Wilamowski B.M., Irwin J.D. The Industrial Electronics Handbook. Second Edition: Industrial Communication Systems

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13-1

13.1 Introduction

 e.past.two.decades.have.brought.tremendous.advances.in.network.technology,.both.in.the.oce.world.

and.in.all.eld

.of.auto

mation.

.Two.obvi

ous

.indi

cators

.for.this.are.on.the.one.hand.the.stun

ning

.succe

of.the.Inte

rnet,

.whose.techn

ological

.prin

ciples

.have.also.wide

.been.adop

ted

.in.smal

l-size

.loca

.area.net-

orks

.(LAN

s).

.On.the.othe

.hand

.the.leng

thy

.and.erc

.stru

ggle

.for.an.accep

table

.comp

romise

.in.eld

bus

stan

dardization

.show

.that.the.auto

mation

.doma

.is.seen.as.an.impo

rtant

.mark

.by.the.big.play

ers.

Conse

quently,

.as.netw

orking

.in.both.worl

.has.reac

hed

.a.matu

.poin

.the.recen

.year

.have.seen.many.

atte

mpts

.to.brin

.the.two.side

.toge

ther

.and.to.nal

.achi

eve

.somet

hing

.that.had.rema

ined

.wish

ful

.thin

ing

.for.a.long.time

.the.idea.of.vert

ical

.inte

gration,

.mean

ing

.a.seaml

ess

.inte

gration

.of.auto

mation

.data.into.

a.high

.leve

.info

rmation

.techn

ology

.(IT).cont

ext

.beyo

.mere.data.acqu

isition

.[WV0

3].

.term.“ver

tical

.inte

gration”

.has.beco

.tren

.in.the.last.year

.and.has.been.used.as.a.mark

eting

argu

ment

.for.a.numbe

.of.autom

ation

.solu

tions.

.Stric

tly

.spea

king,

.howe

ver,

.vert

ical

.inte

gration

.is.not.

a.conc

ept

.pecu

liar

.to.autom

ation.

.In.fact

.it.has.seve

ral

.conn

otations

.in.die

rent

.doma

ins

.that.may.be.

dist

inguished:

•

. In.an.econ

omical

.cont

ext,

.it.deno

tes

.the.exte

.to.whic

.a.comp

any

.has.cont

rol

.of.the.proc

esses

invo

lved

.in.the.manu

facturing

.of.its.prod

ucts.

.Full.vert

ical

.inte

gration

.in.this.case.mean

.full.

cont

rol

.over.the.enti

.valu

.chai

.from.raw.mate

rial

.prod

uction

.unti

.the.asse

mbly

.of.the.nal.

prod

uct

.[RO

03].

•

. In.a.busi

ness

.and.orga

nizational

.cont

ext,

.it.conc

erns

.the.info

rmation

.exch

ange

.betw

een

.the.vario

mana

gement

.leve

.in.a.comp

any

.or.an.aggl

omerate

.of.comp

anies.

. e.rele

vant

.prop

erty

.here.is.the.

cont

rol

.of.the.decis

ion

.ow.acro

.the.hier

archies.

•

. In.an.auto

mation

.cont

ext,

.nal

ly,

.it.mean

.the.data.exch

ange

.betw

een

.all.auto

mation

.leve

.insi

.a.

plan

.In.part

icular,

.it.deno

tes

.the.inte

rconnection

.of.auto

mation

.and.oce.netw

orks

.on.a.techn

logical

.leve

.and.the.link

age

.of.eld

-level

.cont

rol

.and.plan

ning

.tool

.on.an.appl

ication

.leve

.[S07

.chapt

.will.focu

.on.the.latt

.aspe

cts

.of.vert

ical

.inte

gration,

.and.ther

.agai

.espe

cially

.on.

the.tech

nological

.issu

es.

.It.will.shed.some.ligh

.on.the.evol

ution

.of.the.inte

gration

.idea.from.the.rst.

Vertical Integration

13.1. Introduction.....................................................................................13-1

13.2

. Histo

rical

.Bac

kground....................................................................13-2

13.3

. Netw

ork

.Int

erconnections.............................................................13-4

13.4

. Appl

ication

.Vie

w.............................................................................13-7

13.5

. Secu

rity

.Asp

ects

.in.Ver

tical

.Int

egration......................................13-8

13.6

. Tren

.in.Ver

tical

.Int

egration.....................................................13-10

Abbreviations.............................................................................................13-11

References...................................................................................................13-12

Thilo Sauter

Austrian Academy

of Sci

ences

Stefan Soucek

LOyTEC electronics GmbH

Martin

Wollschlaeger

Dresden University

of Tec

hnology

13-2 Industrial Communication Systems

attempts.to.today’s.situation..A.section.is.devoted.to.the.network.interconnection.problem.that.is.a.

cornerstone.for.integration.. e.application.view.of.vertical.integration.will.be.briey.sketched,.and.the.

question.of.how.to.achieve.security.will.be.discussed..Finally,.a.few.trends.of.the.ongoing.evolution.will.

be.highlighted.

13.2 Historical Background

Historically.speaking,.the.idea.of.achieving.a.data.ow.from.the.shop.oor.and.the.eld.level.to.the.

oce.level.together.with.proper.network.integration.is.not.new..What.is.new.is.the.current.focus.on.

