What the Alert Enrollment Object Is
The Alert Enrollment object, defined in Clause 12.52 of ANSI/ASHRAE 135-2024, is an event source that originates alerts. An alert is a notification about a condition that does not represent an alarm or a change in a monitored value; it lets a BACnet device announce something noteworthy, such as a maintenance reminder or an operational message, without impacting the event state of the object the alert concerns.
Present_Value identifies the object the alert is about, and the event-reporting properties (Event_Detection_Enable, Notification_Class, Event_Enable, Notify_Type) route the alert the same way alarms are routed, through the event notification services and a Notification Class. Because the Alert Enrollment is the source, it generates these notifications itself rather than deriving them from a limit or state algorithm on another object.
Where You’ll See It
- Maintenance alerts. A device raises an Alert Enrollment notification for a service-due or filter-change condition without changing any monitored point’s alarm state.
- Operational messages. A controller announces a noteworthy but non-alarm event to operators through the same notification path its alarms use.
- Decoupled reporting. Alerts generated for an object without setting that object into an off-normal event state, keeping alarm and alert streams distinct.
Required Properties
Clause 12.52 requires every Alert Enrollment object to provide these properties. Datatypes are the spec’s names: Unsigned is an integer, BOOLEAN a true/false flag, and the BACnet-prefixed types are structured values defined by the standard. On this object the event-reporting properties are required rather than optional, because generating notifications is its whole purpose.
| Property | Datatype | What it holds |
|---|---|---|
Object_Identifier | BACnetObjectIdentifier | The object’s type and instance number, unique within the device |
Object_Name | CharacterString | The human-readable point name, unique within the device |
Object_Type | BACnetObjectType | Always alert-enrollment for this object |
Present_Value | BACnetObjectIdentifier | The object the alert is about |
Event_State | BACnetEventState | The object’s current event state |
Event_Detection_Enable | BOOLEAN | Whether alert detection is enabled |
Notification_Class | Unsigned | The notification class that routes the alert to its recipients |
Event_Enable | BACnetEventTransitionBits | Which transitions generate a notification |
Acked_Transitions | BACnetEventTransitionBits | Which transitions have been acknowledged |
Notify_Type | BACnetNotifyType | Whether notifications are sent as alarms or events |
Event_Time_Stamps | BACnetARRAY[3] of BACnetTimeStamp | The times of the last to-off-normal, to-fault, and to-normal transitions |
Property_List | BACnetARRAY[N] of BACnetPropertyIdentifier | The list of properties this instance actually implements |
Optional Properties
The properties integrators meet most are the event-message texts and the Event_Algorithm_Inhibit pair that can temporarily suppress alert generation. Description labels the object.
| Property | Datatype | Group |
|---|---|---|
Description | CharacterString | General |
Event_Message_Texts | BACnetARRAY[3] of CharacterString | Intrinsic reporting |
Event_Message_Texts_Config | BACnetARRAY[3] of CharacterString | Intrinsic reporting |
Event_Algorithm_Inhibit_Ref | BACnetObjectPropertyReference | Intrinsic reporting |
Event_Algorithm_Inhibit | BOOLEAN | Intrinsic reporting |
Audit_Level | BACnetAuditLevel | Auditing |
Auditable_Operations | BACnetAuditOperationFlags | Auditing |
Tags | BACnetARRAY[N] of BACnetNameValue | Tagging and profile |
Profile_Location | CharacterString | Tagging and profile |
Profile_Name | CharacterString | Tagging and profile |
Related Objects
- Event Enrollment: monitors another object against an event algorithm to raise alarms, where Alert Enrollment originates non-alarm alerts.
- Notification Class: routes the alerts an Alert Enrollment object generates.
- Notification Forwarder: re-distributes notifications, a related event-distribution object.
What Chipkin Provides
The Alert Enrollment object is modeled in the CAS BACnet Stack and served with its event-reporting properties; the alert-generation behavior is object behavior the device supplies. Talk to us about modeling your device’s points.