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Introduction
Factory Floor Applications
Network Management
Legacy Equipment Applications
Extreme Temperature Applications
Ethernet
Ethernet Challenges
Role of SNMP
General Requirements for the Industrial Environment
Industrial Conversion Products from Transition Networks
Glossary While network managers yearn
for the latest equipment and higher speeds, budgetary restrictions impose
limitations and precipitate a less than homogenous network. Inevitably, network
administrators must contend with a variety of protocols, speeds, and media in
their networks. Media conversion technology was developed to address these
problems and has evolved from a stop gap technology into a technology that
offers network administrators new choices for deploying fiber optics into their
networks cost effectively. Those in industrial environments face the added
challenge of creating interoperability throughout a network in less than ideal
conditions. Network administrators in industrial environments are challenged to
ensure network performance in harsh outdoor and factory floor conditions. The following paper will
provide an overview of media conversion technology and the role it plays in
industrial applications. Introduction to Media Conversion
For those unfamiliar with conversion technology, media converters connect
dissimilar cable types, making it possible to mix media and speed on a
network to optimize price and performance. Whether extending legacy networks
with the latest technology, or connecting inexpensive, lower bandwidth
desktops to a state of the art fiber optic backbone, media converters offer a
viable lower cost solution. Media converters are
commonly used to connect UTP (unshielded twisted pair) copper cabling and
fiber optic cabling in a network cabling plant. Media converters can be
effective in networks that have legacy cabling such as Coaxial or Twinaxial
cabling and need to be integrated with UTP or fiber optic cabling. Converters
are also used to convert multimode fiber into single mode fiber for the
purpose of extending distance. Multimode fiber has a distance limitation of 2
kilometers while single mode fiber can be used to extend distances up to 80
kilometers. Media converters are
protocol specific; meaning an Ethernet converter is needed to convert
10BASE-T to 10BASE-FL. Media converters do not convert protocols, such as
Serial to Ethernet. However, media converters exist for a broad range of
protocols including Ethernet, Fast Ethernet, Gigabit Ethernet, T1, DS3,
RS232, RS485, V.35, analog phone lines, video, and more. Conversion technology solutions offer the ability to: - Add new devices without replacing costly equipment and cabling
- Extend network distances by adding fiber where and when it is needed
- Provide a link between media types, transparent to the network
- Keep pace with growing demand and new technology
- Integrate high bandwidth devices into the network
Converters exist in a
variety of form factors, such as standalone, multi-port, and modular chassis.
These different physical forms address the various applications that
exist.  |  |  | | Stand-Alone | Multiport | Modular Chassis |
|---|
Figure 1: Media Conversion Form Factors Multiple connections as
well as multiple protocols can be easily accommodated by a media conversion
chassis or in a rack for standalone converters.
As alluded to earlier,
there are numerous applications for media conversion products. The following
outlines various industrial applications and media conversion solutions. The
applications have
been grouped into categories for ease of understanding:
-
Factory Floor
Applications
-
Network
Management
-
Legacy Equipment
Applications
-
Extreme Temperature
Environments
Whether you require
several disparate interfaces to be networked or you have Ethernet throughout
the network, Transition Networks can provide you an integrated cost effective
solution. Figure 2 represents
different types of interfaces accommodated by using Transition’s Point
System chassis and various remote end conversion solutions. (click for larger view)
 Figure 2: Indoor Industrial Application There are instances in a large factory in which a connection may have to run
through the manufacturing floor to connect to a remote device.
(Figure 2). Some factory environments, as well as power plants and
sub-stations, have equipment that may produce significant levels of EMI
(electromagnetic interference), which can have adverse effects on data
transmitted across copper based cabling. Use of fiber optic cabling virtually
eliminates any effect EMI may have on the data transmission. Media converters
convert electrical signaling into fiber optic lightwaves, eliminating EMI and
RFI (Radio Frequency Interference). Some network applications
are mission-critical and require SNMP management. SNMP management is useful in
industrial environments where devices may not be accessible during factory
operations or may be inconvenient due to distance or location. SNMP has many advantages.
SNMP management allows network administrators greater monitoring control. One
advantage of SNMP is the ability to set traps. Traps can be used to trigger
alarms in the event of a problem. For example, a wastewater treatment plant
may have a remote pumping station with a SCADA system attached to several
devices. The SCADA system has an un-interruptable power supply.