Internet.technologies.as.upper.level.of.the.interconnection..However,.the.integration.idea.itself.was.

already.part.of.the.computer-integrated.manufacturing.(CIM).concept.suggested.in.the.1970s.[H73]..

 e.approach.put.forward.then.was.to.create.a.transparent,.multilevel.network.to.structure.the.informa-

tion

.ow.required.for.factory.and.process.automation.[DSP88]..To.cope.with.the.expected.complexity,.

a.strict.subdivision.of.the.information.processing.into.a.hierarchical.model.was.devised.that.became.

to.be.known.as.the.automation.pyramid.. e.model.exists.in.various.versions.with.dierent.naming.

conventions.and.numbers.of.levels,.but.it.typically.comprises.four.to.six.functional.levels.as.depicted.

in.Figure.13.1..Along.with.the.denitions.of.functionalities—which.of.course.varied.according.to.the.

application.domain—networks.were.associated.to.the.individual.levels..Originally,.dierent.networks.

were.intended.for.these.purposes..In.recent.years,.however,.the.complexity.of.the.pyramid,.i.e.,.the.

number.of.levels.was.reduced.chiey.because.of.the.consolidation.process.that.took.place.in.the.eld.of.

networking.technologies..Today,.the.upper.levels.are.dominated.by.IP-based.networks.(mostly.on.the.

basis.of.Ethernet).and,.more.generally,.technologies.from.the.oce.domain,.whereas.the.lowest.level.is.

still.home.to.eld-level.networks.in.various.forms.

.critical.review.shows.that.the.CIM.approach.proposed.30.years.ago.practically.opped.. ere.are.

niches.where.integration.became.tight.and.very.successful,.like.in.CAD/CAM.solutions.for.tooling.

machines.or.(micro)electronic.manufacturing.. e.comprehensive.integration.of.all.levels.across.all.

possible.application.areas.however.failed,.and.still.today,.the.term.CIM.has.a.largely.negative.conno-

tation

.in.many.industries.. e.reasons.for.the.spectacular.failure.of.a.basically.good.idea.are.mani-

fold:

. e.overall.concept.was.overloaded.and.far.too.ambitious..In.particular,.it.had.been.designed.

mostly.without.a.view.to.the.feasibility.of.implementation..In.fact,.the.concepts.did.not.show.much.

Process level

Shop oor level

Production level

Finance

controlling

Strategic

planning

Marketing

Development

engineering

Operative and

quality engineering

Stock

Production

Assembly

Shipping

Logistics

Control

Transport-

control

Cell

control

Machine

control

Packaging

control

Market

ERP SCM

Ethernet

Fieldbus/

industrial

ethernet

Fieldbus

Supplier

Production control

Company level

Field level

MES SCADA

FIGURE 13.1 Typical.functional.units.inside.a.contemporary.company.and.their.interrelation.with.the.automa-

tion

.hierarchy.as.well.as.associated.network.technologies.

Vertical Integration 13-3

exibility.or.modularity.that.would.have.facilitated.their.adoption.by.industry..Rather,.it.was.more.

of.an.all-or-nothing.decision.to.be.taken..But.more.important,.critical.technological.elements.were.

simply.missing.or.in.a.premature.stage..Fieldbus.systems.as.low-level.networks.were.not.yet.widely.

known;.actually.the.CIM.concept.was.(also).a.stimulus.for.their.evolution..Microelectronics.had.not.

yet.produced.high.performance.and.aordable.processors.and.controllers,.and.IT.as.a.driving.force.in.

networking.was.not.yet.a.determining.factor.

.timeline.in.Figure.13.2.presents.a.few.technological.milestones.in.the.evolution.of.IT.and.net-

working

.concepts.and.compares.them.with.the.introduction.of.various.application.concepts.relevant.

for.the.implementation.of.vertical.integration..It.reveals.that.one.of.the.most.decisive.factors.also.for.

automation.networks.was.the.denition.if.the.ISO/OSI.model.in.the.late.1970s.. is.reference.model.

was.(and.still.is).the.starting.point.for.the.development.of.many.complex.communication.protocols.. e.

rst.application.of.the.OSI.model.to.the.domain.of.automation.was.the.denition.of.the.Manufacturing.

Automation.Protocol.(MAP),.which.was.the.communication.technological.foundation.of.CIM..MAP.

was.intended.to.be.a.framework.for.the.comprehensive.control.of.industrial.processes,.and.the.result.of.

the.denition.was.a.powerful.and.exible,.but.overly.complex.protocol.that.was.not.accepted.. e.tight-

ened

.standard.Mini-MAP.did.not.have.the.anticipated.success.either;.however,.it.introduced.a.reduced.

three-layer.communication.model.that.became.the.golden.model.for.most.eldbus.systems.[S05]..What.

did.have.success.was.Manufacturing.Message.Specication.(MMS)..It.dened.the.cooperation.of.vari-

ous

.automation.components.by.means.of.abstract.objects.and.services.and.was.used.as.a.starting.point.

for.other.eldbus.denitions.

What

.Figure.13.2.clearly.shows.is.that.CIM.in.its.original.denition.came.far.too.early.. e.golden.

era.of.the.eldbus.was.the.late.1980s.and.especially.the.1990s.with.lots.of.dierent.systems.and.erce.

struggles.in.the.international.standardization.committees..Although.eldbus.systems.were.originally.

also.conceived.as.a.means.to.bridge.the.communication.gap.in.the.lower.levels.of.the.CIM.model,.

the.interconnection.aspect.was.gradually.le.aside.for.the.sake.of.simplicity..In.most.cases,.developers.

adopted.a.pragmatic.viewpoint.and.designed.eldbus.systems.as.isolated.networks.to.get.solutions.ready.

for.the.market.. e.typical.end.point.for.vertical.communication.was,.therefore,.some.sort.of.control.

room,.located.on.the.cell.level.of.the.automation.pyramid.

.great.leap.forward—and.the.revival.of.the.integration.idea.under.a.new.name—came.with.the.

success.of.the.Internet.and,.in.particular,.with.the.invention.of.the.World.Wide.Web.(WWW)..Of.course,.

advances.in.microelectronics.provided.the.technological.backbone.for.the.processing.of.increasingly.

Industrial

ethernet

CIM Fieldbus and Internet

1970 1980 1990 2000

Information

technology

Fieldbus

systems

Planning

tools

Bitbus

MIL 1553

FIP

EN50170

IEC61158

Interbus

EN50254

ControlNet

CAN

WWW

ARPANET

Ethernet

EN50325

IEC61784

DeviceNet

OPC

Powerlink

PROFINET

Modbus/TCP

MRP

IEEE488

GPIB

ISA SP50

MMS

MAP

ISO/OSI

Internet

Profibus

Modbus

Ethernet

EtherCAT

SCM

ERP

MRP II

MES

FIGURE 13.2 Selected.milestones.relevant.for.the.evolution.of.vertical.integration.

