Electricity + Control October 2015

CABLES + CABLE ACCESSORIES

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.

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.

Fast cables with fire

retardant for buses

Electricity+Control

October ‘15