QOpcUaNode Class

QOpcUaNode allows interaction with an OPC UA node. 更多...

头：	#include <QOpcUaNode>
CMake:	find_package(Qt6 REQUIRED COMPONENTS OpcUa) target_link_libraries(mytarget PRIVATE Qt6::OpcUa)
qmake:	QT += opcua
继承：	QObject

所有成员列表，包括继承成员

公共类型

AttributeMap

公共函数

QVariant	属性 (QOpcUa::NodeAttribute 属性 ) const
QOpcUa::UaStatusCode	attributeError (QOpcUa::NodeAttribute 属性 ) const
bool	browse (const QOpcUaBrowseRequest & request )
bool	browseChildren (QOpcUa::ReferenceTypeId referenceType = QOpcUa::ReferenceTypeId::HierarchicalReferences, QOpcUa::NodeClasses nodeClassMask = QOpcUa::NodeClass::Undefined)
bool	callMethod (const QString & methodNodeId , const QList<QOpcUa::TypedVariant> & args = QList<QOpcUa::TypedVariant>())
QOpcUaClient *	client () const
bool	disableMonitoring (QOpcUa::NodeAttributes attr )
bool	enableMonitoring (QOpcUa::NodeAttributes attr , const QOpcUaMonitoringParameters & settings )
bool	modifyDataChangeFilter (QOpcUa::NodeAttribute attr , const QOpcUaMonitoringParameters::DataChangeFilter & filter )
bool	modifyEventFilter (const QOpcUaMonitoringParameters::EventFilter & eventFilter )
bool	modifyMonitoring (QOpcUa::NodeAttribute attr , QOpcUaMonitoringParameters::Parameter item , const QVariant & value )
QOpcUaMonitoringParameters	monitoringStatus (QOpcUa::NodeAttribute attr )
QString	nodeId () const
bool	readAttributeRange (QOpcUa::NodeAttribute 属性 , const QString & indexRange )
bool	readAttributes (QOpcUa::NodeAttributes 属性 = mandatoryBaseAttributes())
`(从 6.7 起)` QOpcUaHistoryReadResponse *	readHistoryEvents (const QDateTime & startTime , const QDateTime & endTime , QOpcUaMonitoringParameters::EventFilter & filter , quint32 numValues = 0)
`(since 6.3)` QOpcUaHistoryReadResponse *	readHistoryRaw (const QDateTime & startTime , const QDateTime & endTime , quint32 numValues , bool returnBounds )
`(从 6.7 起)` QOpcUaHistoryReadResponse *	readHistoryRaw (const QDateTime & startTime , const QDateTime & endTime , quint32 numValues , bool returnBounds , QOpcUa::TimestampsToReturn timestampsToReturn )
bool	readValueAttribute ()
bool	resolveBrowsePath (const QList<QOpcUaRelativePathElement> & path )
QDateTime	serverTimestamp (QOpcUa::NodeAttribute 属性 ) const
QDateTime	sourceTimestamp (QOpcUa::NodeAttribute 属性 ) const
QVariant	valueAttribute () const
QOpcUa::UaStatusCode	valueAttributeError () const
bool	writeAttribute (QOpcUa::NodeAttribute 属性 , const QVariant & value , QOpcUa::Types type = QOpcUa::Types::Undefined)
bool	writeAttributeRange (QOpcUa::NodeAttribute 属性 , const QVariant & value , const QString & indexRange , QOpcUa::Types type = QOpcUa::Types::Undefined)
bool	writeAttributes (const QOpcUaNode::AttributeMap & toWrite , QOpcUa::Types valueAttributeType = QOpcUa::Types::Undefined)
bool	writeValueAttribute (const QVariant & value , QOpcUa::Types type = QOpcUa::Types::Undefined)

信号

void	attributeRead (QOpcUa::NodeAttributes 属性 )
void	attributeUpdated (QOpcUa::NodeAttribute attr , QVariant value )
void	attributeWritten (QOpcUa::NodeAttribute 属性 , QOpcUa::UaStatusCode statusCode )
void	browseFinished (QList<QOpcUaReferenceDescription> children , QOpcUa::UaStatusCode statusCode )
void	dataChangeOccurred (QOpcUa::NodeAttribute attr , QVariant value )
void	disableMonitoringFinished (QOpcUa::NodeAttribute attr , QOpcUa::UaStatusCode statusCode )
void	enableMonitoringFinished (QOpcUa::NodeAttribute attr , QOpcUa::UaStatusCode statusCode )
void	eventOccurred (QVariantList eventFields )
void	methodCallFinished (QString methodNodeId , QVariant result , QOpcUa::UaStatusCode statusCode )
void	monitoringStatusChanged (QOpcUa::NodeAttribute attr , QOpcUaMonitoringParameters::Parameters 项 , QOpcUa::UaStatusCode statusCode )
void	resolveBrowsePathFinished (QList<QOpcUaBrowsePathTarget> 目标 , QList<QOpcUaRelativePathElement> path , QOpcUa::UaStatusCode statusCode )
`(从 6.7 起)` void	valueAttributeUpdated (const QVariant & value )

