QT tcpmodbus 使用示例

好的，我会为您查找 QT tcpmodbus 使用示例。以下是一个基于QT的TCP Modbus主从模拟器，您可以参考：

1. 首先，在QT中创建一个新的工程，选择 QT GUI应用程序类型

2. 在工程目录中创建一个新的文件夹，例如“tcpmodbus”

3. 创建以下文件：

- tcpmodbus.pro
- main.cpp
- modbusconfig.h
- modbusconfig.cpp
- modbusmaster.h
- modbusmaster.cpp
- modbusslave.h
- modbusslave.cpp

4. 打开 tcpmodbus.pro 文件，添加以下内容：

QT += widgets network
HEADERS += modbusconfig.h \
           modbusmaster.h \
           modbusslave.h
SOURCES += main.cpp \
           modbusconfig.cpp \
           modbusmaster.cpp \
           modbusslave.cpp

5. 在 modbusconfig.h 文件中添加以下内容：

#ifndef MODBUSCONFIG_H
#define MODBUSCONFIG_H

const quint16 ModbusPort = 502;
const quint8 ModbusSlaveAddress = 1;

#endif // MODBUSCONFIG_H

6. 在 modbusmaster.h 文件中添加以下内容:

#ifndef MODBUSMASTER_H
#define MODBUSMASTER_H

#include <QObject>
#include <QTcpSocket>

class ModbusMaster : public QObject
{
    Q_OBJECT

public:
    explicit ModbusMaster(QObject *parent = nullptr);

private slots:
    void onConnected();
    void onDisconnected();
    void onError(QAbstractSocket::SocketError socketError);
    void onReadyRead();

private:
    void connectToServer();
    void sendRequest();

    QTcpSocket *tcpSocket;
    QByteArray request;
    QByteArray response;
    int transactionId;
};

#endif // MODBUSMASTER_H

7. 在 modbusmaster.cpp 文件中添加以下内容：

#include "modbusmaster.h"
#include "modbusconfig.h"

ModbusMaster::ModbusMaster(QObject *parent) : QObject(parent)
{
    connectToServer();
}

void ModbusMaster::onConnected()
{
    qDebug() << "Connected to server";

    // Send Modbus request
    sendRequest();
}

void ModbusMaster::onDisconnected()
{
    qDebug() << "Disconnected from server";
}

void ModbusMaster::onError(QAbstractSocket::SocketError socketError)
{
    qDebug() << "Error: " << tcpSocket->errorString();
}

void ModbusMaster::onReadyRead()
{
    // Read response
    response = tcpSocket->readAll();
    qDebug() << "Modbus response: " << response.toHex();

    // Disconnect from server
    tcpSocket->disconnectFromHost();
}

void ModbusMaster::connectToServer()
{
    // Initialize transaction Id
    transactionId = 0;

    // Create socket
    tcpSocket = new QTcpSocket(this);

    // Connect signals and slots
    connect(tcpSocket, &QTcpSocket::connected, this, &ModbusMaster::onConnected);
    connect(tcpSocket, &QTcpSocket::disconnected, this, &ModbusMaster::onDisconnected);
    connect(tcpSocket, static_cast<void(QAbstractSocket::*)(QAbstractSocket::SocketError)>(&QAbstractSocket::error),
            this, &ModbusMaster::onError);
    connect(tcpSocket, &QTcpSocket::readyRead, this, &ModbusMaster::onReadyRead);

    // Connect to server
    tcpSocket->connectToHost("127.0.0.1", ModbusPort);
}

void ModbusMaster::sendRequest()
{
    // Build Modbus request
    transactionId++;

    request.clear();
    request.append(0x00);
    request.append(0x00);
    request.append(0x00);
    request.append(0x00);
    request.append(0x00);
    request.append(0x06);
    request.append(ModbusSlaveAddress);
    request.append(0x01);
    request.append(0x00);
    request.append(0x00);
    request.append(0x00);
    request.append(0x01);

