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10 Issues To Consider Before
Installing Industrial Ethernet
Introduction
This booklet is intended to assist you with the installation of an Industrial Ethernet network. Interest in Industrial
Ethernet as a possible fieldbus replacement has increased dramatically. Ethernet is already recognized as the most
popular local area network technology, and it is finding its way into more applications in factories and process plants.
Still, by itself, Ethernet is not a fieldbus since it is only a physical and data link layer technology. We believe a
fieldbus requires an application layer, and for the present, no universal industrial application layer has been found.
However, there are proposals and we see increasing use of Industrial Ethernet.
Contemporary Controls defines Industrial Ethernet as technology compatible with the Institute of Electrical and
Electronics Engineers (IEEE) 802.3 family of standards, but designed and packaged for the requirements and rigors of
commercial and industrial applications. Although the basic Ethernet technology is over 25 years old, it has been
re-invented several times since its introduction as a half-duplex, shared-media technology. The demands of the much
larger commercial market have driven the development of the standard into a high-capacity, high-speed network
technology. Although not ideal for the industrial user who is familiar with fieldbuses, Ethernet is quite suited for many
applications. It also provides convenient connection to the Internet which offers many possibilities to the designer. Its
perceived lower cost and familiarity to customers adds to its attractiveness. Industrial Ethernet can be effective as long
as you understand how it can be applied.
Like fieldbuses of today, the original Ethernet was constructed as a bus system where individual stations shared a
common backbone connection. This coaxial cable backbone was termed "thicknet" for its bulky appearance. Eventually
the IEEE standardized this physical layer as 10BASE5. A subsequent bus implementation called "Thinnet" was
standardized as 10BASE2. These two bus standards (referred to in IEEE terminology as mixing segments) are no longer
popular. What is popular today is the link segment consisting of either twisted-pair or fiber optic cabling. A link
segment is defined to have only two devices attached to a link. In order to expand an Ethernet network a two-port
repeater or multi-port hub must be used. Popular link standards are 10BASE-T, 10BASE-FL, 100BASE-TX and
100BASE-FX. Since there are several physical layer options, Industrial Ethernet can be a bit confusing. There are issues
when installing Industrial Ethernet, and we address ten of them in this booklet.
Contemporary Controls is a registered trademark of
Contemporary Control Systems, Inc. CTRLink is a
trademark of Contemporary Control Systems, Inc. Other
product names may be trademarks or registered trademarks
of their respective companies.
©Copyright 2002 Contemporary Control Systems, Inc.
Februrary 2002
CCIEBrochureFeb02
1 Topology
3
Topology is the arrangement of cables within the network. A point-to-point connection would involve a
single station connected to a port on a hub, a hub connected to another hub or a station connected to
another station. Most industrial users are familiar with the bus connection where several stations share a
common connection. EIA-485 or Controller Area Network (CAN) are good examples of bus networks.
Unfortunately the bus topology is dead with Industrial Ethernet. Although 10BASE2 and 10BASE5 are indeed
bused coaxial Ethernet networks, they are not popular since they are limited to 10 Mbps half-duplex operation
and, most importantly, they are not included in the commercial building wiring standard TIA/EIA-568-A
which is frequently used when wiring new buildings. For these reasons, Industrial Ethernet is wired in a star
topology requiring either a repeating hub or switching hub to be in the center of the “star.” Therefore, forget
about wiring your conveyor system in a very convenient bus topology. If you want Industrial Ethernet, you
need to wire it in a star or distributed star topology. A distributed star requires a hub-to-hub connection.
2 Cabling
Now that we have eliminated coaxial cable from consideration, what cable can you use? You can use either
shielded twisted-pair (STP), unshielded twisted-pair (UTP), multi-mode or single-mode fiber optic cable. We
will ignore wireless in this discussion. There are several categories of twisted-pair cable based upon
bandwidth and, therefore, performance. At the lower 10 Mbps data rate, there is usually not too much concern
Industrial Ethernet is usually wired in
about cable quality. However, if plans are for eventual migration to 100 Mbps, then either Category 5 or 5e is
a star or distributed star topology.
highly recommended. In fact, if you are pulling new cable only use one of these two cables. UTP is much more
popular than STP. STP will only be effective if shielded RJ-45 jacks are being used on the equipment.
