Lift

A Lift object represents one elevator car. It reports where the car is, which way it is moving, the state of its doors and any alarm or fault. Optional properties add calls, load and drive status. A lift controller exposes one per car so a building system can monitor traffic and equipment.

Typical uses

• Show the floor and direction of each elevator car
• Report door open and closed state for every landing
• Raise an alarm on a passenger alarm button
• Read the car load and the next stopping floor

Key properties

Property	What it holds
Car_Position	The floor the car is at. Required.
Car_Moving_Direction	The direction the car is moving, or that it is stopped. Required.
Car_Door_Status	The state of each door of the car, one entry per door. Required.
Passenger_Alarm	True while a passenger alarm is active. The standard’s intrinsic alarm watches it.
Fault_Signals	The fault codes currently active. Required on a lift.
Elevator_Group	The Elevator Group object this car belongs to.

How it behaves

A Lift is monitoring data, not commandable. Where it reports events itself, the standard pairs it with the CHANGE_OF_STATE algorithm watching Passenger_Alarm for TRUE. Reliability can use the FAULT_LISTED fault algorithm. A client sees the usual Event_State and notifications.

With the CAS BACnet Stack

Enable it with the STACK_OPTION_OBJECT_TYPE_LIFT build option. Do not use BACnetStack_AddObject. Add the Elevator Group object first with BACnetStack_AddElevatorGroupObject, then call BACnetStack_AddLiftOrEscalatorObject with the Lift type, group, Group_ID and Installation_ID. You serve the rest through callbacks: the callback you register with BACnetStack_RegisterCallbackGetPropertyUnsignedInteger for Car_Position, the BACnetStack_RegisterCallbackGetPropertyEnumerated callback for Car_Moving_Direction and Car_Door_Status (the array index is the door number), the BACnetStack_RegisterCallbackGetPropertyBool callback for Passenger_Alarm and Out_Of_Service, and the BACnetStack_RegisterCallbackGetListOfEnumerations callback for Fault_Signals. Enable optional properties with BACnetStack_SetPropertyEnabled. An unserved Car_Position, Car_Moving_Direction, Car_Door_Status or Passenger_Alarm returns an error instead of an invented value. Arm the passenger alarm with BACnetStack_SetAlarmsAndEventsForObjectEnabled and then BACnetStack_SetIntrinsicChangeOfStateAlgorithmBool, with an alarm value of true.

Related object types

Elevator Group, Escalator, Notification Class

Properties

The properties ASHRAE 135-2024 clause 12.59 defines for this object type.

How to read the table:

• Conformance is what the standard asks of every object of this type: R is required, W is required and writable by a client, O is optional. A digit after the letter marks a condition in the standard that decides when the property is present or writable, such as support for intrinsic reporting.
• Present by default: yes means the stack presents the property as soon as you add the object; no means it is optional and you turn it on with BACnetStack_SetPropertyEnabled. This is the stack’s starting setup, so it can differ from the conformance code.
• Writable is whether a client can write the property by default. Change it with BACnetStack_SetPropertyWritable.
• not in profile means the stack does not offer this property for this object type.
• Value when your callback does not answer: “Held by the stack” means the stack stores and serves the value itself and does not ask your callbacks. Otherwise it is the value the stack answers when your callback declines or is not registered.

