industrial data communication industrial...

5.1

Industrial Data Communication

WestermoHandbook

Industrial Ethernet

First edition published december 1994. © Westermo, Sweden 1994.

Second edition published 1996. © Westermo, Sweden 1996.

Edition 2.1 published 1997. © Westermo, Sweden 1997.



Edition 5.0 published 2004. © Westermo, Sweden 2004

Edition 5.1 published 2006. © Westermo, Sweden 2006

Production: Westermo Teleindustri AB, Sweden.

Illustrations:Visual Information Sweden AB, Eskilstuna, Sweden.

Photo: bildN,Västerås.

Repro: Ågerups Repro AB, Eskilstuna, Sweden.

Printing: Eskilstuna Offset AB, Eskilstuna Sweden.

All information in this handbook can be changed without prior notice.

Contact Westermo for latest information.

www.westermo.com2 Industrial Ethernet

http://www.westermo.com

Industrial Ethernet 3www.westermo.com

Dear Reader

You are holding in your hand the fifth edition of the Westermo Handbook.The first

edition of the Handbook was printed 11 years ago in 1994 and has over the years

become a tool used by engineers and others who have an interest in data commu-

nication.

As in the previous editions our goal has been to give not only an in-depth presen-

tation of the Westermo product range but also a comprehensive overview of the

most common theoretical aspects of data communication.The theoretical and gen-

eral application section has been increased in every new edition of the handbook

and this 5th edition is no exception.

This edition of the handbook differs from the previous editions. Due to the huge

increase in our product range we have divided the handbook into sections to be

easier to use.

The different sections are:

… Theoretical and general applications

… Modems & Remote Access

… Industrial Ethernet

… Local Data Communications

Our hope is that the Westermo Handbook will become a useful tool to help

you in your everyday work and a supplement to the service provided by all

the dedicated people we have round the world.


Contents

Industrial Ethernet ............................................................................................................................................................................................... 6–11

Ethernet – Where did the name originate? ........................................................................................................................ 6

What is Ethernet? ............................................................................................................................................................................................... 6–7

Why use Ethernet on industrial systems? .............................................................................................................................. 8

Is Ethernet Deterministic? .............................................................................................................................................................................. 8

How to make Ethernet Industrial! ......................................................................................................................................... 9–11

Westermo Ethernet Products ...................................................................................................................................................... 12–19

Ethernet adapters ................................................................................................................................................................................................... 12

What is an Ethernet adapter ........................................................................................................................................................ 12

Protocols .................................................................................................................................................................................................................. 13–14

User Datagram Protocol (UDP) ............................................................................................................................................. 13

Transmission Control Protocol (TCP) ............................................................................................................................ 13

Point to Point Protocol (PPP) ...................................................................................................................................................... 14

Routers ................................................................................................................................................................................................................................... 15

Switches ................................................................................................................................................................................................................................. 15

Managed switch ......................................................................................................................................................................................................... 16

Ring switch ........................................................................................................................................................................................................................ 17

Time synchronization in switched Ethernet ..........................................................................................................18–19

Ethernet Fibre Optic Connection .......................................................................................................................................... 20–21

Fibre Optic Cable Construction ...................................................................................................................................................... 21

Selection Guide .................................................................................................................................................................................................... 22–25

General Technical Information ...................................................................................................................................................... 26–33

DIN-rail products .................................................................................................................................................................................................... 26

Environmental and mechanical conditions ........................................................................................................................ 26

Electrical conditions ............................................................................................................................................................................................. 27

Safety conditions ...................................................................................................................................................................................................... 28

Installation conditions ........................................................................................................................................................................................ 28

DIN-rail versions / Enclosure .................................................................................................................................................... 29–33

Applications ................................................................................................................................................................................................................ 34–57

Bottle filling machine ........................................................................................................................................................................................... 34

Flatbed printer ............................................................................................................................................................................................................. 35