13-4 Industrial Communication Systems

complex.communication.protocols..However,.from.the.user’s.point.of.view,.it.was.the.sheer.simplicity.

of.the.web.brow

ser

.conc

ept

.that.was.so.appe

aling.

. is.tool.is.easy.to.use,.plat

form

.inde

pendent,

.and.

allo

.to.acce

.dist

ant

.sites.and.data.in.a.near

.triv

ial

.mann

er.

.It.is.no.wond

.that.the.easy.way.of.

navi

gating

.thro

ugh

.hype

rtext

.docu

ments

.in.the.Inte

rnet

.was.soon.take

.as.a.mode

.for.the.(rem

ote)

acce

.to.autom

ation

.data

.and.actu

ally

.many.solu

tions

.avai

lable

.on.the.mark

.today.rely.on.WWW.

tech

nology

.and.web.brow

sers

.as.an.inte

rface.

.Still

.the.impr

ession

.that.“the.Inte

rnet”

.natu

rally

.enta

ils

.a.

unif

orm

.way.of.remo

.acce

.to.autom

ation

.netw

orks

.is.dece

ptive.

. e.user.inte

rface

.is.only.one.aspe

ct,

the.unde

rlying

.mech

anisms

.and.data.stru

ctures

.are.anot

her.

.In.fact

.when.it.come

.to.impl

ementing

.an.

inte

rconnection

.betw

een

.IP-ba

sed

.netw

orks

.and.a.eld

bus,

.ther

.is.a.surp

rising

.vari

ety

.of.possi

bilities

even.in.the.so.much.“sta

ndardized”

.Inte

rnet

.envi

ronment.

.In.part

icular,

.the.web-b

ased

.appr

oach

.is.by.

no.mea

.the.onl

.one

.very.rece

.year

.brou

ght

.agai

.a.tech

nology

.push.in.eld

-level

.netw

orking.

.Toge

ther

.with.the.

last.phas

.of.eld

bus

.stan

dardization,

.Ether

net

.solu

tions

.for.indu

strial

.use.appe

ared

.at.the.turn.of.the.

cent

ury.

.One.of.the.main.argu

ments

.for.thei

.intr

oduction

.was.the.prom

ising—vertical—integration

possi

bility

.in.comp

any

.LANs

.Alth

ough

.mark

eting

.camp

aigns

.trie

.to.pain

.a.brig

.futu

.of.Ether

net

solv

ing

.all.prob

lems

.in.vert

ical

.inte

gration,

.stan

dard

.Ether

net

.obvi

ously

.lack

.real

-time

.capa

bilities,

whic

.is.an.obst

acle

.for.eld

-level

.use..As.a.resp

onse

.to.thes

.dec

iencies,

.new.real

-time

.netw

orks

.base

on.Ethe

rnet

.were.deve

loped

.that.brok

.with.the.orig

inal

.den

ition

.and.can.be.expec

ted

.to.repl

ace

.sever

of.toda

y’s

.el

dbus

.sys

tems

.in.the.lon

.run

What

.does.all.this.mean.for.vertical.integration?.From.a.technology.point.of.view,.all.basic.elements.

need

.are.nal

.avai

lable—contrary

.to.the.situa

tion

.in.the.CIM.era..What.is.requ

ired

.today.is.to.put.

them.toget

her

.in.a.reas

onable

.way.. e.tech

nological

.issu

.invo

lved

.are.consi

dered

.in.the.subs

equent

sect

ions.

.A.furt

her

.chal

lenge

.lurk

.in.the.appl

ication

.leve

.Figu

.13.1.also.show

.how.typi

cal

.func

tional

unit

.are.asso

ciated

.with.the.indi

vidual

.leve

ls.

.It.appe

ars

.that.vert

ical

.inte

gration

.is.reas

onably

.adva

nced

in.both.the.uppe

.and.lowe

.laye

rs.

. is.is.not.surp

rising

.since.the.two.sect

ions

.mirr

.two.die

rent

worl

.insi

.a.com

pany:

•

. Busin

ess-oriented

.appl

ications

.like.ente

rprise

.reso

urce

.plan

ning

.(ERP

)

.tools

.supp

.chai

.man-

gement

.(SCM

.or.nan

cial

.tools.for.acco

unting

.and.book

keeping

.are.tigh

tly

.inte

grated

.today

 e.users.as.well.as.the.developers.of.such.soware.tools.share.an.economics.background.and.are.

focu

sed

.on.a.str

ategic

.vie

.of.the.com

pany.

•

. Produ

ction-oriented

.appl

ications

.like.supe

rvisory

.cont

rol

.and.data.acqu

isition

.(SCA

DA),

.prod

uc-

tion

.cont

rol,

.assem

bly,

.or.to.a.cert

ain

.exte

.also.manu

facturing

.execu

tion

.syst

ems

.(MES

)

.belo

to.the.oper

ational

.worl

.Agai

.they.are.most

.well.inte

grated,

.but.the.back

ground

.of.users.and.

deve

lopers

.is.typi

cally

.engi

neering,

.whic

.stip

ulates

.an.enti

rely

.die

rent

.view.on.the.over

all

.syst

em.

Figure

.13.1.demo

nstrates

.that.thes

.two.worl

.are.also.sepa

rated

.by.die

rent

.netw

orking

.conc

epts.

In.the.busin

ess

.cont

ext,

.LANs.are.pred

ominant

.wher

eas

.the.cont

rol

.leve

.is.home.of.the.eld

bus.