静态公共成员

QOpcUa::NodeAttributes	allBaseAttributes ()
QOpcUa::NodeAttributes	mandatoryBaseAttributes ()

详细描述

The node is the basic building block of the OPC UA address space. It has attributes like browse name, value, associated properties and can have references to other nodes in the address space. Nodes are organized in namespaces and have IDs which can e.g. be numeric, a string, a namespace-specific format (opaque) or a globally unique identifier. A node is identified by the namespace ID and the node ID. This identifier is usually given as a string: The identifier of a node residing in namespace 0 and having the numeric identifier 42 results in the string ns=0;i=42 . A node with a string identifier can be addressed via ns=0;s=myStringIdentifier .

Objects of this type are owned by the user and must be deleted when they are no longer needed. They are valid as long as the QOpcUaClient which created them exists.

Reading and writing of attributes

The node attributes are read from the server when readAttributes () 或 readAttributeRange () is called. The results are cached locally and can be retrieved using 属性 () after the attributeRead signal has been received.

Attributes can be written using writeAttribute (), writeAttributes () 和 writeAttributeRange () if the user has the necessary rights. Success of the write operation is reported using the attributeWritten 信号。

attributeError () contains a status code associated with the last read or write operation on the attribute. This is the low level status code returned by the OPC UA service. This status code can be simplified by converting it to a QOpcUa::ErrorCategory 使用 QOpcUa::errorCategory ().

Subscriptions and monitored items

Subscriptions are a concept in OPC UA which allows receiving of notifications for changes in data or in case of events instead of continuously polling a node for changes. Monitored items define how attributes of a node are watched for changes. They are added to a subscription and any notifications they generate are forwarded to the user via the subscription. The interval of the updates as well as many other options of the monitored items and subscriptions can be configured by the user.

QOpcUaNode offers an abstraction to interact with subscriptions and monitored items. enableMonitoring () enables data change notifications for one or more attributes. The dataChangeOccurred signal contains new values and the local cache is updated. disableMonitoring () disables the data change notifications. The monitoringStatusChanged signal notifies about changes of the monitoring status, e. g. after manual enable and disable or a status change on the server.

Event monitoring uses the same API for setup and life cycle management. The EventNotifier attribute must be monitored using an EventFilter which selects the required event fields and filters the reported events by user defined criteria. The events are reported in the eventOccurred () signal as a QVariantList which contains the values of the selected event fields.

Settings of the subscription and monitored item can be modified at runtime using modifyMonitoring ().

Browsing the address space

The OPC UA address space consists of nodes connected by references. browseChildren follows these references in forward direction and returns attributes from all nodes connected to the node behind an instance of QOpcUaNode 在 browseFinished 信号。 browse () is similar to browseChildren () but offers more options to configure the browse call.

方法调用

OPC UA specifies methods on the server which can be called by the user. QOpcUaNode supports this via callMethod which takes parameters and returns the results of the call in the methodCallFinished 信号。

Resolving browse paths

To support programming against a type description, OPC UA supports the resolution of a path of browse names starting from a certain node to obtain the node id of the target node. The resolveBrowsePath () method follows a path starting from the node it was called on and returns the result in the resolveBrowsePathFinished () 信号。

范例

For connecting the client to a server and getting a QOpcUaNode object, see QOpcUaClient .

After the node has been successfully created, the BrowseName of the root node is read from the server:

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.

成员类型文档编制

QOpcUaNode:: AttributeMap

This type is used by writeAttributes () to write more than one attribute at a time. QVariant values must be assigned to the attributes to be written.

成员函数文档编制

`[static constexpr]` QOpcUa::NodeAttributes QOpcUaNode:: allBaseAttributes ()

Contains all attributes of the OPC UA base node class.

QVariant QOpcUaNode:: 属性 ( QOpcUa::NodeAttribute 属性 ) const

Returns the value of the attribute given in 属性 .

The value is only valid after the attributeRead signal has been emitted. An empty QVariant is returned if there is no cached value for the attribute.

QOpcUa::UaStatusCode QOpcUaNode:: attributeError ( QOpcUa::NodeAttribute 属性 ) const

Returns the error code for the attribute given in 属性 .

The error code is only valid after the attributeRead or attributeWritten 信号已发射。

If there is no entry in the attribute cache, BadNoEntryExists 被返回。

另请参阅 QOpcUa::errorCategory .

`[signal]` void QOpcUaNode:: attributeRead ( QOpcUa::NodeAttributes 属性 )

This signal is emitted after a readAttributes () 或 readAttributeRange () operation has finished. The receiver has to check the status code for the attributes contained in 属性 .

