Technical data
192 • Fieldbus Communication
BACnet/IP
WAGO-I/O-SYSTEM 750
BACnet/IP Controller
4.2 BACnet/IP
4.2.1 General
The "Building Automation and Control Network", BACnet for short, is a stan-
dardized and company-neutral network protocol for building automation, and
is originally geared towards the area of heating, ventilation and air condition-
ing (HVAC).
This protocol has been an ASHRAE standard since 1995, was accepted as a
standard by ANSI (ANSI/ASHRAE 135-2004) and has become anchored in
the DIN EN ISO standard 16484-5 (Building Automation Systems, Data
Communication Protocols).
The BACnet network model works independently of the system. When using
devices, data/information are represented by predefined objects and transmit-
ted with the aid of services over a special BACnet network layer. Communica-
tion is based on the client/server method.
Along with objects and services, network technologies of the lowest levels are
also specified in the Standard.
4.2.1.1 Interoperability
The objective of the BACnet Standard is the creation of an open, interoperable
network. The requirement for the cooperation of different participants in a
BACnet network is a common understanding of the BACnet Standard and
therefore of the use of common communication structures.
For this purpose, each device has a Protocol Implementation Conformance
Statement - PICS). The PICS is a document containing objects, coding, rout-
ing information and BACnet Interoperability Building Blocks - BIBBs defined
by the Standard that the end device supports. These BIBBs indicate which ser-
vices the client and server must support in order to fulfill certain system re-
quirements.
Through the common understanding by customers and manufacturers of the
protocol standard and common functions and communication structures in the
PICS, the interoperability of the network is ensured.
4.2.1.2 BACnet Components
According to the BACnet Standard, 25 different objects and 38 services are
supported (Last update: ANSI/ASHRAE 135-2004, DIN EN ISO 16484-5).
An object is composed of several object-specific properties. Services are also
present and transmit their data in certain structures.