Notification Forwarder

A Notification Forwarder object re-sends event notifications that this device receives to a further set of recipients. It does not create events of its own. It lets a device that can only send to a few destinations reach many, and it lets you change a large set of destinations in one place.

Typical uses

• Fan out alarms from field devices to several workstations
• Let controllers with short recipient lists reach many destinations
• Forward only the notifications this device generates
• Filter forwarded events by process identifier
• Keep one shared destination list for a whole site

Key properties

Property	What it holds
Recipient_List	Fixed destinations, each with valid days, a time window and the transitions to send.
Subscribed_Recipients	Recipients that subscribed to receive forwarded notifications. Clients add and remove their own entries.
Process_Identifier_Filter	Selects which incoming notifications the object forwards, by the process identifier they carry.
Port_Filter	Limits forwarding to notifications that arrived on chosen network ports.
Local_Forwarding_Only	When true, the object forwards only notifications generated in this device.

How it behaves

The object is not commandable and the standard applies no event algorithm to it. Setting Out_Of_Service to true stops it from forwarding. Reliability reports a fault only if the forwarder has no recipient it can reach, because none is configured or every one is unreachable.

With the CAS BACnet Stack

Enable it with the STACK_OPTION_OBJECT_TYPE_NOTIFICATION_FORWARDER build option. It is on in the full target; in the embedded target, define STACK_OPTION_OBJECT_TYPE_NOTIFICATION_FORWARDER yourself (see Configuring a build). CASBACnetStackDLL.h has no function for this type, so create it with BACnetStack_AddObject. The stack serves only the object identifier, object type, property list and status flags itself; your callbacks serve every other property, matched to its datatype.

Related object types

Notification Class, Event Enrollment

Properties

The properties ASHRAE 135-2024 clause 12.51 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.
Reliability	BACnetReliability	R	yes	no	0
Out_Of_Service	Boolean	R	yes	no	false
Recipient_List	BACnetLIST of BACnetDestination	R	yes	no	No default: the read fails.
Subscribed_Recipients	BACnetLIST of BACnetEventNotificationSubscription	W	yes	yes	No default: the read fails.
Process_Identifier_Filter	BACnetProcessIdSelection	R	yes	no	No default: the read fails.
Port_Filter	BACnetARRAY[N] of BACnetPortPermission	O1,3	no	yes	No default: the read fails.
Local_Forwarding_Only	Boolean	R	yes	no	false
Reliability_Evaluation_Inhibit	Boolean	O	no	no	false
Property_List	BACnetARRAY[N] of BACnetPropertyIdentifier	R	yes	no	Held by the stack.
Audit_Level	BACnetAuditLevel	O2	not in profile	not in profile	No default: the read fails.
Auditable_Operations	BACnetAuditOperationFlags	O2	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	""