Image Processing Reference
In-Depth Information
of doors and windows can be detected. Data from multiple sensors may also be fused for additional
expressiveness.
Such integration creates special requirements on the underlying control network. Since the
requirements of safety and security applications differ from those of HVAC control applications,
strict “vertical” separation into systems serving functional domains traditionally persists in building
automation network and system architectures.
The SafetyLon project has led the way in this regard by defining a framework for IEC
compliant communication via LonWorks. SafetyLon enables devices implementing safety relevant
applications to coexist on a shared medium with standard LonWorks devices.
Generally speaking, however, integration at the device level introduces a level of complexity that
still remains a challenge to be handled. As another particular issue, building automation protocols in
use today offer hardly any security support, which is a significant problem when security functions
are considered for integration. Of the open systems discussed, a simple authentication procedure
can be found in LonWorks, while KNX provides no security mechanisms whatsoever. The BACnet
securityinfrastructureiswelldevelopedincomparison,butalsohascertainweaknesses[].
The level of communications security provided by the variety of proprietary, undocumented pro-
tocols mostly proved to be appropriate for isolated BAS. Nowadays security concerns are increasing
rapidly, however. For example, remote access is standard on present-day systems. Protection against
denial-of-service attacks becomes more of an issue as buildings get more dependent on automation
systems. Open media such as PL and, especially, radio communication further increase vulnerabil-
ity, since access to the medium can be gained in an unobtrusive manner. Further, the shift to open
systems reduces the knowledge barrier for intruders.
Any discussion regarding BAS and their implementation is not complete without addressing
design issues. Today's systems are still being installed without formal specification or design. System
integrators have to rely on perceived wisdom, experience, and best practice. Thus, techniques for
better prediction of performance and dependability are required along with automated tools to sup-
port this. Up to now, despite the existence of sophisticated management tools, complete analysis
or precise modeling of the distributed application is still beyond reach. These problems need to be
addressed and leave ample place for future research activities.
References
. K. Daniels,
Advanced Building Systems: A Technical Guide for Architects and Engineers
,Birkhäuser,
Basel, .
.J.K.W.Wong,H.Li,andS.W.Wang,Intelligentbuildingresearch:Areview,
Automation in
Construction
, (), -, .
. C. P. Underwood,
HVAC Control Systems: Modelling, Analysis and Design
,Routledge,NewYork,.
. ISO -,
Building Automation and Control Systems (BACS)—Part : Functions
, .
. J. P. homesse, Fieldbuses and interoperability,
Control Engineering Practice
, (), -, .
. ISO -,
Building Automation and Control Systems (BACS)—Part : Hardware
,.
. IEC ,
AC-Supplied Electronic Ballasts for Tubular Fluorescent Lamps—Performance Requirements
,
.
. EN -,
Heat Meters—Part : Data Exchange and Interfaces
,.
. ANSI/ASHRAE Std. ,
BACnet—A Data Communication Protocol for Building Automation and
Control Networks
,-.
. ISO -,
Building Automation and Control Systems (BACS)—Part : Data Communication
Protocol
,.
. ANSI/EIA/CEA Std. ., Rev. A,
Control Network Protocol Specification,
, .
. EIA/CEA Std. ., Rev. B,
Control Network Protocol Specification,
,.
