Network Port

A Network Port object describes one network interface of the device: its network type, address and settings. A device has one for each data link it uses, and clients read them to learn how to reach the device and how it is configured. Some ports sit on top of others, so a BACnet/IP port can point to the port beneath it.

Typical uses

• BACnet/IP port with address, subnet mask and UDP port
• MS/TP port with MAC address and Max_Master
• BACnet/SC port with hub URIs and certificates
• Virtual network port of a gateway device
• A port whose network number a client changes and then activates

Key properties

Property	What it holds
Network_Type	The kind of network: IPv4, MS/TP, Ethernet, virtual, secure connect and others.
Protocol_Level	Where the port sits in the protocol stack, for example the BACnet application level or the physical level.
Network_Number	The BACnet network number of the port. A client write is held as a pending change until it is activated.
Reference_Port	Points to the Network Port that carries this port’s traffic, one layer down. A port at the lowest layer points to none.
Changes_Pending	True while a configuration change is waiting to be activated.
MAC_Address	The address of the device on this network, for example the IP address and port packed into six octets.

How it behaves

Network Port objects are not commandable and use no COV or event algorithm; the standard applies none to this type. Clients change port settings by writing them, then activating the changes with a ReinitializeDevice request, so a set of edits takes effect together.

With the CAS BACnet Stack

Enable it with the STACK_OPTION_OBJECT_TYPE_NETWORK_PORT build option. Do not use BACnetStack_AddObject; add each port with BACnetStack_AddNetworkPortObject, giving the network type, protocol level, network number, its quality and the reference port. The stack always answers Network_Number, Changes_Pending, APDU_Length, MAC_Address and the BACnet/SC settings itself. For a BACnet/IP port it builds MAC_Address from IP_Address and BACnet_IP_UDP_Port; for an MS/TP port it reads the one-octet MAC through the callback you register with BACnetStack_RegisterCallbackGetPropertyOctetString; for a BACnet/SC port it takes it from the secure-connect state; for a BACnet/IPv6 port it is the device’s three-octet VMAC, and the stack also answers Virtual_MAC_Address_Table, BACnet_IPv6_Mode and, until you serve it, BACnet_IPv6_Multicast_Address ([FF02::BAC0]:47808, eighteen octets: the address and then the UDP port). It also stores Network_Type, Protocol_Level, Reference_Port and Network_Number_Quality, but for these a Get callback that answers wins. Other properties, such as the IP address and subnet mask, come from your callbacks. A client’s write to Network_Number is held as a pending change until a ReinitializeDevice request or BACnetStack_ActivateNetworkPortPendingChanges activates it. A client’s write to a BACnet/IP or BACnet/IPv6 address property (the address, mask or prefix length, gateway, DNS server, automatic addressing, UDP port, IPv6 multicast address) is held pending the same way. On a BACnet/IPv6 port the stack also holds BACnet_IPv6_Mode, FD_BBMD_Address and FD_Subscription_Lifetime itself, and, in a build that also has STACK_OPTION_BVLL_BBMD (which needs BACnet/IP), BBMD_Broadcast_Distribution_Table and BBMD_Accept_FD_Registrations: a client writes them, they are held pending the same way, and activation hands them to the stack’s BACnet/IPv6 data link, which then acts as a foreign device or a BBMD. Without STACK_OPTION_BVLL_BBMD the BBMD properties are absent and BACnet_IPv6_Mode refuses BBMD. Your callbacks are never asked for these, and BBMD_Foreign_Device_Table is the data link’s table. A BDT entry or BBMD address must be an IPv6 address; a host name is refused. The ARCNET, point-to-point, LonTalk, ZigBee and generic Serial network types are not supported.

