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This ObjectType defines diagnostic information about the OPC UA Server. This ObjectType is formally defined in Table 11.

Table 11 – ServerDiagnosticsType Definition

Attribute	Value
BrowseName	ServerDiagnosticsType
IsAbstract	False
References		NodeClass	BrowseName	DataType / TypeDefinition	ModellingRule
Subtype of the BaseObjectType defined in 6.2
HasComponent		Variable	ServerDiagnosticsSummary	ServerDiagnosticsSummaryDataType ServerDiagnosticsSummaryType	Mandatory
HasComponent		Variable	SamplingIntervalDiagnosticsArray	SamplingIntervalDiagnosticsDataType[] SamplingIntervalDiagnosticsArrayType	Optional
HasComponent		Variable	SubscriptionDiagnosticsArray	SubscriptionDiagnosticsDataType[] SubscriptionDiagnosticsArrayType	Mandatory
HasComponent		Object	SessionsDiagnosticsSummary	-- SessionsDiagnosticsSummaryType	Mandatory
HasProperty		Variable	EnabledFlag	Boolean PropertyType	Mandatory

ServerDiagnosticsSummary contains diagnostic summary information for the Server, as defined in 12.9.

SamplingIntervalDiagnosticsArray is an array of diagnostic information per sampling rate as defined in 12.8. There is one entry for each sampling rate currently used by the Server. Its TypeDefinitionNode is the VariableType SamplingIntervalDiagnosticsArrayType, providing a Variable for each entry in the array, as defined in 7.9.

The sampling interval diagnostics are only collected by Servers which use a fixed set of sampling intervals. In these cases, length of the array and the set of contained Variables will be determined by the Server configuration and the NodeId assigned to a given sampling interval diagnostics variable shall not change as long as the Server configuration does not change. A Server may not expose the SamplingIntervalDiagnosticsArray if it does not use fixed sampling rates.

SubscriptionDiagnosticsArray is an array of Subscription diagnostic information per subscription, as defined in 12.15. There is one entry for each Notification channel actually established in the Server. Its TypeDefinitionNode is the VariableType SubscriptionDiagnosticsArrayType, providing a Variable for each entry in the array as defined in 7.11. Those Variables are also used as Variables referenced by other Variables.

SessionsDiagnosticsSummary contains diagnostic information per session, as defined in 6.3.4.

EnabledFlag identifies whether or not diagnostic information is collected by the Server. It can also be used by a client to enable or disable the collection of diagnostic information of the Server. The following settings of the Boolean value apply: TRUE indicates that the Server collects diagnostic information, and setting the value to TRUE leads to resetting and enabling the collection. FALSE indicates that no diagnostic information is collected, and setting the value to FALSE disables the collection without resetting the diagnostic values.

When diagnostics are turned off, the Server can return Bad_NodeIdUnknown for all static diagnostic Nodes except the EnabledFlag Property. Dynamic diagnostic Nodes (such as the Session Nodes) will not appear in the AddressSpace.

If collection of diagnostic information is not supported at all, the EnabledFlag Property will be read only.