`[signal]` void QOpcUaNode:: attributeUpdated ( QOpcUa::NodeAttribute attr , QVariant value )

This signal is emitted after the value in the attribute cache has been updated by a data change notification from the server, a read or a write operation. value contains the new value for the node attribute attr .

另请参阅 属性 (), attributeError (), serverTimestamp (), sourceTimestamp ()，和 valueAttributeUpdated ().

`[signal]` void QOpcUaNode:: attributeWritten ( QOpcUa::NodeAttribute 属性 , QOpcUa::UaStatusCode statusCode )

This signal is emitted after a writeAttribute (), writeAttributes () 或 writeAttributeRange () operation has finished.

Before this signal is emitted, the attribute cache is updated in case of a successful write. For writeAttributes () a signal is emitted for each attribute in the write call. statusCode contains the success information for the write operation on 属性 .

bool QOpcUaNode:: browse (const QOpcUaBrowseRequest & request )

Starts a browse call from this node.

返回 true if the asynchronous call has been successfully dispatched.

All references matching the criteria specified in request are returned in the browseFinished () 信号。

For example, an inverse browse call can be used to find the parent node of a property node:

QOpcUaBrowseRequest request;
request.setBrowseDirection(QOpcUaBrowseRequest::BrowseDirection::Inverse);
request.setReferenceTypeId(QOpcUa::ReferenceTypeId::HasProperty);
propertyNode->browse(request);

bool QOpcUaNode:: browseChildren ( QOpcUa::ReferenceTypeId referenceType = QOpcUa::ReferenceTypeId::HierarchicalReferences, QOpcUa::NodeClasses nodeClassMask = QOpcUa::NodeClass::Undefined)

Executes a forward browse call starting from the node this method is called on. The browse operation collects information about child nodes connected to the node and delivers the results in the browseFinished () 信号。

返回 true if the asynchronous call has been successfully dispatched.

To request only children connected to the node by a certain type of reference, referenceType must be set to that reference type. For example, this can be used to get all properties of a node by passing HasProperty in referenceType . The results can be filtered to contain only nodes with certain node classes by setting them in nodeClassMask .

`[signal]` void QOpcUaNode:: browseFinished ( QList < QOpcUaReferenceDescription > children , QOpcUa::UaStatusCode statusCode )

This signal is emitted after a browseChildren () 或 browse () operation has finished.

children contains information about all nodes which matched the criteria in browseChildren (). statusCode contains the service result of the browse operation. If statusCode 不是 Good , the passed children vector is empty.

另请参阅 QOpcUaReferenceDescription .

bool QOpcUaNode:: callMethod (const QString & methodNodeId , const QList < QOpcUa::TypedVariant > & args = QList<QOpcUa::TypedVariant>())

Calls the OPC UA method methodNodeId with the parameters given via args . The result is returned in the methodCallFinished 信号。

返回 true if the asynchronous call has been successfully dispatched.

QOpcUaClient *QOpcUaNode:: client () const

Returns a pointer to the client that has created this node.

`[signal]` void QOpcUaNode:: dataChangeOccurred ( QOpcUa::NodeAttribute attr , QVariant value )

This signal is emitted after a data change notification has been received. value contains the new value for the node attribute attr .

另请参阅 属性 (), serverTimestamp ()，和 sourceTimestamp ().

bool QOpcUaNode:: disableMonitoring ( QOpcUa::NodeAttributes attr )

This method disables monitoring for the attributes given in attr .

返回 true if the asynchronous call has been successfully dispatched.

After the call is finished, the disableMonitoringFinished signal is emitted and monitoringStatus returns a default constructed value with status code BadMonitoredItemIdIinvalid for attr .

`[signal]` void QOpcUaNode:: disableMonitoringFinished ( QOpcUa::NodeAttribute attr , QOpcUa::UaStatusCode statusCode )

This signal is emitted after an asynchronous call to disableMonitoring () has finished. statusCode contains the status code generated by the operation. After this signal has been emitted, monitoringStatus returns a default constructed value with status code BadMonitoredItemIdIinvalid for attr .

bool QOpcUaNode:: enableMonitoring ( QOpcUa::NodeAttributes attr , const QOpcUaMonitoringParameters & settings )

This method creates a monitored item for each of the attributes given in attr . The settings from settings are used in the creation of the monitored items and the subscription.

返回 true if the asynchronous call has been successfully dispatched.

On completion of the call, the enableMonitoringFinished signal is emitted. There are multiple error cases in which a bad status code is generated: A subscription with the subscription id specified in settings does not exist, the node does not exist on the server, the node does not have the requested attribute or the maximum number of monitored items for the server is reached.