City-wide fire reporting system over WAN ................................................................................................................... 36

Multi-site access control system ....................................................................................................................................................... 37

Connecting legacy equipment to SCADA network .......................................................................................... 38

Oil pipeline monitoring & control ................................................................................................................................................. 39

Water treatment plant .................................................................................................................................................................................... 40

Station signalling system ................................................................................................................................................................................ 41



Drug manufacturing ............................................................................................................................................................................................. 42

Substation automation .................................................................................................................................................................................... 43

Substation automation .................................................................................................................................................................................... 44

Triplicated safety shutdown system ............................................................................................................................................. 45

Pumping safety system .................................................................................................................................................................................... 46

Robot application .................................................................................................................................................................................................... 47

Barrier controls ........................................................................................................................................................................................................... 48

Ethernet within road tunnel .................................................................................................................................................................... 49

Ethernet communications in wind power generator ........................................................................................ 50

Fibre optic Ethernet back bone with remote access and SMS alarms .................................. 51

Redundant fibre optic ring ........................................................................................................................................................................ 52

Time synchronization for off-shore platforms ............................................................................................................. 53

Supervision and traffic control ............................................................................................................................................................ 54

Unmanaged switch, outdoor in harsh environment ........................................................................................... 55

Multi- vendor network redundancy ............................................................................................................................................ 56

Ethernet extender over twisted pair ......................................................................................................................................... 57

Products.............................................................................................................................................................................................................................. 58–93

ED-10 UDP, serial adapter ............................................................................................................................................................ 58–59

ED-10 TCP, serial adapter ............................................................................................................................................................... 60–61

ED-12 TCP, serial adapter ............................................................................................................................................................... 62–63

EDW-100, serial adapter .................................................................................................................................................................. 64–65

EDW-120, serial adapter .................................................................................................................................................................. 66–67

MCW-211, media converter ...................................................................................................................................................... 68–69

ED-20, router .................................................................................................................................................................................................... 70–71

SDW-550, 5 port switch .................................................................................................................................................................. 72–73

SDW-541, 5 port switch .................................................................................................................................................................. 74–75

SDW-532, 5 port switch .................................................................................................................................................................. 76–77

DDW-100, Ethernet SHDSL extender ...................................................................................................................... 78–79

U200, 8 port switch ................................................................................................................................................................................ 80–81

R200, 8 port ring switch ........................................................................................................................................... 82–83

T200, 8 port real-time switch .................................................................................................................................................. 84–85

Lynx 100 / 1100, 8 port switch ............................................................................................................................................ 86–87

Lynx 300 / 1300, 8 port switch ............................................................................................................................................ 88–89

Lynx 400 / 1400, 8 port switch ............................................................................................................................................ 90–91

Lynx 045, 5 port switch .................................................................................................................................................................... 92–93

Glossary ........................................................................................................................................................................................................................... 94–99



Industrial Ethernet

Ethernet as a data communications standard has been with us for many years and is

the basis for the vast majority of office networks around the world today. Despite

many claims over the years that it will be superseded it continues to evolve and offer

the features that the users require and hence will be used for many years to come.

In recent years Ethernet has also gained acceptance in the industrial market.

Ethernet – Where did the name originate?

In 1972, Robert Metcalfe and his team at Xerox developed the first experimental

Ethernet system to interconnect the Xerox Alto, a personal workstation with a

graphical user interface.The experimental

Ethernet network was used to link Altos to

each other, to servers and to laser printers.

The signal clock for the experimental

Ethernet interface was derived from the

Alto’s system clock, which resulted in a data

transmission rate on the experimental

Ethernet of 2.94 Mbit/s. Robert Metcalfe’s first experimental network was called the

Alto Aloha Network.

