Today, there are few reasons not
to extend Ethernet to the factory floor. Ruggedized equipment ranging
from connectors and cables up to networking infrastructure equipment
like switches can stand up to the harshest environments.  Real time
capability has been added for applications that require high-speed
determinism. Plus, a multitude of engineers and technicians are already
familiar with the basics of Ethernet, so installation, diagnostics and
upkeep are comparatively easy for the plant network as well.

Ethernet works because it can now reach down to the machine level.
Ethernet
was first used on the factory floor as a backbone for linking various
industrial networks together. Typically, it was only used to connect a
manufacturing process to the business environment to gather quality
data and manage recipes. But that has changed dramatically in recent
years. Ethernet now reaches down to the machine level, where it handles
I/O and other jobs that only use to be possible with a range of
deterministic field bus protocols.

Ethernet is also displacing
field buses at the system level, linking automation equipment together
in a single homogenous network, even when the equipment is from a
variety of vendors.  Instead of spending unnecessary hours figuring out
how two pieces of equipment can coexist on one network, Ethernet makes
it simple to plug them into a common switch.  These benefits come
without impacting the existing links between manufacturing processes
and the Manufacturing Execution System (MES) tools used to manage the
complete plant.  As a result, it is possible to have one network
infrastructure from the I/O level all the way to the MES.

Why use Ethernet?
There
are many reasons to choose Ethernet throughout the networking
hierarchy. One of the key driving factors in many organizations is the
desire to create compatible networks throughout the entire facility.
Automating operations is a critical factor for success in lean
manufacturing environments. Linking the management systems that bring
in orders to the manufacturing equipment that fulfills those orders
makes it simpler to streamline operations.  Instead of passing and
translating information from one level to the next over several
different types of networks and field buses, Ethernet makes it possible
for the management system to send information directly to individual
pieces of the manufacturing equipment over a single network.  This is
possible because Ethernet supports multiple protocols such as TCP/IP,
HTTP, SNMP, OPC and real time I/O at the same time on the same wire,
which is far more efficient than dedicating a field bus for each
protocol.  Ethernet opens communication possibilities.

Using a
single networking scheme also pays off when problems on the plant floor
are diagnosed.  For instance, it was traditionally difficult to notify
the maintenance staff if a wire broke on an I/O device’s sensor. 
First, the automation controller would have to recognize that there was
an issue on one of its I/O devices on the dedicated field bus.  Then it
would send an alarm to an HMI over another network to notify the
machine operator.  Next, the machine operator had to alert the
maintenance staff.  They would then have to plug their programming
device directly into the automation controller and its field bus to
investigate the problem.  

Here’s how Ethernet can simplify your life.
Using
an Ethernet network greatly simplifies this broken wire situation. 
When the I/O device recognizes a wire break, the information can be
pushed directly onto the Ethernet network by the device itself.  The
diagnostic then can be read in multiple locations by a variety of
devices. For example, the HMI can let the machine operator know that
there is a broken wire, the MES can read the message and record the
issue into its quality database, and the maintenance staff can be
informed via an SMS message sent directly over the plant’s Voice over
IP system that it uses on the same Ethernet infrastructure.  The
maintenance staff can even collect further diagnostics directly from
the I/O device regardless of where the programmer is located in the
plant.  

This sort of Ethernet connectivity extends plant
network visibility, bringing many new possibilities for delivering real
time information and keeping equipment running at peak performance.  

Ethernet can lower your costs.
Cost
is another benefit of Ethernet because compatible network throughout
the enterprise helps keep expenses down.  First, it eliminates the need
for field bus gateways, devices or software that perform media
translation.  Beyond the obvious hardware cost of these gateways, there
is also a cost for installation, commissioning, and maintenance. 
Additionally, supporting multiple networks in a plant means that the
engineering and maintenance staff must be trained on multiple networks
and a number of specialists are needed to support each type of
network.  This means additional expenses.  With Ethernet throughout the
plant, these costs are greatly reduced and in the case of additional
gateways, completely eliminated.

Ethernet opens up a whole new toolbox for you.
Once
a plant decides to standardize on Ethernet, a whole new world of
technologies are available.  New innovations in the Ethernet community
provide constant improvements in automation technology.  These advances
save time and money during design, engineering, and commissioning.  

