BACnet: Life Safety Objects

The BACnet standard describes two types of Life Safety objects. The two types of these objects include:

  • Life Safety Point Object Type
  • Life Safety Zone Object Type

The Life Safety Point object type is defined by the standard as those objects related to fire, safety, and security applications. The condition of this object type is determined by the following two factors:

  • Mode
  • State

The object mode is usually under the control of the device operator. The object state indicates the controller condition depending on the internal logic of the device.

Life Safety Point object applications can include the following automation related devices:

  • Automatic Fire Detectors
  • Sirens
  • Pull Stations

The following table will present the properties and related datatypes of the Life Safety Point object from the BACnet standard:

Property Datatype
Object_Identifier BACnet Object Identifier
Object_Name Character String
Object_Type BACnet Object Type
Present_Value BACnet Life Safety State
Tracking_Value_ BACnet Life Safety State
Description Character String
Device_Type Character String
Status_Flags BACnet Status Flags
Event_State BACnet Event State
Reliability BACnet Reliability
Out_of_Service Boolean
Mode BACnet Life Safety Mode
Accepted_Modes List of BACnet Life Safety Mode
Time_Delay Unsigned
Notification_Class Unsigned
Life_Safety_Alarm_Values List of BACnet Life Safety State
Alarm_Values List of BACnet Life Safety State
Fault_Values List of BACnet Life Safety State
Event_Enable BACnet Event Transition Bits
Acked_Transitions BACnet Event Transition Bits
Notify_Type BACnet Notify Type
Event_Time_Stamps BACnet Array (3) of BACnet Time Stamp
Silenced BACnet Silenced State
Operation_Expected BACnet Life Safety Operation
Maintenance_Required BACnet Maintenance
Setting Unsigned
Direct_Reading Real
Units BACnet Engineering Units
Member_Of List of BACnet Device Object Reference
Profile_Name Character String

The Life Safety Zone object type has similar conditional and property qualities as the Life Safety Point object type, but the focus is concentrated on a group of Life Safety Point and Zone objects.

The following table will present the properties and related datatypes of the Life Safety Zone object from the BACnet standard:

Property Datatype
Object_Identifier BACnet Object Identifier
Object_Name Character String
Object_Type BACnet Object Type
Present_Value BACnet Life Safety State
Tracking_Value BACnet Life Safety State
Description Character String
Device_Type Character String
Status_Flags BACnet Status Flags
Event_State BACnet Event State
Reliability BACnet Reliability
Out_of_Service Boolean
Mode BACnet Life Safety Mode
Accepted_Modes List of BACnet Life Safety Mode
Time_Delay Unsigned
Notification_Class Unsigned
Life_Safety_Alarm_Values List of BACnet Life Safety State
Alarm_Values List of BACnet Life Safety State
Fault_Values List of BACnet Life Safety State
Event_Enable BACnet Event Transition Bits
Acked_Transitions BACnet Event Transition Bits
Notify_Type BACnet Notify Type
Event_Time_Stamps BACnet Array (3) of BACnet Time Stamp
Silenced BACnet Silenced State
Operation_Expected BACnet Life Safety Operation
Maintenance_Required Boolean
Zone_Members List of BACnet Device Object Reference
Member_Of List of BACnet Device Object Reference
Profile_Name Character String

The developer should pay attention to the Mode and State qualities of both Life Safety object types.

The following structure example from the standard will examine both Life Safety object types from actual automation applications. Specifically, the Point object will focus on a building smoke detector. The Zone object will examine the fire zone within a building.

Life Safety Point Object Example:
Property: Object_Identifier = (Life Safety Point, Instance 2)
Property: Object_Name = “SMK3W”
Property: Object_Type = LIFE_SAFETY_POINT
Property: Present_Value = PREALARM
Property: Tracking_Value = PREALARM
Property: Description = “Floor 3, West Zone Smoke Detector”
Property: Device_Type = “Old Smokey model 123″
Property: Status_Flags = {TRUE, FALSE, FALSE, FALSE}
Property: Event_State = LIFE_SAFETY_ALARM
Property: Reliability = NO_FAULT_DETECTED
Property: Out_Of_Service = FALSE
Property: Mode = ON
Property: Accepted_Modes = {ENABLED, DISABLED, TEST}
Property: Time_Delay = 10
Property: Notification_Class = 39
Property: Life_Safety_Alarm_Values = (ALARM)
Property: Alarm_Values = (PREALARM)
Property: Fault_Values = (FAULT)
Property: Event_Enable = {TRUE, TRUE, TRUE}
Property: Acked_Transitions = {TRUE, TRUE, TRUE}
Property: Notify_Type = ALARM
Property: Event_Time_Stamps = ((23-MAR-95, 18:50:21.2), (*-*-*, *:*:*.*),(23-MAR-95, 19:01:34.0))
Property: Silenced = SILENCE_AUDIBLE
Property: Operation_Expected = RESET_ALARM
Property: Maintenance_Required = NONE
Property: Setting = 50
Property: Direct_Reading = 84.3
Property: Units = PERCENT-OBSCURATION-PER-METER
Property: Member_Of = ((Life Safety Zone, Instance 5))

Life Safety Zone Object Example:
Property: Object_Identifier = (Life Safety Zone, Instance 2)
Property: Object_Name = “SMK3″
Property: Object_Type = LIFE_SAFETY_ZONE
Property: Present_Value = PREALARM
Property: Tracking_Value = PREALARM
Property: Description = “Floor 3 Smoke”
Property: Status_Flags = {TRUE FALSE, FALSE, FALSE}
Property: Event_State = LIFE_SAFETY_ALARM
Property: Reliability = NO_FAULT_DETECTED
Property: Out_Of_Service = FALSE
Property: Mode = ON
Property: Accepted_Modes = {ENABLED, DISABLED, TEST}
Property: Time_Delay = 10
Property: Notification_Class = 39
Property: Life_Safety_Alarm_Values = (ALARM)
Property: Alarm_Values = (PREALARM)
Property: Fault_Values = (FAULT)
Property: Event_Enable = {TRUE, TRUE, TRUE}
Property: Acked_Transitions = {TRUE, TRUE, TRUE}
Property: Notify_Type = ALARM
Property: Event_Time_Stamps = ((23-MAR-95, 18:50:21.2), (*-*-*, *:*:*.*),(23-MAR-95,19:01:34.0))
Property: Silenced = UNSILENCED
Property: Operation_Expected = SILENCE_AUDIBLE
Property: Maintenance_Required = NONE
Property: Zone_Members = ((Life Safety Point, Instance 22),(Life Safety Point, Instance 23))
Property: Member_Of = ((Life Safety Zone, Instance 5))

Written by: Scott Cosby

© Chipkin Automation Systems 2007