BACnet Broadcast Messages

The following table lists the names and purposes of the most common BACnet broadcast messages and their responses.

Message	Used for...	Response	Contains
Who-Is*1	Discovering available BACnet devices on the network	I-Am	Device ID, vendor ID, the type of supported segmentation, maximum APDU length.
Who-Has	Discovering the devices whose local databases contain an object with a given object name or a given object identifier.	I-Have	Device ID, object type, object instance number, object name.
Who-Is-Router-To-Network*2	Identifying the router that connects a specific network.	I-Am-Router	The number of the network that is connected to the router.

Notes:

*1 It is sent automatically during a network discovery or it can be initiated by the user. Learn how

*2 It is sent automatically after starting the BACnet point manager or when communicating with an unknown network. Once received, the data is stored in the cache.