With increased demands for
industrial plants to operate more
efficiently, managers are
reviewing the communications and cabling
systems used throughout their facilities. 

There is increasing network convergence
between design and manufacturing functions,
ie between the office and plant floor.

In addition, plant environments are gradually
migrating away from proprietary protocols to
the most prevalent current standards that use
Transmission Control Protocol/Internet
Protocol (TCP/IP) and standard Ethernet
network structures. The future trend is toward
implementing Industrial Ethernet as the linklayer
protocol to one of the legacy protocol
applications, and ultimately Industrial Ethernet
right down to the device level on the machine.

Common Industrial Ethernet protocols,
including EtherNet/IP, Profinet and other
conforming open systems are already proven
in automation applications that require realtime
performance and multiple
communication channels on the same
network. Industrial Ethernet today
predominantly uses twisted pair copper cable
but fibre optic cabling is also making its way
onto the plant floor as it provides a more
reliable transmission over longer cable lengths.

In a dynamic application – that is, an
application where a cable is used to connect
moving parts of a machine – cables may have
to move horizontally, vertically, or even with
a twisted motion, often carried within energy
chains. In today’s high performance
machines, these movements typically take
place at high speed and it is common for
them to be repeated thousands or even
millions of times in a short timescale.

Fibre optic cabling The benefits of fibre optic cabling are well
known in consumer and business
communications – such as a higher
bandwidth – and it has already been installed
in commercial premises. But what additional
advantages are there in an industrial setting?
Fibre optic cables are smaller, lighter, have
higher data rates, longer cable length, and
better EMC safety, all enabling plants to
operate more efficiently.

The travel length of fibre optic cable is
minimally restricted by the transmission
system used and can be several hundred
metres long. In addition, with a properly
designed dynamic fibre optic cable, the increase
in attenuation even at very high cycle rates in
energy chains is so low that the value is often
difficult to measure; any increase in
attenuation to be found is usually near the plug.

The question of how much the attenuation
behaviour changes has been answered following
a series of tests at the igus Technical Centre.

Taking into consideration that standard ST*
plugs have a mean insertion attenuation of
0.3dB and a maximum insertion attenuation
of 0.5dB, measured results showed an
increase in attenuation of approximately 0.1
to 0.15dB – after more than 30 million cycles
in the chain this increase is negligible.

Fibre optic cabling provides safe data
transmission as it has no sensitivity to
electromagnetic interference. As a result,
there is no risk of possible data loss.

By installing fibre optic cables, engineers
can future proof any bus system. Fibre optics
is not bus-protocol dependent, so when the
plant eventually changes to Industrial
Ethernet from proprietary bus systems, no
new cable installation is necessary, saving
valuable time and costs.

Fibre optic cables weigh less than their
copper equivalents, which in turn means that
less energy is needed in the energy chains to
move the cables.

A cable with a smaller dynamic bend
radius (the minimum radius a cable can be
bent repeatedly) has many advantages as it
allows plant managers to save space. A
smaller bend radius can sometimes be
achieved using fibre optic cabling, for example,
igus chainflex optical fibre cables can reduce
the required bending radii by more than 50%
against the similar standard bus cable.

A new generation of dynamic cables, such
as igus’ chainflex has been designed to
overcome this challenge and presents a
practical and reliable solution. chainflex fibre
optic CFLG.2LB cables are lighter, allow
higher data rates, smaller bend radii, longer
cable lengths, better EMC safety and show
lower damping. In addition, optical fibre
cabling is system independent and futureproof
– in case of a change of bus system, no
new cable installation is required.

This dual-fibre fibre optic cable is designed
specifically for energy chain applications,
where extremely small bending radii and
high cycle life are expected without loss of
data. The fibres are designed to reduce the
minimum bend radius from the traditional
10x the outside diameter of the jacketed cable
to 5x, or only 40mm. Because of the matched
length of the fibre optic cores and the aramid
strain and torsion relief, more than 8.5
million double strokes have been proved for
energy chains in a 38mm test set-up.

Where traditional copper bus cables are still
required, igus chainflex bus cables provide a
constantly high data quality in applications
with permanent movement. With different
shield materials such as, PUR, TPE and PVC,
cable lengths (to 400m) and torsion angles (to
±180°/m) they guarantee operational safety for
almost every moving application. Advantages
include: high transfer capacities, mechanical
stability and high EMC safety and durability.

With the help of data from two billion test
cycles per year performed in the igus test
laboratory with more than 1700m2, the
lifetime of almost any cable of the chainflex
family, copper or fibre optic, can be precisely
predetermined.

Provided that such genuine dynamically
flexible cables are used and that they are
selected and installed correctly, solutions of
this type are safe, reliable and cost effective.

It is clear to see that with increasing volumes
and speed of data, fibre optic cables are now
providing real advantages in industrial
applications, enabling plant managers to
operate their factories more efficiently.

*ST is a trademark of Lucent Technologies