    // Send request
    tcpSocket->write(request);
}

8. 在 modbusslave.h 文件中添加以下内容：

#ifndef MODBUSSLAVE_H
#define MODBUSSLAVE_H

#include <QObject>
#include <QTcpServer>
#include <QTcpSocket>

class ModbusSlave : public QObject
{
    Q_OBJECT

public:
    explicit ModbusSlave(QObject *parent = nullptr);

private slots:
    void onNewConnection();
    void onDisconnected();
    void onError(QAbstractSocket::SocketError socketError);
    void onReadyRead();

private:
    void sendResponse(const QByteArray& request);

    QTcpServer *tcpServer;
    QList<QTcpSocket*> sockets;
};

#endif // MODBUSSLAVE_H

9. 在 modbusslave.cpp 文件中添加以下内容：

#include "modbusslave.h"
#include "modbusconfig.h"

ModbusSlave::ModbusSlave(QObject *parent) : QObject(parent)
{
    // Create server
    tcpServer = new QTcpServer(this);

    // Connect signals and slots
    connect(tcpServer, &QTcpServer::newConnection, this, &ModbusSlave::onNewConnection);

    // Listen for incoming connections
    tcpServer->listen(QHostAddress::Any, ModbusPort);
    qDebug() << "Modbus slave listening on port " << tcpServer->serverPort();
}

void ModbusSlave::onNewConnection()
{
    // Accept incoming connection
    QTcpSocket *socket = tcpServer->nextPendingConnection();

    // Connect signals and slots
    connect(socket, &QTcpSocket::disconnected, this, &ModbusSlave::onDisconnected);
    connect(socket, static_cast<void(QAbstractSocket::*)(QAbstractSocket::SocketError)>(&QAbstractSocket::error),
            this, &ModbusSlave::onError);
    connect(socket, &QTcpSocket::readyRead, this, &ModbusSlave::onReadyRead);

    // Add socket to list
    sockets.append(socket);

    qDebug() << "New Modbus connection established";
}

void ModbusSlave::onDisconnected()
{
    // Remove socket from list
    QTcpSocket *socket = static_cast<QTcpSocket*>(sender());
    sockets.removeOne(socket);

    qDebug() << "Modbus connection disconnected";
}

void ModbusSlave::onError(QAbstractSocket::SocketError socketError)
{
    qDebug() << "Error: " << static_cast<QTcpSocket*>(sender())->errorString();
}

void ModbusSlave::onReadyRead()
{
    // Get request
    QTcpSocket *socket = static_cast<QTcpSocket*>(sender());
    QByteArray request = socket->readAll();
    qDebug() << "Modbus request: " << request.toHex();

    // Send response
    sendResponse(request);
}

void ModbusSlave::sendResponse(const QByteArray& request)
{
    QByteArray response;

    // Check slave address
    if (request.at(6) != ModbusSlaveAddress) {
        qDebug() << "Error: wrong slave address";
        return;
    }

    // Check function code
    if (request.at(7) != 0x01) {
        qDebug() << "Error: wrong function code";
        return;
    }

    // Build response
    response.append(request.at(0)); // Transaction Id
    response.append(request.at(1)); // Transaction Id
    response.append(request.at(2)); // Protocol Id
    response.append(request.at(3)); // Protocol Id
    response.append(0x00); // Message length
    response.append(0x06); // Message length
    response.append(ModbusSlaveAddress); // Slave address
    response.append(0x01); // Function code
    response.append(0x01); // Byte count
    response.append(0x00); // Value
    response.append(0x01); // Value

    // Send response to all sockets
    for (QTcpSocket *socket : sockets) {
        socket->write(response);
    }

    qDebug() << "Modbus response: " << response.toHex();
}

10. 在 main.cpp 文件中添加以下内容：

#include <QCoreApplication>
#include "modbusmaster.h"
#include "modbusslave.h"

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    // Start Modbus slave
    ModbusSlave modbusSlave;

    // Start Modbus master after 1 second delay
    QTimer::singleShot(1000, [&]() {
        ModbusMaster modbusMaster;
    });

    return a.exec();
}

11. 编译和执行程序。

12. 打开新的QT控制台，输入以下命令来查看 TCP Modbus 数据：

tcpdump -i lo -A port 502

注意：此示例仅用于演示目的，应根据实际要求进行修改和优化，例如加密和身份验证。