QT进阶 - 7. QTmodubus - 《QTcreator》

基础知识：
- 1.功能码
- 2.使用QT实现

基础知识：

1.功能码

modbus完整支持很多功能码，但是实际在应用的时候常用的也就那么几个。具体如下：

0x01: 读线圈寄存器
0x02: 读离散输入寄存器
0x03: 读保持寄存器
0x04: 读输入寄存器
0x05: 写单个线圈寄存器
0x06: 写单个保持寄存器
0x0f: 写多个线圈寄存器
0x10: 写多个保持寄存器
如上所示一共8种功能码。这其中有涉及到线圈、离散输入、保持、输入四种寄存器。这名字也不知道谁起的，让人看了一点不通俗易懂，搞得晕晕乎乎。实际上你要是看清他的本质就很简单了。下面分别解释一下：

线圈寄存器：实际上就可以类比为开关量，每个bit都对应一个信号的开关状态。所以一个byte就可以同时控制8路的信号。比如控制外部8路io的高低。线圈寄存器支持读也支持写，写在功能码里面又分为写单个线圈寄存器和写多个线圈寄存器。对应上面的功能码也就是：0x01 0x05 0x0f

离散输入寄存器：如果线圈寄存器理解了这个自然也明白了。离散输入寄存器就相当于线圈寄存器的只读模式，他也是每个bit表示一个开关量，而他的开关量只能读取输入的开关信号，是不能够写的。比如我读取外部按键的按下还是松开。所以功能码也简单就一个读的 0x02

保持寄存器：这个寄存器的单位不再是bit而是两个byte，也就是可以存放具体的数据量的，并且是可读写的。比如我我设置时间年月日，不但可以写也可以读出来现在的时间。写也分为单个写和多个写，所以功能码有对应的三个：0x03 0x06 0x10

输入寄存器：只剩下这最后一个了，这个和保持寄存器类似，但是也是只支持读而不能写。一个寄存器也是占据两个byte的空间。类比我我通过读取输入寄存器获取现在的AD采集值。对应的功能码也就一个 0x04

对应的错误返回：
在对应功能码基础上加上0x80

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版权声明：本文为CSDN博主「JiaoCL」的原创文章，遵循CC 4.0 BY-SA版权协议，转载请附上原文出处链接及本声明。
原文链接：https://blog.csdn.net/liboxiu/article/details/86473516

https://blog.csdn.net/kissgoodbye2012/article/details/112105418?ops_request_misc=%257B%2522request%255Fid%2522%253A%2522162701004216780271551414%2522%252C%2522scm%2522%253A%252220140713.130102334.pc%255Fblog.%2522%257D&request_id=162701004216780271551414&biz_id=0&utm_medium=distribute.pc_search_result.none-task-blog-2~blog~first_rank_v2~rank_v29-2-112105418.pc_v2_rank_blog_default&utm_term=QT+modbus%E5%86%99&spm=1018.2226.3001.4450

2.使用QT实现

#ifndef WIDGET_H
#define WIDGET_H
#include <QWidget>
#include <QModbusRtuSerialMaster>
#include <QModbusDataUnit>
#include <QModbusReply>
#include <QVariant>
#include <QSerialPort>
#include <QDebug>
namespace Ui {
class Widget;
}
class Widget : public QWidget
{
  Q_OBJECT
public:
  explicit Widget(QWidget *parent = nullptr);
  void connectSerial();
    void disconnectSerial();
  void readData(int startaddr, int num, int addr);
  bool writeData(int startaddr, int size, QVector<int> value, int addr);
  void onReadReady();
  QString fillNumber(quint16 number);
  ~Widget();
private:
  Ui::Widget *ui;
  QModbusClient *modbusDevice = nullptr;
};
#endif // WIDGET_H
#-------------------------------------------------
#
# Project created by QtCreator 2021-07-22T18:34:43
#
#-------------------------------------------------
QT       += core gui serialbus serialport
greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
TARGET = untitled5
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
CONFIG += c++11
SOURCES += \
        main.cpp \
        widget.cpp
HEADERS += \
        widget.h
FORMS += \
        widget.ui
# Default rules for deployment.
qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target

#ifndef WIDGET_H
#define WIDGET_H
#include <QWidget>
#include <QModbusRtuSerialMaster>
#include <QModbusDataUnit>
#include <QModbusReply>
#include <QVariant>
#include <QSerialPort>
#include <QDebug>
namespace Ui {
class Widget;
}
class Widget : public QWidget
{
  Q_OBJECT
public:
  explicit Widget(QWidget *parent = nullptr);
  void connectSerial();
    void disconnectSerial();
  void readData(int startaddr, int num, int addr);
  bool writeData(int startaddr, int size, QVector<int> value, int addr);
  void onReadReady();
  QString fillNumber(quint16 number);
  ~Widget();
private:
  Ui::Widget *ui;
  QModbusClient *modbusDevice = nullptr;
};
#endif // WIDGET_H