.Agai

this.is.not.surp

rising

.beca

use

.one.of.the.major.desig

.guid

elines

.for.eld

bus

.syst

ems

.was.the.reco

gni-

tion

.that.in.a.(rea

l-time)

.proc

ess

.cont

rol

.cont

ext,

.comp

letely

.die

rent

.netw

orking

.char

acteristics

.are.

requ

ired

.than.in.the.(str

ategic)

.oce.worl

.Henc

.the.gap.to.brid

.today.not.only.conc

erns

.the.link

ing

of.two.di

erent

.net

work

.typ

.but.als

.the.int

erconnection

.of.two.di

erent

.min

dsets.

13.3 Network Interconnections

 e.implementation.of.communication.networks.has.been.designed.for.particular.levels.of.the.commu-

nication

.hier

archy,

.using.dedi

cated

.I/O.buse

.and.eld

buses

.at.the.lowe

.leve

.Typi

cally,

.inte

rmediate

leve

.have.been.using.othe

.tail

ored

.comm

unication

.syst

ems

.up.to.the.high

est

.leve

.Proc

ess

.data.has.

been.abst

racted

.and.proc

essed

.from.leve

.to.leve

.Netw

ork

.inte

rconnections

.usua

lly

.serv

.hori

zontal

comm

unication,

.i.e.,.the.exch

ange

.of.data.on.the.same.leve

.in.the.hier

archy,

.most

.with

.the.same.

tech

nological

.dom

ain.

Vertical Integration 13-5

 e.requirements.for.vertical.access.to.data.throughout.the.various.communications.levels.require.

a.higher.level.of.interconnection..Here,.dierent.communication.media,.dierent.networking.proto-

cols,

.and.dierent.topologies.have.to.be.connected..Among.other.technologies,.the.use.of.Ethernet.and.

IP-based.protocols.serves.as.the.major.integration.platform.of.today’s.automation.systems..IP-based.

systems.possess.the.special.appeal.that.communication.can.be.established.using.the.public.Internet.

infrastructure,.avoiding.costly.and.proprietary.phone.lines.or.data.links..A.set.of.approaches.are.imple-

mented

.that.lead.to.tighter.vertical.integration:

•

. Flat network hierarchy:.While.staying.within.the.same.technology.domain,.vertical.access.can.

still.be.limited.due.to.dierent.physical.media.and.network.partitioning.into.islands..A.at.net-

work

.hierarchy.eliminates.those.boundaries..Routers.and.tunneling.routers.are.used.today.for.

interconnecting.formerly.isolated.trunks.of.eldbus.networks.

•

. Cross-domain communication:.A.number.of.systems.have.been.designed.to.be.specic.to.their.

application.domain..It.is.common.that.separate.systems.are.found.for.heating,.ventilation,.and.

air-conditioning.(HVAC).and.emergency.lighting.in.building.automation.. e.former.advantage.

of.separating.the.installation.and.engineering.tasks.is.now.becoming.a.burden.for.communica-

tion

.between.those.domains..For.gaining.access.to.dierent.domains,.proxies.are.used.

•

. Protocol convergence:.Providing.protocol,.service,.and.data.translation.between.dierent.network-

ing

.technologies.is.necessary.to.fully.distribute.services.around.the.automation.system..Vertical.

access.through.all.levels.requires.a.gateway.approach.. ese.gateways.translate.the.high-level.

services.between.the.dierent.technologies.

 ere

.is.a.tendency.to.eliminate.the.separation.between.the.automation.and.management.network,.

and.the.implied.dierences.in.network.media..In.some.cases,.even.the.eldbus.level.is.integrated.into.the.

same,.global.network.domain.. e.technology.of.choice.today.is.the.IP.transport.over.Ethernet’s.struc-

tured

.cabling..It.also.brings.the.networks.of.building.automation.systems.(BAS).and.factory.automation.

networks.closer.to.the.IT.network,.which.has.formerly.been.separated..For.doing.so,.most.of.the.widely.

deployed.networks.have.specied.and.implemented.an.IP-based.transport.layer.(CEA-852.for.LonWorks.

[CEA852],.KNX/IP.[KNXIP],.BACnet/IP.[BACIP],.Modbus/IP.[ModIP]).

.general,.this.reduces.cabling.eorts.and.increases.maintainability..In.the.eld,.however,.the.advan-

tages

.of.special.eldbus.media.still.persist:.First,.for.the.ease.of.installation,.where.free.topology.allows.

to.install.cabling.tting.more.closely.to.the.nodes.in.a.room,.and.second,.for.better.extendibility.. e.

remaining. trunks. are.coupled. via.control.network/IP.(CN/IP). routers.. ese.routers.are.tunneling.

routers,.which.encapsulate.the.native.frame.formats.into.IP.transport.. is.architecture.is.depicted.in.

Figure.13.3.. e.advantage.of.tunneling.is.that.eldbus.nodes.can.be.le.unmodied,.i.e.,.do.not.need.

to.implement.an.IP.stack.. e.tunneling.routers.are.store-and-forward.routers,.which.can.additionally.

perform.selective.forwarding.. is.means,.the.trac.is.not.broadcast.over.the.IP.network.but.routed.

precisely.to.the.designated.tunneling.routers.based.on.CN.addressing.information..Other.high-end.

nodes.such.as.powerful.building.controllers.or.SCADA.systems.can.implement.the.tunneling.protocol.

CN/IP

router

CN/IP

router

CN/IP

router

Intranet (Ethernet)

IP-based

control

node

Control network

FIGURE 13.3 System.with.tunneling.CN/IP.routers.

13-6 Industrial Communication Systems

themselves.and.process.the.encapsulated.trac.as.a.node,.not.as.a.router.. is.eectively.enables.purely.

IP-b

ased

.el

dbus

.nod

es,

.whi

.can.com

municate

.dir

ectly

.to.leg

acy

.(no

.IP-b

ased)

.nod

.in.the.sys

tem.

 e.tu

nneling

.ap

proach

.ha

.be

.ch

osen

.fo

.Lo

nWorks

.or.KN

X/IP.

Other

.el

dbus

.sys

tems

.imp

lement

.a.ded

icated

.IP.dat

.lin

.lay

.for.the.el

dbus

.pro

tocol

.nat

ively.

