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(Article written for Industrial Ethernet Book November 2010)
All the pundits predict that Industrial Ethernet use is expected to grow by double-digit percentages year on year. CPLA’s Steve Jones says that when you dig down into the numbers, you have to start asking yourself whether there is some resistance to its adoption. Answering his own question, he reckons that CC-Link IE technology has gone further than most to meet the demands of designers and maintenance technicians.
THE CONTINUING DRIVE to improve productivity will encourage more automation networking – of that there is little doubt. Initiatives driving this growth include lean working, improvement to takt times (takt time sets the pace for industrial manufacturing lines), increased track and trace type legislation, and product lifecycle management production (PLM).
Delivering the mass customisation demanded by market forces requires joined-up thinking, and connected manufacturing promises to deliver the required value chain transparently. ERP systems are required to make information available backwards into the supply chain, as well as forwards to customers.
Simply put, everyone wants to see what’s going on (see box). As a result, networks will become ever more important and the information they handle will take on the same order of importance as industrial control functions. So who will look after these networks?
End-users have seen standard Ethernet as a way of communicating shop floor data to the top floor ERP/information systems. As a model, Enterprise IT with its standard network backbone is what attracted plant managers to consider a similar approach for their industrial or manufacturing applications. However, unlike the popular automation networks such as CC-Link and Profibus, standard Ethernet will not deliver the performance needed for modern complex manufacturing. This is especially true for applications needing deterministic (predictable) response times.
There are many different ways to provide determinism in Ethernet and this may explain the rash of Industrial Ethernet protocols introduced over the last few years. It can be argued that Industrial Ethernet does not need to be deterministic and that providing enough bandwidth will adequately cope with most situations, a truism for many applications. However, determinism is certainly required for some, so it makes sense to use a deterministic network provided there are no inherent disadvantages in doing so.
While the majority of industrial Ethernet protocols will meet the network performance needs of most users, they frequently bring unwanted complexity as part of the package. The required skills base can adversely affect downtime, maintenance and the ability to make network configuration changes. Perhaps this partly explains why some users have delayed the move from traditional fieldbus to an Ethernet-based equivalent?
Easier to maintain
Skilled control engineers are increasingly rare on the shop floor. For many companies, having a shortage of engineers to handle advanced automation equipment will lead to serious problems. Few companies can presently afford an army of specialist engineers to maintain the networks; the trend is to employ generalists and bring in experts when required – often their suppliers’ support engineers. If companies cannot afford to shut down production while awaiting the attendance of a control consultant, then the networking technology must become easier to use and maintain. New plant and equipment needs to be as simple as possible, with easy-to-use field devices requiring little or no personnel training. For quick response to problems, easy system self diagnostics and cause identification that don’t rely on an engineer’s intuition or experience are crucially important.
CC-Link on Industrial Ethernet
The CC-Link Partner Association (CLPA), using a decade of accumulated knowledge, developed the CC-Link IE to deal with the skills base question. To be taken into consideration were certain clear requests from system designers and maintenance technicians.
From designers, suggestions included:
- High speed communication enabling sharing of large amounts of data in real time, reduced takt times and predictable performance;
- Reduced costs by using commercially available Ethernet equipment;
- Simplified network configuration for faster implementation/model changes;
- Simple connectivity to enable stations to be accessed from anywhere, even across multiple networks;
- Choice of network topologies and cabling options to reduce cost of ownership;
- • High network availability. Maintenance technicians suggested:
- The flexibility to allow easy addition of new stations, and for making network changes;
- Engineering tools to make wiring problems and errors easy to diagnose;
- Hot swap of devices and station additions without stopping the network;
- Minimise problems caused by EMI.
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