Many
of these new technologies have been enabled by the addition of
real-time protocols to Ethernet.  Because protocols such as TCP/IP and
OPC by themselves do not support real-time capabilities, there has been
considerable innovation that has provided automation-based protocols
for Ethernet.  Several protocols from different field bus organizations
now provide real-time, automation-based solutions.  These field bus
organizations have transformed their real time device level network
strategies of the past into protocols that runs on today’s Ethernet
networks.  As a result, it is possible to do much more on Ethernet
today than in the past.

Give your devices the new party line.
Adopting
the versatile Ethernet network makes it possible to streamline
communications by letting devices talk directly to each other. These
devices can be as simple as an I/O module or as complex as a complete
automation cell.  Device-to-device communications are becoming
increasingly common as engineers figure out how to use data without
taking time for humans to review it. With Ethernet, it is much simpler
to communicate because Ethernet enables more comprehensive protocols. 
In the past, adding a camera to an automation controller was a
difficult task because of the type of data that a camera transmits. 
With Ethernet based protocols, data easily passes between the camera
and the controller.

Ethernet setup is easy. Really!
Equally
important, it is simpler to set up the communications between these
devices. With existing field buses, systems must be hardwired to
communicate, or programmers must figure out the various commands for
each device, writing complex programs to tie them together.  Using
Ethernet opens the door to device-to-device communication protocols,
which let users link pieces of equipment with graphical engineering
tools by simply drawing communication lines. Devices such as
independent machines can be identified on the user’s screen as
component icons that identify the information points going in and out
of the machine. Users do not have to know the application program or
even how to program at all. They can simply link the machines by
drawing lines between these components. That makes it very easy to tie
them together and to alter these machine-to-machine communications as
needs change.

Ethernet lets you unplug and go wireless.
The
benefits of Ethernet’s seamless networking environment extend to
wireless communications as well. For many companies, one of the biggest
potential benefits of Ethernet is the ease of adding wireless
communications. This was not possible with past field network
protocols. Wireless can be a real advantage for industrial
applications. Equipment can be moved without worrying about wiring. A
distributed I/O connected to field devices such as sensors and motors
can be installed in hard-to-reach spots. Temporary monitoring stations
can be installed without the cost or danger of stringing wires around
equipment.

Expanding into wireless technology for automation
is easily accomplished by implementing the Wi-Fi technology that is an
extension of the wide-ranging 802.x Ethernet specifications and the
automation protocols designed for them. A number of companies have been
using Wi-Fi in harsh factory environments for years.
 
Wi-Fi
simplifies the transition to wireless, maintaining all the commands and
protocols of conventional wired Ethernet networks. Employing Wi-Fi
extends the compatibility that comes with using Ethernet throughout the
enterprises, bringing ease of maintenance along with compatibility.

This
trend to wireless communications is expanding rapidly because it brings
a high level of freedom.  Operators who have to move equipment used to
have to deal with wiring trays that were difficult to set up and
manage. Wireless links eliminate that complexity. Similarly, engineers
can add sensors to monitor equipment in a matter of minutes.

Imagine the possibilities if you didn’t need to hard wire.
Eliminating
wires also facilitates the use of autonomous vehicles that can deliver
materials or components. Traditionally, these automatic guided vehicles
(AGVs) communicated back to a central controller over a hardwired
network using slip-ring technology.  This technology, because of its
mechanical nature, had many possibilities for failures, so maintenance
costs were frequently very high.  When these robotic vehicles can
communicate over a wireless network, they can move freely and alter
their routes to maximize efficiency since they are not physically
tethered to a network cable.

Gimme bandwidth! Dedicated circuits and expansion headaches are history.
Ethernet
also has the bandwidth to support protocols for safety signals and
communications.  Eliminating dedicated safety circuits and wiring
provides a significant benefit in plants where expansion and equipment
upgrades are common.

When safety signals are sent over
Ethernet, safety circuits can be handled in ladder logic that runs on
automation controllers. Safety equipment such as a light curtain is
typically linked to a failsafe input card that sends alerts to
automation controllers over Ethernet.

Using Ethernet to carry
these safety signals also makes it simpler to keep a plant up and
running. Conventional safety relays shut down power to broad areas,
regardless of the type of problem. With Ethernet connectivity to all
equipment, it is a straightforward process to program systems to only
shut down the equipment that is related to the safety alert.