The same method is used to enable event monitoring. Events are special objects in the OPC UA address space which contain information about an event that has occurred. If an event is triggered on the server, an event monitored item collects selected values of node attributes of the event object and its child nodes. Every node that has an event source can be monitored for events. To monitor a node for events, the attribute EventNotifier must be monitored using an EventFilter which contains the event fields the user needs and optionally a where clause which is used to filter events by criteria (for more details, see QOpcUaMonitoringParameters::EventFilter ).

`[signal]` void QOpcUaNode:: enableMonitoringFinished ( QOpcUa::NodeAttribute attr , QOpcUa::UaStatusCode statusCode )

This signal is emitted after an asynchronous call to enableMonitoring () has finished. After this signal has been emitted, monitoringStatus () returns valid information for attr . statusCode contains the status code for the operation.

`[signal]` void QOpcUaNode:: eventOccurred ( QVariantList eventFields )

This signal is emitted after a new event has been received.

eventFields contains the values of the event fields in the order specified in the select clause of the event filter.

`[static constexpr]` QOpcUa::NodeAttributes QOpcUaNode:: mandatoryBaseAttributes ()

Contains all mandatory attributes of the OPC UA base node class.

`[signal]` void QOpcUaNode:: methodCallFinished ( QString methodNodeId , QVariant result , QOpcUa::UaStatusCode statusCode )

This signal is emitted after a method call for methodNodeId has finished on the server. statusCode contains the status code from the method call, result contains the output arguments of the method. result is empty if the method has no output arguments or statusCode 不是 Good 。 result variant is either a single value if there is only one output argument or it contains a list of variants in case the called function returned multiple output arguments.

if (result.canConvert<QVariantList>()) {
    // handle list type
} else {
    // handle value type
}

bool QOpcUaNode:: modifyDataChangeFilter ( QOpcUa::NodeAttribute attr , const QOpcUaMonitoringParameters::DataChangeFilter & filter )

Modifies an existing data change monitoring to use filter as data change filter.

返回 true if the filter modification request has been successfully dispatched to the backend.

monitoringStatusChanged for attr is emitted after the operation has finished.

bool QOpcUaNode:: modifyEventFilter (const QOpcUaMonitoringParameters::EventFilter & eventFilter )

Modifies an existing event monitoring to use eventFilter as event filter.

返回 true if the filter modification request has been successfully dispatched to the backend.

monitoringStatusChanged for EventNotifier is emitted after the operation has finished.

bool QOpcUaNode:: modifyMonitoring ( QOpcUa::NodeAttribute attr , QOpcUaMonitoringParameters::Parameter item , const QVariant & value )

This method modifies settings of the monitored item or the subscription. The parameter item of the monitored item or subscription associated with attr is attempted to set to value .

返回 true if the asynchronous call has been successfully dispatched.

After the call has finished, the monitoringStatusChanged signal is emitted. This signal contains the modified parameters and the status code. A bad status code is generated if there is no monitored item associated with the requested attribute, modifying the requested parameter is not implemented or if the server has rejected the requested value.

QOpcUaMonitoringParameters QOpcUaNode:: monitoringStatus ( QOpcUa::NodeAttribute attr )

Returns the monitoring parameters associated with the attribute attr . This can be used to check the success of enableMonitoring () or if parameters have been revised. The returned values are only valid after enableMonitoringFinished or monitoringStatusChanged have been emitted for attr . If the status is queried before a signal has been emitted, QOpcUaMonitoringParameters::statusCode () 返回 BadNoEntryExists .

`[signal]` void QOpcUaNode:: monitoringStatusChanged ( QOpcUa::NodeAttribute attr , QOpcUaMonitoringParameters::Parameters 项 , QOpcUa::UaStatusCode statusCode )

This signal is emitted after an asynchronous call to modifyMonitoring () has finished. The node attribute for which the operation was requested is returned in attr . 项 contains the parameters that have been modified. statusCode contains the result of the modify operation on the server.

QString QOpcUaNode:: nodeId () const

Returns the ID of the OPC UA node.

bool QOpcUaNode:: readAttributeRange ( QOpcUa::NodeAttribute 属性 , const QString & indexRange )

Starts an asynchronous read operation for the node attribute 属性 . indexRange is a string which can be used to select a part of an array. It is defined in OPC UA 1.05 part 4, 7.27. The first element in an array is 0, "1" returns the second element, "0:9" returns the first 10 elements, "0,1" returns the second element of the first row in a two-dimensional array.

返回 true if the asynchronous call has been successfully dispatched.

Attribute values only contain valid information after the attributeRead 信号已发射。

bool QOpcUaNode:: readAttributes ( QOpcUa::NodeAttributes 属性 = mandatoryBaseAttributes())

Starts an asynchronous read operation for the node attributes in 属性 .

返回 true if the asynchronous call has been successfully dispatched.