In 1973, Metcalfe changed the name to “Ethernet,” to make it clear that the system

could support any type of computer- not just the Xerox Alto.To illustrate that his

new network mechanisms had evolved well beyond the basic system he chose to

base the name on the word “ether” as a way of describing an essential feature of the

system.The physical medium (i.e., a cable) carries data to all stations, much the same

way that the old “luminiferous ether” was once thought to propagate electromagnet-

ic waves through space.Thus, Ethernet was born.

What is Ethernet?

The basic principle of Ethernet communication is called CSMA/CD (Carrier Sense

Multiple Access/Collision Detection). Put simply if a device wishes to communicate

then it checks the line to see if it is clear, if it is, then the data is transmitted else it

waits for a clear line. Collision detection is important as it is possible that two or

more devices may transmit simultaneously and the data will collide. By detecting that

a collision has occurred and retransmitting later, no data is lost.


Station

I

Transeiver

Interface

Controller

The Ether

Tap

Interface CableCX

Terminator


The first true Ethernet standard was called

10Base5.The network was based around a

single length of thick coaxial cable up to

500 m (1666 ft) long with transceivers tap-

ping into the cable at points along its length.

The data rate was fixed at 10 Mbit/s. If a

larger network was required then repeaters

could be used.

The next important standard was 10Base2,

again running at 10 Mbit/s, but using a lower

cost thin coaxial cable connected to net-

work interface cards by T pieces.This solu-

tion was much cheaper and became popular

for small networks.

The next big step for the Ethernet network was the introduction of structured

cabling.The 10BaseT standard was developed that relied on using hubs and kept the

cable distance below 100 m (333 ft).

Another step up was the evolution of faster

networks and the use of fibre optic cables

for long distance data transmission. Hence

more standards arose including 100BaseT,

100BaseFX etc.

With mixed standards, higher numbers of

connected devices and now two data rates

to consider, connecting the networks together became more complicated, hence the

development of the Ethernet switch.


10Base5 Coax Cable

Tranceiver Tranceiver Tranceiver TranceiverTransceiver Transceiver

500 metres (1666 ft)

Transceiver Transceiver

10Base5 Coax Cable

10Base2 Coax Cable

Tranceiver Tranceiver Tranceiver TranceiverTransceiver Transceiver

185 metres (616 ft)

Transceiver Transceiver

10Base2 Coax Cable

100 metres (333 ft)UTP cables

Hub



Ethernet Adapter

Networking Device

Ethernet/Serial

Interface

Network Enabling

Serial Devices

Device Server

Serial Server

Network Adapter

ComPort Server

Terminal SServer

Serial Device Server

IP Converter

Why use Ethernet for Industrial Systems?

Fieldbuses have been the traditional way for data communications in industry.

There are many different types and standards meaning interoperability is difficult

and expensive and is the main reason Ethernet started to be considered for

industrial applications. Other benefits include:

Reliability Ethernet is a well defined open standard meaning that interop-

erability is simplified and components are available from multi-

ple sources. Ethernet is open and transparent. Many different

protocols can run simultaneously on the same network.

Speed Data rates of 10 Mbit/s and 100 Mbit/s are common place

with Gigabit solutions also now available – the fastest field-

bus protocols run at 12 Mbit/s and most operate at less

than 2 Mbit/s.

Determinism Protocols already exist to prioritise data and hence make

Ethernet virtually deterministic, the ultimate goal of the

industrial user.

Is Ethernet Deterministic?

Determinism is the key word in many industrial networks – with a deterministic net-

work it is possible to say with complete certainty that an event occurred within a

particular time window.

With the CSMA/CD technique employed in the original Ethernet systems deter-

minism was impossible however with the advent of the Ethernet switch things have

changed. Collisions in the cabling infrastructure no longer occur.The twisted pair or

fibre optic links are point to point and can be full duplex. A packet sent to a switch is

stored and retransmitted to the correct destination port. If that port is busy, the

switch can wait hence no collisions and no retransmissions.The problem is now the

potential wait in the queue.

