CC-Link's 'Non-Stop Open Network' demonstrates the protocol's robustness
09 December 2010
Of the criteria that may influence the choice of an industrial Ethernet network, factors such as speed, ease of integration, open communications, vendor support and so on, can be taken for granted with most major protocols. The same cannot be said, however, for availability; the ability to keep the network running with the minimum of interruptions when subject to the faults and events typical of real-world manufacturing operations is critical.
CC-Link network technology from the CC-Link Partner Association (CLPA) offers a range of technical features that are designed to keep the network functioning even under a range of fault conditions that might usually cause a fieldbus to cease operation. With features such as high noise immunity, ‘floating master’ capability, hot-swap capability and station bypass, CC-Link is believed to lead the field in terms of genuine ‘non-stop’ functionality.
Modern manufacturing environments can be characterised by high levels of electrical noise, and this can be a real problem for fieldbus systems, often requiring the use of optical fibres to achieve noise immunity. CC-Link offers such a fibre option, but the networking technology is also designed to reject a high degree of electrical noise even with standard twisted pair cabling. This gives outstanding noise immunity at the lowest installed cost.
Another cause of loss of production can be the principal controller of the network going offline, due to loss of power, technical fault and so on. With CC-Link’s ‘floating master’ capability, an alternative controller on the network is able to take over operation immediately in order to maintain production without interruption.
Network availability is also increased through CC-Link’s hot-swap capability and station bypass. The hot-swap functions and related technical features mean that stations can be removed from and returned to the network as required without causing any malfunctions. This simplifies maintenance or testing of stations as there is no interruption to plant or factory operation. Station bypass is a feature that makes future expansion of the network just as simple, by allowing network designs to include future stations without actually needing to implement them. Instead, they are bypassed until such time as they are added to the network.
The ‘Non-Stop” principle extends to development, installation and maintenance of the network as well. Since configuration is parameter based and requires no configuration files, CC-Link does not require users to learn any complex software tools, so there is no programming effort and a minimal learning curve. This helps to significantly shorten development time, getting networks up and running more quickly. Standard networks are built around simple twisted pair twisted cables or familiar CAT-5/fibre based Ethernet, making installation quick and simple for anyone, rather than requiring an IT network management specialist. Finally, because problems such as station errors, broken cables or disconnected cables are easily identified using the diagnostics tools, maintenance is a much simpler process, enabling network problems to be rectified much more quickly.
CC-Link currently has just short of eight million nodes installed across the globe and the protocol has attracted many hardware partners, a good many of which are outside of CC-Link's core Asian markets. CLPA Europe general manager, Steve Jones is stepping down from his position and John Browett will take the reins early in 2011. John can be contacted now via email (john.browett@clpa-europe.com) for information about CC-Link product partners and developments such as Non-Stop Open Network.
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