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

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24-12 Industrial Communication Systems

24.6.5 Network redundancy for Safety and Fault tolerance

As.on.any.Ethernet.network,.bit.errors.may.occur..In.this.case,.a.frame.will.be.deleted.thanks.to.detection.

by.an.invalid.Ethernet.frame.check.sequence.(FCS),.and.it.will.not.arrive.at.the.destination..Likewise,.

faulty.equipment.(switch.or.end-system).may.send.rubbish.on.the.network.or.simply.exceed.its.VL.con-

tracts.

.In.this.case,.the.next.switch.on.the.path.will.reject.the.extra.communication.(thanks.to.policing.

mechanisms.in.the.switch.input.ports),.and.prevent.the.faulty.equipment.from.polluting.the.rest.of.the.

network..Again.some.data.will.be.lost.in.the.process.

.order.to.provide.fault.tolerance.for.both.types.of.errors,.the.AFDX.is.actually.doubled.as.depicted.

in.Figure.24.11..End.systems.have.two.Ethernet.network.interfaces.and.the.whole.topology.of.switches.

and.links.is.doubled,.leading.to.a.so.called.“red”.network.and.a.so.called.“blue”.network..An.additional.

parameter.in.the.VL.denition.states/denes.whether.the.VL.needs.redundancy,.i.e.,.whether.frames.of.

this.VL.are.sent.on.both.the.red.and.the.blue.networks..Nearly.all.VLs.are.duplicated.on.the.two.net-

works.

.Of.course,.only.one.frame.is.returned.by.the.protocol.stack.on.a.receiver:.the.rst.valid.frame.to.

arrive.is.returned.and.the.second.one.(if.it.ever.arrives).is.deleted..However,.this.scheme.requires.proper.

matching.of.red.and.blue.frames..For.this.reason,.the.standard.Ethernet.frame.format.has.been.modi-

ed

.to.include.an.8.bits.sequence.number.(protected.by.the.FCS).

Unregulated

flows

VL1

VL2

VL3

Shapers

Multiplexer

BAG BAG BAG

Jitter ≠ 0

Jitter = 0

FIGURE 24.10 AFDX.VLs.scheduling.and.jitter.

FIGURE 24.11 AFDX.redundant.networks.

Embedded Networks in Civilian Aircraft Avionics Systems 24-13

 e.impact.of.this.redundancy.mechanism.on.guaranteed.latencies.is.limited..Of.course,.average.

late

ncy

.for.a.singl

.fram

.impr

oves

.since.Late

ncy

.=.Min.(Lat

ency

red

,.Latency

blue

),.but.as.we.deal.with.

late

ncy

.boun

.and.since.late

ncy

.boun

.whic

.are.most

.the.same.on.both.the.red.and.blue.netw

orks,

the.na

.lat

ency

.bou

.is.una

ected

.by.the.red

undant

.net

work.

24.7 aFDX End-to-End Delay analysis

As.presented.before,.the.main.problem.is.to.guarantee.that.frames.exchanged.between.end.systems.sat-

isfy

.the.temp

oral

.cons

traints

.of.tran

sported

.data

. ere

fore,

.the.end-

to-end

.dela

.of.each.path.of.each.

VL.has.to.be.stu

died.

. e.end

-to-end

.del

.of.eac

.pat

.of.VL.inc

ludes

.the.fol

lowing

.cha

racteristics:

•

. e.lowe

.boun

.for.the.end-

to-end

.dela

.corr

esponds

.to.the.case.wher

.ther

.is.no.wait

ing

.ser-

ice

.time.for.the.fram

.in.queu

es.

. is.can.be.easil

.comp

uted

.by.addi

.tran

smission

.time

.over.

the.phy

sical

.lin

.and.swi

tching

.del

ays.

•

. e.uppe

.boun

.for.the.end-

to-end

.dela

.corr

esponds

.to.the.long

est

.aggr

egate

.wait

ing

.serv

ice

time.for.the.fram

.in.queu

es.

. is.uppe

.boun

.is.mand

atory

.in.avio

nics

.cont

ext

.for.cert

ication

reas

ons.

Dierent

.appr

oaches

.have.been.prop

osed

.in.orde

.to.anal

yze

.netw

orks

.ow’

.end-

to-end

.dela

.and.

jitt

.[AC

OR99,C98,CSC01,CSEF06,IETF89,IETF98,JNTW02,SCP95,TC94].

Deterministic

.netw

ork

.calc

ulus

.(or.wors

t-case

.netw

ork

.calc

ulus)

.has.been.used

.for.cert

ication

.rea-

ons,

.to.comp

ute

.AFDX.uppe

.boun

.[C91

,C95].

