上一文章主要了解下Modbus协议和事务处理流程，本章则直接贴放代码实现qt 上位机与温控器通讯。项目主要实现定时读取温度、设置温度、开始加热和停止加热四个功能。
采用的是 Modbus Rtu 通信
1 Qt modbus 模块依赖
QT += serialbus serialport
源代码
.h文件
#ifndef MODBUSDEVICE_H
#define MODBUSDEVICE_H#include <QObject>
#include <QModbusDevice>
#include <QSerialPort>
#include <QModbusPdu>
#include <QModbusRtuSerialMaster>
#include <QSerialPortInfo>
#include <QTimer>
#define ADDR_READ_PV "0100"
#define ADDR_READ_SV "0300"
#define ADDR_SET_SV "0300"
#define ADDR_RUN "0190"
class ModbusDevice : public QObject
{Q_OBJECT
public:explicit ModbusDevice(QObject *parent = nullptr);~ModbusDevice();void setAddresss(const QVector<quint8> addrs);Q_INVOKABLE void setCom(const QString &com);Q_INVOKABLE QString getCom();void open(const QString &portname);void closeAndDelete();Q_INVOKABLE void close();Q_INVOKABLE void connect(const QString &com);Q_INVOKABLE void disconnect();Q_INVOKABLE bool state();void sendReadPV();void sendSetSV(const float v);void sendRun();void setStopSync(const quint8 addr);void sendStop();void sendSetSV(const quint8 addr,const float v);void sendReadPV(const quint8 addr);void sendReadSV(const quint8 addr);void sendRun(const quint8 addr);void sendStop(const quint8 addr);void stopTimer();signals:void sigError(const QString &msg);void sigDisconnected();void sigConnected();void sigModbusSendError(const QString &msg);void sigInfo(const QString &msg);void sigGetPV(const int index,const float v);void sigGetSV(const int index,const float v);
private slots:void onReplyTimeout();
private:void creatDevice();void reconnect();void creatTimer();void startTimer();void handleSerialPortDisconnected();void readValue(const quint8 address,const QString addr);void setRun(const quint8 address,const bool isRun);void startReplyTimer();void stopReplyTimer();QSerialPort::BaudRate baudRate=QSerialPort::Baud9600;QSerialPort::DataBits dataBits=QSerialPort::Data8;QSerialPort::Parity parity=QSerialPort::EvenParity;QSerialPort::StopBits stopBits=QSerialPort::TwoStop;QTimer m_pvTimer;QTimer m_replyTimer;QString m_strCom;QModbusClient *m_device = nullptr;QVector<quint8> m_deviceAddrs;int m_errCount = 0;int m_timeoutContinousCount = 0;
};#endif // MODBUSDEVICE_H
cpp文件
#include "modbusdevice.h"
#include <QDebug>
#include <QModbusReply>
#include <QCoreApplication>
#include <QThread>
ModbusDevice::ModbusDevice(QObject *parent) : QObject(parent)
{m_deviceAddrs << 1 <<2;creatTimer();creatDevice();
}ModbusDevice::~ModbusDevice()
{stopTimer();closeAndDelete();
}void ModbusDevice::setAddresss(const QVector<quint8> addrs)
{m_deviceAddrs = addrs;
}void ModbusDevice::open(const QString &portname)
{if (!m_device){sigError(QString("串口连接失败,请排查线路"));return;}m_device->setConnectionParameter(QModbusDevice::SerialPortNameParameter,portname);m_device->connectDevice();
}void ModbusDevice::closeAndDelete()
{if (!m_device)return;m_device->disconnectDevice();m_device->disconnect();delete m_device;m_device = nullptr;
}void ModbusDevice::close()
{if (!m_device)return;stopTimer();m_device->disconnectDevice();
}void ModbusDevice::connect(const QString &com)
{setCom(com);open(com);
}void ModbusDevice::disconnect()
{if (!m_device)return ;close();
}bool ModbusDevice::state()
{if (!m_device)return false;return m_device->state() == QModbusDevice::ConnectedState;
}void ModbusDevice::sendReadPV()
{for(auto v:m_deviceAddrs){sendReadPV(v);}
}void ModbusDevice::sendSetSV(const float v)
{for(auto addr:m_deviceAddrs){sendSetSV(addr,v);}
