This section provides examples of Historian instance configuration. It includes both HistoricalData and HistoricalEvent configuration, both internally collected data and externally sourced data.

HistoricalDataNodes are always a part of other Nodes in the AddressSpace. They are never defined by themselves. A simple example of a container for HistoricalDataNodes would be a “Folder Object”.

Figure 3 illustrates the basic AddressSpace Model of DataVariables that includes History.


Figure 3 – Historical Variable with Historical Data Configuration and Annotations

Each HistoricalDataNode with history shall have the Historizing Attribute (see OPC 10000-3) defined and may reference a HistoricalAccessConfiguration Object. In the case where the HistoricalDataNode is itself a Property then the HistoricalDataNode inherits the values from the parent node of the Property.

Not every Variable in the AddressSpace might contain history data. To see if history data is available, a Client will look for the HistoryRead/Write states in the AccessLevel Attribute (see OPC 10000-3 for details on use of this Attribute).

Figure 3 only shows a subset of Attributes and Properties. Other Attributes that are defined for Variables in OPC 10000-3, may also be available.

The following example illustrates a Historian that obtains values for a HistoricalData node from another Server.


Figure 4 - Example Historizing External Data Source

The Pressure Variable has a custom historical configurtion. It also has one or more Annotations associated with it, as indicated by the Annotations property. This configuration has no aggregates configured (the AggregateConfiguration is empty). Since there are no aggregates, a value for Stepped is not provided and thus defaults to false.

HistoricalEventNode Objects or Views in the AddressSpace that expose historical Events. These Nodes are identified via the EventNotifier Attribute, and provide some historical subset of the Events generated by the Server.

Each HistoricalEventNode is represented by an Object or View with a specific set of Attributes. The HistoricalEventFilter Property specifies the fields available in the history.

Not every Object or View in the AddressSpace may be a HistoricalEventNode. To qualify as HistoricalEventNode, a Node has to contain historical Events. To see if historical Events are available, a Client will look for the HistoryRead/HistoryWrite states in the EventNotifier Attribute. See OPC 10000-3 for details on the use of this Attribute.

Figure 5 illustrates the basic AddressSpace Model of an Event model that includes History.


Figure 5 – Representation of an Event with History in the AddressSpace

Figure 6 provides an illustration of information related to Event sources that are in a Historian, where the events are being source from external Servers.


Figure 6 - Event History configuration example