Product category:
Plant- and Machine-Wide Communications
News Release from: CC-Link Partner Association | Subject: CC-Link
Edited by the Engineeringtalk Editorial
Team on 05 May 2008
Explaining worldwide fieldbus
differences
All fieldbus protocols share the same, really rather short, history, but that does not mean they are anything like equal.
CC-Link is the de facto standard for open fieldbuses in Asia, but only 5% of its association members are European Given that Asia is attracting more and more manufacturing because it achieves consistent product quality through the use of newly-installed highly automated plant, are European exporters missing a simple trick?
This article was originally published on Engineeringtalk on 24 Jul 2008 at 8.00am (UK)
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CC-Link is based on a twisted-pair cable, so installation is cheap, making it particularly attractive for networks that cover large areas.
All fieldbus protocols share the same, really rather short, history, but that does not mean they are anything like equal.
One or two have already developed dominant positions, either globally or in a defined niche and seem destined to ultimately see off opposition from less successful competitors.
This sort of consolidation can be seen in many fields of endeavour, you start off with a lot of competitors but over time numbers are whittled down to just a few front runners.
This is evident when a new market opens up, say for PCs, mobile phones or sportswear, but it can also be seen in professional football, party politics, technologies and charities.
Industrial automation as we now understand it started back in the 1960s and 1970s, when car plants started integrating various production processes.
Further reading
Control system monitors entire facility
GB Innomech decided to integrate as many functions as possible into one central control system that could constantly optimise the entire building for energy performance.
Fieldbus protocol offers key to Asian markets
Less well known in Europe, CC-Lick was developed by Mitsubishi Electric in Japan in the 1990s and released to the public domain as an open system in the 2000.
Automation fieldbuses change the world quietly
Steve Jones, General Manager of the CC-Link Partner Association, reviews the principles of fieldbus communications and looks at the advantages.
Originally this meant wiring up literally thousands of individual relay switches to create systems that, although automating a process, were completely inflexible with regards to subsequent change.
Automation could have stalled there, but General Motors kept pushing the envelope and the programmable logic controller (PLC) eventually evolved to replace relay banks and rewrote the rule book for both manufacturing procedures and quality expectations.
This started a technological revolution that has gone on for 25 years, reshaped Western society, given developing countries a leg up and shows no sign yet of abating.
The trouble with automation was that it could create so much wiring that it could become a problem in its own right.
It could also be expensive to install and maintain and at times even difficult to find enough room for.
Again it was GM who led the way.
Noting that in the telecoms world many signals can be passed down a single wire and find their way to the correct receiver station, it wondered about developing a similar system for field devices in an automation network.
What resulted was Manufacturing Automation Protocol/Technical Office Protocol (MAP/TOP) and the first ever industrial fieldbus.
Almost inevitably this was far from perfect, being rather cumbersome in design and limited in ability.
It functioned mainly as a prototype, but did point to a way forward for industrial communications.
Interestingly, the automobile companies were simultaneously working on a similar concept for a different use.
By this time, they were fitting so much electrical equipment into their cars that wiring looms were growing to outrageous proportions and a signal-address bus solution was being developed.
This was called a Controller Area Network (CAN) and, not surprisingly, has transferred into the manufacturing arena with some success.
With the fieldbus genie out of the bottle, it was inevitable that several teams would begin projects to develop the idea almost simultaneously.
Each team had its own agenda and goals, so they went off in slightly different directions.
Some were focussing on perfecting fieldbus for a particular industry, while others wanted to marry it with certain other technologies.
Some were keeping it general, other specialising into defined fields.
By the early 1990s it was well understood that a hierarchy of fieldbuses would be needed, some dealing with simple device instruction digital I/O signals, others collecting data and processing it into complex information for decision making and process management.
A characteristic of development at the instruction level was a need to be able to communicate with devices from many different manufacturers.
This had to be addressed by getting competitors around a table and agreeing how best to proceed for the benefit of the entire industry and was inevitably done on a regional basis.
Thus it is not at all surprising that we have ended up with just a few device level protocols, each strong in a particular geographic region.
ASi and Profibus dominate in Europe; DeviceNet is America's favourite; and CC-Link rules the roost throughout Asia.
These protocols started life in Siemens, Rockwell and Mitsubishi, respectively, but in the 1990s were released into the public domain to become 'open' systems with all interested parties being offered access to the intellectual property and invited to participate in the development programmes.
That these protocols work is not in dispute and comparing their features to determine which is technically best is a spurious activity because their market positions are already assured.
The driving force for adoption of these protocols, both individually and collectively, is no longer technology but is instead economic and political.
This is because their development coincided with globalisation.
With Western economies overheated and debt-laden, the 1990s saw the rise of the first highly technically educated generation of the east and the creation of the new tiger economies.
Capital support, government backing, soft loans and enterprising management suddenly redefined all sorts of accepted wisdom as many eastern countries sought to emulate Japan's success of 20-30 years previously.
No doubt they will have observed from the Japanese lead that a mixed-skill labour force, green field development sites and adequate capital are great for getting going, but the trick is to move on for the next generation; educating the young, improving standards of living and creating an environment for growth.
Investment in industrial automation is essential in all regions, but in Asia it is truly vital as its economies develop from agrarian to industrial.
Industrial development fuelled the growth of the ancient civilisations, the various European empires and America's rise to power. Request a free brochure from CC-Link Partner Association ...
It is doing the same now for Asia and device-level communications is helping to reshape the world.
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