How does BACnet handle data transfer and messaging between different devices?

BACnet uses a client-server model for data transfer and messaging between different devices. The client initiates a request, and the server responds with the requested data or performs the requested action. BACnet defines several types of messages that can be exchanged between clients and servers, including:

• Who-Is/IAm: This message is used for device discovery and allows a new device to identify the other devices on the network.

• Read/Write Property: These messages are used to read or write the value of a specific property of a BACnet object.

• Subscribe/Cov Notification: These messages are used to subscribe to changes in the value of a specific property of a BACnet object and receive notifications when the value changes.

• Alarm/Event Notification: These messages are used to notify clients when an alarm or event occurs in the system.

BACnet messages are typically sent using a connection-oriented protocol, such as TCP/IP or BACnet/SC, to ensure reliable communication between devices. BACnet also defines a standard data format for messages called the BACnet Application Data Layer (ADL), which ensures that messages can be interpreted correctly by all BACnet-compliant devices.