Attribute values only contain valid information after the attributeRead 信号已发射。

`[since 6.7]` QOpcUaHistoryReadResponse QOpcUaNode:: readHistoryEvents (const QDateTime & startTime* , const QDateTime & endTime , QOpcUaMonitoringParameters::EventFilter & filter , quint32 numValues = 0)

Starts a read event history request for this node using the parameters startTime , endTime , filter and numValues 。 filter is used by the server to determine which events and which set of their fields shall be returned.

返回 QOpcUaHistoryReadResponse which contains the state of the request if the asynchronous request has been successfully dispatched. The results are returned in the QOpcUaHistoryReadResponse::readHistoryEventsFinished (const QList<QOpcUaHistoryEvent> &results, QOpcUa::UaStatusCode serviceResult) signal.

The following example retrieves historic events for the last two days. Up to 10 events are returned at a time. While there are more events matching the filter and the provided time range, hasMoreData() will be true and more events can be fetched via readMoreData() .

QScopedPointer<QOpcUaNode> node(opcuaClient->node("ns=2;s=EventHistorian"));
QVERIFY(node != nullptr);
QOpcUaMonitoringParameters::EventFilter filter;
filter << QOpcUaSimpleAttributeOperand("Message");
filter << QOpcUaSimpleAttributeOperand("Time");
const auto response = node->readHistoryEvents(QDateTime::currentDateTime().addDays(-2), QDateTime::currentDateTime(), filter, 10);
QObject::connect(response, &QOpcUaHistoryReadResponse::readHistoryEventsFinished, this,
                 [response](const QList<QOpcUaHistoryEvent> &results, QOpcUa::UaStatusCode serviceResult) {
                     if (serviceResult != QOpcUa::UaStatusCode::Good) {
                         qDebug() << "Service call failed with" << serviceResult;
                         return;
                     }
                     // Print what we got so far
                     for (const auto &result : response->events()) {
                         qDebug() << "Results for" << result.nodeId() << result.statusCode();
                         for (const auto &event : result.events())
                             qDebug() << "    Event:" << event;
                     }
                     if (response->hasMoreData())
                         response->readMoreData();
                 });

该函数在 Qt 6.7 引入。

`[since 6.3]` QOpcUaHistoryReadResponse QOpcUaNode:: readHistoryRaw (const QDateTime & startTime* , const QDateTime & endTime , quint32 numValues , bool returnBounds )

Starts a read history request for this node. This is the Qt OPC UA representation for the OPC UA ReadHistory service for reading raw historical data defined in OPC UA 1.05 part 4, 5.10.3 . It reads the history based on the parementers, startTime , endTime , numValues ，和 returnBounds .

返回 QOpcUaHistoryReadResponse which contains the state of the request if the asynchronous request has been successfully dispatched. The results are returned in the QOpcUaHistoryReadResponse::readHistoryDataFinished (const QList<QOpcUaHistoryData> &results, QOpcUa::UaStatusCode serviceResult) signal.

In the following example, the historic data from the last two days of a node are requested and printed. The result is limited to ten values per node.

QOpcUaHistoryReadResponse *response = node->readHistoryRaw(QDateTime::currentDateTime(),
                                                           QDateTime::currentDateTime().addDays(-2),
                                                           10,
                                                           true);
if (response) {
    QObject::connect(response123, &QOpcUaHistoryReadResponse::readHistoryDataFinished,
                     [] (QList<QOpcUaHistoryData> results, QOpcUa::UaStatusCode serviceResult) {
        if (serviceResult != QOpcUa::UaStatusCode::Good) {
            qWarning() << "Fetching historical data failed with:" << serviceResult;
        } else {
            for (const auto& result : results) {
                qInfo() << "NodeId:" << result.nodeId();
                for (const auto &dataValue : result.result())
                    qInfo() << "Value:" << dataValue.value();
            }
        }
    });
}

该函数在 Qt 6.3 引入。

`[since 6.7]` QOpcUaHistoryReadResponse QOpcUaNode:: readHistoryRaw (const QDateTime & startTime* , const QDateTime & endTime , quint32 numValues , bool returnBounds , QOpcUa::TimestampsToReturn timestampsToReturn )

Starts a read history request for this node. The additional timestampsToReturn parameter determines which timestamps will be returned for each value.

该函数在 Qt 6.7 引入。

bool QOpcUaNode:: readValueAttribute ()

Starts an asynchronous read operation for the node's Value attribute.

返回 true if the asynchronous call has been successfully dispatched.

另请参阅 readAttributes ().

bool QOpcUaNode:: resolveBrowsePath (const QList < QOpcUaRelativePathElement > & path )

Resolves the browse path path to one or more node ids starting from this node using the TranslateBrowsePathsToNodeIds service specified in OPC UA 1.05 part 4, 5.8.4.

返回 true if the asynchronous call has been successfully dispatched.