.Netw

ork

.calc

ulus

.theo

.uses.enve

lopes

.of.arri

val

curv

.and.comp

utes

.a.wors

t-case

.scen

ario

.on.each.node.visit

.by.a.ow,.taki

.into.acco

unt

.maxi

mum

.possi

ble

.jitt

.intr

oduced

.by.prev

iously

.visit

.node

.[LB9

8,LBT01].

. is.appr

oach

.is.obvi

ously

pessi

mistic

.as.it.can.lead.to.impo

ssible

.scen

arios,

.but.it.has.been.usef

.to.prov

.the.dete

rminism

.of.

an.AFDX.netw

ork

.as.it.comp

utes

.a.guar

anteed

.uppe

.boun

.of.end-

to-end

.tran

smission

.dela

.for.each.

VLon.the.netw

ork.

. is.wors

t-case

.comm

unication

.dela

.anal

ysis

.also.give

.inte

rmediate

.info

rmation

on.latency.time.in.switch.output.ports,.which.permits.the.scaling.of.the.switch.memory.buers.and.

avoi

ding

.bue

.over

ows

.(i.e

.fram

.loss

.More

over,

.such.an.appr

oach

.has.been.used.for.the.optim

iza-

tion

.of.a.give

.AFDX.con

guration

.[FFG

06].

.In.conc

lusion,

.a.cert

iable

.netw

ork

.(wit

.no.swit

.bue

over

ow

.and.bou

nded

.lat

ency

.con

guration)

.oe

.und

eruses

.AFD

.net

work

.cap

abilities.

Nevertheless,

.the.pessi

mism

.of.the.netw

ork

.calc

ulus

.appr

oach

.cann

.be.eval

uated

.by.simpl

.com-

aring

.the.end-

to-end

.dela

.meas

ured

.on.a.real.AFDX.con

guration

.with.the.comp

uted

.uppe

.boun

beca

use

.of.the.fact.that.rare.even

.are.dic

ult

.to.obse

rve

.on.a.real.con

guration

.in.a.reas

onable

.time

In.orde

.to.bett

.unde

rstand

.the.real.beha

vior

.of.an.AFDX.netw

ork,

.a.simul

ation

.appr

oach

.has.also.

been.prop

osed.

.A.dist

ribution

.of.obse

rved

.end-

to-end

.dela

.on.a.simul

ated

.AFDX.netw

ork

.can.ther

eby

be.obta

ined

.for.each.ow.[CSF

06].

.Stocha

stic

.netw

ork

.calc

ulus

.as.prop

osed

.in.[H63

,VB01,VB02]

.migh

also.hel

.to.obt

ain

.a.pro

babilistic

.end

-to-end

.del

.ana

lysis

.[SR

F09].

.mode

l-checking

.appr

oach

.migh

.help.to.dete

rmine

.an.exac

.wors

t-case

.end-

to-end

.dela

.and.the.

corr

esponding

.scen

ario

.since.it.expl

ores

.all.possi

ble

.stat

.of.the.netw

ork.

.Yet.up.to.now.mode

.chec

ing

.has.not.been.able.to.be.used.on.a.real

-size

.indu

strial

.netw

ork

.con

guration

.[CSE

F06].

.In.orde

.to.

bett

.eval

uate

.the.pessi

mism

.of.the.end-

to-end

.dela

.uppe

.boun

.obta

ined

.by.dete

rministic

.netw

ork

calc

ulus,

.the.rece

.traje

ctory

.appr

oach

.seem

.to.be.a.prom

ising

.meth

.[MM0

6].

. is.appr

oach

.is.

base

.on.the.anal

ysis

.of.the.wors

t-case

.scen

ario

.expe

rienced

.by.a.pack

.on.its.traje

ctory

.and.not.on.any.

visit

.nod

24.8 Conclusion

 e.traditional.mono-emitter.ARINC.429.data.bus.has.played.a.major.role.in.the.architecture.of.classic.

civi

lian

.avio

nics,

.but.it.can.no.long

.cope.with.the.comm

unication

.need

.of.new.avio

nics

.arch

itectures

base

.on.IMA..A.rst.solu

tion

.was.to.use.a.mult

iplexed

.data.bus.such.as.the.ARIN

.629.data.bus,.

24-14 Industrial Communication Systems

but.the.ARINC.664.network.based.on.Ethernet.full-duplex.switching.is.now.becoming.the.avionics.

ref

erence

.com

munication

.tec

hnology.

.Its.abi

lity

.to.con

nect

.avi

onics

.wor

.and.ope

n-world

.onb

oard

a.civ

ilian

.air

cra

.is.one.of.its.majo

.adv

antages.