Transition’s media converters are placed at each device to provide
fiber to copper conversion. Communication between the pump and the main
control station are done via Ethernet. The SNMP Management software can
monitor the remote media converters and use traps to determine if there is a
power loss to the pump station, which could then send notification to
maintenance. SNMP Management allows for greater control and less downtime. Figure 3 below depicts the functionality of Transition’s SNMP management software, Focal Point. (click for larger view)
 Figure 3: Focal Point Management Software Many industrial locations have intelligent device monitors and other
equipment that needs to be networked together. Media converters can be used
at either end of the fiber optic cable to allow for centralized control. For example, a wastewater
treatment plant has a processing building, a maintenance building, and a main
plant. Each building had legacy PLC (Programmable Logic Controller) stations
located throughout. The PLCs had serial interfaces and were connected to a
main controller within each building. The wastewater treatment plant wanted
to migrate to centralized control. Stand alone High Speed Serial media
converters are used at the remote locations to connect to the remote PLCs and
transmit the data back to the main building. A Point System chassis with High
Speed Serial media conversion cards are used to connect to the new
centralized main controller in the main plant. The High Speed Serial
conversion solution allowed the wastewater treatment plant to move from
distributed control to a more centralized control system while saving
money. (click for larger view)
 Figure 4: Wastewater Treatment application This solution enabled the wastewater treatment plant to incorporate their existing equipment, while
reducing costs and allowing for future growth. In addition to factory applications, industrial products are needed to
address outdoor environments. Outdoor applications are primarily concerned
with temperature extremes. Other elements such as moisture, dust, and debris
are minimized with the use of equipment enclosures. Outdoor enclosures are
subject to industry standards for performance such as standards set by NEMA,
UL, and IEC. An example of an outdoor
industrial application is traffic control. Traffic control systems have
traditionally used coaxial or serial interfaces for the interconnection of
outdoor traffic data devices and the control center. The video Codec in this
application converts the analog video signal into an Ethernet signal. Stand alone Extended
Temperature media converters from Transition Networks are placed at the
remote end, connecting pole top cameras with copper interfaces to fiber optic
cabling. The fiber can extend the distance up to 80 kilometers(depending on
the protocol) using single mode fiber back to the control center. A Point
System chassis located in the data closet at the control center accepts the
fiber signal, converts it, and connects to the copper equipment at the main
site. Extended Temperature media
converters at the remote end ensure successful transmission for non climate
controlled environments.In this scenario, equipment enclosures are used to
protect against other environmental factors such as debris, wind, and
water. (click for larger view)
 Figure 5: Outdoor Media Conversion Application Transition Networks offers
a couple of ways to manage remote media converters. Network administrators
who require more detailed information regarding remote converters can utilize
Transition’s remotely managed converters in conjunction with our SNMP
management software. Transition’s unmanaged media conversion products
offer similar feature functionality through Link Pass Through and Far End
Fault. Media converters with these features allow both near and far end
equipment too be alerted in the event of link loss. Summary
Media converters have evolved from their initial intent of adding one or two
fiber strands to a network as a quick resolution to a problem. Today, media
converters are offered in a wide variety of protocols and form factors to
address the complex needs of industrial applications.
Conversion systems from
Transition Networks offer management software which allows the network
manager to fully monitor and configure the systems. Even unmanaged Transition
converters provide critical features such as Link Pass Through, Far End
Fault, Pause, and Auto negotiation. Transition Networks offers full featured
conversion products to meet the requirements of industrial applications. As
demonstrated in the applications mentioned, media converters provide unique
solutions for difficult problems and cost savings when implementing fiber
into your network.
One of the most common data communication protocols used in Enterprise
applications is Ethernet. The Ethernet protocol was developed in the 1970s by
the Xerox Palo Alto Research center. Primarily used as the Local Area Network
technology for offices, it was standardized in 1983 by IEEE (802.3 standard).
The popularity of Ethernet has pushed many improvements. Increases in
technology have led to the development of Fast Ethernet, Gigabit Ethernet,
and 10Gigabit Ethernet. Bandwidth demands will continue to drive the
evolution of Ethernet. The advantages of Ethernet
are becoming applicable in industrial environments. A more open standard for
data acquisition and transmission is needed for industrial automation. An
increasing number of companies are looking to Ethernet rather than the
traditional proprietary bus topologies, such as Fieldbus, Modbus, Interbus,
Profibus, etc. The use of Ethernet protocol is increasing in process control,
building automation, traffic control systems, power stations, medical, and
wastewater treatment applications. What is giving rise to the use of Ethernet in Industrial Applications?
