Electricity + Control October 2015

CABLES + CABLE ACCESSORIES

Fast cables with fire retardant for buses

By J Lehmann, LAPP Group

Data communication in vehicles is constantly on the rise. Low-frequency data network cables no longer make the grade. For this reason, manufacturers are increasingly equipping their vehicles with high-frequency data network cables, and their use of Ethernet is constantly rising.

D evelopment on the Ethernet standard began in 1973 at the Xerox Research Centre in Palo Alto, and initially it could only manage three megabits per second. The standard, which back then was not yet a standard but a company-specific product from Xerox, now specifies hardware (cables, distributors, network cards in PCs) as well as software protocols for transmitting data packets. Almost everyone has probably held an Ethernet cable in their hands at some point. It connects computers with one another, and a home PC with an internet router if a wireless connection is not being used to go online. The whole internet is based on Ethernet communication. It is important to note that Ethernet not only refers to the well-known network cables with copper conductors, the standard now also en- compasses fibre optic cables and even wireless Ethernet, which has no cables at all. Ethernet has triumphantlymarched its way towards other applica- tions, including production halls in industry where it is increasingly taking over from classic fieldbus systems when it comes to data exchange between sensors, actuators and production control. The advantages are obvious: software used to manage companies – for instance ERP – and software to operatemachines are constantlymerg- ing further together, so it is perfectly understandable that persons responsible for IT in companies also want to have uniform standards for hardware and software protocols. Ethernet can provide a range of benefits in factories: it bridges long distances of over a hundred

metres, it is highly variable in terms of network structure and it ena- bles the connection of new plug and play devices. It is also real-time capable and can cope with time-critical control tasks, for example if an employee presses a red emergency button. The high data rates of up to ten gigabits per second are impressive, and soon 100 gigabits per second will also be possible. These data rates are necessary because data volumes in factories continue to rise, for instance due to the use of cameras for visual quality control or huge numbers of sensors and actuators at field level. Resistant to chemicals and vibrations Ethernet cables used in offices are not suitable for factory use though. There theymust be resistant to oil, chemicals and heat, and often need to withstand millions of movement cycles in drag chains. The cable manufacturers have responded to this and have developed cables and connectors for Industrial Ethernet which are not only resistant to oils and acids but also to vibrations and electromagnetic fields. The Ethernet cables described in the article are extremely resilient and are available for various industrial Ethernet systems such as Profinet and EtherCAT. New challenges are brought, for example, by the foodstuffs industry, in which cables and connectors need to avoid providing attacking surfaces for germs or remaining food, and also have to be compatible with aggressive cleaning agents.

Electricity+Control October ‘15

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