For each fiber optic link, a pair of fibers is required. Usually several fibers are pulled to provide spares. The most popular
multi-mode fiber optic cable is 62.5/125 µm; however, 50/125 µm can be found. A single-mode fiber optic cable will have an inner
core diameter of 10 µm or less. At 10 Mbps, usually multi-mode fiber is used. At 100 Mbps, both single-mode and
multi-mode fiber can be found.
3 Connectors and Connections
For twisted-pair cable, the RJ-45 remains the most popular connector although it is frequently criticized for its lack of robustness.
There has been a movement to utilize IP67 rated micro connectors for data rates up to 100 Mbps. As a compromise, bulkhead
mounted “boot” covered adapters exist to make RJ-45 connectors survive an IP67 environment.
For twisted-pair cabling, two pairs are required for communications. One is for transmitting and the other for receiving. The
pinouts on the RJ-45 connector define the medium-dependent-interface (MDI) and are labeled RD+, RD–, TD+ and TD–. These
signal definitions are for the data terminal equipment (DTE). A DTE is any source or destination for data. An example of a DTE
would be a workstation. On the other end of a link is data communication equipment (DCE). DCEs facilitate data communication.
4
An example of a DCE would be a repeating hub or switching hub. In order to communicate,
transmitters must be tied to receivers so there must be a crossover of signals. If the crossover
function is accomplished at the connector, the connector should be identified as a MDI-X port. This
is what is usually done on hubs so that straight-through cables can be used to attach a DTE to a
DCE. What happens if you want to connect two DTEs together or two DCEs together? You would
need a crossover cable. On some hubs, an uplink port is provided. Instead of being a MDI-X port,
the uplink port is a MDI port so a straight-through cable can be used for cascading hubs.
For fiber optics, there are two types of approved connectors. The quarter-turn ST connector is
used at either 10 or 100 Mbps while the SC can be found only at 100 Mbps. For single-mode cable,
usually the SC connector is used. A pair of fibers are used for each link in order to support
separate receive and transmit paths. Therefore, like twisted-pair connections, receivers must be
tied to transmitters, requiring a crossover cable. Ports on both the DTE and DCE are marked as
TX and RX to guide connections.
4 Industrial Ethernet or COTS
MDI 10BASE-T Port Assignments
RJ-45
Usage
1
TD+
2
TD–
3
RD+
4
Not Used
5
Not Used
6
RD–
7
Not Used
8
Not Used
RJ-45 connector and pinouts
Proponents of Ethernet maintain that low-cost commercial-off-the-shelf (COTS) devices can be
used in industrial control systems. In some applications this is valid. So what is Industrial
Ethernet? Contemporary Controls defines Industrial Ethernet as technology compatible with the IEEE 802.3 family of standards,
but designed and packaged for the requirements and rigors of commercial and industrial applications. Process plants and
factories want to use commercially available Ethernet chips and media, but these plants have requirements that differ from those
in an office. The first obvious concern is environmental with issues such as high temperature, humidity and vibration. The second
concern is convenient mounting with other control equipment in the same control panel. Another requirement is the power
source. For safety, some control panels only provide low-voltage AC or DC power to control devices. Wall-mounted power
supplies may not be acceptable. The electromagnetic compatibility (EMC) requirements differ with industrial locations requiring
a higher immunity to EMI and ESD. Regulatory safety approvals differ from that in an office. Process plants may require
hazardous location ratings. A factory may require an industrial control panel approval while a building automation system may
necessitate a smoke and fire approval rating. These are unique application standards that low-cost, office-grade Ethernet hubs
and switches fail to address. Consider if you want an office hub, mounted with Velcro®, on your $100,000 machine.
