PLC電梯操縱英文文獻(xiàn)五千字翻譯(實(shí)用于本科卒業(yè)設(shè)計(jì))

1、1The,Programmable,Logic,ControllerJohn,R.,Hackworth,Frederick,D.,Hackworth,Jr.Programmable,Logic,Controllers:Programming,Methods,andApplications.,2.52.8,The,Programmable,Logic,Controller,John,R.,Hackworth,Frederick,D.,Hackworth,Jr.First,Edition.London:,Prentice,Hall,2003.3550悉搔邱矯閃報(bào)爆洪揮奶祭擱攣謎凋敞鼎草共鵑圓千酸絕

2、民皺疙核畜泉娟龜PLC電梯控制英文文獻(xiàn)五千字翻譯(適用于本科畢業(yè)設(shè)計(jì))PLC電梯控制英文文獻(xiàn)五千字翻譯(適用于本科畢業(yè)設(shè)計(jì))2.5,System,Block,DiagramA,Programmable,Controller,is,a,specialized,computer.Since,it,is,a,computer,it,has,all,thebasic,component,parts,that,any,other,computer,has;,a,Central,Processing,Unit,Memory,InputInterfacing,and,Output,Interfacing.A

3、,typical,programmable,controller,block,diagram,is,shown,inFigure,2.5.Programmable,Controller,Block,DiagramThe,Central,Processing,Unit,(CPU),is,the,control,portion,of,the,PLC.,It,interprets,theprogram,commands,retrieved,from,memory,and,acts,on,those,commands.In,present,day,PLCsthis,unit,is,a,micropro

4、cessor,based,system.The,CPU,is,housed,in,the,processor,module,ofmodularized,systems.Memory,in,the,system,is,generally,of,two,types;,ROM,and,RAM.The,ROM,memory,containsthe,program,information,that,allows,the,CPU,to,interpret,and,act,on,the,Ladder,Logic,programstored,in,the,RAM,memory.RAM,memory,is,ge

5、nerally,kept,alive,with,an,on-board,battery,sothat,ladder,programming,is,not,lost,when,the,system,power,is,removed.This,battery,can,be,astandard,dry,cell,or,rechargeable,nickel-cadmium,type.,Newer,PLC,units,are,now,available,withElectrically,Erasable,Programmable,Read,Only,Memory,(EEPROM),which,does

6、,not,require,abattery.Memory,is,also,housed,in,the,processor,module,in,modular,systems.Input,units,can,be,any,of,several,different,types,depending,on,input,signals,expected,asdescribed,above.The,input,section,can,accept,discrete,or,analog,signals,of,various,voltage,andcurrent,levels.Present,day,cont

7、rollers,offer,discrete,signal,inputs,of,both,AC,and,DC,voltagesfrom,TTL,to,250,VDC,and,from,5,to,250,VAC.Analog,input,units,can,accept,input,levels,suchas,10,VDC,5,VDC,and,4-20,ma.,current,loop,values.Discrete,input,units,present,each,input,tothe,CPU,as,a,single,1,or,0,while,analog,input,units,conta

8、in,analog,to,digital,conversion,circuitryand,present,the,input,voltage,to,the,CPU,as,binary,number,normalized,to,the,maximum,countavailable,from,the,unit.The,number,of,bits,representing,the,input,voltage,or,current,depends2胡渣臂農(nóng)風(fēng)努委抽抵埠粵衣羨崖槍拉朱襄嚇玉簡(jiǎn)仆寒剔巷蛛鐵吟癡飛喜鑷PLC電梯控制英文文獻(xiàn)五千字翻譯(適用于本科畢業(yè)設(shè)計(jì))PLC電梯控制英文文獻(xiàn)五千字翻譯(適

9、用于本科畢業(yè)設(shè)計(jì))3upon,the,resolution,of,the,unit.This,number,generally,contains,a,defined,number,of,magnitudebits,and,a,sign,bit.Register,input,units,present,the,word,input,to,the,CPU,as,it,is,received,(Binaryor,BCD).Output,units,operate,much,the,same,as,the,input,units,with,the,exception,that,the,unit,ise

10、ither,sinking,(supplying,a,ground),or,sourcing,(providing,a,voltage),discrete,voltages,orsourcing,analog,voltage,or,current.These,output,signals,are,presented,as,directed,by,the,CPU.The,output,circuit,of,discrete,units,can,be,transistors,for,TTL,and,higher,DC,voltage,or,Triacsfor,AC,voltage,outputs.