TranslateBrowsePathsToNodeIds is mainly used to program against type definitions instead of a concrete set of nodes in the OPC UA address space. For example, a type definition for a machine model could consist of a starting node with browse name "Machine" which has a component with browse name "Fan". Fan has a component with browse name "RPM" which is a Variable node holding the current RPM value of the fan. There are multiple machines of that type and each of these machines is mapped into the OPC UA address space as an object of the machine type. For each of these machine objects, the path from the machine node to the "RPM" node is the same. If a client wants to read the current RPM value, it needs to call resolveBrowsePath() with the machine node as starting node and the browse path from the machine to the "RPM" node:

QScopedPointer<QOpcUaNode> node(opcuaClient->node("ns=1;s=machine1"));
QList<QOpcUaRelativePathElement> path;
path.append(QOpcUaRelativePathElement(QOpcUaQualifiedName(1, "Fan"), QOpcUa::ReferenceTypeId::HasComponent));
path.append(QOpcUaRelativePathElement(QOpcUaQualifiedName(1, "RPM"), QOpcUa::ReferenceTypeId::HasComponent));
node->resolveBrowsePath(path);

The result returned in resolveBrowsePathFinished () contains the node id of the "RPM" node which can be used to access the node's attributes:

if (!results.size()) {
    qWarning() << "Browse path resolution failed";
    return;
}
if (results.at(0).isFullyResolved()) {
   QOpcUaNode *rpmNode = client->node(results.at(0).targetId());
   if (!rpmNode) {
       qWarning() << "Failed to create node";
       return;
   }
   // Connect slots, call methods
} else {
    qWarning() << "Browse path could not be fully resolved, the target node is on another server";
    return;
}

`[signal]` void QOpcUaNode:: resolveBrowsePathFinished ( QList < QOpcUaBrowsePathTarget > 目标 , QList < QOpcUaRelativePathElement > path , QOpcUa::UaStatusCode statusCode )

This signal is emitted after a resolveBrowsePath () call has finished.

QOpcUaBrowsePathTarget 目标 contains the matches, statusCode is the status code of the operation. If statusCode 不是 Good , 目标 is empty. The browse path path is the browse path from the request. It can be used to associate results with requests.

QDateTime QOpcUaNode:: serverTimestamp ( QOpcUa::NodeAttribute 属性 ) const

Returns the server timestamp from the last read or data change of 属性 . Before at least one attributeRead or dataChangeOccurred signal has been emitted, a null datetime is returned.

QDateTime QOpcUaNode:: sourceTimestamp ( QOpcUa::NodeAttribute 属性 ) const

Returns the source timestamp from the last read or data change of 属性 . Before at least one attributeRead or dataChangeOccurred signal has been emitted, a null datetime is returned.

QVariant QOpcUaNode:: valueAttribute () const

Returns the value of the node's Value attribute.

The returned value is only valid after the Value attribute has been successfully read or written or after a data change from a monitoring has updated the attribute cache. This is indicated by a attributeRead () 或 attributeWritten () signal with status code Good 或 dataChangeOccurred () signal for the Value attribute.

If there is no value in the attribute cache, an invalid QVariant 被返回。

另请参阅 readValueAttribute (), writeValueAttribute ()，和 valueAttributeError ().

QOpcUa::UaStatusCode QOpcUaNode:: valueAttributeError () const

Returns the error code for the node's Value attribute. The status code Good indicates a valid return value for valueAttribute (). If there is no entry in the attribute cache, BadNoEntryExists 被返回。

`[signal, since 6.7]` void QOpcUaNode:: valueAttributeUpdated (const QVariant & value )

This signal is emitted after the value attribute in the attribute cache has been updated by a data change notification from the server, a read or a write operation. value contains the new value for the value attribute.

该函数在 Qt 6.7 引入。

另请参阅 属性 (), attributeError (), serverTimestamp (), sourceTimestamp ()，和 attributeUpdated ().

bool QOpcUaNode:: writeAttribute ( QOpcUa::NodeAttribute 属性 , const QVariant & value , QOpcUa::Types type = QOpcUa::Types::Undefined)

写入 value to the attribute given in 属性 using the type information from type 。返回 true if the asynchronous call has been successfully dispatched.

若 type parameter is omitted, the backend tries to find the correct type. The following default types are assumed:

Qt MetaType	OPC UA type
Bool	布尔
UChar	Byte
Char	SByte
UShort	UInt16
Short	Int16
Int	Int32
UInt	UInt32
ULongLong	UInt64
LongLong	Int64
Double	Double
Float	Float
QString	字符串
QDateTime	DateTime
QByteArray	ByteString
QUuid	Guid

bool QOpcUaNode:: writeAttributeRange ( QOpcUa::NodeAttribute 属性 , const QVariant & value , const QString & indexRange , QOpcUa::Types type = QOpcUa::Types::Undefined)

写入 value to the attribute given in 属性 using the type information from type 。对于 indexRange ，见 readAttributeRange ().