Ethernet provides many advantages to the office environment. It allows users
to share files, printers, search the Internet, and support other high
bandwidth applications for office workers. A factory floor has more complex
communication needs. Data must be accessed from workstations, I/O devices,
and other automation systems. The data for a factory floor is very time
sensitive and requires real-time communication. For example, the timing for
robotic equipment needs to be real-time in order for the automation process
to work. In the past, industrial
automation protocols were proprietary and locked users into a specific
architecture. Ethernet’s widespread popularity, performance, low cost,
and its standardized PC and Windows compatibility have made it attractive for
industrial applications. Ethernet capability is being built into industrial
measurement equipment such as I/O devices and data acquisition equipment.
Data acquisition and I/O products are use to interface directly
thermocouples, strain gauges, load cells, flowmeters, waveform signals, etc. One issue with Ethernet in the industrial market is interoperability or
interchangeability between devices from different vendors. In regards to the
OSI model, Ethernet only provides physical and data link protocols. The upper
layer protocol determines which devices can connect and interoperate at the
network layer. Determinism, the ability
to predict when information will be delivered, is an issue with standard
Ethernet that needs to be addressed for industrial Ethernet. As mentioned
above, Industrial networks have time critical applications and require
scheduled bandwidth to guarantee delivery. Originally, Ethernet was
half-duplex and existed on a bus topology. In classic or shared Ethernet, all
the network users share one collision domain. In half-duplex environments,
the network access is controlled by CSMA/CD (Carrier Sense Multiple Access
with Collision Detection). Each device on the network senses whether the line
is idle. If the network is idle the device begins to transmit data; other
devices can be transmitting at the same time. Collision occurs when two or
more devices are transmitting. Consider an industrial scenario in which a
robotic arm solders a component, adding a specific part. If the network is
congested the robotic arm fails to add the component at the appropriate time. Several improvements have
been made to Ethernet all of which make it beneficial for industrial
automation: - Segmentation - subdividing the collision domains
- Higher bandwidths – the development of Fast Ethernet, Gigabit, and 10 Gigabit technologies
- Switched Ethernet
- Interoperability
Switched Ethernet
separates collision domains into point to point connections between the
network components and the equipment, allowing full bandwidth availability
for each connection. The separate pair of wires used to detect collision is
now used for transmission, increasing transport speeds. Several proprietary and
open fieldbus networks (application layer) are being used in industrial
automation applications. The most common control networks are Profibus,
DeviceNet, ControlNet, and Foundation Fieldbus. These control networks
include standardization at the application layer and provide a higher level
of interoperability. Ethernet is being considered for these control networks
as well. The advantage of Ethernet is its wide spread acceptance, cost and
speed. The industrial protocols competing for acceptance includes
Ethernet/IP, PROFInet, IDA, and Foundation Fieldbus. A detailed analysis of
Ethernet protocols is beyond the scope of this paper. However, Ethernet/IP is
considered a front runner due to its popularity and sponsorship by The
Industrial Ethernet Association, the Open DeviceNet Vendor Association
(ODVA), and ControlNet
International (CI). Ethernet/IP is an
industrialized version of Ethernet TCP/IP. Ethernet/IP uses TCP/IP
encapsulation to provide a common application layer protocol over Ethernet
designed to handle both implicit and explicit messages. The standard
application layer allows interoperability and interchangeability among
industrial automation and control devices. It does this by using both the
DeviceNet and ControlNet standards called Control and Information Protocol
(CIP). It defines the access, behavior and extensions, which allow different
devices to be accessed using a common protocol. Using the CIP layer over
Ethernet/IP offers consistent devices access. It organizes network devices as
a collection of objects and means it can use one configuration tool to
configure disparate devices on a network. Its tie to Ethernet ensures that
Ethernet/IP will evolve as Ethernet evolves. (See Figure 6) (click for larger view)
 Figure 6: Industrial Protocols Most industrial automation environments require remote device management.
