Image Processing Reference
In-Depth Information
introduced. Over the years, several mutually incompatible languages and dialects were developed
[,]. Originally, they were tailored to individual fieldbus systems (e.g., HART DDL, PROFIBUS
GSD, CANopen EDS, FF DDL) and laid the foundation for user-friendly configuration and engineer-
ing tools. In recent years, the diversity of description languages is being addressed by the increased
usageofuniversallanguageslikeXML[,],whichisalsothebasisfortheelectronicdevice
description language (EDDL) standardized in IEC  [,].
With the increasing importance of LAN and Internet technologies in automation, new approaches
for fieldbus management appeared that may be apt to introduce at least a common view at vari-
ous fieldbusses. All these concepts aim at integrating fieldbus management into existing manage-
ment applications of the higher-level network, which is nowadays typically IP-based. One com-
monly employed high-level network management protocol is simple network management protocol
(SNMP), which can be used to access also fieldbus data points [,]. Another approach involves the
use of Directory Services []. [].These two solutions permit the inclusion of a large number of devices
in specialized network management frameworks. An alternative that has become very popular is the
use of Web technology, specifically HTTP tunneled over the fieldbus, to control device parameters.
This trend is supported by the increasing availability of embedded Web servers and the use of XML
as device description language []. [].The appealing feature of this solution is that no special tools are
required and a standard Web browser is sufficient. However, Web pages are less suitable for the man-
agement of complete networks and rather limited to single-device management. Nevertheless, this
approach is meanwhile pursued by many manufacturers.
20.5.8 Quest for Unification—The NOAH Approach
Standardization bodies recognized quite early that the heterogeneity of current fieldbus solutions
was a problem. While the IEC standardization project still fought for a unified solution, CENELEC in
Europe stimulated a joint research project supported by the European Commission under the ESPRIT
programme. he goal of network-oriented application harmonization (NOAH) was to overcome the
incompatible user interfaces of existing standardized ieldbus systems and to provide a uniform access
layer on top of the individual technologies, thereby enabling true distributed automation systems in
multi-vendor environments. he explicit intention of the project was the achievement of results that
could then directly be pursued as standards. Originally, the focus of the project was the industrial
fieldbusses contained in EN  (P-Net, PROFIBUS, WorldFIP), later the work was extended to
other systems as well (Foundation Fieldbus, HART, CAN). In fact, NOAH and its predecessor projects
ACORN and RACKS were a comprehensive endeavor to tackle three basic aspects in networked
automation systems []:
Independent communication interfaces not only for operational services, but also for
system and network management, i.e., for the setup and maintenance of an automation
network.
Device harmonization through the definition of device profiles that specify certain func-
tions and parameters. The devices provide these functions and parameters for other
profile devices or for control, visualization, supervision, maintenance, and technical man-
agement purposes. Within the scope of this aspect also a new, unified modeling language
(UML)-based device description language (EDDL) was developed after an investigation
of several description languages that existed at that time and were found to be too limited
in capabilities.
System integration in terms of a single and consistent data repository containing all device
and network information [] needed for a complete system life cycle including design,
engineering, installation, configuration, maintenance, and management.
 
Search WWH ::




Custom Search