5 Speed and Distance
Although the IEEE 802.3 standard addresses data rates from 1 Mbps to 1000 Mbps (soon to be 10,000), 10 Mbps and 100 Mbps are
of the most interest. Of course most people think faster is better, however, there are tradeoffs especially when it comes to shared
Ethernet. Shared Ethernet or half-duplex Ethernet is the original technology where medium access is determined by the ever
famous carrier-sense, multiple access with collision detection (CSMA/CD) algorithm. With a half-duplex medium, transmitting
and receiving is possible but not at the same time otherwise a data collision will occur. Before a station initiates a transmission, it
first waits for a clear channel. During the transmission, the originating station listens for a time to ensure that the transmission is
faithfully produced and that no other station attempts a simultaneous transmission. If one occurs, this is called a collision and the
originating station will reinforce the collision by applying a JAM signal. All stations will notice the collision and will discard the
frame. The competing stations will back off for a random amount of time (based upon an algorithm) and will renew their attempt.
In order for this mechanism to function, all stations and all hubs must reside in what is called a collision domain.
In Figure 1 you will notice several devices attached to the same network interconnected with four repeating hubs. The
complete network is contained in one collision domain. All cabling is assumed to be twisted-pair. Also assume that we are
operating at 10 Mbps. There are several factors that limit distance. The first is the maximum segment length which is limited to
100 m at either 10 or 100 Mbps. A segment is a continuous length of cable between any two devices. Devices could be either hubs
or workstations. The second limitation on distance is the
maximum network diameter which is limited by the collision
domain. The distance between the two furthest devices
within the network is called the network diameter. In order
for the collision detection mechanism to function, the round
trip propagation time between the two furthest devices must
be shorter than the Ethernet slot time plus preamble. The slot
time is the time it takes to send 64 bytes, and the preamble
requires 8 bytes. At 10 Mbps this translates to 57.6 µs and at
100 Mbps this translates to only 5.76 µs. Since the time it
takes for a signal to propagate down a twisted-pair cable
(5.65 ns/m) is the same at 10 Mbps as it is at 100 Mbps, the
network diameter is drastically reduced at 100 Mbps. The
Figure 1. With shared Ethernet, all devices and associated
IEEE 802.3 standard has a lengthy discussion on the use of
cabling must reside in a single collision domain.
repeaters to extend network length; however, the rules are
not simple. One rule we can use, however, is the 5-4-3 rule.
The 5-4-3 rule only pertains to 10 Mbps repeater operation. The rule states that a network can have up to five segments, four
repeaters and no more than three mixing segments. A mixing segment is a coaxial bus segment which we are ignoring. Therefore,
Figure 1 represents our maximum sized network. Since twisted-pair segments can be up to 100 m in length, the maximum
network diameter is 500 m. This is a simple and effective rule but somewhat conservative. The rule is not very helpful when it
comes to fiber.
Although fiber optic segments can be up to 2 km, you are not allowed to cascade five segments. The IEEE 802.3 standard says
that if you limit the number of repeaters to three and retain twisted-pair segments at each end of the network, the two remaining
segments can be fiber optic as long as each segment does not exceed 1 km. From this you can assume that if you eliminate one
repeater and one fiber optic segment, the remaining fiber optic segment can be increased to its 2 km limit.
The 5-4-3 rule is not applicable at 100 Mbps. Although 100 Mbps repeaters exist, their use is severely restricted. At
100 Mbps the use of switches is recommended. At 10 Mbps either repeating hubs or switching hubs is recommended.
5
6
6 Hubs Versus Switches
Repeating Hubs
Modern Ethernet networks must be wired in a star topology utilizing either twisted-pair or fiber optic
cabling. Links, consisting of only two devices, are established between a single Ethernet device and a
port on a hub. Hubs are multi-port devices usually capable of having four, eight or twelve ports.
Hubs can be cascaded with a hub-to-hub connection.
Repeating hubs are available
Repeating hubs must conform to the requirements for IEEE 802.3 repeater units. These
in various port counts. Some
requirements include preamble regeneration, symmetry and amplitude compensation. Repeaters
models support fiber optics.
must retime signals so that jitter, introduced by transceivers and cabling, does not accumulate over
multiple segments. These devices detect runt packets and collisions and react by generating
a JAM signal. They automatically partition jabbering ports to maintain network operability.
Point to remember. There is a limit to the number of hubs that can be cascaded. Ethernet’s
contention-based station arbitration method requires that all stations note if a collision has occurred on the
network. The limit of this detection is called the collision domain, and it restricts the network’s overall size.
