cannot subscribe alarm triggered before client run

[Jerry]

Dear support team

when i trigger an alarm in OPC UA server, and then run the opc ua client to subscribe the alarm with example code. i find client cannot subscribe the alarm triggered before client runs.
but then i run the UAExpert, and drag "Server" node to "Event View". it can subscribe the alarm.

how does the UAExpert do that?

looking forward to your reply.

thanks.

[Jerry]

here is the mainly code to create monitoredItem

Code: Select all

    itemsToCreate.create(j+1);

    UaEventFilter            eventFilter;
    UaSimpleAttributeOperand selectElement;
    UaContentFilter*         pContentFilter        = NULL;
    UaContentFilterElement*  pContentFilterElement = NULL;
    UaFilterOperand*         pOperand              = NULL;
	//for data monitoreditem
	for(i=0; i<j; i++)
	{
		itemsToCreate[i].ItemToMonitor.AttributeId = OpcUa_Attributes_Value;
		
		OpcUa_NodeId_CopyTo(m_pConfiguration->getNodesToMonitor().rawData()+i,&itemsToCreate[i].ItemToMonitor.NodeId);
		// itemsToCreate[0].ItemToMonitor.NodeId.Identifier.Numeric = OpcUaId_Server_ServerStatus_CurrentTime;
		itemsToCreate[i].RequestedParameters.ClientHandle = i;
		itemsToCreate[i].RequestedParameters.SamplingInterval = 1;
		itemsToCreate[i].RequestedParameters.QueueSize = 5;
		itemsToCreate[i].RequestedParameters.DiscardOldest = OpcUa_True;
		itemsToCreate[i].MonitoringMode = OpcUa_MonitoringMode_Reporting;
		itemsToCreate[i].ItemToMonitor.IndexRange;

		/*OpcUa_DataChangeFilter* pDataChangeFilter = NULL;
		OpcUa_EncodeableObject_CreateExtension(
			&OpcUa_DataChangeFilter_EncodeableType,
			&itemsToCreate[i].RequestedParameters.Filter,
			(OpcUa_Void**)&pDataChangeFilter);
		if ( pDataChangeFilter ) 
		{
			pDataChangeFilter->DeadbandType = OpcUa_DeadbandType_None;
			pDataChangeFilter->Trigger      = OpcUa_DataChangeTrigger_StatusValueTimestamp;
		}*/
	}
	//for event monitoreditem
	itemsToCreate[j].ItemToMonitor.AttributeId = OpcUa_Attributes_EventNotifier;
    itemsToCreate[j].ItemToMonitor.NodeId.Identifier.Numeric = OpcUaId_Server;
    itemsToCreate[j].RequestedParameters.ClientHandle = j;
    itemsToCreate[j].RequestedParameters.SamplingInterval = 1;
    itemsToCreate[j].RequestedParameters.QueueSize = 0;
    itemsToCreate[j].RequestedParameters.DiscardOldest = OpcUa_True;
    itemsToCreate[j].MonitoringMode = OpcUa_MonitoringMode_Reporting;

	 // Define which eventfields to send with each event
    selectElement.setBrowsePathElement(0, UaQualifiedName("Message", 0), 1);
    eventFilter.setSelectClauseElement(0, selectElement, 7);
    selectElement.setBrowsePathElement(0, UaQualifiedName("SourceName", 0), 1);
    eventFilter.setSelectClauseElement(1, selectElement, 7);
    selectElement.setBrowsePathElement(0, UaQualifiedName("Severity", 0), 1);
    eventFilter.setSelectClauseElement(2, selectElement, 7);
	selectElement.setBrowsePathElement(0, UaQualifiedName("Time", 0), 1);
    eventFilter.setSelectClauseElement(3, selectElement, 7);
	selectElement.setBrowsePathElement(0, UaQualifiedName("EventType", 0), 1);
    eventFilter.setSelectClauseElement(4, selectElement, 7);
	selectElement.setBrowsePathElement(0, UaQualifiedName("SourceNode", 0), 1);
    eventFilter.setSelectClauseElement(5, selectElement, 7);
	selectElement.setBrowsePathElement(0, UaQualifiedName("EventCode", 2), 1);
    eventFilter.setSelectClauseElement(6, selectElement, 7);
	// We only want to receive events of type ControllerEventType
    pContentFilter = new UaContentFilter;
    pContentFilterElement = new UaContentFilterElement;
    // Operator OfType
    pContentFilterElement->setFilterOperator(OpcUa_FilterOperator_OfType);
    // Operand 1 (Literal)
    pOperand = new UaLiteralOperand;
   // ((UaLiteralOperand*)pOperand)->setLiteralValue(m_pConfiguration->getEventTypeToFilter());
	 ((UaLiteralOperand*)pOperand)->setLiteralValue(UaVariant(UaNodeId(2041, 0)));
    pContentFilterElement->setFilterOperand(0, pOperand, 1);
    pContentFilter->setContentFilterElement(0, pContentFilterElement, 1);
    eventFilter.setWhereClause(pContentFilter);
    // set filter for monitored items
    eventFilter.detachFilter(itemsToCreate[j].RequestedParameters.Filter);

	    printf("\nAdding monitored items to subscription ...\n");
		result = m_pSubscription->createMonitoredItems(
        serviceSettings,
        OpcUa_TimestampsToReturn_Both,
        itemsToCreate,
        createResults);

[Jerry]

hi support team,
could anyone give me any comments?

thanks

[Support Team]

Hello Jerry,

the server only sends Events whenever the state of a condition (alarm) changes. If you missed that change in the client you don't receive the event.
For this use case OPC UA defines a method in the server a client can call to have the server send an event for each condition that has the retain flag set to true.
You find a sample code for that in the console client that is installed with the SDK. (see subscribeAlarms()).