Modern switches have features that can guarantee that this queue is never a prob-

lem. Ethernet packets can be configured to carry a priority tag. If a switch supports

prioritisation then that packet jumps to the start of the queue. Another useful fea-

ture in dataflow control is head of line blocking prevention – head of line blocking is

a problem in some switches because they use a FIFO buffering system, meaning that

if a packet is being held up at the front of the queue then the entire queue is

blocked. Some switches have a method of preventing this problem.


How to make Ethernet Industrial!

When designing equipment for industrial environments there are certain features

and functions that are more important than others.Westermo have always designed

equipment for industrial applications so we understand what the market requires

and we know that quality and functionality are important factors when looking at the

total cost of a project.

Important aspects of industrial data communication equipment design include:

The unit must be constructed to eliminate communica-

tion disturbances and downtime.We achieve this by

using high quality components such as long life capaci-

tors and verify the design in harsh environments.

Industrial communication devices are often installed

near equipment like a welder or heavy machinery that

generates electromagnetic noise.We have more than

30 years of experience in designing and manufacturing

data communication equipment for industry and we

use all this knowledge when designing Industrial

Ethernet equipment.

There is often a requirement for extended tempera-

ture ranges in industrial applications.We guarantee this

functionality by using high quality components that

have an extended working temperature range for both

hardware and connectors.

In industrial applications the method of installation is

always important as units can be mounted into

machinery that has to move or is prone to vibration.

All our products are designed for high mechanical per-

formance with DIN-rail mounting.When designing the

products we always look into problems related to

vibration, mechanical connection and security.


Downtime elimination

Industrial EMC design

Extended temperature

range

Mechanical performance


One of the most common causes of data communica-

tion errors is different earth potentials between con-

nected units.This is eliminated with galvanic isolation of

all the interfaces; this is one of the standard features in

all Westermo products.

Industrial equipment is also often exposed to high cur-

rent power lines, reactive loads or high voltage switch-

gear, this kind of equipment often generates transients

that cause communication errors. One way to elimi-

nate this problem is to design products with enhanced

surge/transient protection.

It is important to have a reliable power supply for

industrial equipment, often DC power is used together

with batteries.When charging a battery a higher volt-

age is used and all connected units must be designed

for this circumstance. In some cases it is also important

to use redundant power inputs for extended security.


Galvanic Isolation

Transient suppression

Power


When using equipment in real-time applications it is

important to have different levels of prioritisation. In

the fast, ring and time switches there are built in func-

tions and queues guaranteeing transmission of priori-

tised data.

Our units are installed in many different applications all

over the world.To meet local demands for safety, elec-

trical immunity, ESD and vibration we have designed

the units to meet international standards.


Determinism

Approvals


Westermo Ethernet Products


Serial Ethernet Adaptors

What is a Serial Ethernet Adapter?

A Serial Ethernet Adapter might take many different forms and will be able to

perform any of the functions below. It will not only provide remote connection

to serial devices. It will also give the user the possibility to:

… Extend the life of existing serial equipment.

… Simplify equipment diagnostics and maintenance.

… Save pathway and line usage costs for long-distance communication.

… Integrate peripherals into an existing overall infrastructure.

Each connected device can be accessed directly over the local network, via router,

a WAN or (if enabled) through the Internet.

… Use the same error correction mechanisms linking millions of PCs world-wide.

… Share data with any number of computers and other resources on your network.

… Replace limited distance serial connections.

… Use a high number of long distance, virtual COM ports without the need for

bulky cabling.



Protocols

User Datagram Protocol (UDP)

UDP provides a connectionless datagram service.This means that

the arrival of datagrams or data packets is not controlled and the

reliability of the communication is the responsibility of the applica-

tion. In this way UDP is a simpler method of communication than

TCP. As data is sent and received without any established connec-

tion the data transfer is more efficient and often faster. UDP is

therefore used in applications that require efficient use of the

bandwidth and also have higher level protocols to handle lost

data.