11、,For,higher,current,applications,and,situations,where,a,physical,contactclosure,is,required,mechanical,relay,contacts,are,available.,These,higher,currents,however,aregenerally,limited,to,about,2-3,amperes.The,analog,output,units,have,internal,circuitry,whichperforms,the,digital,to,analog,conversion,

12、and,generates,the,variable,voltage,or,current,output.2.6,Update,-,Solve,the,Ladder,-,UpdateWhen,power,is,applied,to,a,programmable,logic,controller,the,PLCs,operation,consists,oftwo,steps:,(1),update,inputs,and,outputs,and,(2),solve,the,ladder.This,may,seem,like,a,verysimplistic,approach,to,somethin

13、g,that,has,to,be,more,complicated,but,there,truly,are,only,thesetwo,steps.If,these,two,steps,are,thoroughly,understood,writing,and,modifying,programs,andgetting,the,most,from,the,device,is,much,easier,to,accomplish.With,this,understanding,thethings,that,can,be,undertaken,are,then,up,to,the,imaginati

14、on,of,the,programmer.You,will,notice,that,the,“update,-,solve,the,ladder”,sequence,begins,after,startup.The,actualstartup,sequence,includes,some,operations,transparent,to,the,user,or,programmer,that,occurbefore,actual,PLC,operation,on,the,user,program,begins.During,this,startup,there,may,beextensive

15、,diagnostic,checks,performed,by,the,processor,on,things,like,memory,I/O,devices,communication,with,other,devices,(if,present),and,program,integrity.In,sophisticated,modularsystems,the,processor,is,able,to,identify,the,various,module,types,their,location,in,the,systemand,address.This,type,of,system,a

16、nalysis,and,testing,generally,occurs,during,startup,beforeactual,program,execution.2.7,UpdateThe,first,thing,the,PLC,does,when,it,begins,to,function,is,update,I/O.This,means,that,alldiscrete,input,states,are,recorded,from,the,input,unit,and,all,discrete,states,to,be,output,aretransferred,to,the,outp

17、ut,unit.Register,data,generally,has,specific,addresses,associated,with,it,forboth,input,and,output,data,referred,to,as,input,and,output,registers.These,registers,are,availableto,the,input,and,output,modules,requiring,them,and,are,updated,with,the,discrete,data.Since,this狡兒韭足舜證嚇侈圓歧慧饋陣啥桿抄拒凋卒簧訊蔥幫淬亂餒設(shè)茹莊

18、拔惕歐PLC電梯控制英文文獻(xiàn)五千字翻譯(適用于本科畢業(yè)設(shè)計(jì))PLC電梯控制英文文獻(xiàn)五千字翻譯(適用于本科畢業(yè)設(shè)計(jì))is,input/output,updating,it,is,referred,to,as,I/O,Update.The,updating,of,discrete,input,and,outputinformation,is,accomplished,with,the,use,of,input,and,output,image,registers,set,aside,in,the,PLCmemory.Each,discrete,input,point,has,associated,

19、with,it,one,bit,of,an,input,imageregister.Likewise,each,discrete,output,point,has,one,bit,of,an,output,image,register,associatedwith,it.When,I/O,updating,occurs,each,input,point,that,is,ON,at,that,time,will,cause,a,1,to,be,setat,the,bit,address,associated,with,that,particular,input.If,the,input,is,o

20、ff,a,0,will,be,set,into,the,bitaddress.Memory,in,todays,PLCs,is,generally,configured,in,16,bit,words.This,means,that,oneword,of,memory,can,store,the,states,of,16,discrete,input,points.Therefore,there,may,be,anumber,of,words,of,memory,set,aside,as,the,input,and,output,image,registers.At,I/O,update,th

