Schedule

A Schedule object runs a time plan. It holds a week of daily time and value pairs, optional exception days, and a default, and it works out which value is in force right now. It can write that value into properties of other objects on its own, so a device can switch lighting, setpoints or modes by the clock.

Typical uses

• Occupied and unoccupied times for an office
• Holiday exceptions that override the weekly plan
• Setpoint changes at fixed times of day
• Lighting on and off by the clock
• Run a plan only between two dates

Key properties

Property	What it holds
Weekly_Schedule	Seven daily plans, Monday to Sunday. Each is a list of times and the value that starts at that time.
Exception_Schedule	Special days, such as holidays, with their own time and value pairs and a priority. They override the weekly plan.
Schedule_Default	The value used when no weekly or exception entry is in force.
Effective_Period	The range of dates in which the schedule is active.
List_Of_Object_Property_References	The properties the schedule writes its value to.
Present_Value	The value now in force. Clients read it but do not write it.

How it behaves

The object is not commandable and the standard applies no event algorithm to it. It writes Present_Value to each referenced property when the value changes, at the priority set in Priority_For_Writing.

With the CAS BACnet Stack

Enable it with the STACK_OPTION_OBJECT_TYPE_SCHEDULE build option. Add the object with BACnetStack_AddObject first, then call BACnetStack_AddScheduleObject. That call makes Weekly_Schedule and Schedule_Default writable by any client. Build the plan with BACnetStack_AddScheduleWeeklyTimeValue, BACnetStack_SetScheduleDefault, BACnetStack_AddScheduleExceptionEventWithCalendarEntry, BACnetStack_AddScheduleExceptionEventWithCalendarReference, BACnetStack_AddScheduleExceptionTimeValue, BACnetStack_SetScheduleEffectivePeriod, BACnetStack_AddScheduleObjectPropertyReference and BACnetStack_SetSchedulePriorityForWriting. The stack evaluates the plan against the Device object’s Local_Date and Local_Time, so enable both and serve them with the callback you register with BACnetStack_RegisterCallbackGetPropertyDate and the BACnetStack_RegisterCallbackGetPropertyTime callback; until they read, no value is computed. Object_Name, Reliability and Out_Of_Service come from callbacks. A scheduled value can be Null, Boolean, Unsigned, Signed, Real or Enumerated; the customer interface cannot schedule a Double, a string, a date, a time or an object identifier. Use Enumerated for a Binary Output or Binary Value target.

Related object types

Calendar, Timer, Device

Properties

The properties ASHRAE 135-2024 clause 12.24 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.
Present_Value	Any	R	yes	no (yes while Out_Of_Service is true)	Computed by the stack from the plan, once the Device object’s Local_Date and Local_Time can be read.
Description	CharacterString	O	no	no	""
Effective_Period	BACnetDateRange	R	yes	no	Held by the stack.
Weekly_Schedule	BACnetARRAY[7] of BACnetDailySchedule	O1	no	yes, after BACnetStack_AddScheduleObject	Held by the stack.
Exception_Schedule	BACnetARRAY[N] of BACnetSpecialEvent	O1	no	no	Held by the stack.
Schedule_Default	Any	R	yes	yes, after BACnetStack_AddScheduleObject	Held by the stack.
List_Of_Object_Property_References	BACnetLIST of BACnetDeviceObjectPropertyReference	R	yes	no	Held by the stack.
Priority_For_Writing	Unsigned(1..16)	R	yes	no	Held by the stack.
Status_Flags	BACnetStatusFlags	R	yes	no	Held by the stack.
Reliability	BACnetReliability	R	yes	no (yes while Out_Of_Service is true)	0
Out_Of_Service	Boolean	R	yes	no	false
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	""
Reliability_Evaluation_Inhibit	Boolean	O	no	no	false
Write_Every_Scheduled_Action	Boolean	O	no	no	false
Property_List	BACnetARRAY[N] of BACnetPropertyIdentifier	R	yes	no	Held by the stack.
Audit_Level	BACnetAuditLevel	O4	not in profile	not in profile	No default: the read fails.
Auditable_Operations	BACnetAuditOperationFlags	O4	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	""