Many Historians will collection information from internal nodes or from some underlying system. The collected information might be obtained using non-OPC UA communication. This type of historical configuration is vendor specific.

Some Historians might collected information from other OPC UA Servers. The Historian might mirror the point in their own information models and use the HasCurrentData or the HasCurrentEvent Reference to indicate the source node for the data or Event. Mirroring Variables is typically simple. Variables usually do not have complex structure or nested Variables under them. For Events, the source of Events might be the Server Node or some higher level Object and replicating that Object or entire Server and the complex structure under it would not make sense.

Instance of this ObjectType are used in a Historian to indicate the historical collection related details of an event stream that is being sourced from another OPC UA Server. An instance of this ObjectType shall include a HasCurrentEvent reference to the remote Server Object that is the source of the Events that are being collected.

Table 12 – HistoricalExternalEventSourceType definition

Attribute

Value

BrowseName

HistoricalExternalEventSourceType

IsAbstract

False

References

NodeClass

BrowseName

DataType

TypeDefinition

ModellingRule

HasProperty

Variable

Server

String

PropertyType

Optional

HasProperty

Variable

EndpointUrl

String

PropertyType

Optional

HasProperty

Variable

SecurityMode

MessageSecurityMode

PropertyType

Optional

HasProperty

Variable

SecurityPolicyUri

String

PropertyType

Optional

HasProperty

Variable

IdentityTokenPolicy

UserTokenPolicy

PropertyType

Optional

HasProperty

Variable

TransportProfileUri

String

PropertyType

Optional

HasProperty

Variable

HistoricalEventFilter

EventFilter

PropertyType

Mandatory

ConformanceUnits

Historical Access External Event Source

All instances of HistoricalExternalEventSourceType shall set the Object Attributes bits as described in 5.4.4.

An instance of this ObjectType may also have a HasHistoricalConfiguration to an instance of HistoricalEventConfigurationType, if it does not then the Server level default configuration shall apply.

The following optional information can be provided to describe how the Historian connects to receive the event stream:

HistoricalEventFilter is mandatory and is defined in 5.4.2