21、estatus,of,the,input,image,register,is,set,according,to,the,state,of,all,discrete,inputs,and,the,statusof,the,output,image,register,is,transferred,to,the,output,unit.This,transfer,of,informationtypically,only,occurs,at,I/O,update.It,may,be,forced,to,occur,at,other,times,in,PLCs,which,havean,Immediat

22、e,I/O,Update,command.This,command,will,force,the,PLC,to,update,the,I/O,at,othertimes,although,this,would,be,a,special,case.One,major,item,of,concern,about,the,first,output,update,is,the,initial,state,of,outputs.Thisis,a,concern,because,their,may,be,outputs,that,if,initially,turned,on,could,create,a,

23、safety,hazard,particularly,in,a,system,which,is,controlling,heavy,mechanical,devices,capable,of,causing,bodilyharm,to,operators.In,some,systems,all,outputs,may,need,to,be,initially,set,to,their,off,state,toinsure,the,safety,of,the,system.However,there,may,be,systems,that,require,outputs,to,initially

24、,beset,up,in,a,specific,way,some,on,and,some,off.This,could,take,the,form,of,a,predetermined,setupor,could,be,a,requirement,that,the,outputs,remain,in,the,state,immediately,beforepower-down.More,recent,systems,have,provisions,for,both,setup,options,and,even,a,combinationof,the,two.This,is,a,prime,co

25、ncern,of,the,engineer,and,programmer,and,must,be,defined,as,thesystem,is,being,developed,to,insure,the,safety,of,personnel,that,operate,and,maintain,theequipment.Safety,as,related,to,system,and,program,development,will,be,discussed,in,a,laterchapter.2.8,Solve,the,LadderAfter,the,I/O,update,has,been,

26、accomplished,the,PLC,begins,executing,the,commandsprogrammed,into,it.These,commands,are,typically,referred,to,as,the,ladder,diagram.The,ladderladder,is,drawn,with,contacts,to,the,left,side,of,the,sheet,and,coils,to,the,right.This,is,aholdover,from,the,time,when,control,systems,were,relay,based.This,

27、type,of,diagram,was,usedfor,the,electrical,schematic,of,those,systems.A,sample,ladder,diagram,is,shown,in,Figure,2-6.4殿稅勾石迎纓鑷藹矽吾脹呢笆宇皖泰筍頸蝶鹿衣滔藝乏餓烷梆嫁緝鵝撿困PLC電梯控制英文文獻(xiàn)五千字翻譯(適用于本科畢業(yè)設(shè)計(jì))PLC電梯控制英文文獻(xiàn)五千字翻譯(適用于本科畢業(yè)設(shè)計(jì))Sample,Ladder,DiagramThe,symbols,used,in,Figure,2.6,may,be,foreign,at,this,point,so,a,short,expl

28、anation,will,benecessary.The,symbols,at,the,right,of,the,ladder,diagram,labeled,CR1,CR2,CR3,and,CR4,andare,circular,in,shape,are,the,software,coils,of,the,relays.The,symbols,at,the,left,which,look,likesymbols,that,look,like,capacitors,without,the,diagonal,lines,through,them,are,normally,opencontacts

29、.These,are,analogous,to,a,switch,that,is,normally,off.When,the,switch,is,turned,on,thecontact,closes.The,contact,symbols,at,the,left,that,look,like,capacitors,with,diagonal,linesthrough,them,are,normally,closed,contacts.A,normally,closed,contact,is,equivalent,to,a,switchthat,is,normally,turned,on.It

30、,will,turn,off,when,the,switch,is,actuated.As,can,be,seen,in,Figure,2.6,contact,and,coil,position,is,as,described,above.Also,one,cansee,the,reason,for,the,term,ladder,diagram,if,the,rungs,of,a,stepladder,are,visualized.In,fact,eachcomplete,line,of,the,diagram,is,referred,to,as,one,rung,of,logic.The,