Nod

.in.the

.sys

tems

.can.be.con

nected

.dir

ectly

.onto.the.Ethe

rnet

.net

work

.wit

hout

.the.use.of.a.tun

nel-

ing

.tec

hnique.

.Exa

mples

.are.BAC

net/IP

.or.Mod

bus

.ove

.TCP

.To.acc

ess

.oth

er,

.non.IP-b

ased

.CN.nod

es,

rou

ters

.ar

.us

ed.

Notwithstanding

.the.eas

.of.IP.eve

rywhere,

.a.sep

aration

.of.el

d-level

.and.oc

e-level

.net

works

.is.sti

rec

ommended

.for.per

formance

.and.sec

urity

.rea

sons,

.eve

.if—

.in.the.cas

.of.ind

ustrial

.Ethe

rnet—a

dir

ect

.int

egration

.of.bot

.net

works

.is.pos

sible.

.Ano

ther

.iss

.in.usin

.IP-b

ased

.tra

nsport

.sys

tems

.for.

el

dbus

.pro

tocols

.is.tha

.the.ori

ginal,

.nat

ive

.com

munication

.med

.had.par

tly

.di

erent

.pro

perties.

For.exa

mple,

.del

.tim

es,

.del

.var

iance,

.and.pac

ket

.ord

ering

.may.imp

air

.the.el

dbus

.pro

tocol

.sta

mac

hine

.its

elf.

. es

.ee

cts

.are.typ

ically

.comb

ated

.by.usin

.ext

.seq

uence

.numb

ers

.and.syn

chronized

tim

e-stamping

.on.the.tun

nel.

.Onc

.the.pro

tocol

.sta

.mac

hines

.are.mai

ntained,

.the.app

lication

.on.

top.is.sti

.in

uenced

.in.its.desi

gn.

.App

lication

.tim

ers

.or.fee

dback

.con

trol

.loo

.mus

.be.awa

.of.the.

cha

nged

.ti

ming

.re

lations.

Once

.the.pro

blem

.of.mer

ging

.iso

lated

.net

work

.isl

ands

.into.a.at.net

work

.hie

rarchy

.is.sol

ved,

.log

ical

bou

ndaries

.wit

hin

.the.sam

.net

working

.tec

hnology

.sti

.exi

st.

. es

.are.typ

ically

.imp

osed

.by.di

erent

app

lication

.dom

ains

.to.kee

.the.tra

c,

.add

ressing,

.and.ins

tallation

.tas

.sep

arated.

.Whi

.com

munica-

tion

.would.be.enabled.over.the.at.network,.the.domain.boundary.bars.trac.. e.use.of.proxy.devices.

sol

ves

.thi

.pro

blem.

.Pro

xies

.are.basi

cally

.dev

ices

.tha

.pas

.the.pro

cess

.dat

.and.exp

ose

.it.fro

.one.

dom

ain

.into.ano

ther.

.An.imp

lementation

.of.a.pro

.is.pla

ced

.as.one.ins

tance

.in.eac

.dom

ain.

.Stri

ctly

spe

aking,

.a.pro

.can.be.see

.as.a.gat

eway

.bet

ween

.the.sam

.tec

hnologies.

.An.exa

mple

.for.usin

.pro

xies

is.Lon

Works

.in.auto

mation

.sys

tems.

.In.thi

.sys

tem,

.add

ress

.spa

ces

.are.sep

arated

.by.add

ress

.dom

ains.

 e.add

ress

.dom

ains

.are.set.up.acc

ording

.to.di

erent

.app

lication

.dom

ains,

.suc

.as.HVA

.or.eme

rgency

lig

hting.

.A.Lon

Works

.pro

.can.exp

ose

.dat

.poi

nts

.of.one.dom

ain

.to.ano

ther

.dom

ain.

.Oth

.exa

mples

of.pro

xies

.are.HTT

.pro

xies.

. es

.are.fre

quently

.use

.to.iso

late

.loc

.fro

.pub

lic

.IP.tra

c

.for.sec

urity

rea

sons.

.For.ins

tance,

.the.oc

e-level

.net

work

.nee

.acc

ess

.to.Web.ser

vices

.in.the.el

d-level

.net

work.

Whi

.it.is.com

mon

.pra

ctice

.to.kee

.tho

.two.IP.net

works

.sep

arate,

.an.HTT

.pro

.can.est

ablish

.the.

Web.se

rvice

.li

nk.

Another

.are

.of.foc

.is.pro

tocol

.con

vergence.

.Tod

ay’s

.auto

mation

.sys

tems

.rep

resent

.hig

hly

.het

ero-

geneous

.sys

tems.

.Di

erent

.app

lication

.ser

vice

.dom

ains

.may.use.di

erent

.CN.tec

hnologies.

. e.goa

for.ver

tical

.acc

ess

.or.dis

tribution

.of.com

munication

.ser

vices

.is.cle

arly

.a.sea

mless

.com

munication

.als

bet

ween

.th

.ap

plication

.do

mains

.an

.ac

ross

.al

.la

yers

.of.th

.au

tomation

.sy

stem.

. e.cl

assical

.ap

proach

to.let.sys

tem

.A.com

municate

.wit

.sys

tem

.B.is.the.use.of.gat

eways.

. is.con

cept

.is.bei

.ado

pted

.wid

ely.

Gat

eways

.abs

tract

.the.net

work

.ser

vice

.at.the.app

lication

.lev

.(e.

g.,

.dat

.poi

.val

ues,

.tre

.dat

.sch

ed-

ules,

.and.ala

rms)

.and.rep

resent

.it.in.di

erent

.net

working

.tec

hnologies.

.Com

monly

.use

.gat

eway

.con

cepts

.toda

.are.bas

.on.mon

olithic

.gat

eways.

. es

.are.dev

ices

.tha

.hav

.the.glo

bal

.vie

.of.one.sys

tem

and.exp

ose

.it.to.ano

ther

.sys

tem.