返回 true if the asynchronous call has been successfully dispatched.

bool QOpcUaNode:: writeAttributes (const QOpcUaNode::AttributeMap & toWrite , QOpcUa::Types valueAttributeType = QOpcUa::Types::Undefined)

Executes a write operation for the attributes and values specified in toWrite .

返回 true if the asynchronous call has been successfully dispatched.

The valueAttributeType parameter can be used to supply type information for the value attribute. All other attributes have known types.

另请参阅 writeAttribute ().

bool QOpcUaNode:: writeValueAttribute (const QVariant & value , QOpcUa::Types type = QOpcUa::Types::Undefined)

写入 value to the node's Value attribute using the type information from type .

返回 true if the asynchronous call has been successfully dispatched.

另请参阅 writeAttribute ().

QOpcUaNode Class

公共类型

公共函数

信号

静态公共成员

详细描述

Reading and writing of attributes

Subscriptions and monitored items

Browsing the address space

方法调用

Resolving browse paths

范例

成员类型文档编制

QOpcUaNode:: AttributeMap

成员函数文档编制

[static constexpr] QOpcUa::NodeAttributes QOpcUaNode:: allBaseAttributes ()

QVariant QOpcUaNode:: 属性 ( QOpcUa::NodeAttribute 属性 ) const

QOpcUa::UaStatusCode QOpcUaNode:: attributeError ( QOpcUa::NodeAttribute 属性 ) const

[signal] void QOpcUaNode:: attributeRead ( QOpcUa::NodeAttributes 属性 )

[signal] void QOpcUaNode:: attributeUpdated ( QOpcUa::NodeAttribute attr , QVariant value )

[signal] void QOpcUaNode:: attributeWritten ( QOpcUa::NodeAttribute 属性 , QOpcUa::UaStatusCode statusCode )

bool QOpcUaNode:: browse (const QOpcUaBrowseRequest & request )

bool QOpcUaNode:: browseChildren ( QOpcUa::ReferenceTypeId referenceType = QOpcUa::ReferenceTypeId::HierarchicalReferences, QOpcUa::NodeClasses nodeClassMask = QOpcUa::NodeClass::Undefined)

[signal] void QOpcUaNode:: browseFinished ( QList < QOpcUaReferenceDescription > children , QOpcUa::UaStatusCode statusCode )

bool QOpcUaNode:: callMethod (const QString & methodNodeId , const QList < QOpcUa::TypedVariant > & args = QList<QOpcUa::TypedVariant>())

QOpcUaClient *QOpcUaNode:: client () const

[signal] void QOpcUaNode:: dataChangeOccurred ( QOpcUa::NodeAttribute attr , QVariant value )

bool QOpcUaNode:: disableMonitoring ( QOpcUa::NodeAttributes attr )

[signal] void QOpcUaNode:: disableMonitoringFinished ( QOpcUa::NodeAttribute attr , QOpcUa::UaStatusCode statusCode )

bool QOpcUaNode:: enableMonitoring ( QOpcUa::NodeAttributes attr , const QOpcUaMonitoringParameters & settings )

[signal] void QOpcUaNode:: enableMonitoringFinished ( QOpcUa::NodeAttribute attr , QOpcUa::UaStatusCode statusCode )

[signal] void QOpcUaNode:: eventOccurred ( QVariantList eventFields )

[static constexpr] QOpcUa::NodeAttributes QOpcUaNode:: mandatoryBaseAttributes ()

[signal] void QOpcUaNode:: methodCallFinished ( QString methodNodeId , QVariant result , QOpcUa::UaStatusCode statusCode )

bool QOpcUaNode:: modifyDataChangeFilter ( QOpcUa::NodeAttribute attr , const QOpcUaMonitoringParameters::DataChangeFilter & filter )

bool QOpcUaNode:: modifyEventFilter (const QOpcUaMonitoringParameters::EventFilter & eventFilter )

bool QOpcUaNode:: modifyMonitoring ( QOpcUa::NodeAttribute attr , QOpcUaMonitoringParameters::Parameter item , const QVariant & value )

QOpcUaMonitoringParameters QOpcUaNode:: monitoringStatus ( QOpcUa::NodeAttribute attr )

[signal] void QOpcUaNode:: monitoringStatusChanged ( QOpcUa::NodeAttribute attr , QOpcUaMonitoringParameters::Parameters 项 , QOpcUa::UaStatusCode statusCode )

QString QOpcUaNode:: nodeId () const

bool QOpcUaNode:: readAttributeRange ( QOpcUa::NodeAttribute 属性 , const QString & indexRange )

bool QOpcUaNode:: readAttributes ( QOpcUa::NodeAttributes 属性 = mandatoryBaseAttributes())

[since 6.7] QOpcUaHistoryReadResponse *QOpcUaNode:: readHistoryEvents (const QDateTime & startTime , const QDateTime & endTime , QOpcUaMonitoringParameters::EventFilter & filter , quint32 numValues = 0)