.As.cer

tied

.AFD

.net

works

.are.oe

.und

erused

.for.

avi

onics

.app

lications,

.the.nex

.ste

.wil

.be.to.use.the.AFD

.net

work

.for.oth

.app

lications

.pro

vided

.thi

has.abs

olutely

.no.con

sequences

.on.cri

tical

.avi

onics

.app

lications:

.Qua

lity

.of.ser

vice

.(Qo

S)-aware

.AFD

swi

tches

.cou

.be.pro

posed

.for.det

erministic

.ARI

.664.net

works.

.Suc

.a.net

work

.cou

.be.see

.as.a.

fed

erator

.net

work,

.whi

.int

erconnects,

.via.spe

cic

.gat

eways,

.oth

.com

munication

.net

works

.or.bus

(cl

assic

.Ethe

rnet,

.el

.bus

es,

.etc

.).

.In.the.nea

.fut

ure,

.avi

onics

.arc

hitectures

.wil

.hav

.to.han

dle

.het

ero-

geneous

.co

mmunication

.o

.an

.he

terogeneous

.co

mmunication

.me

ans.

abbreviations

AEEC. Airlines.Electronic.Engineering.Committee

AFDX

. Avi

onics

.Fu

ll-DupleX

.Sw

itched

.Eth

ernet

AIMS

. Air

plane

.In

formation

.Ma

nagement

.Sy

stem

APEX

. APp

lication

.EX

ecutive

API

. App

lication

.Pr

ogramming

.In

terface

ARINC

. Aer

onautical

.Ra

dio

.IN

Corporated

ARINC

.42

. Mar

.33.Di

gital

.In

formation

.Tr

ansfer

.Sy

stem

ARINC

.62

. Mul

ti-Transmitter

.Da

.Bu

ARINC

.65

. Desi

.Gu

idance

.fo

.In

tegrated

.Mo

dular

.Av

ionics

ARINC

.65

. Avi

onics

.Ap

plication

.So

ware

.Sta

ndard

.In

terface

ARINC

.65

. Bac

kplane

.Da

.Bu

ARINC

.66

. Air

cra

.Da

.Ne

twork

ARP

. Add

ress

.Re

solution

.Pr

otocol

ARP

.47

. Cer

tication

.Co

nsiderations

.fo

.Hi

ghly

.In

tegrated

.or.Co

mplex

.Ai

rcra

.Sy

stems

ASG

. Ape

riodic

.Sy

nchronization

.Ga

. Ape

riodic

.Ti

meout

BAG

. Ban

dwidth

.Ac

cess

.Ga

BEB

. Bin

ary

.Ex

ponential

.Ba

.O

. Basi

.Pr

otocol

. Concatenation.Event

. Comb

ined

.Pr

otocol

CPM

. Cor

.Pr

ocessing

.Mo

dule

CPU

. Cen

tral

.Pr

ocessing

.Un

CSMA/CA

. Car

rier

.Se

nse

.Me

dium

.Ac

cess/Collision

.Av

oidance

CSMA/CD

. Car

rier

.Se

nse

.Me

dium

.Ac

cess/Collision

.De

tection

DATAC

. Dig

ital

.Au

tonomous

.Te

rminal

.Ac

cess

.Co

mmunication

DITS

. Dig

ital

.In

formation

.Tr

ansfer

.Sy

stem

FCS

. Fra

.Ch

eck

.Se

quence

GARP

. Gen

eric

.At

tribute

.Re

gistration

.Pr

otocol

GMRP

. Gar

.Mu

lticast

.Re

gistration

.Pr

otocol

IEEE

. Ins

titute

.of.El

ectrical

.an

.El

ectronics

.En

gineers

IEEE

.80

. Loc

.an

.Me

tropolitan

.Ar

.Ne

tworks

IEEE

.80

2.1d

. Med

.Ac

cess

.Co

ntrol

.Le

vel

.Br

idging

IEEE

.80

2.3

. CSM

A/CD

.Ac

cess

.Me

thod

IMA

. Int

egrated

.Mo

dular

.Av

ionics

LRM

. Lin

.Re

placeable

.Mo

dule

LRU

. Lin

.Re

placeable

.Un

MIL-STD-1553

. Air

cra

.In

ternal

.Ti

.Di

vision

.Co

mmand/Response

.Mu

ltiplex

.Da

.Bu

Embedded Networks in Civilian Aircraft Avionics Systems 24-15

MC. Model.Checking

. Net

work

.Ca

lculus

PSG

. Per

iodic

.Sy

nchronization

.Ga

SAE

. Soc

iety

.of.Au

tomotive

.En

gineers

SDI

. Sou

rce/Destination

.Id

entier

. Syn

chronization

.Ga

SSM

. Sig

n/Status

.Ma

trix

TDMA

. Tim

.Di

vision

.Mu

ltiple

.Ac

cess

. Ter

minal

.Ga

. Tra

nsmit

.In

terval

. Vir

tual

.Li

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. Info

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.Augu

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.44,.1087–1096,.Ma

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the Internet,

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3-540-42184-X.

