BACnetStack_GetFDTEntry

uint32_t BACnetStack_GetFDTEntry(
  const uint32_t networkPortInstance,
  const uint16_t index,
  uint8_t * ipAddress,
  const uint8_t ipAddressLength,
  uint16_t * timeToLive,
  uint16_t * timeRemaining);

Reads one entry of THIS device’s own foreign device table by index.

As with BACnetStack_GetBDTEntry() there is NO count export, so enumeration means reading from index 0 until this returns false, and that terminating probe LOGS AN ERROR. Indices SHIFT after any BACnetStack_DeleteFDTEntry() and after the BBMD purges an expired registration, so a read-then-delete loop skips entries unless it re-enumerates from 0 after every delete.

Note

Requires the STACK_OPTION_NM_BBMDC (with STACK_OPTION_DATA_LINK_LAYER_IPV4 and STACK_OPTION_OBJECT_TYPE_NETWORK_PORT) build option (it turns on STACK_OPTION_BVLL_BBMD, the macro this function checks).

BACnet reference: ANSI/ASHRAE 135-2024 Annex J: J.5.2.1 (Foreign Device Table).

Parameters

Parameter	Direction	Description
networkPortInstance	in	The IPv4 Network Port object instance whose foreign device table is being read.
index	in	The zero-based table position to read. Out of range returns false and logs.
ipAddress	out	Receives 6 bytes: the 4-octet IPv4 address followed by the 2-octet UDP port in BIG-endian order. Must not be NULL.
ipAddressLength	in	EXACT, not a maximum. Must be exactly 6; any other value returns false.
timeToLive	out	Receives the time-to-live, in seconds, the foreign device registered with. Must not be NULL.
timeRemaining	out	Receives the time left, in seconds, before this entry expires. Must not be NULL.

Returns

The number of bytes written to ipAddress (always ipAddressLength, i.e. 6, on success) if an entry exists at the index and was copied out - timeToLive and timeRemaining are fully written too. 0 if the index is out of range, any pointer is NULL, ipAddressLength is not 6, networkPortInstance does not match any claimed IPv4 Network Port, or BBMD support was not compiled.

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