Exceeding the collision domain by introducing too many repeating hubs creates an unstable
Miniature repeating hubs can
network with lost messages and generally poor performance. However, on a properly designed
be DIN-rail mounted for a
network, repeating hubs are simple to understand and use, not to mention very effective.
neat industrial appearance.
Repeating hubs have been criticized because they do not improve the determinism of Ethernet.
With contention-based networks, such as Ethernet, it is impossible to predict the amount of time it takes
for a station-to-station message when collisions occur since the backoff time is variable. A potential solution
to this problem is to avoid collisions altogether.
Industrial automation systems frequently utilize master/slave protocols where a response from a slave only
occurs after a command is initiated by the master. This type of protocol tends to limit collisions and thereby
improves determinism. Repeating hubs will function quite well in this situation.
Media Converters
Miniature switching hubs achieve
higher network performance
than repeating hubs.
Another class of physical devices are the media converters. Sometimes called transceivers, these devices convert
one type of media to another. The most important conversion is from twisted-pair cable to fiber optics. Since
some hubs do not have any fiber optic ports, media converters are required in order to support fiber optic cable
in a network. Media converters should appear to the network as transparent devices. They are two-port devices
that do not store frames or detect collisions. They only convert the signals sent over one medium to compatible
signals over another.
A media converter simply
converts twisted-pair cabling
to fiber optic cabling.
Switching Hubs
7
It is possible to replace repeating hubs with switching hubs and achieve higher network
performance. Unlike repeating hubs, which are physical layer devices, the switching hub is
actually a bridge that connects two data links together. By doing so, collision domains terminate at
each switch port. Therefore, adding a switch doubles the possible geographic limit of the
network. Switches can be cascaded for an even larger network.
Switches are much more complex than repeating hubs. Each twisted-pair port automatically
negotiates with its attached device the data rate for that port, be it 10 or 100 Mbps. The flow control
By utilizing two fiber ports on a switch,
mechanism is also negotiated. For full-duplex segments, the PAUSE scheme is used. For half-duplex a fiber backbone can be achieved for
segments, the backpressure approach is used. The switch learns the port locations of Ethernet
reliable inter-building communication.
devices by reading complete Ethernet frames and observing source addresses. The switch then
creates and maintains a table of source addresses and corresponding port assignments. From that time on, traffic is restricted to
only those ports involved in a transmission. This allows for improved throughput since simultaneous transmissions can be
initiated on those ports without activity. Table values are aged to automatically accommodate changes to the field wiring.
If a broadcast, multicast or unicast transmission to an unknown destination is received on a port, all other ports are
flooded with the transmission.
In Figure 2 we have the same identical network as the preceding example except that all the repeating hubs have been
replaced by switching hubs. The result is that instead of one overall collision
domain we have several collision domains allowing us to have a much greater
overall network diameter. Within each collision domain you must follow the
same rules as stated before. You could add repeating hubs connected to switch
ports. You could also make it easy on yourself by only specifying switching hubs
and not repeating hubs. If you do that, the maximum twisted-pair segment
length remains at 100 m; however, switches can be cascaded with little concern.
If you want the same flexibility using fiber optics, we need to address the half-,
full-duplex issue first.
Repeating Hub Versus Switching Hub Debate
Figure 2. Because switches break the network into
multiple collision domains, the physical size
of the network is virtually unlimited.
From the above discussion, it would seem like switching hubs are an all around best choice over repeating hubs. However,
repeating hubs have their advantages. Repeating hubs are simple to understand, and you can connect a network analyzer to any
free port to observe traffic. This is not the case with switches which restrict traffic on ports depending upon the type of
transmission. A “flood” port on the switch is required in order to observe all traffic on the network. Switching hubs are bridges
that store and forward complete Ethernet frames creating a degree of data latency. Repeating hubs operate on the various
symbols sent down the cable and do not suffer any measurable data latency. Cascading switches aggravate the problem.
Therefore, you can see that repeating hubs, as well as switching hubs, have their place with Industrial Ethernet.