Available products

EDW-100

EDW-120

ED-10 UDP

Transmission Control Protocol (TCP)

TCP is a connection-oriented delivery service. Connection-

oriented means that a session must be established before hosts

can exchange data. An acknowledgement is used to verify that

the data was received by the other host. For each data segment

sent, the receiving host must return an acknowledgement (ACK).

If an ACK is not received, the data is retransmitted. Flow-control

between the hosts is managed by TCP. For larger amounts of data

that have to be split between packets TCP provides a method for

reliably reassembling the data in the correct order. Because of the

requirement to establish a session and acknowledge transmissions

TCP takes longer to transmit data than UDP and uses more

bandwidth.

Available products

EDW-100

EDW-120

ED-10 TCP

ED-12 TCP

Serial/IP

TCP

UDP / User Datagram Protocol

Connectionless

… No sessions are established

… No Server/Client needed

Reliability is the responsibility of the application

Applications

Does not guarantee delivery

… No sequence numbers

… No acknowledgements

… Point to point

… One to Many

TCP

Application

Internet

Network

Transport

Data

Data

Ack

Application

Internet

Network

… Point to point … Server/Client

Transport


Point to Point Protocol (PPP)

The Point to Point Protocol (PPP) originally emerged as an encapsulation protocol

for transporting IP traffic over point to point links, typically over PSTN lines between

modems. PPP established a standard for assigning and managing IP addresses, asyn-

chronous and bit-oriented synchronous encapsulation, network protocol multiplexing,

link configuration, link quality testing, error detection and option negotiation for

added networking capabilities. PPP provides a method for transmitting datagrams

over serial point to point links, which include the following three components:

… PPP uses the High-Level Data Link Control (HDLC) protocol as a basis for

encapsulating datagrams over point to point links.

… An extensive Link Control Protocol (LCP) to establish, configure and test the

connection.

… A family of Network Control Protocols (NCP) for establishing and configuring

different network layer protocols.

PPP is capable of operating across any DTE/DCE interface and does not impose any

restriction regarding transmission rate other than those imposed by the particular

DTE/DCE interface in use.

COM port redirector software

COM port redirector software is used to create a virtual COM

port within a PC, with these ports applications can immediately

use a serial server’s serial ports as if they were local serial ports.

The software will redirect data, originally sent to a local COM

port using TCP/IP to the remote serial server. No change of

computer application software is then necessary.

Available products

COM port redirector software,Viritual IP and Serial IP.


Application software

Application software

Data to / from COM3

Data to / from COM4

Data to / from COM5

Data to / from COM256

COM port

redirector software


Routers

In a network, a router is a device or, in some cases, software in a computer,

that determines the next network point to which a packet should

be forwarded toward its final destination.The router is connected

to at least two networks and decides which way to send each

information packet based on its current understanding of the

state of the networks it is connected to.

IP routers provide a connection between subnets.When a

host wishes to send data to a host in another IP subnet the host

sends the data to its gateway or router address which then knows how to forward

that data packet to the correct network.

Available products

ED-20

Ethernet Switches

A switch is a device used to construct Ethernet networks and control the data flow

and bandwidth of the network.

A switch stores incoming packets and then tests the packet for check sum errors,

if an error is found the packet is discarded. After that a decision is made as to which

port or ports the packet should be forwarded to.This decision is made based on

tables of Media Access Control (MAC) addresses. All MAC tables are created and

maintained automatically from the received packets.When the switch receives a

packet on a port it stores the source MAC address in the MAC table that corre-

sponds to that port. If a node is silent for a long time the MAC address will “age

out” and be removed from the table.

A switch can operate in full duplex mode, this ensures that an Ethernet controller

will never see any collisions occurring when operated in such a manner.

A switch can be either managed or unmanaged, an unmanaged switch can not be

reconfigured using external software tools.