Property	Datatype	Conformance	Present by default	Writable	Value when your callback does not answer
Object_Identifier	BACnetObjectIdentifier	R	yes	no	Held by the stack.
Object_Name	CharacterString	R	yes	no	"Object <type>,<instance>", such as "Object 0,1" for Analog Input 1.
Object_Type	BACnetObjectType	R	yes	no	Held by the stack.
Description	CharacterString	O	no	no	""
Status_Flags	BACnetStatusFlags	R	yes	no	Built by the stack from your callbacks.
Elevator_Group	BACnetObjectIdentifier	R	yes	no	Held by the stack.
Group_ID	Unsigned8	R	yes	no	Held by the stack; a Get callback that answers wins.
Installation_ID	Unsigned8	R	yes	no	Held by the stack; a Get callback that answers wins.
Floor_Text	BACnetARRAY[N] of CharacterString	O	no	no	""
Car_Door_Text	BACnetARRAY[N] of CharacterString	O	no	no	""
Assigned_Landing_Calls	BACnetARRAY[N] of BACnetAssignedLandingCalls	O	no	no	No default: the read fails.
Making_Car_Call	BACnetARRAY[N] of Unsigned8	O	no	no (yes while Out_Of_Service is true)	0
Registered_Car_Call	BACnetARRAY[N] of BACnetLiftCarCallList	O	no	no	No default: the read fails.
Car_Position	Unsigned8	R	yes	no (yes while Out_Of_Service is true)	No default: value-not-initialized until a callback or a client write supplies one.
Car_Moving_Direction	BACnetLiftCarDirection	R	yes	no (yes while Out_Of_Service is true)	No default: value-not-initialized until a callback or a client write supplies one.
Car_Assigned_Direction	BACnetLiftCarDirection	O	no	no (yes while Out_Of_Service is true)	0
Car_Door_Status	BACnetARRAY[N] of BACnetDoorStatus	R	yes	no (yes while Out_Of_Service is true)	No default: value-not-initialized until a callback or a client write supplies one.
Car_Door_Command	BACnetARRAY[N] of BACnetLiftCarDoorCommand	O	no	no (yes while Out_Of_Service is true)	0
Car_Door_Zone	Boolean	O	no	no (yes while Out_Of_Service is true)	false
Car_Mode	BACnetLiftCarMode	O	no	no (yes while Out_Of_Service is true)	0
Car_Load	Real	O	no	no (yes while Out_Of_Service is true)	0.0
Car_Load_Units	BACnetEngineeringUnits	O1	no	no	0
Next_Stopping_Floor	Unsigned8	O	no	no (yes while Out_Of_Service is true)	0
Passenger_Alarm	Boolean	R	yes	no (yes while Out_Of_Service is true)	No default: value-not-initialized until a callback or a client write supplies one.
Time_Delay	Unsigned	O2,3	no	no	0
Time_Delay_Normal	Unsigned	O3	no	no	0
Energy_Meter	Real	O	no	no (yes while Out_Of_Service is true)	Held by the stack.
Energy_Meter_Ref	BACnetDeviceObjectReference	O	no	no	Held by the stack once you set it with BACnetStack_SetLiftOrEscalatorEnergyMeterRef.
Reliability	BACnetReliability	O	no	no	0
Out_Of_Service	Boolean	R	yes	no	false
Car_Drive_Status	BACnetLiftCarDriveStatus	O	no	no (yes while Out_Of_Service is true)	0
Fault_Signals	BACnetLIST of BACnetLiftFault	R	yes	no	0
Landing_Door_Status	BACnetARRAY[N] of BACnetLandingDoorStatus	O	no	no	No default: the read fails.
Higher_Deck	BACnetObjectIdentifier	O	no	no	Held by the stack once you set it with BACnetStack_SetLiftHigherLowerDeck.
Lower_Deck	BACnetObjectIdentifier	O	no	no	Held by the stack once you set it with BACnetStack_SetLiftHigherLowerDeck.
Event_Detection_Enable	Boolean	O2,3	no	no	false
Notification_Class	Unsigned	O2,3	no	no	0
Event_Enable	BACnetEventTransitionBits	O2,3	no	no	An empty bit string.
Event_State	BACnetEventState	O2,3	no	no	0
Acked_Transitions	BACnetEventTransitionBits	O2,3	no	no	An empty bit string.
Notify_Type	BACnetNotifyType	O2,3	no	no	0
Event_Time_Stamps	BACnetARRAY[3] of BACnetTimeStamp	O2,3	no	no	No default: the read fails.
Event_Message_Texts	BACnetARRAY[3] of CharacterString	O3	no	no	""
Event_Message_Texts_Config	BACnetARRAY[3] of CharacterString	O3	no	no	""
Event_Algorithm_Inhibit_Ref	BACnetObjectPropertyReference	O3	no	no	No default: the read fails.
Event_Algorithm_Inhibit	Boolean	O3,4	no	no	false
Reliability_Evaluation_Inhibit	Boolean	O5	no	no	false
Property_List	BACnetARRAY[N] of BACnetPropertyIdentifier	R	yes	no	Held by the stack.
Audit_Level	BACnetAuditLevel	O6	not in profile	not in profile	No default: the read fails.
Auditable_Operations	BACnetAuditOperationFlags	O6	not in profile	not in profile	No default: the read fails.
Tags	BACnetARRAY[N] of BACnetNameValue	O	no	no	No default: the read fails.
Profile_Location	CharacterString	O	no	no	""
Profile_Name	CharacterString	O	no	no	""