. is.con

cept,

.how

ever,

.pre

sents

.an.inh

erent

.pro

blem:

. e.com

plexity

to.int

egrate

.an.arb

itrary

.numb

.of.sys

tems

.is.of.qua

dratic

.ord

er.

.Ano

ther

.pro

blem

.is.tha

.the.gat

eway

is.a.sin

gle

.po

int

.of.fa

ilure

.(S

POF)

.in.th

.sy

stem.

.the.mov

.to.a.mor

.ser

vice-oriented

.mod

el,

.the.com

munication

.ser

vices

.suc

.as.dat

.poi

nts,

sch

eduling,

.tre

nding,

.or.ala

rming

.can.be.abs

tracted

.and.pre

sented

.in.a.sing

.int

erface,

.whi

.is.tec

nology

.ind

ependent

.[DP

AL].

.App

lications

.dev

eloped

.on.suc

.dev

ices

.use.the.abs

tracted

.int

erface

.and.

are.ess

entially

.mad

.ind

ependent

.fro

.the.und

erlying

.net

working

.sys

tem.

.It.is.imp

ortant

.to.not

.tha

thi

.app

roach

.is.onl

.fea

sible

.for.act

ual

.dat

.com

munication,

.not.the.con

guration

.of.suc

.dev

ices,

whi

.st

ill

.re

mains

.te

chnology

.sp

ecic.

.com

puting

.pow

.is.rea

dily

.ava

ilable,

.dev

ices

.can.add.ano

ther

.net

work

.pro

tocol

.sta

.to.pro

vide

nat

ive

.acc

ess

.to.cer

tain

.ser

vices

.to.the.sys

tem

.of.ano

ther

.tec

hnology.

.Fig

ure

.13.

.pre

sents

.an.exa

ple

.for.thi

.sce

nario.

.A.con

troller

.imp

lements

.not.onl

.the.Lon

Works

.tec

hnology

.but.als

.the.BAC

net

Vertical Integration 13-7

technology.(multi-protocol.device).. is.way,.the.eldbus.node.A.can.directly.retrieve.process.data.from.

the.controller..Nodes.B.and.C,.which.do.not.need.access.to.the.respective.other.network.technology,.can.

still.be.accessed.by.the.operator.workstation’s.native.protocol..No.additional.gateway.is.needed.as.the.

area.of.overlap.does.contain.the.needed.technologies..A.given.number.of.those.multi-protocol.devices.

can.be.seen.as.a.distributed.gateway.. is.means.the.SPOF.has.been.eliminated..Also,.the.complexity.of.

gateway.conguration.is.reduced.as.the.nodes.know.already.about.their.data.points.natively..Clearly,.not.

all.nodes.can.be.equipped.with.an.arbitrary.number.of.networking.technologies.

13.4 application View

An.important.aspect.of.vertical.integration.is.the.interconnection.of.the.soware.application.frame-

works

.that.are.needed.for.the.individual.levels.of.the.automation.hierarchy..From.today’s.view,.the.link.

between.the.top-level.strategic.planning.and.administration.tools.usually.comprised.in.ERP.systems.

and.the.distributed.control.systems.on.the.factory.oor.is.to.be.seen.in.the.MES.concepts.that.translate.

the.overall,.mainly.long-.and.mid-term.plans.into.short-term.work.and.production.orders..To.achieve.

this.integration,.there.is.still.work.to.be.done.[V02]..In.the.context.of.enterprise.engineering,.the.current.

focus.is.on.ecient.modeling.languages.and.techniques,.on.analysis.methods,.and.advanced.computer-

based

.tools.[MPZM03].

.eminent.role.is.played.by.standardization.. e.more.CIM.and.its.successors.found.the.approval.of.

industry,.the.more.it.became.apparent.that.only.concerted.actions.could.nally.produce.results.with.a.high.

application.potential..Standards.generally.provide.the.basis.for.durable.solutions.and.nally.products,.

which.is.particularly.important.in.such.complex.areas.as.the.integration.of.rather.diverse.functions.inside.

an.enterprise..Aer.all,.the.problems.of.enterprise.integration.in.actual.practice.are.not.so.much.the.func-

tional

.modules.as.such.(the.ERP,.MES,.SCADA.systems.in.all.their.varieties).but.the.interfaces.between.

them..Only.standardized.interfaces.together.with.appropriate.functional.models.for.the.application.pro-

cesses

.and.their.data.objects.ultimately.allow.for.interoperability.between.solutions.from.dierent.vendors.

Consequently,

.work.being.done.in.various.standardization.groups.covers.all.aspects.ranging.from.

the. provision. of. modeling. frameworks. and.languages. through. concrete. reference. and.data. models.

for.enterprise.systems.or.subsystems.down.to.standards.for.IT.services.and.infrastructures.[CV04]..

Among.the.many.standards.developed.in.this.context,.the.two.most.relevant.for.this.chapter.are.the.

Manufacturing.Execution.Systems.Association.(MESA).model.and,.in.particular,.the.ISA.S95.Standard.

for.Enterprise-Control.System.Integration,.both.of.which.have.already.been.widely.adopted.as.a.refer-

ence

.for.the.implementation.of.vertical.integration.on.the.higher.level.of.the.automation.hierarchy.[S07].

MESA

.provided.a.denition.of.11.distinct.functional.areas.of.MES.that.cover.the.basic.informa-

tion

.needed.to.run.any.type.of.plant—much.in.contrast.to.ERP.systems.that.have.no.clearly.dened.

functionalities.. is.model.has.become.an.essential.starting.point.for.many.MES.tools.currently.on.the.

market.. e.purpose.of.ISA.S95,.on.the.other.hand,.is.to.dene.the.interface.between.control.functions.

Field

level

Operator

workstation

CEA-852 and BACnet/IP

BACnet

LonWorks

Network 1

Network 2

IP backbone

Management

level

Multi-

protocol

device

LonWorks +

BACnet

router

CEA-852

router

FIGURE 13.4 Protocol.convergence.using.multi-protocol.gateways.