Related object types

Device, Channel

Properties

The properties ASHRAE 135-2024 clause 12.56 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
Network_Type	BACnetNetworkType	R	yes	no	Held by the stack; a Get callback that answers wins.
Protocol_Level	BACnetProtocolLevel	R	yes	no	Held by the stack; a Get callback that answers wins.
Reference_Port	Unsigned	O1	no	no	Held by the stack; a Get callback that answers wins.
Additional_Reference_Ports	BACnetLIST of Unsigned	O2	no	no	0
Changes_Pending	Boolean	R	yes	no	Held by the stack.
Command	BACnetNetworkPortCommand	O3	no	yes	Held by the stack; a Get callback that answers wins.
Current_Health	BACnetHealth	O	no	no	No default: the read fails.
Command_Validation_Result	BACnetHealth	O	no	no	No default: the read fails.
Event_Detection_Enable	Boolean	O5	no	no	false
Notification_Class	Unsigned	O5	no	no	0
Event_Enable	BACnetEventTransitionBits	O5	no	no	An empty bit string.
Acked_Transitions	BACnetEventTransitionBits	O5	no	no	An empty bit string.
Notify_Type	BACnetNotifyType	O5	no	no	0
Event_Time_Stamps	BACnetARRAY[3] of BACnetTimeStamp	O5	no	no	No default: the read fails.
Event_Message_Texts	BACnetARRAY[3] of CharacterString	O5	no	no	""
Event_Message_Texts_Config	BACnetARRAY[3] of CharacterString	O5	no	no	""
Event_State	BACnetEventState	O4	no	no	0
Reliability_Evaluation_Inhibit	Boolean	O	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	""
Network_Number	Unsigned16	O	no	yes, held until activated	Held by the stack.
Network_Number_Quality	BACnetNetworkNumberQuality	O	no	no	Held by the stack; a Get callback that answers wins.
APDU_Length	Unsigned	O	no	no	Held by the stack.
Routing_Table	BACnetLIST of BACnetRouterEntry	O	no	no	Held by the stack; a Get callback that answers wins.
MAC_Address	OctetString	O	no	no	Held by the stack: built from IP_Address and BACnet_IP_UDP_Port on a BACnet/IP port, read from your octet-string callback on an MS/TP port, taken from the secure-connect state on a BACnet/SC port.
Link_Speed	Real	O	no	no	0.0
Link_Speeds	BACnetARRAY[N] of Real	O	no	no	0.0
Link_Speed_Autonegotiate	Boolean	O	no	no	false
Network_Interface_Name	CharacterString	O	no	no	""
Device_Address_Proxy_Enable	Boolean	O	no	yes	false
Device_Address_Proxy_Timeout	Unsigned	O	no	yes	0
BACnet_IP_Mode	BACnetIPMode	O	no	no	Held by the stack; a Get callback that answers wins.
BACnet_IP_UDP_Port	Unsigned16	O	no	no	0
BACnet_IP_Multicast_Address	OctetString	O	no	yes	An empty octet string.
BACnet_IP_NAT_Traversal	Boolean	O	no	yes	false
BACnet_IP_Global_Address	BACnetHostNPort	O	no	yes	No default: the read fails.
BBMD_Broadcast_Distribution_Table	BACnetLIST of BACnetBDTEntry	O	no	yes	No default: the read fails.
BBMD_Accept_FD_Registrations	Boolean	O	no	yes	false
BBMD_Foreign_Device_Table	BACnetLIST of BACnetFDTEntry	O	no	no	No default: the read fails.
FD_BBMD_Address	BACnetHostNPort	O	no	no	The stack’s own foreign-device registration, or the not-configured value.
FD_Subscription_Lifetime	Unsigned16	O	no	no	The time-to-live of the stack’s own foreign-device registration, or 0.
IP_Address	OctetString	O	no	no	An empty octet string.
IP_Subnet_Mask	OctetString	O	no	no	An empty octet string.
IP_Default_Gateway	OctetString	O	no	no	An empty octet string.
