReg")))
            ok = modbusDevice->setData(QModbusDataUnit::HoldingRegisters, id, value.toUShort(&ok, 16));

        if (!ok)
            statusBar()->showMessage(tr("Could not set register: ") + modbusDevice->errorString(),
                                     5000);
    }
}

//更新窗口部件
void MainWindow::updateWidgets(QModbusDataUnit::RegisterType table, int address, int size)
{
    for (int i = 0; i < size; ++i) {
        quint16 value;
        QString text;
        switch (table) {
        case QModbusDataUnit::Coils:
            modbusDevice->data(QModbusDataUnit::Coils, quint16(address + i), &value);
            coilButtons.button(address + i)->setChecked(value);
            break;
        case QModbusDataUnit::HoldingRegisters:
            modbusDevice->data(QModbusDataUnit::HoldingRegisters, quint16(address + i), &value);
            registers.value(QStringLiteral("holdReg_%1").arg(address + i))->setText(text
                .setNum(value, 16));
            break;
        default:
            break;
        }
    }
}



//设置设备数据
void MainWindow::setupDeviceData()
{
    if (!modbusDevice)
        return;

    //遍历所有bit位信息写入寄存器
    for (quint16 i = 0; i < coilButtons.buttons().count(); ++i)
        modbusDevice->setData(QModbusDataUnit::Coils, i, coilButtons.button(i)->isChecked());

    for (quint16 i = 0; i < discreteButtons.buttons().count(); ++i) {
        modbusDevice->setData(QModbusDataUnit::DiscreteInputs, i,
            discreteButtons.button(i)->isChecked());
    }

    bool ok;
    for (QLineEdit *widget : qAsConst(registers)) {
        if (widget->objectName().startsWith(QStringLiteral("inReg"))) {
            modbusDevice->setData(QModbusDataUnit::InputRegisters, quint16(widget->property("ID").toUInt()),
                widget->text().toUShort(&ok, 16));
        } else if (widget->objectName().startsWith(QStringLiteral("holdReg"))) {
            modbusDevice->setData(QModbusDataUnit::HoldingRegisters, quint16(widget->property("ID").toUInt()),
                widget->text().toUShort(&ok, 16));
        }
    }
}

//设置窗口容器
void MainWindow::setupWidgetContainers()
{
    coilButtons.setExclusive(false);
    discreteButtons.setExclusive(false);

    QRegularExpression regexp(QStringLiteral("coils_(?<ID>\\d+)"));
    const QList<QCheckBox *> coils = findChildren<QCheckBox *>(regexp);
    for (QCheckBox *cbx : coils)
        coilButtons.addButton(cbx, regexp.match(cbx->objectName()).captured("ID").toInt());
    connect(&coilButtons, &QButtonGroup::idClicked, this, &MainWindow::coilChanged);

    regexp.setPattern(QStringLiteral("disc_(?<ID>\\d+)"));
    const QList<QCheckBox *> discs = findChildren<QCheckBox *>(regexp);
    for (QCheckBox *cbx : discs)
        discreteButtons.addButton(cbx, regexp.match(cbx->objectName()).captured("ID").toInt());
    connect(&discreteButtons, &QButtonGroup::idClicked, this, &MainWindow::discreteInputChanged);

    regexp.setPattern(QLatin1String("(in|hold)Reg_(?<ID>\\d+)"));
    const QList<QLineEdit *> qle = findChildren<QLineEdit *>(regexp);
    for (QLineEdit *lineEdit : qle) {
        registers.insert(lineEdit->objectName(), lineEdit);
        lineEdit->setProperty("ID", regexp.match(lineEdit->objectName()).captured("ID").toInt());
        lineEdit->setValidator(new QRegularExpressionValidator(QRegularExpression(QStringLiteral("[0-9a-f]{0,4}"),
            QRegularExpression::CaseInsensitiveOption), this));
        connect(lineEdit, &QLineEdit::textChanged, this, &MainWindow::setRegister);
    }
}

运行效果:

modbus4android 发送十六进制 modbus发送接收实例_qt_02