}void ModbusDevice::sendRun()
{for(auto addr:m_deviceAddrs){sendRun(addr);}
}void ModbusDevice::setStopSync(const quint8 addr)
{if (!m_device)return ;if(m_device->state() != QModbusDevice::ConnectedState)return;QModbusReply *reply = nullptr;const QByteArray pduData = QByteArray::fromHex("01900000");quint16 fc = 0x06;reply = m_device->sendRawRequest(QModbusRequest(QModbusRequest::FunctionCode(fc), pduData),addr);while (!reply->isFinished()) {QCoreApplication::processEvents();if (QCoreApplication::instance()->closingDown()) {break;}QThread::msleep(10);}if (reply->error() == QModbusDevice::NoError) {qDebug() << "Command sent successfully.";} else {qWarning() << "Failed to send command:" << reply->errorString();}reply->deleteLater();
}void ModbusDevice::sendStop()
{for(auto addr:m_deviceAddrs){sendStop(addr);}
}void ModbusDevice::sendSetSV(const quint8 addr,const float v)
{if (!m_device)return ;if(m_device->state() != QModbusDevice::ConnectedState)return;QModbusReply *reply = nullptr;short tmp = (v*10);QString msg = QString("0300%1").arg(tmp, 4, 16, QLatin1Char('0')).toUpper();const QByteArray pduData = QByteArray::fromHex(msg.toLatin1());quint16 fc = 0x06;reply = m_device->sendRawRequest(QModbusRequest(QModbusRequest::FunctionCode(fc), pduData),addr);startReplyTimer();if (!reply->isFinished()) {QObject::connect(reply, &QModbusReply::finished, this, [=]() {stopReplyTimer();if (reply->error() == QModbusDevice::NoError) {sigInfo(QString("设置指令发送成功"));qDebug() << "setD1Value reveive:" << reply->rawResult();} else if (reply->error() == QModbusDevice::ProtocolError) {QString msg = QString("setValue response error: %1 Mobus exception: 0x%2").arg(reply->errorString()).arg(reply->rawResult().exceptionCode(), -1, 16);qDebug() << msg;emit sigModbusSendError(msg);} else {QString msg = (tr("setValue response error: %1 (code: 0x%2)").arg(reply->errorString()).arg(reply->error(), -1, 16));qDebug() << msg;emit sigModbusSendError(msg);}reply->deleteLater();});} else {stopReplyTimer();// broadcast replies return immediatelyqDebug() << "Receive: Synchronous response pdu: " << reply->rawResult() << Qt::endl;reply->deleteLater();}
}void ModbusDevice::sendReadPV(const quint8 addr)
{readValue(addr,ADDR_READ_PV);
}void ModbusDevice::sendReadSV(const quint8 addr)
{readValue(addr,ADDR_READ_SV);
}void ModbusDevice::sendRun(const quint8 addr)
{setRun(addr,true);
}void ModbusDevice::sendStop(const quint8 addr)
{setRun(addr,false);
}void ModbusDevice::setCom(const QString &com)
{if(com != m_strCom){m_strCom = com;}
}QString ModbusDevice::getCom()
{return m_strCom;
}void ModbusDevice::reconnect()
{if (!m_device)return ;if (m_device->state() != QModbusDevice::ConnectedState) {qInfo() << "Attempting to reconnect...";m_device->connectDevice();}
}void ModbusDevice::creatDevice()
{m_device = new QModbusRtuSerialMaster;//m_device->setConnectionParameter(QModbusDevice::SerialPortNameParameter,portname);m_device->setConnectionParameter(QModbusDevice::SerialParityParameter, parity);m_device->setConnectionParameter(QModbusDevice::SerialDataBitsParameter,dataBits);m_device->setConnectionParameter(QModbusDevice::SerialStopBitsParameter,stopBits);m_device->setConnectionParameter(QModbusDevice::SerialBaudRateParameter,baudRate);m_device->setTimeout(1000);m_device->setNumberOfRetries(1);QObject::connect(m_device, &QModbusDevice::errorOccurred, this, [=](QModbusDevice::Error) {QString msg = m_device->errorString();qDebug().noquote() << QStringLiteral("Error: %1").arg(msg);emit sigError(msg);}, Qt::QueuedConnection);QObject::connect(m_device, &QModbusDevice::stateChanged, [=](QModbusDevice::State state) {switch (state) {case QModbusDevice::UnconnectedState:{qDebug().noquote() << QStringLiteral("State: Entered unconnected state.");stopTimer();emit sigDisconnected();}break;case QModbusDevice::ConnectingState:qDebug().noquote() << QStringLiteral("State: Entered connecting state.");break;case QModbusDevice::ConnectedState:{qDebug().noquote() << QStringLiteral("State: Entered connected state.");sendReadPV();startTimer();emit sigConnected();}break;case QModbusDevice::ClosingState:qDebug().noquote() << QStringLiteral("State: Entered closing state.");break;}});
}void ModbusDevice::handleSerialPortDisconnected(){qWarning() << "Serial port disconnected.";close();}void ModbusDevice::creatTimer()
{m_pvTimer.setInterval(4000);QObject::connect(&m_pvTimer,&QTimer::timeout,this,[=]{sendReadPV();});m_replyTimer.setInterval(3000);m_replyTimer.setSingleShot(true);QObject::connect(&m_replyTimer,SIGNAL(timeout()),this,SLOT(onReplyTimeout()));
}void ModbusDevice::startTimer()
{m_pvTimer.start();
}void ModbusDevice::stopTimer()
{m_pvTimer.stop();
}void ModbusDevice::onReplyTimeout()
{m_timeoutContinousCount++;qDebug() << __func__;sigModbusSendError(QString("发包响应超时,请排查线路"));if(m_timeoutContinousCount>3){sigError(QString("通信超时,请排查线路"));m_timeoutContinousCount=0;close();}
}void ModbusDevice::readValue(const quint8 address,const QString addr)
{if (!m_device)return ;if(m_device->state() != QModbusDevice::ConnectedState)return;QModbusReply *reply = nullptr;QString msg = addr+"0001";const QByteArray pduData = QByteArray::fromHex(msg.toLatin1());//qDebug() << "Send: Sending PDU with predefined function code.";quint16 fc = 0x03;reply = m_device->sendRawRequest(QModbusRequest(QModbusRequest::FunctionCode(fc), pduData),address);startReplyTimer();if (!reply->isFinished()) {QObject::connect(reply, &QModbusReply::finished, this, [=](){stopReplyTimer();if (reply->error() == QModbusDevice::NoError) {const QByteArray rawData = reply->rawResult().data();//ex:0x030200dcQByteArray lastTwoBytes = rawData.mid(rawData.size() - 2, 2);// 使用 QDataStream 进行字节序转换QDataStream stream(lastTwoBytes);quint16 shortValue;stream >> shortValue;if(addr == ADDR_READ_PV){emit sigGetPV(address,(float)shortValue/10);}else if(addr == ADDR_READ_SV){emit sigGetSV(address,(float)shortValue/10);}} else if (reply->error() == QModbusDevice::ProtocolError) {QString msg = QString("readValue response error: %1 Mobus exception: 0x%2").arg(reply->errorString()).arg(reply->rawResult().exceptionCode(), -1, 16);qDebug() << msg;emit sigModbusSendError(msg);} else {QString msg = (tr("readValue response error: %1 (code: 0x%2)").arg(reply->errorString()).arg(reply->error(), -1, 16));qDebug() << msg;m_errCount ++;if(m_errCount > 3){emit sigError(QString("温控%1 连接已断开").arg(address));m_errCount = 0;reconnect();}emit sigModbusSendError(msg);}reply->deleteLater();});} else {stopReplyTimer();// broadcast replies return immediatelyqDebug() << "Receive: Synchronous response pdu: " << reply->rawResult() << Qt::endl;reply->deleteLater();}
}void ModbusDevice::setRun(const quint8 address,const bool isRun)
