Event Categories in the A&E COM Server are represented in the UA Server as ObjectTypes which are subtypes of BaseEventType. The BrowseName and DisplayName of the ObjectType Node for Simple and Tracking Event Types are constructed by appending the text ‘EventType’ to the Description of the Event Category. For Condition Event Types the text ‘AlarmType’ is appended to the Condition Name.

These ObjectType Nodes have a super type which depends on the A&E Event Type, the Event Category Description and the Condition Name; however, the best mapping requires knowledge of the semantics associated with the Event Categories and Condition Names. If an A&E COM UA Wrapper does not know these semantics then Simple Event Types are subtypes of BaseEventType, Tracking Event Types are subtypes of AuditEventType and Condition Event Types are subtypes of the AlarmType. Table D.1 defines mappings for a set of “well known” Category description and Condition Names to a standard super type.

Table D.1 – Mapping from standard Event categories to OPC UA Event types

COM A&E Event Type

Category Description

Condition Name

OPC UA EventType

Simple

---

---

BaseEventType

Simple

Device Failure

---

DeviceFailureEventType

Simple

System Message

---

SystemEventType

Tracking

---

---

AuditEventType

Condition

---

---

AlarmType

Condition

Level

---

LimitAlarmType

Condition

Level

PVLEVEL

ExclusiveLevelAlarmType

Condition

Level

SPLEVEL

ExclusiveLevelAlarmType

Condition

Level

HI HI

NonExclusiveLevelAlarmType

Condition

Level

HI

NonExclusiveLevelAlarmType

Condition

Level

LO

NonExclusiveLevelAlarmType

Condition

Level

LO LO

NonExclusiveLevelAlarmType

Condition

Deviation

---

NonExclusiveDeviationAlarmType

Condition

Discrete

---

DiscreteAlarmType

Condition

Discrete

CFN

OffNormalAlarmType

Condition

Discrete

TRIP

TripAlarmType

There is no generic mapping defined for A&E COM sub-Conditions. If an Event Category is mapped to a LimitAlarmType then the sub Condition name in the Event are be used to set the state of a suitable State Variable. For example, if the sub-Condition name is “HI HI” then that means the HighHigh state for the LimitAlarmType is active

For Condition Event Types the Event Category is also used to define subtypes of BaseConditionClassType.

Figure D.1 illustrates how ObjectType Nodes created from the Event Categories and Condition Names are placed in the standard OPC UA HasNotifier hierarchy.

image036.png

Figure D.1 – The type model of a wrapped COM AE server