QtModbus Serial 简单示例

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Qt Modbus在QtCreator的示例里面有例子，直接搜modbus就可以看到了，简单学一下就能学会了。

首先，QT5是自带Modbus相关类的，使用时需要在pro文件里面添加一行：

QT += serialbus

My_Modbus.h

/*
 * My_Modbus.h
 *
 *  Created on: 2021年3月11日
 *      Author: elikang
 */

#ifndef MY_MODBUS_H
#define MY_MODBUS_H

#include <QObject>
#include <QSerialPort>
#include <QModbusDataUnit>
#include <QModbusRtuSerialMaster>

class My_Modbus : public QObject
{
    Q_OBJECT
    
public:
    My_Modbus();
    ~My_Modbus();
    
    void modbusConnect(void);
    void modbusDisconnect(void);
    void modbusRead(int serverAddress, QModbusDataUnit::RegisterType table, int startAddress, int numOfEntries);
    void modbusWrite(int serverAddress, QModbusDataUnit::RegisterType table, int startAddress, int numOfEntries, QVector<quint16> data);
    
signals:
    void modbusReadReady(QModbusDataUnit dataUnit);
        
public slots:
    void modbusStateChanged(void);    
    void modbusReadData(void);
    
    void modbusMessage(void);
    void modbusMessage(QString mess);
    
public:
    struct Settings {
        QString portName;
        int parity = QSerialPort::EvenParity;
        int baud = QSerialPort::Baud115200;
        int dataBits = QSerialPort::Data8;
        int stopBits = QSerialPort::OneStop;
        int responseTime = 1000;
        int numberOfRetries = 1;
    };        
    
private:
    QModbusClient *modbusDevice = nullptr;
    
    Settings m_settings;        
}

#endif

My_Modbus.cpp

/*
 * My_Modbus.cpp
 *
 *  Created on: 2021年3月11日
 *      Author: elikang
 */

#include “my_modbus.h”
#include “qdebug.h”

My_Modbus::My_Modbus()
{
    modbusDevice = new QModbusRtuSerialMaster(nullptr);
    connect(modbusDevice, SIGNAL(errorOccurred()), this, SLOT(modbusMessage()));
    
    if(modbusDevice)
    {
        qDebug("创建 Modbus Master 成功。");
        connect(modbusDevice, &QModbusClient::stateChanged, this, &My_Modbus::modbusStateChanged);
    }
    else
    {
        qDebug("创建 Modbus Master 失败。");        
    }
}

My_Modbus::~My_Modbus()
{
    delete modbusDevice;
}

void My_Modbus::modbusConnect(void)
{
    if(!modbusDevice) return;
    
    if(modbusDevice->state() != QModbusDevice::Connected)
    {
           modbusDevice->setConnectionParameter(QModbusDevice::SerialPortNameParameter, m_settings.portName);        
           modbusDevice->setConnectionParameter(QModbusDevice::SerialBaudRateParameter, m_settings.baud);   
           modbusDevice->setConnectionParameter(QModbusDevice::SerialParityParameter, m_settings.parity);             
           modbusDevice->setConnectionParameter(QModbusDevice::SerialDataBitsParameter, settings.dataBits);        
           modbusDevice->setConnectionParameter(QModbusDevice::SerialStopBitsParameter, m_settings.stopBits);        
           
           modbusDevice->setTimeout(m_settings.responseTime);        
           modbusDevice->setNumberOfRetries(m_settings.numberOfRetries);           
           
           if(modbusDevice->connectDevice())
           {
                qDebug("Modbus 连接成功。");
           }
           else
           {
                qDebug("Modbus 连接失败。");
           }
    }
}

void My_Modbus::modbusDisconnect(void)
{
    if (modbusDevice)   modbusDevice->disconnectDevice();    
    delete modbusDevice;
    modbusDevice = nullptr;    
}

void My_Modbus::modbusStateChanged(int state)
{
    if(state == QModbusDevice::UnconnectedState)
    {
        qDebug("Modbus 已断开。");
    }
    else if(state == QModbusDevice::ConnectedState)
    {
        qDebug("Modbus 已连接。");
    }
}

void My_Modbus::modbusMessage(void)
{
    qDebug() << modbusDevice->errorString();
}

void My_Modbus::modbusMessage(QString mess)
{
    qDebug() << mess;
}


void My_Modbus::modbusRead(int serverAddress, QModbusDataUnit::RegisterType table, int startAddress, int numOfEntries, QVector<quint16> data)
{
        if(!modbusDevice || modbusDevice->state() != QModbusDevice::ConnectedState) 
        {
                qDebug("Modbus Device is not connected!");        
                return;    
        }
        
        QModbusDataUnit dataUnit = QModbusDataUnit(table, startAddress, numOfEntries);    
        
        if(auto *reply = modbusDevice->sendReadRequest(dataUnit, serverAddress))
        {
                if(reply->isFinished())
                {
                    connect(reply, &QModbusReply::finished, this, &My_Modbus::modbusReadData);
                }
        }
        else
        {
             modbusMessage(tr("Write error:") + modbusDevice->errorString());
        }
}

void My_Modbus::modbusReadData()
{
    QModbusDataUnit dataUnit;
    auto reply = qobject_cast<QModbusReply *>(sender());
    if(!reply) return;
    
    if(reply->error() == QModbusDevice::NoError)
    {
        dataUnit = reply->result();
        emit modbusReadReady(dataUnit);
    }
    else if(reply->error() == QModbusDevice::ProtocolError)
    {
        modbusMessage(tr("Read response error: %1 (Modbus exception :0x%2)")
                                        .arg(reply->errorString()).arg(reply->rawResult().exceptionCode(), -1 ,16));
    }
    else
    {
        modbusMessage(tr("Read response: %1 (code :0x%2)")
                                        .arg(reply->errorString()).arg(reply->rawResult().exceptionCode(), -1 ,16));    
    }
    
    reply->deleteLater();
}

//服务器地址、寄存器类型、起始地址、变量数量、写入数据
void My_Modbus::modbusWrite(int serverAddress, QModbusDataUnit::RegisterType table, int startAddress, int numOfEntries, QVector<quint16> data)
{
        if(!modbusDevice || modbusDevice->state() != QModbusDevice::ConnectedState) 
        {
                qDebug("Modbus Device is not connected!");        
                return;    
        }
        
        //QModbusDataUnit，是用来处理通过串口一次传输的数据    
        QModbusDataUnit dataunit = QModbusDataUnit(table, startAddress, numOfEntries);
        
        for(uint i = 0; i < dataunit.valueCount(); i++)
        {
                dataunit.setValue( i,  data.at(i));
        }
        
        if(auto *reply = modbusDevice->sendWriteRequest(dataunit,  serverAddress))
        { 
                      connect(reply, &QModbusReply::finished, this, [this, reply](){
                                if(reply->error() == QModbusDevice::ProtocolError){          
                                          modbusMessage(tr("Write response error:%1 (modbus exception:0x%2)")
                                                                           .arg(reply->errorString()).arg(reply->rawResult().exceptionCode(), -1, 16), 5000);                
                                }else{         
                                          modbusMessage(tr("Write response:%1 (code:0x%2)")
                                                                           .arg(reply->errorString()).arg(reply->rawResult().exceptionCode(), -1, 16), 5000);                
                                }
     
                                reply->deleteLater();            
                                });                       
         }
         else{            
                        statusBar()->showMessage(tr("Write error:") + modbusDevice->errorString(), 5000);        
               }    
   }