The Analog Alarm extension adds the alarming capability for attributes with real values, such as the Present Value of an Analog Input Object. This extension detects an alarm based on up to four limits and can be configured to report that alarm. It also sets the Alarm State attribute of the object to which it is added. The Analog Alarm Extension is also used with the Graphic Setting Preferences, which are used to establish color choices for alarm conditions in graphics.
For example, you can configure the Analog Alarm extension to issue an alarm if the temperature in a room falls below 15.6˚C (60˚F).