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.

The CC-Link fieldbus protocol has over 850 compatible products made by partner companies and approaching 4,000,000 installed nodes in Asia.

European control companies, OEMs and machine builders need to have CC-Link capabilities if they are serious about exporting to the world's fastest growing manufacturing region.

Throughout Asia automation is synonymous with manufacturing.

Engineers in China, India, the Tiger Economies, Japan and across the Pacific Rim have long known that they cannot rely solely on low labour costs and that automation is essential for the development of their economies.

Predictable and consistent product quality is the greatest arbiter in today's global markets.

Low and lowering prices are increasingly a given, on-time delivery is simply expected and regular product redesigns are taken for granted.

Quality is the one differentiator that manufacturers can offer.

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.

It was developed in recognition of the need for a rugged, flexible, high-speed and deterministic device-level network for manufacturing companies.

CC-Link's recognition in Europe is still low, with only 5% of the CLPA's (CC-Link Partners' Association) members being European.

But its recent installed base and growth is far higher than most competitor protocols, because so much control equipment used in Europe is of Asian origin.

If the end-user or OEM leaves the decision of which protocol to use to the controls supplier, the chances are that CC-Link will be selected.

A great attraction of CC-Link is that it uses an RS 485 topology, so it feels familiar to most engineers and has the advantage that the wiring route does not have to be consecutive between field devices.

This is very useful because most installations are subject to constant minor reconfigurations through their working lives.

Communication speed is 10Mbit, faster than most comparable protocols.

Cable runs can be up to 12km, useful for large sites and for applications involving remote stations.

Most control systems are designed with a view to future expansion and development.

CC-Link networks can be configured to include dummy stations which can later be converted into operational status using the hot-swap capabilities.

Other features include auto-start-up and auto recovery and self-healing capabilities.

CC-Link provided the flexibility that allowed Longslow Dairies in Colwyn Bay to buck the industry trend and supply milk in environmentally-friendly glass bottles rather than disposable plastic containers.

The improved control of the plant has increased efficiency from 60% to 90%, providing a reduction in energy consumption and the virtual elimination of bottle breakages on the line.

The system was designed to be modular so that it could be installed in a series of steps while the plant continued to operate.

A CC-Link communications backbone was installed around the dairy.

A master PLC providing strategic command was also installed and provides the portal for the proposed connection of remote diagnostic and maintenance tools and a high-level enterprise management system.

Much of the CC-Link's data handling is real time.

Feedback systems constantly trim conveyor speeds to prevent bottle pressure build up.

A vision system checks for bottles that are dirty, misshapen or retaining rinse water from the cleaning processes.

Production is co-ordinated to just-in-time completion with the arrival of delivery lorries.

Additionally the whole plant can be cleaned and switched over to orange juice packaging in less than 20 minutes.

Subsea cable laying engines have had to become very much more sensitive to cope with the switch from robust armoured copper cables to more delicate fibre optics.

The tension with which cable is laid has to be constant, despite the movement of the ship in the ocean swell, a requirement which requires constant monitoring and speed trimming of the multiple pairs of pinch wheels which pay out the cable.

The latest generation of engines developed by Fraser Hydraulic Power of Newcastle uses a powerful PLC for controlling a PID loop for each pair of wheels.

The PLCs communicate with one another and with an HMI via a CC-Link fieldbus network.

A major problem can occur when the engine is free-spooling cable onto the seabed, as this can turn the drive motor into a generator.

Previously this has been addressed by incorporating a huge braking resistor into the engine, but the precision control provided by the CC-Link allows the variable speed drive to switch instantly into a regenerating mode.

Operators have taken to the new Fraser engines, because they can be used from far smaller (and thus cheaper) vessels and their precision control has reduced the amount of downtime due to cable breakages by an order of magnitude.

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