Image Processing Reference
In-Depth Information
Internet
Computer science
Ethernet
WWW
ISO/OSI
Arpanet
MMS
MAP
C4004
C8080
C8086
80386
80486
Pentium
Microprocessors
BacNet
Building and home
automation
CEbus
EIB
X10
Powerlink
Batibus
LON
Ethernet/IP
EtherCAT
Modbus/TCP
FF
PROWAY
PROFINET
ISA SP50
Modbus
FIP
ControlNet
IEC61158
Industrial and
process
Arcnet
P-NET
Profibus
SDS
IEC61784
EN50254
Interbus
ASi
PDV-Bus
Bitbus
EN50325
EN50170
Sercos
Hart
DeviceNet
Automotive and avionics
ARINC
FlexRay
CAN
TTP
MIL 1553
LIN
SwiftNet
Interfaces,
instrumentation, and
PCB busses
I
²
C
M-Bus
IEEE488
HP-IL
CAMAC
Meas. Bus
GPIB
RS485
Predecessors
Proprietary and open systems
International standards
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9
7
0
1
9
8
0
1
9
9
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2
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FIGURE .
Milestones of fieldbus evolution and related fields.
enough to support the development of elaborated communication protocols. his was also the birth
date for the fieldbus as an individual term. Different application requirements generated different
solutions, and from today's point of view it seems that creating new fieldbus systems was a trendy
and fashionable occupation for many companies in the automation business. Those mostly propri-
etary concepts never had a real future, because the number of produced nodes could never justify the
development and maintenance costs. Figure . depicts the evolution timeline of fieldbus systems
and their environment. The list of examples is of course not comprehensive, only systems that still
have some significance have been selected. Details about the individual solutions are summarized in
thetablesintheappendix.
As the development of fieldbus systems was a typical “technology push” activity driven by the
device vendors, the users first had to be convinced of the new concepts. Even though the benefits
were quite obvious, the overwhelming number of different systems appalled rather than attracted the
customers, who were used to perfectly compatible current-loop or simple digital I/Os as interfaces
between field devices and controllers and were reluctant to use new concepts that would bind them
to one vendor. What followed was a fierce selection process where not always the fittest survived,
but often those with the highest marketing power behind them. Consequently, most of the newly
developed systems vanished or remained restricted to small niches. After a few years of struggle
and confusion on the user's side, it became apparent that proprietary fieldbus systems would always
have only limited success and that more benefit lies in creating “open” specifications, so that different
vendors may produce compatible devices, which gives the customer back their freedom of choice
[,]. As a consequence, user organizations were founded to carry on the definition and promotion
of the fieldbus systems independent of individual companies []. It was this idea of open systems
that finally paved the way for the breakthrough of the fieldbus concept.
The final step to establish the fieldbus in the automation world was international standardization.
The basic idea behind it is that a standard establishes a specification in a very rigid and formal way,
ruling out the possibility of quick changes. This attaches a notion of reliability and stability to the
specification, which in turn secures the trust of the customers and, consequently, also the market
position. Furthermore, a standard is vendor-independent, which guarantees openness. Finally, in
many countries standards have a legally binding position, which means that when a standard can be
