Alarm suppression refers to suppression of alarm and event notifications in the Desigo system. Thus, sending BACnet event notifications is suppressed. Alarm suppression does NOT prevent detection of alarm states.

Alarm suppression types

The following types of alarm suppression exist in Desigo:

  • Alarm suppression by automation station using function block AS_STA allows for implementing alarm suppression at the automation station level.
  • Hierarchical alarm suppression is made possible via the common alarm object based on the structure of the technical view.
  • Specific alarm suppression: All alarmable objects offer alarm suppression by object.
  • Exceptions for alarm suppression: Each alarmable object has a pin SupEcpt. This pin allows for defining exceptions to hierarchical alarm suppression.

Validity for alarm suppression

All types of alarm suppression apply to Desigo PX. Desigo room automation devices can generate and suppress alarms.

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:

DesigoFirmware 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.

Combination of multiple alarm suppressions

The above options to suppress alarms can overlap. For an object impacted already by multiple types of suppression, the following rule applies: One type of alarm suppression cannot be overridden by another type of alarm suppression.

AS_STA.
SupEvt

CMN_ALM.
SupEvt

CMN_ALM.
EnSupEcp

FB.SupEcpt

FB.EnEvt

Resulting alarm suppression for function block

True

•

•

•

•

suppressed

•

•

•

•

(F, F, F)

suppressed

False

False

•

•

(T,T,T)

not suppressed

False

True

False

•

(T,T,T)

suppressed

False

True

True

True

(T,T,T)

not suppressed

False

True

True

False

(T,T,T)

suppressed