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.Was

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.Aircra

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.Comm

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.Mul

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B02]

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.Yo

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.2002.

25-1

25.1 Introduction

 e.expression.“process.automation”.confronts.us.with.two.meaningful.words:.process.and.automation..

Usua

lly

.the.fol

lowing

.de

nition

.is.pre

sented

.in.the.tec

hnical

.lit

erature,

.e.g

.[PO

L94],

.for.a.pro

cess:

.proc

ess

.repr

esents

.the.enti

rety

.of.cons

ecutive

.inte

racting

.acti

vities

.with

.a.syst

.to.tran

sform,

store.or.tra

nsport

.mat

erial,

.ene

rgy

.or.inf

ormation.

.den

ition

.cove

.not.only.proc

esses

.enco

untered

.in.tech

nical

.doma

ins

.but.also.nont

echnical

ones.such.as.busin

ess

.proc

esses.

. ere

fore,

.the.tech

nical

.lite

rature

.prov

ides

.us.with.a.den

ition

.for.a.

tech

nical

.pro

cess

.as.fol

lows:

.techn

ical

.proc

ess

.is.a.proc

ess,

.whose.phys

ical

.value

.are.meas

ured

.and.inu

enced

.by.techn

ical

means.

.word.autom

ation

.is.deri

ved

.from.the.anci

ent

.Gree

.word.auto

matos

.mean

ing

.“sel

.movi

ng,

.self.

thin

king.”

.Autom

ation

.impl

icates

.the.usag

.of.arti

cial

.inst

ruments

.to.enab

.the.autom

atic

.exec

ution

of.a.proc

ess.

.With.resp

ect

.to.the.tech

nical

.doma

in,

.it.mean

.equi

pping

.an.inst

allation

.with.cert

ain

mach

ines

.and.ins

truments

.to.ens

ure

.its.auto

matic

.job.exe

cution.

Process

.autom

ation

.ther

efore

.refe

.to.the.autom

ation

.of.proc

esses,

.incl

uding

.also.nont

echnical

.ones

In.the.cas

.of.tec

hnical

.pro

cesses,

.it.inv

olves

.thr

.cou

pled

.kin

.of.sys

tems:

•

. A.tec

hnical

.sys

tem

.(a.tec

hnical

.pro

duct

.or.ins

tallation)

.wit

.an.exe

cuted

.tec

hnical

.pro

cess

•

. A.dat

.pro

cessing

.and.com

munication

.sys

tem

.wit

.an.exe

cuted

.inf

ormation

.pro

cess

•

. Oper

ator

.pers

onnel

.that.guid

.and.obse

rve

.the.job.exec

ution

.and.reac

.in.the.case.of.exce

ptions

or.sys

tem

.err

ors

Process Automation

25.1. Introduction.....................................................................................25-1

25.2

. Struc

tures

.and.Mod

els

.of.Bat

.Man

ufacturing

.Sys

tems.........25-3

Process.Model. •. Physical.Model. •. Procedural.Control.Model. •. .

Equipment.Entities. •. Recipes. •. Classication.of.Process.

Cells. •. Tasks.and.Functions.of.a.Batch.Management.and.Operation.

System. •. Integration.of.Batch.Management.and.Operation.System.

with.Other.Information.Systems

25.3. Currently.Applied.Communication.Systems..............................25-8

25.4

. Upco

ming

.Requ

irements

.of.Dist

ributed

.Proc

ess

Auto

mation...................................................................................25-8

25.5

. Indu

strial

.Ethe

rnet

.as.the.“Si

lver

.Bul

let”

.for.Fut

ure

Proc

ess

.Auto

mation

.Com

munication

.Nee

ds............................25-10

References...................................................................................................25-11

Alois Zoitl

Vienna University

of Tec

hnology

Wilfried Lepuschitz

Vienna University

of Tec

hnology

25-2 Industrial Communication Systems

Dierent.types.of.processes.can.be.identied.and.their.application.domains.are.depicted.in.Figure.25.1..

 e.process.types.are.characterized.as.follows:

•

. Discrete.processes.contain.data.of.xed.points.in.time.and.space.to.follow.determined.time.sched-

ules

.and.determined.target.locations..Discrete.processes.can.therefore.be.regarded.as.nonstationary.

processes.. ey.usually.appear.at.the.production.of.individual.work.pieces.with.a.dened.shape.and.

determined.measurements..Common.activities.involve.the.treatment.of.surfaces,.shaping.of.work.

pieces,.and.the.assembly.of.parts.to.create.more.complex.products.such.as.the.engine.of.a.car.

