Historical Event Access addresses the handling of historical time series events. The AddressSpace of HEA Servers contains Historical Nodes representing the history of Event Sources (Objects or Views). HEA Clients deal with historical events by accessing these Nodes with the HistoryRead and HistoryUpdate Services.
Examples of historical events are:
- System alarms
- Operator action events
- System triggers (such as new orders to be processed)
Note – Historical Access is specified in OPC UA Part 11