OPC AE Mapping

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The OPC Alarms and Events data model represents each alarm/event as a message with a pre-defined structure. The MetaServer protocol includes support for queues of messages where each queue's structure can be flexibly defined. The mapping from the OPC AE data model simply presents each field in an OPC event as a column in a MetaServer queue's message structure.

 

The OPC AE specification defines three central event types:

•Condition Events. A condition event indicates that an alarm has occurred. Condition events can be activated and deactivated. Deactivated condition events implies the event state is not monitored by the OPC AE Server. There is an acknowledgement mechanism for condition events, though the OPC MetaBridge implementation does not support this acknowledgement functionality.
•Tracking Events. These record the occurrence of an event where the cause is not within the process being monitored. An example of a tracking event include operator intervention actions.
•Simple Events. These are events that are not related to an alarm condition and can not be tracked.

 

The message column structure that is generated by the OPC MetaBridge application in response to OPC AE events is documented in the following table.

 

Column Name

Data Type

Description

Simple

Tracking

Condition

TIME

Time

The time the event occurred.

ü

ü

ü

ACTIVE

Time

The time that the condition event became active.

ü

ü

ü

SOURCE

Text

The source of the event notification. This is an OPC AE server implementation specific indication of the origins of the event.

ü

ü

ü

MESSAGE

Text

A message that describes the event.

ü

ü

ü

EVTYPE

Text

The type of the event e.g. Condition, Tracking, Simple.

ü

ü

ü

CATEGORY

Integer

The category of the event.

ü

ü

ü

SEVERITY

Integer

The severity of the event in the range 1...1000.

ü

ü

ü

ACTORID

Text

A identifier for the actor that performed an action that initiated the event. This identifier can be used for tracking events.

 

ü

ü

CHGMASK

Integer

Indicates which properties of the condition have changed. The mask is encoded as a single integer value where each bit in the integer represents a change in an aspect of the event state.

1

Active State

2

Ack State

4

Enable State

8

Quality

16

Severity

32

Subcondition

64

Message

128

Attribute

 

 

ü

CHGMASKT

Text

A representation of CHGMASK in more human readable text.

 

 

ü

NEWSTATE

Integer

Specifies the new state of the condition. This state is defined in a single integer value where the bits of the integer represents a different state.

1

Enabled

2

Active

4

Acknowledged

 

 

ü

NEWSTATET

Text

A representation of NEWSTATE in more human readable text.

 

 

ü

CONDITION

Text

The name of the condition related to this event notification e.g. LOLO, LO, DV_LO etc.

 

 

ü

SUBCOND

Text

The name of the sub-condition for multi-state conditions or the condition name for single state conditions.

 

 

ü

QUALITY

Integer

Defines the quality associated with this condition state.

 

 

ü

QUALITYT

Text

A representation of QUALITY in more human readable text.

 

 

ü

ACKREQ

Integer

Indicates whether this event requires acknowledgement.

 

 

ü

COOKIE

Integer

A server defined cookie value associated with the event.

 

 

ü