Table C.1lists EEMUA terms and how OPC UA terms maps to them.

Table C.1– EEMUA Terms

EEMUA Term

OPC UA Term

EEMUA Definition

Accepted

Acknowledged=True

An Alarmis accepted when the Operatorhas indicated awareness of its presence.

In OPC UA this can be accomplished with the Acknowledge Method.

Active Alarm

Active = True

An Alarm Conditionwhich is on (i.e. limit has been exceeded and Conditioncontinues to exist).

Alarm Message

Message Property (defined in OPC 10000-5.)

Test information presented to the Operatorthat describes the Alarm Condition.

Alarm Priority

Severity Property (defined in OPC 10000-5.)

The ranking of Alarmsby severity and response time.

Alert

-

A lower priority Notificationthan an Alarmthat has no serious consequence if ignored or missed. In some Industries also referred to as a Prompt or Warning”.

No direct mapping! In UA the concept of Alertscan be accomplished by the use of severity. E.g., Alarmsthat have a severity below 50 may be considered as Alerts.

Cleared

Active = False

An Alarm state that indicates the Conditionhas returned to normal.

Disable

Enabled = False

An Alarmis disabled when the system is configured such that the Alarmwill not be generated even though the base Alarm Conditionis present.

Prompt

Dialog

A request from the control system that the Operatorperform some process action that the system cannot perform or that requires Operatorauthority to perform.

Raised

Active = True

An Alarmis Raisedor initiated when the Conditioncreating the Alarmhas occurred.

Release

OneShotShelving

A ‘release’ is a facility that can be applied to a standing (UA = active) Alarmin a similar way to which Shelvingis applied. A released Alarmis temporarily removed from the Alarmlist and put on the shelf. There is no indication to the Operatorwhen the Alarmclears, but it is taken off the shelf. Hence, when the Alarmis raised again it appears on the Alarmlist in the normal way.

Reset

Retain=False

An Alarmis Reset when it is in a state that can be removed from the Display list.

OPC UA includes Retainflag which as part of its definition states: “when a Clientreceives an Eventwith the Retainflag set to False, the Clientshould consider this as a Condition/Branch that is no longer of interest, in the case of a “current Alarmdisplay” the Condition/Branch would be removed from the display”

Shelving

Shelving

Shelvingis a facility where the Operatoris able to temporarily prevent an Alarmfrom being displayed to the Operatorwhen it is causing the Operatora nuisance. A Shelved Alarmwill be removed from the list and will not re-annunciate until un-shelved.

Standing

Active = True

An Alarmis Standingwhilst the Conditionpersists (Raisedand Standingare often used interchangeably)’.

Suppress

Suppress

An Alarmis suppressed when logical criteria are applied to determine that the Alarmshould not occur, even though the base Alarm Condition(e.g. Alarmsetting exceeded) is present.

Unaccepted

Acknowledged = False

An Alarmis accepted when the Operatorhas indicated awareness of its presence. It is unaccepted until this has been done.