#include "widget.h"
#include "ui_widget.h"
#include <QPushButton>
#include <QTimer>
#include <QEventLoop>
Widget::Widget(QWidget *parent) :
  QWidget(parent),
  ui(new Ui::Widget)
{
  ui->setupUi(this);
  connect(ui->btnConnect, &QPushButton::clicked, this, &Widget::connectSerial);
  connect(ui->btnQuit, &QPushButton::clicked, this, &Widget::disconnectSerial);
  QTimer *mytimer = new QTimer(this);
  connect(mytimer, &QTimer::timeout, this, [=](){
      // 0A 03 00 01 00 02
      readData(0x01, 0x02, 0x0A);
      // 0A 06 00 36 00 00
      writeData(0x36, 1, ,0, 0x0A);
  });
  connect(ui->pushButton, &QPushButton::clicked, [=](){
      mytimer->start(1000);
  });
}
void Widget::connectSerial()
{
    //1. 创建QModbusDevice对象
    modbusDevice = new QModbusRtuSerialMaster(this);
    //2. 如果处于连接状态，则返回
    if (modbusDevice->state() == QModbusDevice::ConnectedState)
    {
       return;
    }
    //3. 设置串口相关参数
    //设置串口信息
    modbusDevice->setConnectionParameter(QModbusDevice::SerialPortNameParameter, QVariant("ttyUSB0"));
    //设置校验 无校验
    modbusDevice->setConnectionParameter(QModbusDevice::SerialParityParameter, QSerialPort::NoParity);
    //设置波特率
    modbusDevice->setConnectionParameter(QModbusDevice::SerialBaudRateParameter, QSerialPort::Baud9600);
    //设置停止位
    modbusDevice->setConnectionParameter(QModbusDevice::SerialStopBitsParameter, QSerialPort::OneStop);
    //设置数据位
    modbusDevice->setConnectionParameter(QModbusDevice::SerialDataBitsParameter, QSerialPort::Data8);
    //其他设置
    //设置超时时间
    modbusDevice->setTimeout(300);
    //失败次数
    modbusDevice->setNumberOfRetries(3);
    bool ok = modbusDevice->connectDevice();
    if (!ok)
    {
        qDebug() << "连接到串口失败： " << modbusDevice->errorString();
        ui->labelState->setText("串口设置有误，连接失败");
    }
    else
    {
        qDebug() << "连接到串口成功";
        ui->labelState->setText("串口连接成功");
    }
}
void Widget::disconnectSerial()
{
    if(modbusDevice->state() != QModbusDevice::UnconnectedState)
    {
        modbusDevice->disconnectDevice();
        ui->labelState->setText("关闭连接");
    }
}
void Widget::readData(int startaddr, int num, int addr)
{
    if(modbusDevice->state() == QModbusDevice::UnconnectedState) {
        return;
    }
    //读取2个保存寄存器的值 寄存器起始地址为1
    QModbusDataUnit data(QModbusDataUnit::HoldingRegisters, startaddr, num);
    data.setValue(0, 0);
    QModbusReply* reply = modbusDevice->sendWriteRequest(data, addr);
    if (nullptr == reply)
    {
       qDebug() << "发送请求数据失败: " << modbusDevice->errorString();
       return;
    }
       else
       {
           if (!reply->isFinished())
           {
               QEventLoop loop;
               connect(reply, &QModbusReply::finished,&loop,&QEventLoop::quit);
               loop.exec();
           }
    }
    if (reply->error() == QModbusDevice::NoError)
    {
        //读取响应数据
        const auto responseData = reply->rawResult();
        auto values = responseData.data().toHex();
        qDebug() << values;
        if(values.size() == 2) {
            bool ok;
            QString mystring = fillNumber(values.at(1)) + fillNumber(values.at(0));
            int getFLoat = mystring.toUInt(&ok, 16);
            //转换为浮点数
            float floatdata = *(float*)&getFLoat;
            ui->textEdit->append(QString("%1").arg(floatdata));
        }
        if(values.size() == 1) {
            ui->textEdit->append(QString("%1").arg(values.at(0)));
        }
    }
    else if (reply->error() == QModbusDevice::ProtocolError)
    {
        qDebug() << "Read response Protocol error: " << reply->errorString();
    }
    else
    {
        qDebug() << "Read response Error: " << reply->errorString();
    }
}
bool Widget::writeData(int startaddr, int size, QVector<int> value, int addr)
{
    if(modbusDevice->state() == QModbusDevice::UnconnectedState) {
        return;
    }
    //读取2个保存寄存器的值 寄存器起始地址为1
    QModbusDataUnit data(QModbusDataUnit::HoldingRegisters, startaddr, size);
    for(int i = 0; i < size; i++) {
        data.setValue(i, value.at(i));
    }
    data.setValue(0, value);
    QModbusReply* reply = modbusDevice->sendWriteRequest(data, addr);
    if (nullptr == reply)
    {
       qDebug() << "发送请求数据失败: " << modbusDevice->errorString();
       return;
    }
       else
       {
           if (!reply->isFinished())
           {
               QEventLoop loop;
               connect(reply, &QModbusReply::finished,&loop,&QEventLoop::quit);
               loop.exec();
           }
    }
    if (reply->error() == QModbusDevice::NoError)
    {
        return true;
    }
    else
    {
        qDebug() << "Read response Error: " << reply->errorString();
        return false;
    }
}
void Widget::onReadReady()
{
    auto reply = qobject_cast<QModbusReply*>(sender());
    if (nullptr == reply)
    {
        return;
    }
    //删除reply
    reply->deleteLater();
}
QString Widget::fillNumber(quint16 number)
{
    QString str = QString::number(number, 16);
    while (str.size() < 4) {
        str += "0";
    }
    return str;
}
Widget::~Widget()
{
  delete ui;
}