31、actual,interpretation,of,thediagram,will,also,be,discussed,later,although,some,explanation,is,required,here.The,contactconfiguration,on,the,left,side,of,each,rung,can,be,visualized,as,switches,and,the,coils,on,the,rightas,lights.If,the,switches,are,turned,on,and,off,in,the,proper,configuration,the,l

32、ight,to,the,rightwill,illuminate.The,PLC,executes,this,program,from,left,to,right,and,top,to,bottom,in,thatorder.It,first,looks,at,the,switch,(contact),configuration,to,determine,if,current,can,be,passed,tocurrent,can,be,passed,the,light,(coil),will,then,be,turned,on.If,not,the,light,(coil),will,be,

33、turnedoff.This,is,recorded,in,the,output,image,register.Once,the,PLC,has,looked,at,the,left,side,oftherung,it,ignores,the,left,side,of,the,rung,until,the,next,time,it,solves,that,particular,rung.,Once5理窟蓬蛛孟炎巍趟侯曙鋤仇沏薛修政轍腸芬睦著恍頒躍俱葡分痔鴕達(dá)尊鉆PLC電梯控制英文文獻(xiàn)五千字翻譯(適用于本科畢業(yè)設(shè)計(jì))PLC電梯控制英文文獻(xiàn)五千字翻譯(適用于本科畢業(yè)設(shè)計(jì))the,light,(co

34、il),has,been,either,turned,on,or,off,it,will,remain,in,that,state,until,the,next,time,thePLC,solves,that,particular,rung.After,solving,a,rung,the,PLC,moves,on,to,solve,the,next,rung,inthe,same,manner,and,so,forth,until,the,entire,ladder,has,been,executed,and,solved.One,rule,thatis,different,from,gen

35、eral,electrical,operation,is,the,direction,of,current,flow,in,the,rung.In,aladder,logic,rung,current,can,only,flow,from,left,to,right,and,up,and,down;,never,from,right,toleft.As,an,example,in,the,ladder,shown,in,Figure,2.7,coil,CR1,will,energize,if,any,of,thefollowing,conditions,exist:Illustration,o

36、f,allowed,current,flow,in,ladder,rung1.,CR7,is,off,CR6,is,on.2.,CR7,is,off,CR2,is,on,CR5,is,on.3.,CR7,is,off,CR2,is,on,CR3,is,on.4.,CR1,is,on,CR4,is,on,CR3,is,on.5.,CR1,is,on,CR4,is,on,CR5,is,on.You,will,notice,that,the,current,flow,in,the,circuit,in,each,of,the,cases,listed,above,is,fromleft,to,rig

37、ht,and,up,and,down.,CR1,will,not,energize,in,the,case,listed,below:CR1,is,on,CR4,is,on,CR2,is,on,CR6,is,on,CR5,is,off,CR3,is,off,CR7,is,on.This,is,because,current,would,have,to,flow,from,right,to,left,through,the,CR2,contact.This,is,not,allowed,in,ladder,logic,even,though,current,could,flow,in,this,

38、direction,if,we,were,tobuild,it,with,real,relays.Remember,we,are,working,in,the,software,world,not,the,hardwareworld.To,review,after,the,I/O,update,the,PLC,moves,to,the,first,rung,of,ladder,logic.It,solves,thecontact,configuration,to,determine,if,the,coil,is,to,be,energized,or,de-energized.It,then,e

39、nergizesor,de-energizes,the,coil.After,this,is,accomplished,it,moves,to,the,left,side,of,the,next,rung,andrepeats,the,procedure.This,continues,until,all,rungs,have,been,solved.When,this,procedure,iscomplete,with,all,rungs,solved,and,all,coils,in,the,ladder,set,up,according,to,the,solution,of,eachrun

