Command

A Command object runs a set of actions when a client writes a number to it. Each number selects a list of writes to other objects. One write can put a whole zone into a mode, such as occupied or unoccupied.

Typical uses

• Set a zone to occupied or unoccupied
• Switch a room to a lighting scene
• Apply a night setback
• Start a warm-up sequence

Key properties

Property	What it holds
Present_Value	The action code. Writing it selects which list of actions to run.
In_Process	TRUE while the actions run. A write during that time is refused as busy.
All_Writes_Successful	TRUE if every write in the last run succeeded.
Action	The lists of writes, one per action code. Each names an object, a property and a value.
Action_Text	Optional labels that describe each action code.

How it behaves

When some writes in an action fail, the Command object reports which ones failed; the standard does not ask it to reverse the writes that worked. The standard applies no event algorithm to this type.

With the CAS BACnet Stack

Enable it with the STACK_OPTION_OBJECT_TYPE_COMMAND build option and add each object with BACnetStack_AddObject. Present_Value is served through the callback you register with BACnetStack_RegisterCallbackGetPropertyUnsignedInteger and the BACnetStack_RegisterCallbackSetPropertyUnsignedInteger callback. The standard applies no event algorithm to this type and the stack serves no event state for it, so there is nothing to arm: BACnetStack_SetAlarmsAndEventsForObjectEnabled accepts the object but changes nothing a client can see.

Related object types

Schedule, Channel, Multi-state Value, Notification Class

Properties

The properties ASHRAE 135-2024 clause 12.10 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	""
Present_Value	Unsigned	W	yes	yes	No default: value-not-initialized.
In_Process	Boolean	R	yes	no	false
All_Writes_Successful	Boolean	R	yes	no	false
Action	BACnetARRAY[N] of BACnetActionList	R	yes	no	No default: the read fails.
Action_Text	BACnetARRAY[N] of CharacterString	O	no	no	""
Property_List	BACnetARRAY[N] of BACnetPropertyIdentifier	R	yes	no	Held by the stack.
Status_Flags	BACnetStatusFlags	O1	no	no	Built by the stack from your callbacks.
Event_State	BACnetEventState	O1	no	no	0
Reliability	BACnetReliability	O1	no	no	0
Event_Detection_Enable	Boolean	O1,2	no	no	false
Notification_Class	Unsigned	O1,2	no	no	0
Event_Enable	BACnetEventTransitionBits	O1,2	no	no	An empty bit string.
Acked_Transitions	BACnetEventTransitionBits	O1,2	no	no	An empty bit string.
Notify_Type	BACnetNotifyType	O1,2	no	no	0
Event_Time_Stamps	BACnetARRAY[3] of BACnetTimeStamp	O1,2	no	no	No default: the read fails.
Event_Message_Texts	BACnetARRAY[3] of CharacterString	O2	no	no	""
Event_Message_Texts_Config	BACnetARRAY[3] of CharacterString	O2	no	no	""
Reliability_Evaluation_Inhibit	Boolean	O3	no	no	false
Value_Source	BACnetValueSource	O4,5,6	no	no	No default: the read fails.
Audit_Level	BACnetAuditLevel	O7	not in profile	not in profile	No default: the read fails.
Auditable_Operations	BACnetAuditOperationFlags	O7	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	""