•

. Continuous.processes.remain.in.a.constant.operational.state.without.down.times.due.to.a.continu-

ous

.supply.of.material.and.energy..Simultaneously,.these.processes.produce.a.continuous.output..All.

characteristic.values.(such.as.pressure,.temperature,.or.concentration).along.the.ow.path.within.

the.process.equipment.are.locally.dierent.but.temporally.constant.. erefore,.a.continuous.process.

runs.stationary.. is.type.of.processes.usually.appears.at.the.production.of.shapeless.materials.such.

as.gas,.liquid,.or.powder..It.aims.at.the.alteration.of.the.material’s.nature,.structure,.property,.or.

chemical.composition..Continuous.processes.are.found,.for.instance,.in.a.petrochemical.renery.

•

. Batch.processes.are.neither.discrete.nor.continuous..Nevertheless.they.share.similarities.with.both.

other.process.types..On.the.one.hand,.batch.processes.represent.a.subset.treatment.of.goods.nor-

mally

.treated.in.continuous.processes.but.moreover.also.follow.determined.time.schedules.similar.

to.discrete.processes..Regarding.an.ideal.material.mixture,.all.characteristic.values.within.the.pro-

cess

.equipment.are.locally.equal.but.change.during.the.dwell.period..Hence,.a.batch.process.runs.

nonstationary.. e.name.is.derived.from.the.term.“batch,”.which.represents.the.amount.of.material.

located.in.the.reactor.vessel.that.is.treated.as.a.whole.within.in.the.process..Batch.processes.are.

found,.for.instance,.in.the.food.and.beverage.industry.as.well.as.the.pharmaceutical.industry.

.already.stated,.the.term.process.automation.can.be.used.widely.for.a.broad.range.of.domains..

Nevertheless,.it.is.commonly.deemed.to.be.closely.connected.with.technical.domains.and.more.specic.

oen.with.those.domains.that.treat.the.production.of.shapeless.materials..In.fact,.the.German.word.

Verfahrenstechnik,.which.represents.only.one.possible.translation.for.process.engineering,.is.more.

specic.and.indeed.only.related.to.technical.engineering.

For

.our.purposes,.we.adopt.the.common.understanding.of.process.automation.in.the.context.of.

material.transforming.processes.of.shapeless.materials..Furthermore,.our.focus.lies.on.batch.processes,.

as.they.combine.attributes.of.both.discrete.and.continuous.processes.and.are.more.complex.to.handle.

Discrete

processes

Batch

processes

Continuous

processes

Pulp and paper industry

Petrochemical industry

Refineries

Pharmaceutical industry

Food industry

Breweries

Automotive industry

Mechanical engineering

Textile industry

FIGURE 25.1 Types.of.processes.and.application.domain.examples.

Process Automation 25-3

during.start-up.as.well.as.in.operation..Production.plants.with.batch.processes.need.to.be.more.exible.

and.are.oen.connected.to.facilities.with.applied.discrete.processes.such.as.bottling.plants..Nevertheless,.

the.shown.communication.system.architectures.and.requirements.especially.from.the.continuous.parts.

of.batch.processes.can.be.applied.also.to.continuous.processes.

25.2 Structures and Models of Batch Manufacturing Systems

International.standards.comprise.commonly.agreed.reference.points.and.specications.and.therefore.

are.of.vital.importance.for.companies.to.be.competitive..With.respect.to.the.automation.of.batch.manu-

facturing

.plants,.the.standard.ISA/ANSI.S88.Batch.Control.and.its.counterpart.IEC.61512.Batch.Control.

provide.a.standardized.terminology.and.a.consistent.set.of.methods..Both.standards.are.similar.and.

separated.into.the.following.four.parts:

•

. ISA/ANSI.S88.01.(IEC.61512-1).Batch.Control,.Part.1:.Models.and.Terminology

•

. ISA/ANSI.S88.02.(IEC.61512-2). Batch.Control,.Part.2:.Data.Structures.and.Guidelines.for.Languages

•

. ISA/ANSI.S88.03.(IEC.61512-3).Batch.Control,.Part.3:.General.and.Site.Recipe.Models

•

. ISA/ANSI.S88.03.(IEC.61512-4).Batch.Control,.Part.4:.Batch.Production.Records

Especially,

.Part.1.of.this.standard,. Models. and. Terminology.[IEC97],.assists. in. determining. the.

requirements.for.communications.systems.by.providing.reference.models.for.batch.control.as.applied.in.

the.process.industries..In.general,.the.utilization.of.this.standard.shall.lead.to

•

. A.shortening.of.the.setup.time.of.production.facilities.to.manufacture.new.products

•

. Easier.development.of.tools.for.implementing.batch.control

•

. Enabling.the.users.to.better.determine.their.requirements

•

. Easier.development.of.recipes.without.the.services.of.a.control.systems.engineer

•

. A.cost.reduction.of.automating.batch.processes

•

. A.decrease.of.life-cycle.engineering.eorts

According

.to.the.standard,.the.described.models.may.be.diminished.or.extended.as.long.as.the.con-

sistency

.of.each.model.remains.assured..Currently.employed.batch.control.systems.are.based.on.these.

models,.allowing.a.certain.grade.of.interoperability.between.these.products..ISA/ANSI.S88.introduces.a.

set.of.structural.models.that.deal.with.processes,.physical.equipment,.and.control.soware..Figure.25.2.

shows.the.correlations.between.the.procedural.control.model,.the.physical.model,.and.the.process.model.