Available products

Unmanaged switches see page 17


Router

Subnet A

B C

Subnet B

Host A Host D


Managed Ethernet Switches

A switch can be managed or unmanaged. A managed switch allows access to its

functions to allow it to be reconfigured or monitored.This management can be

inband- using protocols on the network or outband via a local management port or

fault contacts. A managed switch often uses SNMP (Simple Network Management

Protocol) for inband management. SNMP is the Internet standard protocol devel-

oped to manage nodes (servers, workstations, routers, switches and hubs etc.) on an

IP network. SNMP enables network administrators to manage network performance,

find and solve network problems, and plan for network growth.

Network Redundancy

Network redundancy means that alternative network paths exist in the network, and

that alternative paths are activated when a network topology change is detected.

Many different concepts and protocols are available on the market. Non industrial

networks are often based on the well established IEEE standard Spanning Tree

Protocol (STP). A new improved version of STP has recently been released. This

protocol is called Rapid Spanning Tree Protocol (RSTP). RSTP can reconfigure the

network topology faster than STP. The network topology reconfiguration time is a

critical factor for some network applications. Some applications can tolerate minutes

and some only milliseconds of downtime. Fast reconfiguration is required in most

cases for industrial networks. Data is often sent cyclically with short intervals on such

networks.The system operation might be badly affected if too many packets of data

are lost during reconfiguration of the network topology.

Traditional protocols such as STP and RSTP are in many cases not fast enough for

industrial networks.Therefore, special protocols have been developed for this market

in order to offer faster reconfiguration times. Most of these protocols only support a

simple ring topology, while STP and RSTP support mesh structured networks. It

should however be noted that all network redundancy protocols have topology

rules. Some of the special network redundancy protocols are able to cope with

more complex network topologies.Two or more redundant rings can be connected

together in a redundant manner. Such a redundant topology is referred to as

Redundant Bridged Rings.The R200 uses a Fast Re-configuration of Network

Topology (FRNT) (patent pending) protocol.The pictures on the next page

shows a comparison of network redundancy.

Each switch has knowledge of the network topology, not only its neighbouring

switches as in the case for STP. An FRNT topology change event packet will be sent

directly to the focal point switch in case of a topology change (e.g. a link loss or a link



establishment), while an STP implementation will only send STP control packets one

network hop. The focal point switch will then based on the received topology

change event packet, generate a topology change command. This packet is sent to

each member switch in the ring.

Ring Switch

A ring switch is a switch with redundant ring technology.The switch can be used in a

single ring network or in a multiple ring network with bridge link redundancy.This

eliminates network failure caused by fibre or copper failures.The speed of ring recov-

ery is an essential part of designing your network.The R200 can recover from a fail-

ure in only 30mS if such a failure does occur.When used in conjunction with redun-

dant power supplies a very reliable system can be designed.

The switch also incorporates two priority queues, which are designed to ensure

that the network data is deterministic.This is achieved by implementation of Layer 2

and Layer 3 priority. In addition, head of line blocking prevention ensures that the

switch does not become congested by low priority data.This allows engineers to

design a reliable, deterministic and redundant network, while prioritising data into

low and high priority queues.


Single ring

Multiple ring with bridge link

redundancy

Unmanaged switches:

SDW-550 5 TX ports.

SDW-541 4 TX and 1 FX port.

SDW-532 3 TX and 2 FX.

Lynx 045 5 TX ports M12 connectors.

U200 8 port fast switch with connectivity options from 8 TX to 8 FX ports.

Managed switches:

R200 8 port ring switch with R200 8 port ring switch with connectivity options from 8 TX to 8 FX ports.

Lynx 100 8 port switch with 6 TX and connectivity options from 2 FX ports.

Lynx 300 8 port ring switch with 6 TX and connectivity options from 2 FX ports.

Lynx 400 8 port VLAN ring switch with 6 TX and connectivity options from 2 FX ports.

