目录

前言：

一：测试软件安装与使用

1.opc服务端程序：kepserverex 

2.opc客户端程序：uaexpert   提取码：0kpmuaexpert   提取码：

3.使用KEPServerv6进行OPC_UA的服务器搭建：服务器搭建

4. 使用KEPServerv6添加仿真：此链接第五步或者此链接前两步

5.通过uaexpert访问kepservere

二：Qt搭建客户端

总结：

前言：

        本文章介绍如何使用Qt搭建客户端并并和服务端完成简单的读写操作

一：测试软件安装与使用

1.opc服务端程序：kepserverex 

2.opc客户端程序：uaexpert   提取码：0kpm

3.使用KEPServerv6进行OPC_UA的服务器搭建：服务器搭建

4. 使用KEPServerv6添加仿真：此链接第五步或者此链接前两步

5.通过uaexpert访问kepservere

 (1)先给KEPServerv6添加仿真

​

（2）让uaexpert访问kepservere

​ 

 点击OK即可连接成功，然后按下面步骤找到对应节点的信息

​

​ 

双击s1得到下面方框中的信息，这里面包含节点的信息，其中NodeId用于后面Qt访问

​ 

二：Qt搭建客户端

1.打开Qt，并在.pro文件和.h文件中分别加入：

QT       += opcua

#include <QOpcUaClient>
#include <QOpcUaNode>
#include <QtOpcUa>
#include <QDebug>

2.在.ui文件里面加入三个按钮，并如下命名

​

 三个按钮的槽函数分别如下：

void MainWindow::on_btn_requestEndpoints_clicked()
{
    client->requestEndpoints(QUrl("opc.tcp://127.0.0.1:49320"));
}

void MainWindow::on_btn_readnode_clicked()
{
    node->readAttributes(QOpcUa::NodeAttribute::Value);
    qDebug()<<"readnode"<<node->nodeId();
}

void MainWindow::on_btn_writeAttribute_clicked()
{
    QOpcUa::NodeAttribute attribute ;
    attribute = QOpcUa::NodeAttribute::Value;
    QVariant var=12;
    //node->writeAttribute(attribute,QString("ssss"),QOpcUa::Types::String);
    node->writeAttribute(attribute,var);
}

3.创建QOpcUaClient对象，官方例子如下

QOpcUaProvider provider;
if (provider.availableBackends().isEmpty())
    return;
QOpcUaClient *client = provider.createClient(provider.availableBackends()[0]);
if (!client)
    return;
// Connect to the stateChanged signal. Compatible slots of QObjects can be used instead of a lambda.
QObject::connect(client, &QOpcUaClient::stateChanged, [client](QOpcUaClient::ClientState state) {
    qDebug() << "Client state changed:" << state;
    if (state == QOpcUaClient::ClientState::Connected) {
        QOpcUaNode *node = client->node("ns=0;i=84");
        if (node)
            qDebug() << "A node object has been created";
    }
});
QObject::connect(client, &QOpcUaClient::endpointsRequestFinished,
                 [client](QList<QOpcUaEndpointDescription> endpoints) {
    qDebug() << "Endpoints returned:" << endpoints.count();
    if (endpoints.size())
        client->connectToEndpoint(endpoints.first()); // Connect to the first endpoint in the list
});
client->requestEndpoints(QUrl("opc.tcp://127.0.0.1:4840")); // Request a list of endpoints from the server

创建 QOpcUaClient 使用 QOpcUaProvider , request a list of endpoints from the server using requestEndpoints 和调用 connectToEndpoint () to connect to one of the available endpoints. After the connection is established, a QOpcUaNode object for the root node is requested.

接下来按官方例子创建QOpcUaClient对象，并连接到服务器

（1）在.h文件中输入下面代码

public slots:

    void on_btn_requestEndpoints_clicked();
    void on_btn_readnode_clicked();
    void on_btn_writeAttribute_clicked();

    void SLOT_endpointsRequestFinished (QVector<QOpcUa::QEndpointDescription> endpoints , QOpcUa::UaStatusCode statusCode);
    void SLOT_attributeRead ( QOpcUa::NodeAttributes attributes );
    void SLOT_stateChanged (QOpcUaClient::ClientState state ); 

private:
 
    Ui::MainWindow *ui;
    QOpcUaClient *client;
    QOpcUaProvider* provider;
    QOpcUaNode* node;

（2）创建QOpcUaClient对象，并像例子中一样连接槽

provider = new QOpcUaProvider(this);
client = provider->createClient(QString("open62541"));

connect(client,&QOpcUaClient::endpointsRequestFinished,this,&MainWindow::SLOT_endpointsRequestFinished);
connect(client,&QOpcUaClient::stateChanged,this,&MainWindow::SLOT_stateChanged);

（3）按下按钮requestEndpoints，如果请求成功会跳到槽函数SLOT_endpointsRequestFinished

void MainWindow::SLOT_endpointsRequestFinished(QVector<QOpcUa::QEndpointDescription> endpoints, QOpcUa::UaStatusCode statusCode)
{
    qDebug()<<endpoints.at(0).endpointUrl();
    qDebug()<<statusCode;
    qDebug() << "Endpoints returned:" << endpoints.count();
    qDebug()<<endpoints.size();
    if (endpoints.size())
        client->connectToEndpoint(endpoints.at(0).endpointUrl()); // Connect to the first endpoint in the list
}