13-8 Industrial Communication Systems

and.other.enterprise.functions,.eectively.between.the.ERP.and.MES.levels.of.an.enterprise.. e.scope.

of.the.standardization.work,.as.seen.by.the.committee,.is

•

. Dene.in.detail.an.abstract.model.of.the.enterprise,.including.manufacturing.control.functions.

and.business.functions,.and.its.information.exchange.

•

. Establish.common.terminology.for.the.description.and.understanding.of.enterprise,.including.

manufacturing.control.functions.and.business.process.functions,.and.its.information.exchange.

•

. Dene.electronic.information.exchange.between.the.manufacturing.control.functions.and.other.

enterprise.functions.including.data.models.and.exchange.denitions.

ISA

.S95.addresses.exclusively.the.information.ow.between.the.control.domain.and.the.enterprise.

domain.of.a.company..Consequently,.in.the.model.adopted.by.ISA,.the.MES.functionality.is.explicitly.

included.in.the.control.domain.(Figure.13.5).. e.information.exchanged.between.the.levels.can.be.cat-

egorized

.in.information.about.the.product.itself.(its.denition),.the.availability.of.production.capabilities,.

and.the.production.of.the.product.itself.(scheduling.and.performance.information)..Functions.concerning.

only.the.ERP.level.or.the.control.level.are.beyond.the.scope.of.the.standard.and.are.therefore.not.covered.

ISA

.S95.should.be.regarded.in.connection.with.ISA.S88.(Batch.processing.model),.which.covers.the.

lower.levels.of.the.automation.model..Both.have.been.developed.in.parallel,.and.they.are.converging.in.

that.there.are.direct.mappings.between.the.two.standards.for.models.and.representations..Likewise,.

the.reference.model.suggested.by.MESA.has.inuenced.the.work,.and.cross.references.between.the.two.

approaches.are.given.in.order.to.facilitate.common.understanding.

.standard.does.not.describe.an.actual.implementation;.it.provides.only.terminology,.functional.

requirements,.and.formal.models..Yet,.inside.the.standardization.group,.the.common.belief.was.that.

XML.might.be.a.promising.approach..Consequently,.a.working.group.was.formed.under.the.umbrella.

of. the. World. Batch. Forum,. and. developed. the. XML. schema. “Business. to. Manufacturing. Markup.

Language”.(B2MML).. is.reference.implementation.was.released.in.a.rst.version.in.2002.and.is.con-

stantly

.being.updated.and.enhanced.

13.5 Security aspects in Vertical Integration

Vertical.integration.in.the.sense.of.connecting.automation.systems.to.a.more.open.environment.natu-

rally

.raises.security.questions..It.has.already.been.stated.that.even.though.network.interconnection.was.

an.essential.goal.of.the.old.CIM.idea,.fieldbus.systems.were.mostly.developed.as.isolated.solutions..

Level 1

Level 2

Level 3

MES

Level 4

ERP

Manufacturing operations management

Dispatching, detailed production scheduling, production tracking, etc.

Business logistics

Plant production scheduling, shipping, receiving, inventory, etc.

Production capability

information

(what is available

for use)

Product definition

information

(how to make

a product)

Production schedule

(what to make

and use)

Production

performance

(what was made

and used)

Batch production

control

Continuous

production control

Discrete production

control

ISA—IEC/ISO

interface standards

ISA 95.01

ISA 95.02

ISA functional model

ISA 95.03

IEC, OPC interface

standards

Level 0

FIGURE 13.5 Scope.of.ISA.95.and.ISA.88.

Vertical Integration 13-9

As. the.timeline.in. Figure. 13.2.shows,. most.of. these. developments. were. concluded.long. before.the.

Internet.became.known.and.was.widely.employed.by.the.broad.public..It.is.thus.no.wonder.that.security.

considerations.never.played.a.prominent.role.in.automation.before.the.end.of.the.1990s.[D97,PS00].

.most.promising.approach.to.cope.with.the.heterogeneity.of.the.networks.is.a.hierarchical.security.

model.following.the.defense-in-depth.approach..Figure.13.6.shows.the.three.typical.interconnection.

zones.in.the.company.network.. e.zones.are.separated.from.each.other.by.dedicated.network.nodes.

that.can.be.used.as.anchor.points.for.the.security.strategy.. e.inner.connection.node.(access.point).to.

the.actual.eldbus.is.the.gateway.or.proxy.already.discussed.in.Section.13.3.

.existing.standards.cannot.be.changed,.the.only.viable.option.for.the.eld.level.is.to.use.the.eld-

bus

.simply.as.a.transport.channel.and.to.tunnel.secure.packets.over.standard.eldbus.protocols.and.

services.[SS02]..Such.an.application-level.approach.could.easily.achieve.end-to-end.security,.which.is.

desired.in.most.applications,.anyway..Unfortunately,.it.is.likely.to.cause.problems.with.interoperability.

unless.all.nodes.in.the.network.adhere.to.this.enhanced.standard,.i.e.,.a.mixture.of.secure.and.insecure.

devices.would.normally.not.be.feasible..In.addition,.the.limited.messages.size.in.some.eldbuses.leaves.

only.little.room.for.the.additional.data.blocks.required.by.ecient.security.extensions.. is.problem.is.

similar.to.the.one.encountered.in.IP.tunneling.discussed.in.Section.13.3.

.access.point.itself.has.so.far.been.the.focal.point.of.interest.for.most.researchers..Given.the.lack.

of.general.eld-level.security,.it.is.the.only.part.of.the.automation.system.(apart.from.the.Internet.side).

where.security.can.easily.be.applied..One.very.common.approach.is.to.combine.the.access.point.with.a.

rewall,.which.is.the.most.widely.employed.security.measure.in.the.design.of.network.interconnections.

today.even.in.the.eld.of.automation.[D97]..Indeed,.the.term.“rewall”.is.nowadays.frequently.used.as.a.

synonym.for.network.security..In.practice,.however,.their.application.is.not.so.straightforward..Owing.

to.the.inherently.asymmetric.operation.of.a.rewall.(transparent.from.the.private.network,.opaque.

from.outside),.it.is.dicult.to.place.a.standard.rewall.in.front.of.a.eldbus.access.point;.it.is.better.to.

tightly.integrate.the.rewall.into.the.access.point.and.use,.e.g.,.port.forwarding.to.control.the.trac.