The device requesting information is referred to as the manager, while the
agent is the device being managed. SNMP is an application layer protocol that
uses UDP (datagram) protocol for communication between the manager and the
agent. SNMP allows network managers to monitor the health of the network and
the devices attached to the network. In analyzing devices for industrial
environments SNMP management is an important consideration. Ethernet works well in controlled office environments, but most equipment
developed for commercial use is not robust enough for the demanding industrial
environment. Dust, temperature extremes, moisture, and other outside factors
affect industrial applications and play havoc on equipment. Ethernet equipment
designed for an office generally does not work in an industrial environment. If
it does, it may only work temporarily. New products are being
introduced to meet Ethernet needs for the industrial workplace. The industry
standards are still being finalized, but companies are beginning to release
industrial Ethernet products. Transition Networks brings their reputation of product excellence to the
industrial environment. Transition Networks’ extended temperature media
converters can be placed in harsh temperature environments where many
traditional conversion products fail to meet the extended temperature range
necessary for reliable operation. Transition’s industrial Ethernet media converters have: -
Extended temperature
operating ranges
-
Tradition of
ruggedness
-
Choice of wide input 18
– 72 VDC power
-
DIN-Rail mounting
options
Transition’s
industrial offering includes extended temperature ranges for Ethernet and
Fast Ethernet. The Extended Temperature media converters have a broad
operating temperature range of -25°C to +70°C, which is a drastic
improvement over many competitive products with a 0°C to +40°C
operating temperature range. In addition, both products include many of the
extensive features commonly found on Transition’s stand-alone media
converters. The extended temperature Ethernet product includes
AutoCross™ and Link Alert™, while the extended temperature Fast
Ethernet product includes Auto-Negotiation, AutoCross™, Link Pass
Through™, Far End Fault (FEF) and Pause. Feature functionality is
important in industrial applications to determine link failure. 
Figure 7: Extended Temperature Media Conversion Application Transitions’
Din-Rail mounting options take the converter off the workstation and out of
the way. Use Din-Rail to mount multiple media converters on the wall, making
installation simple and efficient. 
Figure 8: Din Rail mounting bracket Transition’s
Extended Temp Ethernet and Fast Ethernet products are available immediately.
Both are offered in a stand-alone form factor only. Transition Networks
continues to monitor the progress of industrial Ethernet standards and
continually adds features to meet the needs of our industrial clients. Please contact Transition
Networks at (800) 526-9267 or +952-941-7600 to determine how we can meet your
industrial requirements. ControlNet
– a real-time, control layer network providing for high speed
transport of both time critical I/O data and messaging data, including upload
and download of programming and configuration data and peer to peer
messaging, on a single physical media link. Ethernet/IP
– an industrial application layer protocol designed for industrial
automation applications. It is built on the standard TCP/IP protocol and uses
Ethernet hardware and software to define an application layer protocol for
configuring and controlling industrial devices. It is based on the Control
and Information Protocol (CIP) layer used in ControlNet and DeviceNet. IEC
- International Electrotechnical Commission – The global organization
that prepares and publishes international standards for all electrical,
electronic and related technologies. These serve as a basis for national
standardization and as references when drafting international tenders and
contracts. ISO
- ISO, founded in 1947, is a worldwide federation of national standards
bodies from some 100 countries, one from each country. Among the standards it
fosters is Open Systems Interconnection (OSI), a universal reference model
for communication protocols. Many countries have national standards
organizations such as the American National Standards Institute (ANSI) that
participate in and contribute to ISO standards making. Modbus
– a protocol that is a messaging structure developed by Modicon in
1979. Modbus is used to establish primary-secondary/client-server
communication between intelligent devices. OSI Model
- Open Systems Interconnection is a standard reference model for
communication between two end users in a network. The OSI Reference Model
describes seven layers of related functions that are needed at each end when
a message is sent from one party to another party in a network. PLC
– Programmable Logic Controller. A device used to automate monitoring
and control of industrial plant. Can be used stand-alone or in conjunction
with a SCADA or other system. PROFIbus HSE
- One of the fieldbus standards represented by the Fieldbus Foundation,
which is designated for an Ethernet backbone and for industrial automation.
It uses TCP, UDP, and IP protocols. UDP/IP
– User Datagram Protocol/Internet Protocol. Used by Ethernet/IP for
real-time messaging. UPD/IP can multicast and send implicit and explicit
messages. SCADA
– (Supervisory Control and Data Acquisition) is a category of software
application program for process control, the gathering of data in real time
from remote locations in order to control equipment and conditions. SCADA is
used in power plants as well as in oil and gas refining, telecommunications,
transportation, and water and waste control. SNMP
- Simple Network Management Protocol (SNMP) is the protocol governing
network management and the monitoring of network devices and their functions. TCP/IP
- (Transmission Control Protocol/Internet Protocol) is the basic
communication language or protocol of the Internet. It can also be used as a
communications protocol in a private network (either an intranet or an
extranet). UL
– Underwriters Laboratories Inc. Enclosure rating organization which
requires performance testing by qualified evaluators. An independent,
not-for-profit product safety testing and certification organization. (back to top)
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