What the Life Safety Zone Object Is
The Life Safety Zone object, defined in Clause 12.16 of ANSI/ASHRAE 135-2024, is how a BACnet device represents an arbitrary group of Life Safety Point and other Life Safety Zone objects in a fire, life-safety, or security application. Like a point, its condition is described by a mode and a state together: Present_Value is the current life-safety state, and Mode sets the operating mode that governs the object’s internal logic. The members it aggregates are referenced through Zone_Members.
Typical applications include fire zones, panel zones, detector lines, and extinguishing controllers. A zone can be silenced, reports the expected operator action through Operation_Expected, and responds to the LifeSafetyOperation service. Life Safety Zone objects that support intrinsic reporting apply the CHANGE_OF_LIFE_SAFETY event algorithm and deliver alarms through the event notification services.
Where You’ll See It
- Fire zones. A floor or wing whose detectors are Life Safety Points rolls up into one Life Safety Zone for panel-level reporting.
- Life-safety controllers. Devices carrying the B-LSC Life Safety Controller profile host Life Safety Zone objects that summarize their points.
- Zone silence and reset. An operator acts on a whole zone through the LifeSafetyOperation service, and
Silencedreports the result.
Required Properties
Clause 12.16 requires every Life Safety Zone object to provide these properties. Datatypes are the spec’s names: BOOLEAN is a true/false flag, Unsigned an integer, and the BACnet-prefixed types are structured values defined by the standard.
| 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 life-safety-zone for this object |
Present_Value | BACnetLifeSafetyState | The zone’s current life-safety state (quiet, alarm, fault, and similar). Read-only |
Tracking_Value | BACnetLifeSafetyState | The state the zone is tracking toward, used during transitions |
Status_Flags | BACnetStatusFlags | Four health flags: in-alarm, fault, overridden, out-of-service |
Event_State | BACnetEventState | The object’s current event state (normal, off-normal, or fault) |
Reliability | BACnetReliability | Names the reason whenever the fault flag is set |
Out_Of_Service | BOOLEAN | When true, Present_Value is decoupled from the underlying members for testing |
Mode | BACnetLifeSafetyMode | The operating mode that governs the object’s internal logic. Writable |
Accepted_Modes | BACnetLIST of BACnetLifeSafetyMode | The modes this object will accept |
Silenced | BACnetSilencedState | Whether and how the zone has been silenced |
Operation_Expected | BACnetLifeSafetyOperation | The operator action the zone is expecting next |
Zone_Members | BACnetLIST of BACnetDeviceObjectReference | The Life Safety Point and Zone objects that make up this zone |
Property_List | BACnetARRAY[N] of BACnetPropertyIdentifier | The list of properties this instance actually implements |
Optional Properties
The properties integrators meet most are the life-safety group (Life_Safety_Alarm_Values, Alarm_Values, Fault_Values, Maintenance_Required) and Member_Of, which links the zone into larger zones. The intrinsic-reporting group generally appears or is absent as a set. Audit_Level and Auditable_Operations are the audit-logging controls added in 135-2024.
| Property | Datatype | Group |
|---|---|---|
Description | CharacterString | General |
Device_Type | CharacterString | General |
Life_Safety_Alarm_Values | BACnetLIST of BACnetLifeSafetyState | Intrinsic reporting |
Alarm_Values | BACnetLIST of BACnetLifeSafetyState | Intrinsic reporting |
Fault_Values | BACnetLIST of BACnetLifeSafetyState | Fault detection |
Time_Delay | Unsigned | Intrinsic reporting |
Notification_Class | Unsigned | Intrinsic reporting |
Event_Enable | BACnetEventTransitionBits | Intrinsic reporting |
Acked_Transitions | BACnetEventTransitionBits | Intrinsic reporting |
Notify_Type | BACnetNotifyType | Intrinsic reporting |
Event_Time_Stamps | BACnetARRAY[3] of BACnetTimeStamp | Intrinsic reporting |
Event_Message_Texts | BACnetARRAY[3] of CharacterString | Intrinsic reporting |
Event_Message_Texts_Config | BACnetARRAY[3] of CharacterString | Intrinsic reporting |
Event_Detection_Enable | BOOLEAN | Intrinsic reporting |
Event_Algorithm_Inhibit_Ref | BACnetObjectPropertyReference | Intrinsic reporting |
Event_Algorithm_Inhibit | BOOLEAN | Intrinsic reporting |
Time_Delay_Normal | Unsigned | Intrinsic reporting |
Reliability_Evaluation_Inhibit | BOOLEAN | Fault detection |
Maintenance_Required | BOOLEAN | Life safety |
Member_Of | BACnetLIST of BACnetDeviceObjectReference | Life safety |
Floor_Number | Unsigned8 | Life safety |
Value_Source | BACnetValueSource | Commanding |
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
- Life Safety Point: the individual devices this zone groups and summarizes.
- Binary Value: the general-purpose two-state value, when a zone summary needs no life-safety mode and state model.
What Chipkin Provides
The Life Safety Zone object, including its member aggregation and CHANGE_OF_LIFE_SAFETY intrinsic reporting, is a first-class object type in the CAS BACnet Stack. Talk to us about modeling your device’s points.