Building automation systems - Intelligent Buildings and Building Automation - page 33

and adopted in the industry. Many communication and software technologies
commonly used by Internet/intranet or within the computing networking
field have been adopted directly by the BAS industry.
The main feature of today's BAS can be summarized as follows. The use of
open and standard communication protocols allows BA systems from differ-
ent manufacturers to be integrated without much difficulty or effort. The use
of IP and standard Internet/intranet technologies allows BAS to be integrated
with enterprise computing networks conveniently. The convergence network
provides a unified network platform for all information in buildings. BAS
integration and information management can be achieved via the global
Internet infrastructure.
3.2.6 Progress of BAS compared with computing technology
Figure 3.5 shows the progress of computing and BAS technologies and their
interconnection. It is obvious that the evolution of BAS technology has
followed the progress of computing technology due to the fact that BAS is
actually the application of computing and IT technologies in building control
and management. However, there was a clear boundary between the building
automation systems and computing systems and networks in the first three
stages, although the technologies originated from computing technologies.
The typical BAS of the fourth generation is compatible with computing net-
works involving communication protocols and the means for information
processing. There is no boundary between BAS and an intranet any more.
The systems can be integrated easily at very large scales in terms of number
of systems and geometry.
3.3 Programming and monitoring platforms and
environment
3.3.1 Typical architecture of building automation systems and
control stations
Figure 3.6 shows an example of a typical network architecture of a building
automation system, although BAS are very different in terms of their scale
and network configuration. In practical terms BAS, particularly large-scale
BAS, may often involve more levels or layers of networks.
Field control networks typically connect the field control stations. The
control stations are interfaced with the building services system via sensors,
detectors and control actuation devices. Network control stations serve as the
router/converter to integrate the field control networks into the management
(higher level) network. They typically have relatively larger memory space
and higher computation power. Network control stations may or may not
have inputs and outputs for interfacing with building services systems directly.
Field control networks typically have a lower communication speed.