As the strongest fieldbus protocol in Asia, CC-Link, has over 850 compatible products made by partner companies, and approaching 4,000,000 installed nodes. So 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.
It is not surprising therefore that Asia is building automated plants far faster than anywhere else in the world. And for device level communications the fieldbus protocol of choice is CC-Link. 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 percent 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 – very useful considering that most installations are subject to constant minor reconfigurations through their working lives. Communications speed is 10Mbit, faster than most comparable protocols, and cable runs can 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.
Going green
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 percent to 90 percent, allowed a 30 percent increase in throughput, 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 early onto which each newly-automated section was connected in turn. In all seven sections, each controlled by a local PLC were added to the backbone. 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. For instance feedback systems are constantly trim conveyor speeds to prevent bottle pressure build up, a vision system check for bottles that are dirty, misshapen or retaining rinse water from the cleaning processes, and 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
Going underground
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.
Going hygienically
Turnaround time on the cross-channel Eurostar train is limited, yet a cleaning has to be to the highest standard for this most prestigious of services. Empty and cleaning of the effluent tanks has been upgrade to being fully automatic following upgrade of the Lavatory Discharge Apron at the London terminus. It now sports over 40 PLC controlled out-pumping stations, all connected via a CC-Link network.
The cleaning cycle at each pump is self-optimising and includes, emptying, rinsing disinfecting. The operator merely connects the extraction pipe and waits for the cycling completion indicator to come on. Notably the system is programmed to recognise five different types of train and to select the appropriate cycle.
Going at Speed
When Becatron Mechatronica in Belgium wanted to control energy usage on its 40 aluminium foil rewind machines, it decided to integrate their control a CC-Link fieldbus. Each rewinder is quite energy hungry, being heavy, high speed and temperature controlled.
Start up of the rewinders is now sequenced over the CC-Link to prevent power surges, and machines that are not in used can be shut down between production runs to save energy. With the plant split into seven sections, each comprising two distinct system, a master controller is also required on the network. Originally a multi-drop RS 485 architect was used in the control system, but the CC-Link has simplified the design and led to better controller, faster reactions and improved reliability. Additionally noise immunity in this high energy environment has been proven.
Payback of the CC-Link installation costs has been achieved in under a year thanks to the energy saved.
CC-Link is perhaps the unsung hero of the fieldbus world. A powerhouse in Asia, its use in Europe is higher than most people realise, but there is a growing recognition that it must be brought to the fore if Europe is going to win exports to the fastest developing region in the world.
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