Lynx 1100 8 port Gigabit switch with 6 TX and connectivity options from 2 FX ports.

Lynx 1300 8 port Gigabit ring switch with 6 TX and connectivity options from 2 FX ports.

Lynx 1400 8 port Gigabit VLAN ring switch with 6 TX and connectivity options from 2 FX ports.

Available products


Time synchronization in switched Ethernet

Distributed systems with real time requirements have often been based on fieldbuses

as the communication solution, but switched Ethernet is now a preferred alternative

for many applications due to the never ending price decrease driven by the office

Ethernet market, high bandwidth, priority features (e.g.VoIP) and the availability of

Ethernet switches and Ethernet enabled products fulfilling industrial environmental

requirements. However, the switch latency will vary depending on the switch load.

Variable switch latency means that raw data sent from two different data acquisition

nodes to the same receiving node may be delayed differently. This is a problem, but

can be solved if the packets of data are time stamped. The receiving node can

resample the incoming raw data based on the time stamps, and raw data from

several sources can be correctly compared. This requires time synchronization.

The timing accuracy that can be achieved in a LAN, based on switched Ethernet,

where time synchronization data is distributed via this infrastructure, depends on two

factors:

1. Time stamping of incoming and outgoing time packets. Time stamping should

preferably be performed at the lowest possible level in the OSI protocol stack

in order to avoid variable latency through the stack.

2. Variable network latency.The switch latency depends on the network load,

drop link speed, packet sizes and the switch architecture.

Which protocol is used for time synchronization is of less importance as

long as the issues above are handled properly.We do, however, recom-

mend SNTP/NTP as the time synchronization protocol since this is an

open internet standard with few limitations. Source code for this proto-

col is also available.

Time stamping

The timing accuracy depends on where the time stamping of incoming

and outgoing time packets was performed, and the variation in the net-

work latency.Time stamping can be performed in the SNTP/NTP appli-

cation layer, Ethernet driver level (software) or Ethernet data link/physi-

cal layer (hardware).

Why is switch latency a problem?

The figure shows a traditional time synchronization implementation,

where time packets are sent through a switched Ethernet infrastructure.

The network latency depends on the network load, drop link speed, packet sizes, the


Time client

Time delay

Time delayTime server


switch architecture and the number of switches between the

server and the client. The switch latency may vary from a

few tens of microseconds up to several milliseconds.

The packet may be further delayed if other packets are

queued for transmission on the same output port.

Protecting the time packets by using prioritization does not

improve the situation, because the transmission of another

packet may already be started when the time packet arrives

at the output port.

Time server in the Ethernet switch

The switch latency problem can be removed if the time server is integrated in to the

Ethernet switch. There will only be one drop link (direct wire) between the server

and the client if this implementation is used, and the timing accuracy will be inde-

pendent of the network load if the time packets are time stamped in hardware.

An accuracy of better than one microsecond can be achieved at the time client if

the time client also performs time stamping in hardware.The figure above shows

this implementation, where an integrated GPS receiver is used as the time base.

Available products

T200 8 port time switch with connectivity options from 8 TX to 8 FX ports


TCP UDP

MAC

802.3

IP

TCP UDP

MAC

802.3

IP

T2

T0

T0 T0 T0

SNTP*

HW**

SNTP*

HW**

Ethernet switch withSNTP time server

End node with SNTP time client


Ethernet Fibre Optic Connection

Historically the standard medium for factory networking has been copper cable

because in the past fibre optic cables were expensive and difficult to terminate.

Instead of conducting electrical signals as in the case of the copper cable, fibre

optic cable propagates light waves.A fibre optic cable is made up of core and

cladding layers of glass.The difference in the refractive index of the two types of

glass cause total internal reflection of the light within the core to occur and hence

propagation of that light. Surrounding the fibre there is a protective layer which

acts as a buffer. Electrical signals are converted to light using LEDs or lasers and

photodiodes are used to receive the light and convert back to the electrical sig-

nals.

