IT Jan 2008 - Industrial Technology Magazine

SENSORS & SYSTEMS
Industrial Ethernet
Delivering the
universal solution
for plant networks
Industrial Ethernet is the fastest growing industrial network
choice, but what exactly is it, how does its implementation
differ from that of a traditional fieldbus, and does it really
offer the single universal solution that is so often talked
about? We put these questions to the experts in the field
Against a background where there is increasing
pressure on manufacturers in all sectors of
industry to improve processes, reduce costs and
boost productivity, Ethernet technology is being
hailed as the key to achieving all these goals, and so
boosting companies’ competitiveness on increasingly
aggressive global markets.
The move to industrial Ethernet has been fast paced
across all sectors of industry, and is a step change from the
standardisation on the various open and proprietary
fieldbus protocols that we saw though the 1990s. But
what exactly is industrial Ethernet? Steve Jones of CLPA
(CC-Link Partner Association) explains: “Industrial
Ethernet, in essence, is the use of Ethernet as the data link
layer protocol in the OSI seven layer model, with a fieldbus
protocol as the application layer. This is conceptually
similar to the various fieldbus options that are actually the
use of RS232/485 as the data link layer, with the fieldbus
protocol itself at the application layer.”
There are many advantages to moving to industrial
Ethernet, not least of which is a vast increase in speed, up
from the sub-10kbps typical with RS232 to the gigabit
and beyond potential of Ethernet. Overall performance is
also increased, and costs are significantly reduced, since
industrial Ethernet offers the ability to use standard access
points, routers, switches, hubs and cables which are far
cheaper than equivalent serial port devices. “From the
user’s point of view, however, the biggest advantage aside
from cost is the significantly greater interoperability
between devices offered by industrial Ethernet,” says
Jones. “In particular, there is the potential for a seamless
flow of data from field devices all the way up to higher level
business systems, and back, delivering huge gains in
flexibility for manufacturers looking to boost their
productivity to the max.”
The latest development in industrial Ethernet promises
a ten-fold increase in communications rates to 1Gbps. This
has come with the release of CC-Link IE – the first
completely integrated gigabit Ethernet network for industrial
automation. “It really does define the new threshold for
open standards for Industrial Ethernet,” says Jones.
Time-critical applications
It is the evolution of Ethernet technology from a 10Mbps
bus/tree topology to a gigabit, switch-based topology that
has really paved the way for using Ethernet to support such
time-critical applications in industrial networks. The
infrastructure of switches provides the determinism and
throughput required for control applications, and switches
can be added to split the data load between segments,
resulting in higher performance.
The Ethernet switch also makes it possible to build
redundancy into the industrial Ethernet network. Dave
Cook of GarrettCom Europe comments: “At field device
level, dual connectivity is the standard approach for
providing redundancy, but the lack of PLCs and field
devices with dual connectivity built in for sensor and
controller applications has made this almost impossible to
achieve cost effectively. Modern Ethernet switches provide
a solution to the problem, with the advent of dual homing
technology built into even the smallest of switch products.
Offering convenient plug-and-play dual connectivity in a
physically small package, these products provide high
reliability to enable redundancy for nodes at the edge of the
network at a low cost.”
Further, Ethernet has the unique characteristic of being
a network with an active infrastructure, enabling the
network to accommodate a virtually unlimited number of
point-to-point nodes, and so providing users with
unsurpassed flexibility in designing networks that
accommodate their current requirements while enabling
easy, cost-effective expansion in the future. In addition,
recent hardware developments have removed the
communications distance limitations that have been a
recognised issue with the move to gigabit Ethernet, giving
users a simple upgrade path to the increased performance
afforded by this high-speed technology. The new CSG14
converter switches from GarrettCom Europe allow
industrial installations with multi-mode fibre to achieve
2000m gigabit connectivity that has previously only been
available when using single-mode fibre cable.
With its performance benefits, then, industrial Ethernet
is a good fit for applications where the required volume and
speed of data exchange among plant floor controllers and
between controllers and information systems is exploding.
In addition, being based on standard Ethernet, the network
addresses the increasing need to reduce total cost of
ownership of production processes across development,
commissioning, operation, and maintenance.
Stefan Knauf of Mitsubishi Electric says: “As industrial
Ethernet extends its reach to even the most lowly field
devices, so the various controllers, PLCs and ERP systems
are able to access any sensor connected to the control and
device network. The result is better information on
manufacturing processes, with process operators able to
monitor and fine tune system performance, access plant
information and communicate directly with their
production line managers.”
Perhaps most importantly, and in contrast to the
fieldbus options of the past, industrial Ethernet frees up the
user to a far greater extent from the danger of being locked
into a single solution, enabling the system integrator to
focus on installing the network without having to worry
about the protocol that will eventually be used over it,
whether that be CC-Link IE, EtherNet/IP, Profinet or one of
the others. “An industrial Ethernet infrastructure will
happily accommodate multiple application protocols in use
at the same time, with the switch network routing the data
packets appropriately,” says Knauf. “This means users can
make a decision on an industrial Ethernet protocol based
on today’s requirements, confident that the investment will
not have been wasted should tomorrow’s requirements in
a different area of the plant dictate the use of a different
protocol.”
MORE INFORMATION:
CLPA: enter Z365 on the card
GarrettCom Europe: enter Z366 on the card
Mitsubishi: enter Z367 on the card
Or visit ‘latest issue stories’ at www.industrialtechnology.co.uk
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INDUSTRIAL TECHNOLOGY • January 2008