Dismiss a latched alarms

When the alarm latched state is enabled, alarms will continue to be shown, even after the alarm has been acknowledged and the out-of-range value that triggered the alarm has returned to normal. The user must issue a dismiss command to remove the latched alarm from the display. See Alarm latching for additional information.

Alarms are dismissed by users who view the latched alarms from their client applications such as InTouch HMI or AVEVA OMI. Latched alarms continue to show in the run-time application, until an authorized user issues a dismiss command.

Key points about latched alarms

Only users with Ack permission can issue a dismiss command to clear a latched alarm.

The basic workflow to dismiss an alarm consists of the following general steps:

• The alarm is detected and reported to any subscribed alarm clients. The alarm is unacknowledged unless it is of a priority level that does not require acknowledgement.

• An authorized user attempts to acknowledge the alarm from the client. The user can type an optional comment when acknowledging the alarm.

• The user sends an acknowledge request to the detecting object’s alarm feature. The acknowledgment must pass through standard security checks first. The acknowledge request contains the user’s name and any alarm comment.

• The alarm condition returns to normal but continues to be displayed in the subscribed alarm clients as a latched alarm.

• The user sends a dismiss command. This is subject to same safeguards as an acknowledgement request.

• The latched alarm is removed from display of the subscribed alarm clients, but the user who issued the dismiss command and the time the command was issued is historized.

For the alarm utility, the alarm is acknowledged within the alarm feature immediately. The user name, comment, and acknowledged time are also saved. Alarm comments can be localized into any supported language.

Acknowledge and dismiss are considered a change to the alarm state, which is sent to all subscribed clients. When an alarm is acknowledged or dismissed, the current AppEngine timestamp is used as the acknowledgement or dismissed time.

After an alarm is acknowledged for the first time, any additional (extra) acknowledgement attempts for the same alarm are rejected and an error is returned.