Typically in Ethernet systems there are two types of fibre optic cable used; single-

mode and multimode.

Singlemode fibre typically has a core diameter of 9 microns and when used in con-

junction with light of 1300 nm allows the propagation of only a singlemode

of light.The advantage of this is that the pulses of light can not be distorted

by waves taking different paths through the core.This means that single-

mode systems can be used over much greater distances and with higher bandwidths

than multimode cable.

Multimode fibre tends to have core diameters of 50 or 62.5 microns. More distor-

tion of the light pulses mean that transmission distances are much lower

than for singlemode fibres. Components for multimode systems tend to be

much cheaper than those for singlemode thus compensating for the lower

transmission ranges.

The greatest advantage of the fibre optic cable is that it is immune to electrical and

magnetic interference. Consequently, it is highly suitable for harsh industrial environ-

ments, guarantees secure transmission and has a very high transmission capacity.

www.westermo.com20 Fibre optic


Fibre Optic Cable Construction

Fibre optic cable is composed of:

Core The centre of the fibre and the medium for the transmission of

optical (light) signals. It ranges in diameter from 5 to 200 microns.

Cladding The optical material which surrounds the core and causes the light

from the core that strikes it to be reflected keeping the optical

information in the core.The cladding increases the diameter of the

glass fibre to the range of 125 to 230 microns.

Connectors There are many connectors on the market for fibre cables, but

there are four main connectors used for professional Ethernet

installations and they are:

SC simplex connector used for

multi- or singlemode.

LC duplex connector used for

singlemode.

MTRJ duplex connector used for

multi- or singlemode.

ST simplex connector used for

multimode.

Core

Cladding

Fibre optic 21www.westermo.com


ED-10UDP ED-10TCP ED-12TCP EDW-100

Application

Serial to Ethernet … … … …

Switch

Router

Media converter

SHDSL Ethernet Extender

Interface

RS-232 or RS-422/485 … … … …

10 Mbit TX (copper) … … … …

100 Mbit TX (copper) …

100 Mbit FX (fibre)

Flexible combination copper/fibre

Number of Ethernet ports 1 1 1 1

Number of serial ports 1+1* 1+1* 2 1

DSL

Functionality

Managed ICMP/SNMP … / – … / – … / – … / –

VLAN Transparent

Ethernet Bridge

Isolation between interfaces … … … ** …

Extended temperature range …***

DIN-mounted … … … …

Rack or wall mountable

Designed to industrial standards … … … …

Product guide


* Used for local configuration/Status only ** Not between RS-232 *** Relesed Q1-2006


EDW-120 MCW-211 ED-20 SDW-550 SDW-541 SDW-532 DDW-100

…

… … …

…

… … …

…

… …

… … … … … … …

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… … …

… …

1 2 1 5 5 5 1

2 1+1*

…

… / – … / – … / –

… … … … …

…

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… … … … … … …



Ethernet U200 R200 T200 Lynx 045

Application

Switch … … … …

Media converter … … …

Interface

10/100 Mbit TX (copper) … … … …

10/100 Mbit M12 connector …

100 Mbit FX (fibre) … … …

1 Gbit TX (copper)

1 Gbit FX (fibre)

Flexible combination copper/fibre … … …

Number of Ethernet ports 8 8 8 5

Functionality

Managed ICMP/SNMP … / – … / … … / …

Prioritization … … …

Redundant ring … …

Time synchronization …

VLAN … …

IGMP Snooping … …

Isolation between interfaces … … … …

Extended temperature range … … … …

DIN-mounted … … … …

Rack or wall mountable … … … …

Designed to industrial standards … … … …

www.westermo.com24 Ethernet

Product guide


Lynx 100 Lynx 300 Lynx 400 Lynx 1100 Lynx 1300 Lynx 1400

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8 8 8 8 8 8

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… …

… …

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Ethernet 25www.westermo.com


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