[since 6.3] QOpcUaHistoryReadResponse *QOpcUaNode:: readHistoryRaw (const QDateTime & startTime , const QDateTime & endTime , quint32 numValues , bool returnBounds )

[since 6.7] QOpcUaHistoryReadResponse *QOpcUaNode:: readHistoryRaw (const QDateTime & startTime , const QDateTime & endTime , quint32 numValues , bool returnBounds , QOpcUa::TimestampsToReturn timestampsToReturn )

bool QOpcUaNode:: readValueAttribute ()

bool QOpcUaNode:: resolveBrowsePath (const QList < QOpcUaRelativePathElement > & path )

[signal] void QOpcUaNode:: resolveBrowsePathFinished ( QList < QOpcUaBrowsePathTarget > 目标 , QList < QOpcUaRelativePathElement > path , QOpcUa::UaStatusCode statusCode )

QDateTime QOpcUaNode:: serverTimestamp ( QOpcUa::NodeAttribute 属性 ) const

QDateTime QOpcUaNode:: sourceTimestamp ( QOpcUa::NodeAttribute 属性 ) const

QVariant QOpcUaNode:: valueAttribute () const

QOpcUa::UaStatusCode QOpcUaNode:: valueAttributeError () const

[signal, since 6.7] void QOpcUaNode:: valueAttributeUpdated (const QVariant & value )

bool QOpcUaNode:: writeAttribute ( QOpcUa::NodeAttribute 属性 , const QVariant & value , QOpcUa::Types type = QOpcUa::Types::Undefined)

bool QOpcUaNode:: writeAttributeRange ( QOpcUa::NodeAttribute 属性 , const QVariant & value , const QString & indexRange , QOpcUa::Types type = QOpcUa::Types::Undefined)

bool QOpcUaNode:: writeAttributes (const QOpcUaNode::AttributeMap & toWrite , QOpcUa::Types valueAttributeType = QOpcUa::Types::Undefined)

bool QOpcUaNode:: writeValueAttribute (const QVariant & value , QOpcUa::Types type = QOpcUa::Types::Undefined)

内容

`[static constexpr]` QOpcUa::NodeAttributes QOpcUaNode:: allBaseAttributes ()

`[signal]` void QOpcUaNode:: attributeRead ( QOpcUa::NodeAttributes 属性 )

`[signal]` void QOpcUaNode:: attributeUpdated ( QOpcUa::NodeAttribute attr , QVariant value )

`[signal]` void QOpcUaNode:: attributeWritten ( QOpcUa::NodeAttribute 属性 , QOpcUa::UaStatusCode statusCode )

`[signal]` void QOpcUaNode:: browseFinished ( QList < QOpcUaReferenceDescription > children , QOpcUa::UaStatusCode statusCode )

`[signal]` void QOpcUaNode:: dataChangeOccurred ( QOpcUa::NodeAttribute attr , QVariant value )

`[signal]` void QOpcUaNode:: disableMonitoringFinished ( QOpcUa::NodeAttribute attr , QOpcUa::UaStatusCode statusCode )

`[signal]` void QOpcUaNode:: enableMonitoringFinished ( QOpcUa::NodeAttribute attr , QOpcUa::UaStatusCode statusCode )

`[signal]` void QOpcUaNode:: eventOccurred ( QVariantList eventFields )

`[static constexpr]` QOpcUa::NodeAttributes QOpcUaNode:: mandatoryBaseAttributes ()

`[signal]` void QOpcUaNode:: methodCallFinished ( QString methodNodeId , QVariant result , QOpcUa::UaStatusCode statusCode )

`[signal]` void QOpcUaNode:: monitoringStatusChanged ( QOpcUa::NodeAttribute attr , QOpcUaMonitoringParameters::Parameters 项 , QOpcUa::UaStatusCode statusCode )

`[since 6.7]` QOpcUaHistoryReadResponse QOpcUaNode:: readHistoryEvents (const QDateTime & startTime* , const QDateTime & endTime , QOpcUaMonitoringParameters::EventFilter & filter , quint32 numValues = 0)

`[since 6.3]` QOpcUaHistoryReadResponse QOpcUaNode:: readHistoryRaw (const QDateTime & startTime* , const QDateTime & endTime , quint32 numValues , bool returnBounds )

`[since 6.7]` QOpcUaHistoryReadResponse QOpcUaNode:: readHistoryRaw (const QDateTime & startTime* , const QDateTime & endTime , quint32 numValues , bool returnBounds , QOpcUa::TimestampsToReturn timestampsToReturn )

`[signal]` void QOpcUaNode:: resolveBrowsePathFinished ( QList < QOpcUaBrowsePathTarget > 目标 , QList < QOpcUaRelativePathElement > path , QOpcUa::UaStatusCode statusCode )

`[signal, since 6.7]` void QOpcUaNode:: valueAttributeUpdated (const QVariant & value )