Alarm Manager
The Alarm Manager maintains a record of alarm activity, and keeps track of the current status of all alarms in the system, whether they are active, acknowledged, shelved, etc. This information is stored as records in an alarm database.
To record and store information, the Alarm Manager uses a VTScada Historian. By default, the System Alarm Historian is used, but others may be created and selected as part of application development.
Alarm data and process I/O data should always be stored with separate Historians.
Alarms are linked to Historians via Alarm Database tags. Two Alarm DB tags are standard with every VTScada installation: System Alarm DB is the default for all user-created alarms and events. System Event DB is used for all built-in VTScada events including security logs and operator-control actions. System Alarm DB is the default for alarm tags and alarms integrated into other tags such as I/O & Calculations tags. If you create a new Alarm Database tag, you can link tags to it either by default by making the tags descendants of the Alarm Database tag or manually through the properties dialog.
Note that the alarm files, Alarms.DB and Alarms.LOG are obsolete as of VTScada version 11.2. For legacy applications that are upgraded to 11.2 or later, all alarm history will be transferred to Historians as a one-time process. In the event that you intend to add extra Alarm Database tags to your application and store certain alarm information with those custom databases, do so before transferring the alarm history.
Programmers can use the Alarm Manager API described in this chapter for the following tasks.
- Add alarm features to tags that they code from scratch.
- Customize the columns and other display characteristics of alarm lists.
- Query alarm status information for use in modules such as custom reports.
- Query or modify alarm properties to view or change the Alarm Manager configuration.