IP_DNS_Server	BACnetARRAY[N] of OctetString	O	no	no	A one-entry array holding 0.0.0.0 (not configured).
IP_DHCP_Enable	Boolean	O	no	no	false
IP_DHCP_Lease_Time	Unsigned	O	no	no	0
IP_DHCP_Lease_Time_Remaining	Unsigned	O	no	no	0
IP_DHCP_Server	OctetString	O	no	no	An empty octet string.
Virtual_MAC_Address_Table	BACnetLIST of BACnetVMACEntry	O	no	no	No default: the read fails.
BACnet_IPv6_Mode	BACnetIPMode	O	no	no	0
BACnet_IPv6_UDP_Port	Unsigned16	O	no	no	0
BACnet_IPv6_Multicast_Address	OctetString	O	no	no	An empty octet string.
IPv6_Address	OctetString	O	no	no	An empty octet string.
IPv6_Prefix_Length	Unsigned8	O	no	no	0
IPv6_Default_Gateway	OctetString	O	no	no	An empty octet string.
IPv6_DNS_Server	BACnetARRAY[N] of OctetString	O	no	no	An empty octet string.
IPv6_Auto_Addressing_Enable	Boolean	O	no	no	false
IPv6_DHCP_Lease_Time	Unsigned	O	no	no	0
IPv6_DHCP_Lease_Time_Remaining	Unsigned	O	no	no	0
IPv6_DHCP_Server	OctetString	O	no	no	An empty octet string.
IPv6_Zone_Index	CharacterString	O	no	no	""
Subordinate_Proxy_Enable	Boolean	O	no	no	false
Manual_Subordinate_Address_Binding	BACnetLIST of BACnetAddressBinding	O	no	no	No default: the read fails.
Auto_Subordinate_Discovery	Boolean	O	no	no	false
Subordinate_Address_Binding	BACnetLIST of BACnetAddressBinding	O	no	no	No default: the read fails.
Max_Manager	Unsigned8	O	no	no	0
Max_Info_Frames	Unsigned8	O	no	no	0
Max_BVLC_Length_Accepted	Unsigned	O	no	yes	Held by the stack.
Max_NPDU_Length_Accepted	Unsigned	O	no	yes	Held by the stack.
SC_Primary_Hub_URI	CharacterString	O	no	yes	Held by the stack.
SC_Failover_Hub_URI	CharacterString	O	no	yes	Held by the stack.
SC_Minimum_Reconnect_Time	Unsigned	O	no	yes	Held by the stack.
SC_Maximum_Reconnect_Time	Unsigned	O	no	yes	Held by the stack.
SC_Connect_Wait_Timeout	Unsigned	O	no	yes	Held by the stack.
SC_Disconnect_Wait_Timeout	Unsigned	O	no	yes	Held by the stack.
SC_Heartbeat_Timeout	Unsigned	O	no	yes	Held by the stack.
SC_Hub_Connector_State	BACnetSCHubConnectorState	O	no	no	Held by the stack.
Operational_Certificate_File	BACnetObjectIdentifier	O	no	no	Held by the stack.
Issuer_Certificate_Files	BACnetARRAY[2] of BACnetObjectIdentifier	O	no	no	Held by the stack.
Certificate_Signing_Request_File	BACnetObjectIdentifier	O	no	no	Held by the stack.
SC_Primary_Hub_Connection_Status	BACnetSCHubConnection	O	no	no	No default: the read fails.
SC_Failover_Hub_Connection_Status	BACnetSCHubConnection	O	no	no	No default: the read fails.
SC_Hub_Function_Enable	Boolean	O	no	no	false
SC_Hub_Function_Accept_URIs	BACnetARRAY[N] of CharacterString	O	no	no	""
SC_Hub_Function_Binding	CharacterString	O	no	no	""
SC_Hub_Function_Connection_Status	BACnetLIST of BACnetSCHubFunctionConnection	O	no	no	No default: the read fails.
SC_Direct_Connect_Initiate_Enable	Boolean	O	no	yes	false
SC_Direct_Connect_Accept_Enable	Boolean	O	no	yes	false
SC_Direct_Connect_Accept_URIs	BACnetARRAY[N] of CharacterString	O	no	no	""
SC_Direct_Connect_Binding	CharacterString	O	no	no	""
SC_Direct_Connect_Connection_Status	BACnetLIST of BACnetSCDirectConnection	O	no	no	No default: the read fails.
SC_Failed_Connection_Requests	BACnetLIST of BACnetSCFailedConnectionRequest	O	no	no	No default: the read fails.