QT MODBUSRTU 一主多从 示例

以下是一个QT MODBUSRTU 一主多从的示例，其中包含一个主站和两个从站的通信。

主站代码：

#include <QCoreApplication>
#include <QModbusRtuSerialMaster>
#include <QSerialPort>
#include <QDebug>

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

    QSerialPort serialPort;
    serialPort.setPortName("COM1");
    serialPort.setBaudRate(QSerialPort::Baud9600);
    serialPort.setDataBits(QSerialPort::Data8);
    serialPort.setStopBits(QSerialPort::OneStop);
    serialPort.setParity(QSerialPort::NoParity);

    if (!serialPort.open(QIODevice::ReadWrite)) {
        qDebug() << "Failed to open serial port:" << serialPort.errorString();
        return 1;
    }

    QModbusRtuSerialMaster modbusMaster(&serialPort);
    modbusMaster.setConnectionParameter(QModbusDevice::SerialPortNameParameter, "COM1");
    modbusMaster.setConnectionParameter(QModbusDevice::SerialParityParameter, QSerialPort::NoParity);
    modbusMaster.setConnectionParameter(QModbusDevice::SerialBaudRateParameter, QSerialPort::Baud9600);
    modbusMaster.setConnectionParameter(QModbusDevice::SerialDataBitsParameter, QSerialPort::Data8);
    modbusMaster.setConnectionParameter(QModbusDevice::SerialStopBitsParameter, QSerialPort::OneStop);
    modbusMaster.setTimeout(1000);
    modbusMaster.setNumberOfRetries(3);

    if (!modbusMaster.connectDevice()) {
        qDebug() << "Failed to connect to the Modbus device:" << modbusMaster.errorString();
        return 1;
    }

    quint16 slave1Address = 1;
    quint16 slave2Address = 2;

    QModbusDataUnit readUnit(QModbusDataUnit::HoldingRegisters, 0, 10);
    QModbusDataUnit writeUnit(QModbusDataUnit::HoldingRegisters, 0, 10);

    if (auto *reply = modbusMaster.sendReadRequest(readUnit, slave1Address)) {
        if (!reply->isFinished()) {
            QCoreApplication::processEvents(QEventLoop::AllEvents, 5000);
        }
        if (reply->error() == QModbusDevice::NoError) {
            readUnit = reply->result();
            for (uint i = 0; i < readUnit.valueCount(); ++i) {
                qDebug() << "Slave 1 register" << i << "=" << readUnit.value(i);
            }
        } else {
            qDebug() << "Modbus error:" << reply->errorString();
        }
        delete reply;
    }

    writeUnit.setValue(0, 100);
    writeUnit.setValue(1, 200);
    writeUnit.setValue(2, 300);

    if (auto *reply = modbusMaster.sendWriteRequest(writeUnit, slave2Address)) {
        if (!reply->isFinished()) {
            QCoreApplication::processEvents(QEventLoop::AllEvents, 5000);
        }
        if (reply->error() == QModbusDevice::NoError) {
            qDebug() << "Write to slave 2 successful";
        } else {
            qDebug() << "Modbus error:" << reply->errorString();
        }
        delete reply;
    }

    modbusMaster.disconnectDevice();
    serialPort.close();

    return 0;
}

从站1代码：

#include <QCoreApplication>
#include <QModbusRtuSerialSlave>
#include <QSerialPort>
#include <QDebug>

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

    QSerialPort serialPort;
    serialPort.setPortName("COM1");
    serialPort.setBaudRate(QSerialPort::Baud9600);
    serialPort.setDataBits(QSerialPort::Data8);
    serialPort.setStopBits(QSerialPort::OneStop);
    serialPort.setParity(QSerialPort::NoParity);

    if (!serialPort.open(QIODevice::ReadWrite)) {
        qDebug() << "Failed to open serial port:" << serialPort.errorString();
        return 1;
    }

    QModbusRtuSerialSlave modbusSlave(&serialPort);
    modbusSlave.setConnectionParameter(QModbusDevice::SerialPortNameParameter, "COM1");
    modbusSlave.setConnectionParameter(QModbusDevice::SerialParityParameter, QSerialPort::NoParity);
    modbusSlave.setConnectionParameter(QModbusDevice::SerialBaudRateParameter, QSerialPort::Baud9600);
    modbusSlave.setConnectionParameter(QModbusDevice::SerialDataBitsParameter, QSerialPort::Data8);
    modbusSlave.setConnectionParameter(QModbusDevice::SerialStopBitsParameter, QSerialPort::OneStop);
    modbusSlave.setServerAddress(1);
    modbusSlave.setTimeout(1000);

    if (!modbusSlave.connectDevice()) {
        qDebug() << "Failed to connect to the Modbus device:" << modbusSlave.errorString();
        return 1;
    }

    modbusSlave.setData(QModbusDataUnit::HoldingRegisters, 0, QVector<quint16>{ 100, 200, 300 });

    return a.exec();
}

从站2代码：

#include <QCoreApplication>
#include <QModbusRtuSerialSlave>
#include <QSerialPort>
#include <QDebug>

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

    QSerialPort serialPort;
    serialPort.setPortName("COM1");
    serialPort.setBaudRate(QSerialPort::Baud9600);
    serialPort.setDataBits(QSerialPort::Data8);
    serialPort.setStopBits(QSerialPort::OneStop);
    serialPort.setParity(QSerialPort::NoParity);

    if (!serialPort.open(QIODevice::ReadWrite)) {
        qDebug() << "Failed to open serial port:" << serialPort.errorString();
        return 1;
    }

    QModbusRtuSerialSlave modbusSlave(&serialPort);
    modbusSlave.setConnectionParameter(QModbusDevice::SerialPortNameParameter, "COM1");
    modbusSlave.setConnectionParameter(QModbusDevice::SerialParityParameter, QSerialPort::NoParity);
    modbusSlave.setConnectionParameter(QModbusDevice::SerialBaudRateParameter, QSerialPort::Baud9600);
    modbusSlave.setConnectionParameter(QModbusDevice::SerialDataBitsParameter, QSerialPort::Data8);
    modbusSlave.setConnectionParameter(QModbusDevice::SerialStopBitsParameter, QSerialPort::OneStop);
    modbusSlave.setServerAddress(2);
    modbusSlave.setTimeout(1000);

    if (!modbusSlave.connectDevice()) {
        qDebug() << "Failed to connect to the Modbus device:" << modbusSlave.errorString();
        return 1;
    }

    return a.exec();
}

在这个示例中，主站通过串口与从站1和从站2通信。主站首先从从站1读取保持寄存器中的前10个值，并打印到控制台。然后，主站将3个值写入从站2的保持寄存器中，并在写入成功后打印消息。从站1和从站2分别设置了自己的地址，并初始化了3个保持寄存器。