{if (!m_device)return ;if(m_device->state() != QModbusDevice::ConnectedState)return;QModbusReply *reply = nullptr;const QByteArray pduData = isRun? QByteArray::fromHex("01900001"):QByteArray::fromHex("01900000");quint16 fc = 0x06;reply = m_device->sendRawRequest(QModbusRequest(QModbusRequest::FunctionCode(fc), pduData),address);startReplyTimer();if (!reply->isFinished()) {QObject::connect(reply, &QModbusReply::finished, this, [=]() {stopReplyTimer();if (reply->error() == QModbusDevice::NoError) {if(isRun)sigInfo(QString("开始指令发送成功"));else {sigInfo(QString("停止指令发送成功"));}qDebug() << "setRun reveive:" << reply->rawResult();} else if (reply->error() == QModbusDevice::ProtocolError) {QString msg = QString("setRun response error: %1 Mobus exception: 0x%2").arg(reply->errorString()).arg(reply->rawResult().exceptionCode(), -1, 16);qDebug() << msg;emit sigModbusSendError(msg);} else {QString msg = (tr("setRun response error: %1 (code: 0x%2)").arg(reply->errorString()).arg(reply->error(), -1, 16));qDebug() << msg;emit sigModbusSendError(msg);}reply->deleteLater();});} else {// broadcast replies return immediatelystopReplyTimer();qDebug() << "setRun Receive: Synchronous response pdu: " << reply->rawResult() << Qt::endl;reply->deleteLater();}
}void ModbusDevice::startReplyTimer()
{m_replyTimer.start();
}void ModbusDevice::stopReplyTimer()
{m_replyTimer.stop();
}
异常处理
1. 通信断开异常检测
测试过程中发现，拔掉串口线，QModbusClient 并未检测到任何异常，这时候发包也不会有任何异常提示，所以在发包之后自己启动一个timer,来通过超时判断是否串口连接出现问题。有更好的方法可以分享下。
void ModbusDevice::sendSetSV(const quint8 addr,const float v)
{if (!m_device)return ;if(m_device->state() != QModbusDevice::ConnectedState)return;QModbusReply *reply = nullptr;short tmp = (v*10);QString msg = QString("0300%1").arg(tmp, 4, 16, QLatin1Char('0')).toUpper();const QByteArray pduData = QByteArray::fromHex(msg.toLatin1());quint16 fc = 0x06;reply = m_device->sendRawRequest(QModbusRequest(QModbusRequest::FunctionCode(fc), pduData),addr);startReplyTimer();if (!reply->isFinished()) {QObject::connect(reply, &QModbusReply::finished, this, [=]() {stopReplyTimer();if (reply->error() == QModbusDevice::NoError) {sigInfo(QString("设置指令发送成功"));qDebug() << "setD1Value reveive:" << reply->rawResult();} else if (reply->error() == QModbusDevice::ProtocolError) {QString msg = QString("setValue response error: %1 Mobus exception: 0x%2").arg(reply->errorString()).arg(reply->rawResult().exceptionCode(), -1, 16);qDebug() << msg;emit sigModbusSendError(msg);} else {QString msg = (tr("setValue response error: %1 (code: 0x%2)").arg(reply->errorString()).arg(reply->error(), -1, 16));qDebug() << msg;emit sigModbusSendError(msg);}reply->deleteLater();});} else {stopReplyTimer();// broadcast replies return immediatelyqDebug() << "Receive: Synchronous response pdu: " << reply->rawResult() << Qt::endl;reply->deleteLater();}
}
其中 startReplyTimer() 和 stopReplyTimer() 来实现链路检测。
2. 程序关闭时，需要发送一条指令，等发送和响应结束后才能关闭App
因为是加热设备，为了安全起见，程序关闭时，会主动停止加热。此时就需要实现一个同步发送的指令。等待返回后才能关闭App
void ModbusDevice::setStopSync(const quint8 addr)
{if (!m_device)return ;if(m_device->state() != QModbusDevice::ConnectedState)return;QModbusReply *reply = nullptr;const QByteArray pduData = QByteArray::fromHex("01900000");quint16 fc = 0x06;reply = m_device->sendRawRequest(QModbusRequest(QModbusRequest::FunctionCode(fc), pduData),addr);while (!reply->isFinished()) {QCoreApplication::processEvents();if (QCoreApplication::instance()->closingDown()) {break;}QThread::msleep(10);}if (reply->error() == QModbusDevice::NoError) {qDebug() << "Command sent successfully.";} else {qWarning() << "Failed to send command:" << reply->errorString();}reply->deleteLater();
}