This specification extends the standard EventType ( see OPC 10000-3, OPC 10000-5 and OPC 10000-9 EventTypes). Figure 6 – BaseLogEventType Figure 6 illustrates the event fields that are mapped to the LogRecordStructure. Any Object that has a Reference to one of these EventTypes shall generate LogRecords in the LogObject related to the defined BaseLogEventType.
Additional EventTypes can be defined as needed for specific log information. If desired, subtypes of ConditionType or any of the AlarmTypes might also be used. The only requirement for an Event to be recorded in the LogObject is for the Event to have a ConditionClassId or SubConditionClassId of LogEntryConditionClass. The following fields from BaseEventType are mapped to the LogRecord:
- Time – The time associated with this event.
- EventType – as defined in BaseEventType in OPC 10000-5
- SourceNode – identifies the Node that the Event originated from, as defined in BaseEventType in OPC 10000-5. For LogObject Events, this node is the node that the LogRecord is related to.
- SourceName - provides a description of the source of the Event, this might be a browse path to a variable under the SourceNode, if the LogRecord is related to the variable, or it might be as defined in BaseEventType in OPC 10000-5.
- Message – shall describe the issue that is being represented in the LogRecord.
- Severity – in the Event system is defined as a number between 1 and 1000 inclusive. Typically, the full range of numbers is mapped to sub ranges. See 5.3 for a description of LogRecord use of this field.