40、g,the,PLC,proceeds,to,the,next,step,of,its,sequence,the,I/O,update.6騎瑟贓哄祭影首揚(yáng)幸霜詞忻僳睫類睛脹氈躊楞令否遂攜撕筆隔態(tài)焙蘭桔架PLC電梯控制英文文獻(xiàn)五千字翻譯(適用于本科畢業(yè)設(shè)計(jì))PLC電梯控制英文文獻(xiàn)五千字翻譯(適用于本科畢業(yè)設(shè)計(jì))At,I/O,update,the,states,of,all,coils,which,are,designated,as,outputs,are,transferred,from,theoutput,image,register,to,the,output,unit,and,the,sta

41、tes,of,all,inputs,are,transferred,to,the,inputimage,register.Note,that,any,input,changes,that,occur,during,the,solution,of,the,ladder,areignored,because,they,are,only,recorded,at,I/O,update,time.The,state,of,each,coil,is,recorded,tothe,output,image,register,as,each,rung,is,solved.,However,these,stat

42、es,are,not,transferred,to,theoutput,unit,until,I/O,update,time.Figure2.8,Scan,CycleThis,procedure,of,I/O,update,and,solving,the,ladder,diagram,and,I/O,update,is,referred,to,asscanning,and,is,represented,in,Figure,2.8.,The,period,between,one,I/O,update,and,the,next,isreferred,to,as,one,Scan.The,amoun

43、t,of,time,it,takes,the,PLC,to,get,from,one,I/O,update,to,thenext,is,referred,to,as,Scan,Time.Scan,time,is,typically,measured,in,milliseconds,and,is,related,tothe,speed,of,the,CPU,and,the,length,of,the,ladder,diagram,that,has,to,be,solved.The,slower,theprocessor,or,the,longer,the,ladder,diagram,the,l

44、onger,the,scan,time,of,the,system.The,speed,atwhich,a,PLC,scans,memory,is,referred,to,as,Scan,Rate.Scan,rate,units,are,usually,listed,inmsec/K,of,memory,being,utilized,for,the,program.As,an,example,if,a,particular,PLC,has,a,ratedscan,rate,of,8,msec/K,and,the,program,occupies,6K,of,memory,it,will,tak

45、e,the,PLC,48,msec,tocomplete,one,scan,of,the,program.7組覆賒威迭屎胡梭斜之腎薛皖淀揩眷腦芋芹磨牛擠桿舀怯擄拾拽職領(lǐng)鎳齲PLC電梯控制英文文獻(xiàn)五千字翻譯(適用于本科畢業(yè)設(shè)計(jì))PLC電梯控制英文文獻(xiàn)五千字翻譯(適用于本科畢業(yè)設(shè)計(jì))1.1,MotivationProgrammable,Logic,Controllers,(PLC),a,computing,device,invented,by,Richard,E.,Morleyin,1968,have,been,widely,used,in,industry,including,manufactu

46、ring,systems,transportationsystems,chemical,process,facilities,and,many,others.,At,that,time,the,PLC,replaced,thehardwired,logic,with,soft-wired,logic,or,so-called,relay,ladder,logic,(RLL),a,programminglanguage,visually,resembling,the,hardwired,logic,and,reduced,thereby,the,configuration,timefrom,6,

47、months,down,to,6,days,Moody,and,Morley,1999.Although,PC,based,control,has,started,to,come,into,place,PLC,based,control,will,remainthe,technique,to,which,the,majority,of,industrial,applications,will,adhere,due,to,its,higherperformance,lower,price,and,superior,reliability,in,harsh,environments.,Moreov

48、er,according,toa,study,on,the,PLC,market,of,Frost,and,Sullivan,1995,an,increase,of,the,annual,sales,volumeto,15,million,PLCs,per,year,with,the,hardware,value,of,more,than,8,billion,US,dollars,has,beenpredicted,though,the,prices,of,computing,hardware,is,steadily,dropping.,The,inventor,of,thePLC,Richa

49、rd,E,Morley,fairly,considers,the,PLC,market,as,a,5-billion,industry,at,the,presenttime.Though,PLCs,are,widely,used,in,industrial,practice,the,programming,of,PLC,based,controlsystems,is,still,very,much,relying,on,trial-and-error.,Alike,software,engineering,PLC,softwaredesign,is,facing,the,software,di

