BACnetStack_SendRegisterForeignDevice

bool BACnetStack_SendRegisterForeignDevice(
  const uint32_t networkPortInstance,
  const uint16_t timeToLive,
  const uint8_t * connectionString,
  const uint8_t connectionStringLength);

Sends a RegisterForeignDevice BVLL message to a specified BBMD (BACnet Broadcast Management Device) to register as a foreign device on the BACnet IP network.

SIDE EFFECTS of a successful registration (the BBMD’s BVLC-Result of success): the IPv4 Network Port object’s BACnet_IP_Mode becomes FOREIGN, and the first success after this device was unregistered (it never registered, was refused with a NAK, or let the time-to-live lapse) also announces it with an I-Am sent through the BBMD (Distribute-Broadcast-To-Network), so it is discoverable across the internetwork. A renewal sends no I-Am. FD_BBMD_Address and FD_Subscription_Lifetime are present and writable on every BACnet/IP Network Port (135-2024 cl. 12.56.41, 12.56.42), so a BACnet client can write them: a written value is held until a ReinitializeDevice of ACTIVATE_CHANGES or WARMSTART and then handed to the host’s Set callbacks. The stack does not re-register by itself; the host’s next call to this function decides where to register, and for how long.

PRECONDITION: BACnetStack_RegisterCallbackGetSystemTime() must have been registered first; without a clock the time-to-live cannot be tracked and this returns false before sending.

connectionStringLength must be exactly 6 (BACnet/IP). Any other length is refused before anything is sent, and this returns false.

BACnet reference: ANSI/ASHRAE 135-2024 Annex J: J.2.6 (Register-Foreign-Device) and J.5.2.2 (its use by a BBMD).

Parameters

Parameter	Direction	Description
`timeToLive`	in	How many seconds this device has to register again with the BBMD; if it does not, the BBMD may drop it from its Foreign Device Table. THE STACK DOES NOT AUTO-RENEW. It tracks the deadline locally and, when it passes, drops its own foreign-device state and resets the Network Port’s BACnetIPMode to normal. The host must call this function again before the time-to-live expires. 0 is accepted but expires on the next tick, cancelling the registration locally while the BBMD may still hold the entry - it does NOT mean “forever”.

Parameters

Parameter	Direction	Description
`networkPortInstance`	in	The IPv4 Network Port object instance to send on.
`connectionString`	in	The connection string that represents the IP Address and Port of the BBMD to send the RegisterForeignDevice message. Example: 0xC0, 0xA8, 0x01, 0x05, 0xBA, 0xC0 is 192.168.1.5:47808. It must be exactly 6 octets; any other connectionStringLength returns false and sends nothing.
`connectionStringLength`	in	The number of bytes in the connection string.

Returns

True if successfully sent, otherwise false.

Topic: BACnet/IP: BBMD and foreign devices. Declared in CASBACnetStackDLL.h.