Image Processing Reference
In-Depth Information
with real-time extensions, under standardization by IEC/SCC committee, is a fieldbus technol-
ogy which incorporates Ethernet for the lower two layers in the OSI model. Additional profiles for
ISO/IEC . (Ethernet) based communication networks in real-time applications were defined in
the IEC - standard []. [].There are already a number of implementations, which use one of the
three different approaches to meet real-time requirements. First approach is based on retaining the
TCP/UDP/IP protocols suite unchanged (subject to nondeterministic delays), all real-time modifi-
cations are enforced in the top layer. Implementations in this category include Modbus/TPC (Profile
/ & /) [] (defined by Schneider Electric and supported by Modbus-IDA []), EtherNet/IP
(Profile / & /.) [] (defined by Rockwell and supported by the Open DeviceNet Vendor Asso-
ciation (ODVA) [] and ControlNet International []), P-Net (Profile /) [] (proposed by the
Danish P-Net national committee), and Vnet/IP (Profile /) (developed by Yokogawa, Japan []).
In the second approach, the TCP/UDP/IP protocols suite is bypassed, the Ethernet functionality
is accessed directly—in this case, RTE protocols use their own protocol stack in addition to the
standard IP protocol stack. he implementations in this category include Ethernet Powerlink (EPL)
(Profile /) (defined by Bernecker + Rainer (B&R), and now supported by the EPL Standardisa-
tion Group []), TCnet (Profile /) (a Time-critical Control Network—a proposal from Toshiba),
EPA (Profile / & /) (Ethernet for Plant Automation) (a Chinese proposal), and PROFIBUS
CBA (Profile /) (Component-Based Automation) [] (defined by several manufacturers including
Siemens, and supported by PROFIBUS International []). Finally, in the third approach, the Ether-
net mechanism and infrastructure are modiied. he implementations include SERCOS III (Profile
/) [] (under development by SERCOS), EtherCAT (Profile / & /) [] (defined by Beckhoff
andsupportedbytheEtherCATTechnologyGroup[]),andPROFINETIO(Proile/,/,/)
(defined by several manufacturers including Siemens, and supported by PROFIBUS International).
The use of standard components such as protocol stacks, Ethernet controllers, bridges, etc. allows
to mitigate the ownership and maintenance cost. The direct support for the Internet technologies
allows for vertical integration of various levels of industrial enterprise hierarchy to include seam-
less integration between automation and business logistic levels to exchange jobs and production
(process) data; transparent data interfaces for all stages of the plant life cycle; the Internet- and Web-
enabled remote diagnostics and maintenance, as well as electronic orders and transactions. In case
of industrial automation, the advent and use of networking have allowed for horizontal and vertical
integration of industrial enterprises.
With the growing trend for networking of embedded system and their internetworking with LAN,
WAN, and the Internet (for instance, there is a growing demand for remote access to process data at
the factory floor), many of those systems may become exposed to potential security attacks, which
may compromise their integrity and cause damage as a result. Potential security solutions for this
kind of systems depend heavily on the specific device or system protected, application domain, and
extent of internetworking and its architecture.
Typically, office IT operational security requirements involve confidentiality to protect data from
unauthorized entities, integrity to protect against unauthorized data manipulation, and availability
to ensure data are available when needed. Operational security requirements for automation and
process control systems, unlike in the office IT, focus on safety to guarantee absence of catastrophic
consequences for humans and environment, and system/plant availability—the automation system
and plant have to be safe operational over extended periods, even if they continue operation in a
degraded mode in the presence of a fault caused by a security attack. Electronic security attacks may
compromise the integrity of these systems and endanger plant, personnel, and even public safety.
Unavailability may result in financial losses.
The security measures to be taken at the corporate and control network levels in the automated
plant control hierarchy are essentially the same as in general networking. he situation is though dif-
ferent at the field and device level. At the field level, fieldbuses, in general, do not have any embedded
 
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