BACnetStack_SendWhoIsRouterToNetwork

bool BACnetStack_SendWhoIsRouterToNetwork(
  const uint16_t network,
  const bool useNetworkNumber,
  const uint8_t * connectionString,
  const uint8_t connectionStringLength,
  const uint32_t networkPortInstance,
  const bool broadcast,
  const uint16_t destinationNetwork,
  const uint8_t * destinationAddress,
  const uint8_t destinationAddressLength);

Sends a Who-Is-Router-To-Network NPDU message, requesting to know which router(s) can reach a given network (or all reachable networks, if useNetworkNumber is false).

Note

Requires one of the build options STACK_OPTION_GW_VN_B, STACK_OPTION_NM_RC_B, STACK_OPTION_ROUTER_PHYSICAL (any of them turns on STACK_OPTION_ROUTER, the macro this function checks).

BACnet reference: ANSI/ASHRAE 135-2024 clause 6.4.1 (Who-Is-Router-To-Network).

Parameters

Parameter	Direction	Description
network	in	The network number being queried for.
useNetworkNumber	in	If true, restrict the query to network; if false, query for all networks.
connectionString, connectionStringLength	in	The datalink address to send TO (the destination) - not the local address to send from. For IPv4 this is 6 bytes: 4 octets of IPv4 address followed by 2 octets of port, big-endian (e.g. 0xC0,0xA8,0x01,0x05,0xBA,0xC0 = 192.168.1.5:47808; see BACnetStack_SendRegisterForeignDevice() for a worked example); on BACnet/IPv4 the stack refuses to send to a connection string of any other length, except that a broadcast from a device registered as a foreign device goes to its BBMD and does not use the connection string. MS/TP and BACnet/SC use a different connection-string shape; see their respective Set/Send exports.
networkPortInstance	in	The Network Port object instance to send the message on, or BACNET_NETWORK_PORT_DEFAULT (4194303) for the default/single port.
broadcast, destinationNetwork, destinationAddress, destinationAddressLength	in	broadcast selects a broadcast or a unicast where the data link has the choice: on BACnet/IP an Original-Broadcast-NPDU or an Original-Unicast-NPDU (a broadcast from a device registered as a foreign device goes to its BBMD as a Distribute-Broadcast-To-Network); on BACnet/SC the broadcast VMAC; on MS/TP it is ignored and connectionString decides. destinationNetwork 0 keeps the message on the local network; 1 to 65534 routes it to that network, to the device whose MAC address is destinationAddress/destinationAddressLength or, with NULL and 0 there, to every device on that network; 65535 is a global broadcast to every network.

Returns

True if the message was sent, otherwise false.

Topic: Routing and virtual networks. Declared in CASBACnetStackDLL.h.