（4）跳到该槽函数后，会让创建的客户端对象连接到服务器，如果连接成功，会跳到槽函数SLOT_stateChanged

void MainWindow::SLOT_stateChanged(QOpcUaClient::ClientState state)
{
    qDebug() << "Client state changed:" << state;
    if (state == QOpcUaClient::ClientState::Connected) {
        //QOpcUaNode定义
            node = client->node("ns=2;s=my.plc.s1");
            if (node)
                qDebug() << "A node object has been created";
        }
    connect(node,&QOpcUaNode::attributeRead,this,&MainWindow::SLOT_attributeRead);

}

当创建的客户端对象连接到服务端之后，会进入到这个槽函数中，在这里面定义一个节点，其中节点的名字为在uaexpert中得到的nodeid，然后连接槽，如果读到节点属性后，就转到槽，官方创建节点例子如下

QOpcUaNode *rootNode; // Created before, see QOpcUaClient documentation.
// Connect to the attributeRead signal. Compatible slots of QObjects can be used instead of a lambda.
QObject::connect(rootNode, &QOpcUaNode::attributeRead, [rootNode, client](QOpcUa::NodeAttributes attr) {
    qDebug() << "Signal for attributes:" << attr;
    if (rootNode->attributeError(QOpcUa::NodeAttribute::BrowseName) != QOpcUa::UaStatusCode::Good) {
        qDebug() << "Failed to read attribute:" << rootNode->attributeError(QOpcUa::NodeAttribute::BrowseName);
        client->disconnectFromEndpoint();
    }
    qDebug() << "Browse name:" << rootNode->attribute(QOpcUa::NodeAttribute::BrowseName).value<QOpcUaQualifiedName>().name();
});
rootNode->readAttributes(QOpcUa::NodeAttribute::BrowseName); // Start a read operation for the node's BrowseName attribute.

 这里面定义的节点没有赋值，我在操作的时候提示错误，所以我上面提前定义的时候就赋值了

（5）按下按钮readnode，转到槽SLOT_attributeRead，开始读节点内容

void MainWindow::SLOT_attributeRead(QOpcUa::NodeAttributes attributes)
{
    qDebug() << "Signal for attributes:" << attributes;
    qDebug()<<"value:"<<node->attribute(QOpcUa::NodeAttribute::Value);
}

节点的属性很多，在按钮readnode中，读的是Value，因此这里输出的就是Value，如果读的是其他值，这里可以得到其他值。（初值可以在KEPServerv6的客户端中更改）

（6）按下按钮writeAttribute，就可以对节点写入所定义的属性，这里属性可以参考：属性

 总结：

#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    provider = new QOpcUaProvider(this);
    //if (provider.availableBackends().isEmpty())
    client = provider->createClient(QString("open62541"));

    connect(client,&QOpcUaClient::endpointsRequestFinished,this,&MainWindow::SLOT_endpointsRequestFinished);
    connect(client,&QOpcUaClient::stateChanged,this,&MainWindow::SLOT_stateChanged);
}

MainWindow::~MainWindow()
{
    delete ui;
}


void MainWindow::on_btn_requestEndpoints_clicked()
{
    client->requestEndpoints(QUrl("opc.tcp://127.0.0.1:49320"));
}

void MainWindow::on_btn_readnode_clicked()
{
    node->readAttributes(QOpcUa::NodeAttribute::Value);
    qDebug()<<"readnode"<<node->nodeId();
}

void MainWindow::on_btn_writeAttribute_clicked()
{
    QOpcUa::NodeAttribute attribute ;
    attribute = QOpcUa::NodeAttribute::Value;
    QVariant var=12;
    //node->writeAttribute(attribute,QString("ssss"),QOpcUa::Types::String);
    node->writeAttribute(attribute,var);
}

void MainWindow::SLOT_endpointsRequestFinished(QVector<QOpcUa::QEndpointDescription> endpoints, QOpcUa::UaStatusCode statusCode)
{
    qDebug()<<endpoints.at(0).endpointUrl();
    //qDebug() <<endpoints.first().endpointUrl();
    qDebug()<<statusCode;
    qDebug() << "Endpoints returned:" << endpoints.count();
    qDebug()<<endpoints.size();
    if (endpoints.size())
        client->connectToEndpoint(endpoints.at(0).endpointUrl()); // Connect to the first endpoint in the list
}

void MainWindow::SLOT_attributeRead(QOpcUa::NodeAttributes attributes)
{
    qDebug() << "Signal for attributes:" << attributes;
//    if (node->attributeError(QOpcUa::NodeAttribute::BrowseName) != QOpcUa::UaStatusCode::Good) {
//        qDebug() << "Failed to read attribute:" << node->attributeError(QOpcUa::NodeAttribute::BrowseName);
//        client->disconnectFromEndpoint();
//    }
    //qDebug() << "Browse name:" << node->attribute(QOpcUa::NodeAttribute::BrowseName).value<QOpcUa::QQualifiedName>().name();
    qDebug()<<"value:"<<node->attribute(QOpcUa::NodeAttribute::Value);

}

void MainWindow::SLOT_stateChanged(QOpcUaClient::ClientState state)
{
    qDebug() << "Client state changed:" << state;
    if (state == QOpcUaClient::ClientState::Connected) {
        //QOpcUaNode定义
            node = client->node("ns=2;s=my.plc.s1");
            if (node)
                qDebug() << "A node object has been created";
        }
    connect(node,&QOpcUaNode::attributeRead,this,&MainWindow::SLOT_attributeRead);

}