The
system can analyze the reason for a safety alert, and then determine
whether all equipment in the area of the alert should be shut down or
whether sections of the system can continue running without danger.
Since Ethernet and Wi-Fi are tightly integrated, these benefits extend
to all equipment linked to the safety system even with a wireless
connection.

Toss out the limitations of field bus technology.
Using
Ethernet allows for many more possibilities in the types and number of
devices that can be communicated across a network.  Traditionally,
distributed devices at the controller level were limited by the field
bus technology.  These field buses were limited and dedicated, so only
a set number of devices could be connected to the network. The amount
of data sent back to the controller was limited to relatively small
packet sizes.  This was fine for normal I/O and drives, but became
challenging for peer communications or very large installations. 

Be flexible and sophisticated while you’re lowering costs.
With
Ethernet, another level of freedom comes from the ease of communicating
with sophisticated devices like motion controllers and automated vision
systems. Ethernet has the bandwidth to support them, and its I/O
structure makes it simple to add, upgrade or move these devices as
needed. Ethernet can support several thousand addresses, making it
possible to add large numbers of devices.  Removing the restrictions
posed by traditional field buses makes it easier to design a complete
machine communication infrastructure. 

Bandwidth expansions will increase to give you more capabilities.
This
bandwidth will continue to increase further in the future. Industrial
versions of Ethernet now use the standard 1 Gbit/second, with the
promise of 10 Gbits/second coming as this version expands into the
mainstream of the commercial world.  The IEEE standards body is already
working on a 100 Gbits/second version, offering a road map that simply
does not exist for many existing field buses, which are limited to
existing speeds.

Enter the web server…. now you’re global fast!
Another
interesting technology that is made possible by Ethernet is the use of
Web servers for displaying data about a device or machine system. 
Embedding a Web server inside a device on an Ethernet network makes it
possible to link into it with a standard Web browser from a remote
location to display current status or diagnostic information.  Since
the Web server is part of the device itself, no programming is needed
to display a wealth of information.

Yes, the factory is not your home.
Though
installing Ethernet in a manufacturing environment is fairly
straightforward, adopters must realize that there are differences over
the plug and play aspects of home networks. First is the physical
network itself. Ruggedization and shielding must be added in industrial
applications. Often, network wires must be heavy duty, shielded cables
to block out noise interference produced by the equipment inside the
plant. 

Additionally, industrial switches exist which are
designed for the automation environment.  These switches perform the
same function as a non-industrial rated switch, but are designed to run
in industrial applications where the environments are harsher than in
the typical back office.  While these switches can coexist with the IT
network, they are configured in the automation engineering environment
and are able to be diagnosed by the automation controller and HMI. 
 
One
of the keys for many industrial operations is the need for determinism.
In factories, messages that start or stop operations have to arrive on
time. Delays of just a few milliseconds can destroy entire production
runs or injure workers. This is an aspect of the industrial environment
that does not exist in offices where there is rarely an impact if an
e-mail arrives a few seconds late.

Gain the benefit of real-time communications.
Over
the past few years, many different Ethernet protocols have emerged to
address the factory’s need for precise timing.  These protocols provide
determinism without impacting compatibility with existing data
transfer.  This means that real-time communications can connect a
controller and a servo drive on the same Ethernet network that sends
database records to the MES.  The real-time protocol guarantees that
the drive data is delivered from the controller on time with higher
priority than transferring the record to the database.  Since this is a
property of the protocol itself, the user does not have to worry about
special programming for deterministic data. 

Gaining all these
benefits does not require a lot of effort.  Ethernet is well proven in
the industrial field. The ARC Advisory Group pegged the market at 1
million nodes in 2007, forecasting an increase to over 3 million nodes
by 2012.  The size of the market underscores the availability of
components, systems and installation expertise.

Adding all these
factors together has led many management teams to the same conclusion:
Ethernet offers a low cost, high bandwidth, standard network
infrastructure that greatly simplifies connectivity, ease of
installation, and maintenance while still meeting the performance needs
of the automation environment.  Integrating this network infrastructure
into factory floor automation offers solutions that can greatly
increase productivity in ways that were not possible before.

Written by Eric Kaczor, Product Marketing Manager, Siemens Energy & Automation, Inc.