User Manual

Alarm management
Alarm suppression
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Alarm suppression by automation station
AS_STA (Device Access) is a Desigo PX function block that allows to suppress all alarms of an automation
station. The function block allows for suppressing BACnet event notifications by means of an application.
Thus, sending of alarms and events during, e.g., maintenance, can be suppressed, e.g., via a key switch.
Alarm suppression is controlled via pin SupEvt. The following values are defined for SupEvt:
● true: The automation station sends NO BACnet event notifications.
● false: The automation station sends BACnet event notifications.
For more information on function block AS_STA, see:
Desigo Firmware blocks, automation level, Overview (CM110749)
Desigo Vxx Firmware blocks (CM110729)
Desigo room automation supports the suppression of all alarms of an automation station. To do this, it uses
the device infrastructure objects CommonEvent and CommonEventEnrollment.
Hierarchical alarm suppression
Hierarchical alarm suppression allows for suppressing alarms of a plant, partial plant, aggregate,
component, or subcomponent. Hierarchical suppression is based on suppressing alarms of any part of a
partial tree in the technical structure.
For Desigo PX hierarchical alarm suppression is carried out via the Alarm Collection (CMN_ALM) object.
CMN_ALM comprises all alarmable BACnet objects as a group on the same or lower hierarchies in the
technical view. Thus, CMN_ALM allows for controlling alarm suppression for all alarmable BACnet objects
of a group.
Alarm suppression is controlled via pin SupEvt. The following values are defined for SupEvt:
● true: Alarmable BACnet objects of a group do NOT send BACnet event notifications.
● false: Alarmable BACnet objects of a group send BACnet event notifications.
Desigo room automation supports the hierarchical suppression of alarms. It uses the CommonEvent and
CommonEventEnrollment objects.
The CommonEvent object aggregates the alarm state of all BACnet objects on the same or the lower
hierarchy levels of the technical view.
The CommonEventEnrollment object monitors the CommonEvent object. The hierarchical alarm
suppression can be turned on or off in the CommonEventEnrollment object.
Specific alarm suppression
All alarmable BACnet objects allow for specific suppression. Each alarmable BACnet objects offers pin
EnEvt for this type of alarm suppression.
The following values make sense for EnEvt:
● (False, False, False): The object sends NO BACnet event notification.
● (True, True, True): The object sends BACnet event notification.
Value combinations with True and False for EnEvt should be avoided.
Alarm suppression exceptions
A possible application is to activate alarm suppression during plant maintenance. Vital alarms must be
excepted from alarm suppression.
For Desigo PX exceptions can be defined for hierarchical alarm suppression with CMN_ALM.
Function block CMN_ALM has pin EnSupEcp. This exception specifies if exceptions are possible within the
alarmable BACnet objects of the group. The following values are defined for EnSupEcp:
● true: Exceptions for alarm suppression within the group of alarmable BACnet objects are considered.
● false: Exceptions for alarm suppression within the group of alarmable BACnet objects are NOT
considered.
Each alarmable BACnet object can be exempted from hierarchical alarm suppression with CMN_ALM. To
do this, each alarmable BACnet object has pin SupEcpt. The following values are defined for SupEcpt:
● true: The object is considered as an exception for alarm suppression.
● false: The object is NOT considered as an exception for alarm suppression.