8
7 Half-Duplex or Full-Duplex
Full-duplex links are the key to extending the maximum network diameter of Fast (100 Mbps) Ethernet. Full-duplex requires
separate receive and transmit paths (link segments consisting of no more than two devices). These devices can be Ethernet
adapters or switching hub ports. Notice that we did not mention repeating hub ports. A repeating hub is part of the collision
domain and reinforces collisions received on any of its other ports. A repeating hub is not capable of full-duplex operation.
Although it is possible to have just two Ethernet adapters configured for full-duplex, expansion beyond two adapters requires a
switching hub capable of supporting full-duplex operation.
Half-duplex means transmitting and receiving over the same medium but not at the same time. Full-duplex allows for
simultaneous sending and receiving. Coaxial-based transceivers such as 10BASE5 and 10BASE2 are not able to invoke
full-duplex since they do not have separate receive and transmit paths. However, 10BASE-T and 10BASE-FL do have separate
receive or transmit paths and are capable of full-duplex operation depending upon the sophistication of the Ethernet adapter or
switching hub. If these interfaces are configured for half-duplex, then the simultaneous detection of receive and transmit activity
will trigger collision detection. These same interfaces configured for full-duplex would disable this collision detection logic since
full-duplex does not follow the CSMA/CD rules of shared Ethernet.
It is very important that a full-duplex link be configured properly. A station or switching hub port will send out frames at
will, ignoring the CSMA/CD protocol of shared Ethernet, if it is configured for full-duplex. If the other end is configured for
half-duplex, it will incorrectly detect collisions and take actions that could cause late collisions (which are not automatically
re-sent) and CRC errors. The result is a general slowdown of the network negating the benefits of migrating to Fast Ethernet.
As mentioned before, at 100 Mbps the maximum network diameter is short because of the limited collision domain at this
speed. This is not a problem with twisted-pair link segments and switch ports because the maximum twisted-pair segment length
is 100 m which is within the collision domain limit. The problem is with fiber optic ports which allow segment lengths of 2 km for
multi-mode operation and 15 km or greater for single-mode operation. Under the rules for half-duplex CSMA/CD Ethernet, our
point-to-point fiber optic segment is limited by the collision domain to 412 m. However, with full-duplex operation, which
ignores the CSMA/CD algorithm, fiber optic segments can be extended to their limit.
With Fast Ethernet, the use of switch technology is recommended. When using Fast Ethernet over fiber optic cabling,
full-duplex operation is recommended.
8 Auto-Negotiation
With the proliferation of Fast Ethernet and the similarity of the cabling components to conventional Ethernet, a means was
proposed in IEEE 802.3u to automatically configure Fast Ethernet ports to work with either legacy Ethernet ports or other Fast
Ethernet ports. This configuration protocol was based upon National Semiconductor’s NWay standard. There is a way for
twisted-pair links to automatically configure compatible formats in order for links to begin communicating. This scheme was
intended for twisted-pair links and not coaxial buses. Coaxial cable is a legacy 10 Mbps standard that is not in the plans for
evolving Ethernet. Fiber optics is a different story. Although fiber optics is very much in the plans for evolving Ethernet, there is
no simple way for two fiber optic devices to auto-negotiate data rates since a 10BASE-FL device operates at 850 nm while a
100BASE-FX device operates at 1300 nm. These devices will not interoperate. However, there is nothing in the Auto Negotiation
protocol to prevent two fiber optic devices to auto-negotiate if communication is possible. Recognizing this, the 100BASE-SX
standard was recently introduced which incorporates 850 nm fiber optic components that can function at either 10 or 100 Mbps.
At 100 Mbps, these devices are limited to 300 m segment lengths. Therefore, it is important that the installer fully understand the
capabilities of the fiber optic equipment. Frequently with fiber optics, the data rate is fixed and not
1000BASE-T full-duplex
negotiated. The auto-negotiation protocol functions best on twisted-pair links.
