Qt Modbus通信(RTU模式)

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Qt Modbus通信(RTU模式)

通信流程

创建QModbusRtuSerialMaster对象m_modbusDevice，并设置串口通信参数：

1  m_modbusDevice.setConnectionParameter(QModbusDevice::SerialParityParameter, QSerialPort::EvenParity);
2  m_modbusDevice.setConnectionParameter(QModbusDevice::SerialBaudRateParameter, QSerialPort::Baud9600);
3  m_modbusDevice.setConnectionParameter(QModbusDevice::SerialDataBitsParameter, QSerialPort::Data8);
4  m_modbusDevice.setConnectionParameter(QModbusDevice::SerialStopBitsParameter, QSerialPort::OneStop);

串口连接：

1 bool connectDevice()
2 {
3     //implement
4 }

连接成功后，发送请求：

1 QModbusResponse sendModbusRawRequest(const QModbusRequest &request) const
2 {
3     //implement
4 }

断开连接：

1 void disconnectDevice()
2 {
3     //implement
4 }

示例代码

tempCtrl.h

 1 #ifndef TEMPCTRL_H2 #define TEMPCTRL_H3 4 #include 5 6 class TempCtrl7 {8 private:9     TempCtrl();
10 
11 public:
12     ~TempCtrl();
13     static TempCtrl* instance();
14 
15 public:    
16     void connectDevice();
17     void disconnectDevice();
18     
19 private:
20     QModbusResponse sendModbusRawRequest(const QModbusRequest &request) const;
21 
22 private:
23     bool m_channelConnected;
24     int m_channelAddr;
25     mutable QModbusRtuSerialMaster m_modbusDevice;
26 };
27 #endif // TEMPCTRL_H

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tempCtrl.cpp

  1 #include "TempCtrl.h"2 3 #include 4 #include 5 #include 6 7 #include 8 #include 9 #include 10 11 TempCtrl::TempCtrl()12     , m_channelConnected(false)13     , m_channelAddr(0)14     , m_modbusDevice()15 {16     m_modbusDevice.setConnectionParameter(QModbusDevice::SerialParityParameter, QSerialPort::EvenParity);17     m_modbusDevice.setConnectionParameter(QModbusDevice::SerialBaudRateParameter, QSerialPort::Baud9600);18     m_modbusDevice.setConnectionParameter(QModbusDevice::SerialDataBitsParameter, QSerialPort::Data8);19     m_modbusDevice.setConnectionParameter(QModbusDevice::SerialStopBitsParameter, QSerialPort::OneStop);20 }21 22 TempCtrl::~TempCtrl()23 {24     disconnectDevice();25 }26 27 TempCtrl* TempCtrl::instance()28 {29     static TempCtrl* theInstance = new TempCtrl();30     return theInstance;31 }32 33 bool TempCtrl::connectDevice()34 {35     disconnectDevice(); 36     37     const auto serialPortInfos = QSerialPortInfo::availablePorts();38     if(!pty())39     {40         QModbusRequest echoTest(QModbusRequest::Diagnostics, quint16(0x0000), quint16(0x1234));41 42         bool comportFound(false);43         for (const QSerialPortInfo &serialPortInfo : serialPortInfos)44         {45             m_modbusDevice.setConnectionParameter(QModbusDevice::SerialPortNameParameter, serialPortInfo.portName());46 47             if(tDevice())48             {49                 auto curTimePt = std::chrono::steady_clock::now();50                 double duration = 0;51 52                 while(m_modbusDevice.state() != QModbusDevice::ConnectedState && duration < 2.0)53                 {54                     QCoreApplication::processEvents(QEventLoop::ExcludeUserInputEvents, 20);55                     std::chrono::duration d = std::chrono::steady_clock::now()-curTimePt;56                     duration = d.count();57                 }58 59                 if(m_modbusDevice.state() == QModbusDevice::ConnectedState)60                 {61                     try62                     {63                         QModbusResponse reply = sendModbusRawRequest(echoTest); 64                         if(reply.isValid())65                         {66                             if(reply.data() == QByteArray::fromHex("00001234"))67                             {68                                 if(!comportFound)69                                 {70                                     comportFound = true;71                                 }72                              m_channelConnected = true;73                             }74                         }75                     }76                     catch(...)77                     {78                     }79                 }80 81                 if(comportFound)82                 {83                     break;84                 }85                 else86                 {87                     m_modbusDevice.disconnectDevice();88                 }89             }90         }91     }92 93     m_modbusDevice.setTimeout(500);94     m_modbusDevice.setNumberOfRetries(3);95     return m_channelConnected;96 }97 98 void TempCtrl::disconnectDevice()99 {
100     if(m_modbusDevice.state() != QModbusDevice::UnconnectedState)
101     {
102         m_modbusDevice.disconnectDevice();
103     }
104     m_channelConnected = false;
105 }
106 
107 QModbusResponse TempCtrl::sendModbusRawRequest(const QModbusRequest &request) const
108 {
109     QModbusReply* reply = m_modbusDevice.sendRawRequest(request, m_channelAddr);
110 
111     if(reply)
112     {
113         while(!reply->isFinished())
114         {
115             QCoreApplication::processEvents(QEventLoop::ExcludeUserInputEvents, 20);
116         }
117 
118         reply->deleteLater();
119 
120         if(reply->error() == QModbusDevice::NoError)
121         {
122             auto response = reply->rawResult();
123             std::this_thread::sleep_for(std::chrono::milliseconds(5));
124             return response;
125         }
126         else if (reply->error() == QModbusDevice::ProtocolError)
127         {
128             QString error = "Protocol error: " + reply->errorString();
129             throw std::StdString().c_str());
130         }
131         else if (reply->error() == QModbusDevice::TimeoutError)
132         {
133             throw std::exception("Timeout error");
134         }
135         else
136         {
137             throw std::exception("Unknown error");
138         }
139     }
140     else
141     {
142         return QModbusResponse();
143     }
144 }