[PS00]..On.top.of.this,.the.access.point.is.also.the.ideal.point.to.control.and.manage.access.to.the.eldbus.

zone..A.suitable.model.for.handling.access.rights.is.role-based.access.control,.where.all.communication.

partners.(users,.devices,.tools).are.associated.with.particular.roles.depending.on.the.context.of.the.data.

exchange..In.the.IT.world,.this.concept.is.widely.employed,.and.it.can.also.be.used.in.an.automation.

context.[WB04].

Security

.in.the.Internet.nally.is.a.well-researched.topic.with.a.large.number.of.meanwhile.very.

mature.solutions..In.fact,.for.nearly.all.Internet.application.layer.protocols,.secure.versions.exist,.or.

conventional.insecure.protocols.can.be.used.on.top.of.a.secure.transport.layer.. is.standard.mecha-

nism

.of.rst.establishing.an.encrypted.channel.between.communication.partners.is.called.Transport.

Internet

Intranet

Fieldbus

Firewall, network address translation

Firewall, role-based access

Reduced security, proprietary solutions

Controlled access (maintenance staff)

Frequent, automated attacks (port scans)

Standard IT solutions: VLANs, SSH, TLS

Main threat: malicious software

Restricted, controlled user group

FIGURE 13.6 Defense-in-depth.security.model.for.vertically.integrated.company.networks.

13-10 Industrial Communication Systems

Layer.Security.(TLS).and.is.transparent.to.the.application.protocol,.which.therefore.can.remain.mostly.

unchanged;.it.only.requires.the.initialization.of.a.secure.channel.by.negotiating.crypto.algorithms.and.

session.keys..As.soon.as.the.secured.connection.is.established,.the.application.protocol.can.start.

13.6 trends in Vertical Integration

Vertical.integration.has.come.a.long.way.since.its.rst.inception.in.the.CIM.era.. is.chapter.tried.to.

shed.light.on.some.aspects,.by.far.not.all.of.them..An.important.recognition.is.that.the.recent.techno-

logical

.developments.not.only.stimulated.or.revived.the.old.idea,.they.accelerated.and.tightened.the.

integration..As.a.matter.of.fact,.the.large-scale.introduction.of.Internet.technologies.caused.the.multi-

level

.automation.pyramid.to.crumble.down.to.at.maximum.three.levels.(Figure.13.7).. e.company.level.

is.the.strategic.one;.a.further.subdivision.according.to.functional.domains.like.in.Figure.13.1.may.be.

useful;.from.a.technological.viewpoint,.however,.it.is.no.longer.necessary,.not.even.in.large.globalized.

enterprises..Internet.has.already.provided.the.means.to.fully.integrate.remote.branches.in.one.single.

corporate.network.with.one.common.management.or.planning.framework..From.the.many.operational.

levels,.only.two.remain:.the.actual.eld.level.with.the.process.control.devices.and.an.intermediate.level.

typically.for.controlling.purposes.

From

.the.networking.point.of.view,.there.are.in.fact.only.two.levels.le.today..In.the.oce.world.and.

the.upper.automation.level,.IP-based.networks.and.Ethernet.dominate..Even.if.eldbus.systems.still.

have.their.share.on.the.cell.level,.they.are.bound.to.vanish.within.the.next.few.years..It.is.the.eld.level.

that.will.still.belong.to.them,.maybe.with.some.additional.specialized.and.low-level.local.sensor/actua-

tor

.systems.integrated.via.controllers.acting.as.simple.gateways..Nevertheless,.the.recent.emergence.of.

real-time.Ethernet.extensions.already.sparked.new.competition.in.the.eld..In.the.long.run,.real-time.

industrial.Ethernet.will.oer.a.tempting.alternative.to.the.classical.eldbus.systems.and.will.most.prob-

ably

.make.one.or.the.other.obsolete.

But,

.also.from.the.application.point.of.view,.there.is.a.trend.toward.a.further.reduction.of.the.hierar-

chy.

.In.plant.automation,.which.was.traditionally.strictly.centralized.in.the.upper.two.levels,.modular.

concepts.are.becoming.popular.. e.overall.goal.is.to.enhance.exibility.of.planning.systems.and.to.

allow.for.solutions.tailored.to.the.needs.of.the.customer.. is.makes.ERP.and,.especially,.manufactur-

ing

.execution.tools.attractive.also.for.smaller.companies.that.so.far.could.not.benet.from.full-edged.

solutions..One.step.ahead.are.approaches.to.decentralize.essential.parts.of.the.planning.and.control.

functionality..Ideas.like.holonic.manufacturing.systems.or.agent-based.automation.practically.dissolve.

the.rigid.middle.layer.of.the.pyramid,.implementing.its.functionality.in.soware.agents.attached.to.the.

outer.levels.of.the.hierarchy.

.tendency.is.supported.by.complementary.trends.in.the.control.and.enterprise.eld:.In.the.long.

run,.control.devices.will.resemble.standard.PCs.in.terms.of.computing.resources.and.network.inter-

faces

.(Ethernet.and.IP).. us,.they.will.be.able.to.run.more.complex.planning.tasks..On.the.other.hand,.

MES and SCADA

(Cell level)

ERP

and SCM

(company level)

Control (PLCs, NCs)

(field level)

MES

MES and SCADA

(cell level)

ERP

and SCM

(company level)

Control (PLCs, NCs)

(field level)

IP-based

networks

Field area

networks

Strategic

level

Operational

levels

MES

FIGURE 13.7 Decentralization.of.the.middle.level.in.a.typical.industrial.automation.context.