Program

A Program object gives a network view of an application program running in the device. A client can see whether the program is running, halted or idle, and can ask it to load, run, halt, restart or unload. What the program actually does stays private to the device.

Typical uses

• Control sequence a technician can start and stop remotely
• Report why a program halted
• Restart a stuck application from a workstation
• Show which program file a device runs
• Expose a vendor-specific application to tools

Key properties

Property	What it holds
Program_State	The current state of the program, such as idle, loading, running, waiting, halted or unloading.
Program_Change	Where a client requests a change: ready, load, run, halt, restart or unload. The program returns it to ready when it has acted.
Reason_For_Halt	Why the program last stopped, for example normal, load failed or a program fault.
Description_Of_Halt	Optional text giving more detail about the halt.
Program_Location	Optional text naming where the program is held.

How it behaves

The object is not commandable and the standard applies no event algorithm to it. When it reports intrinsic faults, a reliability fault is shown through Event_State. Which changes a program accepts, and how it moves between states, is up to the program.

With the CAS BACnet Stack

The customer interface has no function for this type and no callback for a change request. A client’s write to Program_Change reaches the callback you register with BACnetStack_RegisterCallbackSetPropertyEnumerated like any other enumerated write, and your application must act on it and update Program_State itself. The type is on in the full target. In the embedded target, define STACK_OPTION_OBJECT_TYPE_PROGRAM yourself (see Configuring a build). Create the object with BACnetStack_AddObject. The stack serves the object identifier, object type, property list and status flags itself; your callbacks serve every other property.

Related object types

Device, Command

Properties

The properties ASHRAE 135-2024 clause 12.22 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.
Program_State	BACnetProgramState	R	yes	no	0
Program_Change	BACnetProgramRequest	W	yes	yes	0
Reason_For_Halt	BACnetProgramError	O1	no	no	0
Description_Of_Halt	CharacterString	O1	no	no	""
Program_Location	CharacterString	O	no	no	""
Description	CharacterString	O	no	no	""
Instance_Of	CharacterString	O	no	no	""
Status_Flags	BACnetStatusFlags	R	yes	no	Built by the stack from your callbacks.
Reliability	BACnetReliability	O	no	no	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	O4	no	no	false
Property_List	BACnetARRAY[N] of BACnetPropertyIdentifier	R	yes	no	Held by the stack.
Audit_Level	BACnetAuditLevel	O5	not in profile	not in profile	No default: the read fails.
Auditable_Operations	BACnetAuditOperationFlags	O5	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	""