The DeviceHealthDiagnosticAlarmType is a specialization of the InstrumentDiagnosticAlarmType intended to represent abnormal device conditions as defined by NAMUR NE 107. This type can be used in filters for monitored items. Only subtypes of this type will be used in actual implementations. The Alarm becomes active when the device condition is abnormal. It is formally defined in Table 31.

Table 31 – DeviceHealthDiagnosticAlarmType definition

Attribute	Value
BrowseName	DeviceHealthDiagnosticAlarmType
IsAbstract	False
References	NodeClass	BrowseName	DataType	TypeDefinition	ModellingRule
Subtype of the InstrumentDiagnosticAlarmType defined in OPC 10000-9.
HasSubtype	ObjectType	FailureAlarmType	Defined in clause 5.12.3
HasSubtype	ObjectType	CheckFunctionAlarmType	Defined in clause 5.12.4
HasSubtype	ObjectType	OffSpecAlarmType	Defined in clause 5.12.5
HasSubtype	ObjectType	MaintenanceRequiredAlarmType	Defined in clause 5.12.6

Conditions of subtypes of DeviceHealthDiagnosticAlarmType become active when the device enters the corresponding abnormal state.

The Message field in the Event notification shall be used for additional information associated with the health status (e.g. the possible cause of the abnormal state and suggested actions to return to normal).

A Device may be in more than one abnormal state at a time in which case multiple Conditions will be active.