50、lemma,or,crisis,in,a,similar,way.,Morley,himself,emphasized,thisaspect,most,forcefully,by,indicating,Moody,and,Morley,1999,p.,110:If,houses,were,built,like,software,projects,a,single,woodpecker,could,destroy,civilization.”Particularly,practical,problems,in,PLC,programming,are,to,eliminate,software,b

51、ugs,and,toreduce,the,maintenance,costs,of,old,ladder,logic,programs.,Though,the,hardware,costs,of,PLCsare,dropping,continuously,reducing,the,scan,time,of,the,ladder,logic,is,still,an,issue,in,industryso,that,low-cost,PLCs,can,be,used.In,general,the,productivity,in,generating,PLC,is,far,behind,compar

52、ed,to,other,domains,forinstance,VLSI,design,where,efficient,computer,aided,design,tools,are,in,practice.,Existentsoftware,engineering,methodologies,are,not,necessarily,applicable,to,the,PLC,based,softwaredesign,because,PLC-programming,requires,a,simultaneous,consideration,of,hardware,andsoftware.,Th

53、e,software,design,becomes,thereby,more,and,more,the,major,cost,driver.,In,many閏武躊懷術(shù)熔勤呀支格紗德旗勻楓咆良閃誰(shuí)詛夠瞄琶妹輯焉替殼推痘域苞PLC電梯控制英文文獻(xiàn)五千字翻譯(適用于本科畢業(yè)設(shè)計(jì))PLC電梯控制英文文獻(xiàn)五千字翻譯(適用于本科畢業(yè)設(shè)計(jì))industrial,design,projects,more,than,SO0/a,of,the,manpower,allocated,for,the,control,systemdesign,and,installation,is,scheduled,for,test

54、ing,and,debugging,PLC,programs,Rockwell,1999.In,addition,current,PLC,based,control,systems,are,not,properly,designed,to,support,thegrowing,demand,for,flexibility,and,reconfigurability,of,manufacturing,systems.,A,furtherproblem,impelling,the,need,for,a,systematic,design,methodology,is,the,increasing,

55、softwarecomplexity,in,large-scale,projects.1.2,Objective,and,Significance,of,the,ThesisThe,objective,of,this,thesis,is,to,develop,a,systematic,software,design,methodology,for,PLCoperated,automation,systems.,The,design,methodology,involves,high-level,description,based,onstate,transition,models,that,t

56、reat,automation,control,systems,as,discrete,event,systems,a,stepwisedesign,process,and,set,of,design,rules,providing,guidance,and,measurements,to,achieve,asuccessful,design.,The,tangible,outcome,of,this,research,is,to,find,a,way,to,reduce,theuncertainty,in,managing,the,control,software,development,p

57、rocess,that,is,reducingprogramming,and,debugging,time,and,their,variation,increasing,flexibility,of,the,automationsystems,and,enabling,software,reusability,through,modularity.,The,goal,is,to,overcomeshortcomings,of,current,programming,strategies,that,are,based,on,the,experience,of,theindividual,soft

58、ware,developer.Design,Theory,DevelopmentToday,the,primary,focus,of,most,design,research,is,based,on,mechanical,or,electricalproducts.,One,of,the,by-products,of,this,proposed,research,is,to,enhance,our,fundamentalunderstanding,of,design,theory,and,methodology,by,extending,it,to,the,field,of,engineeri

59、ngsystems,design.,A,system,design,theory,for,large-scale,and,complex,system,is,not,yet,fullydeveloped.,Particularly,the,question,of,how,to,simplify,a,complicated,or,complex,design,taskhas,not,been,tackled,in,a,scientific,way.,Furthermore,building,a,bridge,between,design,theoryand,the,latest,epistemo

60、logical,outcomes,of,formal,representations,in,computer,sciences,andoperations,research,such,as,discrete,event,system,modeling,can,advance,future,development,inengineering,design.Application,in,Logical,Hardware,DesignFrom,a,logical,perspective,PLC,software,design,is,similar,to,the,hardware,design,of荊