The benefit of auto-negotiation is to provide hands-free configuration of the two devices attached
1000BASE-T
to the link segment. At connection time, each of the two devices will advertise all their technical
abilities. These abilities have been ranked by the standard as shown in Table 1 on the right. The
100BASE-T2 full-duplex
lowest possible ranking is 10BASE-T which assumes half-duplex or shared Ethernet operation. The
very next ranking is 10BASE-T full-duplex indicating that full-duplex has higher performance than
100BASE-TX full-duplex
half-duplex. Finally, the highest ranking is 1000BASE-T full-duplex. This ranking scheme has been
provided for completeness. It is not assumed that a particular adapter can handle all technologies. In
100BASE-T2
fact, some of these technologies may not have been commercialized. However, they are all listed
consistent with the IEEE 802.3 standard.
100BASE-T4
Each device examines each other’s technical abilities and determines the lowest common
denominator. For example, if an Ethernet adapter can only handle 10BASE-T while a switch port can
100BASE-TX
handle either 10BASE-T or 100BASE-TX, 10BASE-T will be chosen by both. If two Ethernet adapters
connect, one only advertising 10BASE-T and the other only advertising 100BASE-TX, there will be no
10BASE-T full-duplex
subsequent communication since no compatibility exists.
Auto-negotiation can be very helpful or it can be a source of problems especially in the area of
half-, full-duplex selection since it is difficult to ascertain what was selected. Usually a switching hub 10BASE-T
and adapters have indicators that will denote Fast Ethernet selection; however, there is usually no
Table 1. Auto-Negotiation assumes a
indication for half-, full-duplex operation.
ranking of priorities. 10BASE-T
is at the bottom.
9 Transport Layer Protocols
APPLICATION
Ethernet is termed a data link and physical layer technology and, therefore, occupies layers two and
PRESENTATION
one of the OSI Reference Model. The original designers never intended the technology to guarantee
SESSION
end-to-end message delivery. This responsibility is given to the transport layer (layer four) of the
TRANSPORT
OSI model in Figure 3. Responsibility for internetworking (communication between two networks)
NETWORK
is given to layer three—the network layer. The transport and internetworking layer functionality
becomes part of the protocol stack and two have found much use with Ethernet—TCP/IP and
DATA LINK
SPX/IPX. These two protocols will not directly interoperate so it is important that all Ethernet nodes
PHYSICAL
on the network utilize compatible protocols. Since TCP/IP powers the Internet, this is the protocol
Figure 3. Ethernet defines the lower two
that has won out and the one recommended for Industrial Ethernet.
layers of the OSI Reference Model.
Actually TCP/IP is a set of protocols defined by a series of RFCs (request for comments) that
have evolved over the years. In Figure 4 you will notice how the TCP/IP stack of protocols relates to the OSI model. TCP/IP will
work with other data link technologies besides Ethernet so it resides above the data link/physical layer. At the transport layer
there are two important protocols. The Transmission Control Protocol (TCP) acknowledges receipt of messages while the User
9
10
Datagram Protocol (UDP) does not. Both are useful. At the very top of the protocol
TELNET
FTP
SMTP
DNS
SNMP
DHCP
Application
Presentation
stack, there are several useful application layer protocols that find use in Industrial
Session
RIP
Ethernet. TCP/IP is a complex subject and it will not be addressed here. To the installer,
Transport
RTP
Transmission
User Diagram
OSPF
RTCP
Control Protocol
Protocol
the most important issue is the addressing of nodes which is a network layer issue.
The Internet Protocol (IP) handles the routing of packets between stations that may
ICMP
IGMP
reside on different networks. Each station must have a unique 32-bit address that not
Internet Protocol
Network
only identifies the host (station) but the network as well. Addresses are best shown as
ARP
four bytes in a decimal-dot-decimal notation. A valid address would be 128.8.120.5 but
it is difficult to determine what part of the address is the host address and what part is
Data Link
Ethernet
ARCNET
Token Ring
FDDI
Physical
the network address. Addresses are defined as residing in either one of five classes—A,
B, C, D or E. Table 2 defines the classes by observing the value of the first byte of the
Figure 4. The TCP/IP stack is actually a set
of protocols. IP resides at the network
address. It is the class that determines the <host><netid> split.
layer of the OSI Reference Model.
Assigning IP addresses is not simple and they are usually assigned by the network
administrator. Once assigned they must be applied to each station in the network. Depending upon
the system installed, IP addresses may be dynamically assigned or statically assigned.
