In the section below, as an example you define an alarm group with only one alarm. The alarm is used to monitor a variable whose value returns the parts shortage in a plant. When this value fulfills a certain condition, the alarm is triggered. To do this, use the Digital monitoring type in the example and define the alarm condition there.
The alarm also gets an assigned latch variable. This is a variable which provides additional information from the application at the time when the alarm becomes active. The contents of this variable can be included into the alarm message. Moreover, the variable can be used in the alarm visualization to filter the alarms.
Requirement: A suitable alarm class PartsShortage and alarm storage DatabaseFileAlarmStorage are already configured in the alarm management of the application.
In the device tree, select the Alarm Configuration object.
For the Archiving, specify the alarm storage DatabaseFileAlarmStorage which is already configured.
Note: You have to specify an alarm storage here because you have defined an alarm of a class with archiving.
If the variable bPart1Empty switches to TRUE at runtime, then a message is issued by the alarm management. The value of the variable iFillLevel is issued with the message. The acknowledgment response and the display are executed according to the PartsShortage alarm class. The alarm is archived.
According to the value of the latch variables defined for the alarm, you can filter the alarms in an alarm visualization. To do this, configure the Alarm Table or Alarm Banner elements accordingly and program an element for specifying the filter value.
Alarm Display in Online Mode
You can create the alarm management and alarm visualization in such a way that the operator still has options to control the display in online mode: filtering of alarms, display for a specific time period, clear history.