Process

model

Physical

model

Procedural

control model

Procedure

Unit

procedure

Operation

Phase

Process cell

Unit

Equipment

module

Process

stage

Process

operation

Process

action

Combined

with

Delivers

FIGURE 25.2 Procedural.control.mapped.onto.equipment.to.achieve.process.functionality..(Based.on.IEC.TC65,.

IEC.61512-1:.Batch.Control—Part.1:.Models.and.terminology..International.Electrotechnical.Commission,.1997.)

25-4 Industrial Communication Systems

25.2.1 Process Model

A.batch.process.can.be.segmented.hierarchically.according.to.the.process.model.of.the.standard.into.

pro

cess,

.pr

ocess

.st

age,

.pr

ocess

.op

eration,

.an

.pr

ocess

.ac

tion.

•

. A.pro

cess

.rep

resents

.the.seq

uence

.of.che

mical,

.phy

sical,

.or.bio

logical

.act

ivities

.for.the.tra

nsfor-

mation,

.tra

nsport,

.or.stor

age

.of.mat

erial

.or.ene

rgy.

.IEC.615

.pre

sents

.the.pro

duction

.of.pol

yvi-

nyl

.ch

loride

.(P

VC)

.as.a.ba

tch

.pr

ocess

.ex

ample.

•

. A.pro

cess

.con

sists

.of.one.or.mor

.pro

cess

.sta

ges

.tha

.usu

ally

.run.ind

ependently

.fro

.eac

.oth

in.a.ser

ial

.or.par

allel

.arb

itration

.to.con

duct

.a.sch

eduled

.seq

uence

.of.tra

nsformations

.of.the.pro

cessed

.mat

erial.

.Reg

arding

.the.PVC.pro

cess,

.typ

ical

.pro

cess

.sta

ges

.cou

.be.the.pol

ymerization

.of.

vin

.ch

loride

.mo

nomer

.to.po

lyvinyl

.ch

loride

.or.th

.dr

ying

.of.PV

.po

wder.

•

. A.process.stage.contains.a.number.of.process.operations..Each.process.operation.refers.to.a.larger.

pro

cess

.act

ivity,

.whi

.in.fac

.mea

.usu

ally

.one.che

mical

.or.phy

sical

.tra

nsformation

.of.the.pro

cessed

.mat

erial.

.Typ

ical

.pro

cess

.ope

rations

.of.the.PVC.pro

cess

.cou

.be.the.pre

paration

.of.the.

rea

ctor

.or.th

.re

action

.it

self.

•

. Pro

cess

.act

ions

.rep

resent

.sma

ller

.pro

cess

.act

ivities

.tha

.are.com

bined

.to.a.pro

cess

.ope

ration.

 e.pro

cess

.op

eration

.“r

eaction”

.co

uld

.co

nsist

.of.th

.fo

llowing

.pr

ocess

.ac

tions:

. 1.. Fil

.a.ce

rtain

.am

ount

.of.ca

talyst

.in

.th

.re

actor.

. 2.. Fil

.a.ce

rtain

.am

ount

.of.vi

nyl

.ch

loride

.mo

nomer

.in

.th

.re

actor.

. 3.. Hea

.up.th

.re

actor

.to.a.te

mperature

.be

tween

.55

°C

.an

.60

°C.

. 4.. Hol

.th

.re

actor

.te

mperature

.be

tween

.55

°C

.an

.60

°C

.un

til

.th

.re

actor

.pr

essure

.dr

ops.

25.2.2 Physical Model

 e.physical.model.abstracts.the.physical.organization.of.a.batch.manufacturing.company.into.a.hierarchical.

str

ucture.

.Usu

ally,

.gro

upings

.of.low

.lev

els

.are.mer

ged

.to.for

.a.high

.lev

.but.ISA

/ANSI

.S88.tre

ats

.the.

upp

.thr

.lev

els—enterprise,

.sit

.and.are

a—of

.the.phy

sical

.mod

.onl

.mar

ginally

.sin

.the

.lev

els

.are.

conn

ected

.clo

ser

.to.ent

repreneurial

.tha

.tec

hnical

.reg

ards.