Class A:
1-127
Dynamically assigned addresses come from a server while statically assigned addresses must be
entered for each station as part of the configuration. IP addresses are either public or private. A
Class B:
128-191
public address can usually be seen on the Internet. The following addresses are private and
cannot be assessed through a router and, therefore, will not be seen on the Internet:
10.0.0.0 to 10.255.255.255
172.16.0.0 to172.31.255.255
192.168.0.0 to 192.168.255.255
IP addressing should not be confused with Ethernet MAC addresses. An Ethernet MAC
address is assigned by the equipment vendor so as to be unique worldwide. IP addresses are
assigned during installation and can be reassigned as necessary.
Class C:
192-223
Class D:
224-239
Class E:
240-254
Table 2. The class of an IP address
can be quickly identified by
observing only the first byte.
10 Application Layer Protocols
Now that we have determined our connector and cable needs, selected either hubs or switches, and assigned the required IP
addresses, we should be able to communicate between stations. This is not necessarily true. We still need compliance at the
highest level of the OSI reference model. There are several industrial automation protocols that are being proposed such as
EtherNet/IP, iDA, PROFInet and MODBUS/TCP. This does not include the traditional Internet applications such as FTP, SNMP,
SMTP and TELNET. Your equipment may not support all these application protocols so you must understand the capabilities of
your system. It is also possible that your equipment can handle all these applications. This is another advantage for using a TCP/IP stack.
This is where our discussion stops. Industrial Ethernet offers many possibilities; however, because of this flexibility the
subject is somewhat complex. You may not have all the answers but you should have a better feeling about some of the questions
that need to be asked.
SUMMARY
We hope this book has been helpful. For a more in-depth analysis of Industrial Ethernet,
we have written several articles on the subject, copies of which are free for the asking or
can be downloaded from our web site www.CTRLink.com. These articles have appeared in the
EXTENSION supplement of our newsletter. Subscription to our newsletter is also free. What
follows is a listing of relevant Industrial Ethernet articles.
Volume 1•Issue 3, Fall 1999, Introduction to Ethernet, Ethernet for Control—Understanding the Basics
Volume 1•Issue 4, Winter 1999, Introduction to the Internet Protocol, How Does IP Impact Control Networks?
Volume 1•Issue 5, March-April 2000, Introduction to the Transmission Control Protocol, How Does TCP and UDP Impact Control Networks?
Volume 1•Issue 6, May-June 2000, Multi-Segment Ethernet Networks, Using Repeaters to Increase Network Diameter
Volume 1•Issue 8, September-October 2000 Introduction to Subnetting, How to Maximize Network Addresses
Volume 1•Issue 9, November-December 2000, Introduction to Switch Technology, Improving the Performance of Ethernet Networks
Volume 2•Issue 4, July-Aug. 2001, Introduction to Industrial Networking
Volume 2•Issue 6, November-December 2001, Introduction to Fast Ethernet
www.CTRLink.com
www.CTRLink.co.uk
www.CTRLink.com.cn
www.CTRLink.de
11
Contemporary Control Systems, Inc.
Contemporary Controls Ltd
2431 Curtiss Street
Downers Grove, IL 60515 USA
Tel:
1-630-963-7070
Fax:
1-630-963-0109
Barclays Venture Centre
University of Warwick Science Park
Sir William Lyons Road
Coventry CV4 7EZ UK
Tel:
+44 (0)24 7641 3786
Fax:
+44 (0)24 7641 3923
E-mail: [email protected]
www.ccontrols.com
www.ccontrols.co.uk
Contemporary Controls (U.S.)
Shanghai Representative Office
Room 1012, Zhongchuang Building
819 Nanjing Road (W.)
Shanghai 200041 China
Tel:
+86 (0)21 62551335
Fax:
+86 (0)21 62552925
E-mail: [email protected]
www.ccontrols.com.cn
Contemporary Controls GmbH i. G.
Herner Strasse 5
D-06295 Eisleben Germany
Tel:
+49 (0)3475 6501 60
Fax:
+49 (0)3475 6501 66
E-mail: [email protected]
www.ccontrols.de

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