. e.low

.fou

.lev

els—process

.cel

.uni

.equ

ip-

ment

.mod

ule,

.and.con

trol

.mod

ule—represent

.del

imited

.gro

upings

.of.equ

ipment.

.Comb

ining

.equ

ipment

int

.fun

ctional

.gro

upings

.eas

.ope

rational

.tas

.sin

.eac

.of.the

.gro

upings

.can.be.tre

ated

.as.a.lar

ger

sin

gle

.dev

ice.

•

. An.ent

erprise

.is.an.org

anization

.tha

.coo

rdinates

.the.ope

ration

.of.one.or.mor

.site

.Pro

duct

dec

isions

.are.mad

.on.thi

.lev

.as.wel

.as.det

erminations

.abo

.the.man

ufacturing

.loc

ation

.and.

production.methods.

•

. A.site.rep

resents

.a.str

ucturally,

.geo

graphically,

.or.log

ically

.lim

ited

.par

.of.a.bat

.pro

ducing

ent

erprise.

.Gen

erally,

.the

.lim

itations

.are.bas

.rat

her

.on.org

anizational

.as.wel

.as.ent

repre-

neurial

.th

.on.te

chnical

.cr

iteria.

•

. An.are

.ref

ers

.to.a.str

ucturally,

.geo

graphically,

.or.log

ically

.lim

ited

.par

.of.a.bat

.pro

ducing

site

.Lik

ewise,

.reg

arding

.site

.the

.lim

itations

.are.bas

.on.org

anizational

.and.ent

repreneurial

cri

teria.

•

. A.pro

cess

.cel

.is.a.log

ical

.gro

uping

.of.equ

ipment

.to.pro

cess

.one.or.mor

.bat

ches.

.Log

ical

.con

trol

pos

sibilities

.are.de

ned

.acc

ording

.to.the.str

ucture

.of.pro

cess

.cel

.wit

hin

.an.are

.to.dev

elop

.con

trol

.st

rategies

.(e

.g.,

.in.th

.ca

.of.em

ergency

.sit

uations).

•

. A.uni

.con

tains

.con

trol

.mod

ules

.and

/or

.equ

ipment

.mod

ules

.to.con

duct

.lar

ger

.pro

cess

.act

ivities

of.one.bat

.(e.

g.,

.rea

ction

.or.cry

stallization

.of.a.dil

ution).

.A.uni

.comb

ines

.all.nec

essary

.pro

cess

dev

ices

.to.con

duct

.the

.act

ivities

.as.an.ind

ependent

.equ

ipment

.gro

uping

.and.may.all

ocate

.als

common.resources.for.its.tasks..Generally,.its.elements.are.arranged.around.a.processing.instal-

lation

.(e.

g.,

.a.rea

ctor

.tan

k).

.Acc

ording

.to.ISA

/ANSI

.S88

.a.uni

.pro

cesses

.not.mor

.tha

.a.sing

bat

.or.on

.pa

.of.it.at.an

.po

int

.in.ti

me.

Process Automation 25-5

•. An.equipment.module.refers.to.a.functional.aggregation.of.devices,.which.is.generally.arranged.

aro

und

.a.sma

ller

.pro

cessing

.ins

tallation

.(e.

g.,

.a.lt

er)

.to.con

duct

.sma

ller

.pro

cess

.act

ivities

.(e.

g.,

dosi

.of.mat

erial).

.It.may.eit

her

.be.par

.of.a.uni

.or.act.as.a.com

mon

.res

ource

.if.de

ned

.as.an.

ind

ependent

.de

vice.

•

. A.con

trol

.mod

ule

.rep

resents

.the.low

est

.lev

.of.dev

ice

.agg

regation

.and.is.cap

able

.of.per

forming

basi

.con

trol

.act

ivities.

.Typ

ically,

.it.con

tains

.sen

sors,

.act

uators,

.and.oth

.con

trol

.mod

ules

.to.

for

.a.fun

ctional

.uni

.tha

.can.be.ope

rated

.as.a.sing

.ent

ity

.(fo

.exa

mple,

.a.clo

sed-loop

.con

trol

dev

ice

.th

.co

nsists

.of.a.tr

ansmitter,

.a.co

ntroller,

.an

.a.co

ntrol

.va

lve).

25.2.3 Procedural Control Model

 e.procedural.control.model.consists.of.the.four.levels.procedure,.unit.procedure,.operation,.and.phase.

•

. A.pro

cedure

.ref

ers

.to.a.str

ategy

.to.con

duct

.a.pro

cess

.(e.

g.,

.the.pro

duction

.of.a.bat

ch)

.and.is.de

ned

by.a.seq

uence

.of.uni

.pro

cedures.

.As.an.equ

ipment

.pro

cedure,

.it.is.par

.of.the.equ

ipment

.con

trol,

whi

.en

ables

.an.en

tity

.(i

.e.,

.a.te

chnical

.de

vice)

.to.be.co

ntrollable.

•

. A.uni

.pro

cedure

.rep

resents

.a.str

ategy

.to.exe

cute

.a.pro

cess

.wit

hin

.a.uni

.and.con

tains

.a.seq

uence

of.ope

rations

.as.wel

.as.sta

rt,

.con

trol,

.and.org

anization

.alg

orithms.

. es

.ope

rations

.can

not

.be.

dis

tributed

.ove

.sev

eral

.uni

.and.onl

.one.ope

ration

.may.be.act

ive

.wit

hin

.its.uni

.dur

ing

.any.

poi

.in.tim

.Nev

ertheless,

.sev

eral

.uni

.pro

cedures

.of.one.pro

cedure

.can.be.exe

cuted

.simu

ltane-

ously

.if.dis

tributed

.ove

.sev

eral

.uni

ts—one

.uni

.pro

cedure

.per.uni

.As.an.equ

ipment

.uni

.pro

ce-

dure,

.it.is.part.of.the.equipment.control.

•

. An.ope

ration

.is.an.ind

ependent

.pro

cess

.act

ivity

.and.con

sists

.of.a.seq

uence

.of.pha

ses

.as.wel

.as.

sta

rt,

.con

trol,

.and.org

anization

.alg

orithms.

.Typ

ically,

.an.ope

ration

.ref

ers

.to.one.che

mical

.or.

phy

sical

.tr

ansformation.

.As.an.eq

uipment

.op

eration,

.it.is.pa

.of.th

.eq

uipment

.co

ntrol.

•

. A.pha

.rep

resents

.the.low

est

.lev

.of.pro

cedural

.ele

ments

.wit

hin

.the.pro

cedural

.con

trol

.mod

el.

It.ref

ers

.to.a.sma

.pro

cess-oriented

.tas

.and.can.be.seg

mented

.into.ste

.and.tra

nsitions

.as.in.

a.seq

uential

.fun

ction

.cha

rt.

. e.tas

.of.a.pha

.is.the.exe

cution

.of.a.pro

cess-oriented

.act

ion,

whe

reas

.its.ste

.foc

.on.the.tec

hnical

.spe

cications

.of.the.use

.equ

ipment.

.For.exa

mple,

.a.ste

cou

.be.the.act

ivation

.or.dea

ctivation

.of.a.clo

sed-loop

.con

trol.

.A.pha

.tha

.is.par

.of.an.equ

ip-

ment

.co

ntrol

.is.ca

lled

.an.eq

uipment

.ph

ase.

25.2.4 Equipment Entities

Equipment.entities.are.composed.by.combining.the.lower.four.levels.of.the.physical.model.with.the.ele-

ments

.of.the.pro

cedural

.con

trol

.mod

.to.pro

vide

.the.nec

essary

.fun

ctionality

.to.pro

duce

.a.bat

ch.

.Bas

on.thi

.con

text,

.the.ter

.pro

cess

.cel

.uni

.equ

ipment

.mod

ule,

.and.con

trol

.mod

ule

.sti

.ref

.to.the.

phy

sical

.en

tities

.bu

.al

.in

clude

.th

.co

rresponding

.eq

uipment

.co

ntrol.

The

.cor

relations

.bet

ween

.the.pro

cedural

.con

trol

.mod

el,

.the.phy

sical

.mod

el,

.and.the. pro

cess

mod

.are.dep

icted

.in.Fig

ure

.25.

.Pro

cess

.fun

ctionality

.can.be.ach

ieved

.by.map

ping

.the.pro

ce-

dural

.con

trol

.ont

.the.phy

sical

.equ

ipment.

.Tho

ugh

.all.mod

els

.res

emble

.eac

.oth

.wit

.res

pect

to.the.num

ber

.of.lev

els

.(as.alr

eady

.men

tioned

.onl

.the.low

.fou

.lev

els

.of.the.phy

sical

.mod

.are.

tre

ated

.in.thi

.sta

ndard),

.ele

ments

.of.dif

ferent

.lev

els

.are.com

bined

.to.pro

vide

.pro

cess

.fun

ctionality

of.a.cer

tain

.lev

el.

25.2.5 recipes

A.“recipe”.contains.the.minimal.necessary.information.and.requirements.to.produce.a.certain.product..

It.rep

resents

.a.met

hod

.to.des

cribe

.a.pro

duct

.inc

luding

.its.cor

responding

.pro

duction

.pro

cedures

.and.

pro

cess-related

.inf

ormation.

. e.sta

ndard

.dis

tinguishes

.gen

eral

.rec

ipe,

.site.rec

ipe,

.mas

ter

.rec

ipe,

.and.

con

trol

.re

cipe.