电气工程及其自动化专业_外文文献_英文文献_外文翻译_plc方面.pdf

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1、 1、外文原文 A:Fundamentals of Single-chip Microcomputer Th e si ng le-c hi p mic ro co mput er i s t he c ul mi na ti on of both t h e de ve lo pmen t o f t he d ig it al co mpu te r an d th e i n te gr at ed c i rc ui t a rg ua bl y t h e to w mos t s ig ni f ic an t i nv en ti on s of t he 20th c e nt

2、 ur y 1.Th es e t ow ty pe s of ar ch it ec tu re a re fo un d i n s in gle-ch i p mi cr oc ompu te r.So me em pl oy t he spl i t pr og ra m/da ta memory o f th e Ha rv ar d ar ch it ect ure,sh own in Fi g.3-5A-1,o th ers fo ll ow t he ph il os op hy,wi del y a da pt ed f or ge ner al-pur po se co m

3、pu te rs a nd mi cr op ro ce ss or s,o f maki ng n o log i ca l di st in ct ion be tw ee n pr og ra m an d d at a memory a s i n t he P r in ce to n ar ch ite c tu re,sh own i n F ig.3-5 A-2.In g en er al te r ms a s in gl e-chi p m ic ro co mput er i s c h ar ac te ri ze d by t he i nc or po ra ti

4、on of a ll t he un it s of a co mputer i n to a s in gl e d ev i ce,as s ho wn in Fi g3-5A-3.Program memory Input&CPU Output unit Data memory Fig.3-5A-1 A Harvard type Input&CPU Output unit Fig.3-5A-2.A conventional Princeton computer External System Timer/Timing clock Counter components Serial I/O

5、Reset Interrupts Power ROM Prarallel I/O RAM CPU Fig3-5A-3.Principal features of a microcomputer Read only memory(ROM).R OMi s us ua ll y f or th e p erm an ent,no n-vo la ti le s tor age o f an a pp lic ati on s pr og ra m.Man y mi cr oc ompu te rs an d m ar e in te nd e d f or hi gh-v ol ume a ppl

6、 ic at ions an d he nc e t he eco nomic al m an uf act ure o f th e de vic es re qu ir es t h at t he co nt en t s of t he pr og ra m memor y b e co mmit t ed pe rm ane ntly du ri ng t he m an ufa c tu re o f ch ip s.Cl ea rl y,t hi s i mpl ie s a r i go ro us a pp ro ach to R OMc od e de ve l op me

7、nt s in ce ch ang es c an not be mad e af te r manu f ac tu re.Th is d ev elo pmen t pr oc ess ma y in vo lv e emul at io n us in g a so ph is ti ca te d d eve lo pmen t sy ste m w it h a ha rd ware e mula tio n c ap ab il it y as wel l as t he u se o f po werf ul s o ft ware t oo ls.Some m an uf ac

8、t ure rs p ro vi de ad d it io na l ROM opt i on s by i n cl ud in g i n th eir r ange d ev ic es wi t h(or i nt en de d f or u se wit h)us er p ro gr ammable memory.Th e sim ple st o f th es e i s u su al ly de vi ce w hi ch c an o per at e in a mi cro pro ce ss or mod e b y u si ng s ome of t he i

9、 np ut/o utp ut li ne s as a n a ddr es s an d da ta b us f or ac ce ss in g ex te rna l m emor y.T hi s t y pe o f de vi ce ca n b eh av e 2 f u nc ti on al ly a s t he si ng le ch ip mi cr oc ompu te r fro m w hi ch it is de ri ve d al be it wi t h re st ri ct ed I/O a nd a m od if ied ex te rn al

10、 c i rc ui t.Th e u se o f th es e dev ic es i s c ommon e ve n i n pr od uc ti on c i rc ui ts wh er e t he vo lu me do es no t j us ti f y t h e dev el opmen t costs of c us to m o n-ch i p ROM2;t he re c a n s ti ll be a s ig nif i ca nt sa ving i n I/O an d o th er c hip s c ompa re d t o a co n

11、v en ti on al mi c ro pr oc es sor ba se d ci rc ui t.Mo r e ex ac t re pl ace men t fo r ROM dev i ce s ca n be ob ta in ed i n th e f orm o f va ri an ts wit h p ig gy-b ack EPROM(Er as ab le pr o gr ammabl e RO M)s oc ke ts o r d ev ic e s wi th EP ROM i n st ea d of ROM。Th es e d ev ic es are na

12、 tu ra ll y more ex pen si ve th an eq ui va le nt R OMde v ic e,b ut d o pro v id e co mple te ci r cu it eq ui va le nt s.E PROM b as ed de vi ce s a r e al so ex tr emel y a tt ra ct ive f o r lo w-vo lu me ap p li ca ti on s wh ere th ey pr ov id e th e a dv an ta ges of a si ng le-c hi p d evi

13、ce,i n te rm s o f on-c hi p I/O,et c.,wi th t he c o nv en ie nc e of fl exi bl e us er p rog r ammabi li ty.Random access memory(RAM).RAM i s fo r th e st or ag e o f wo rk ing v a ri ab le s an d d at a u se d d ur in g pr ogr am e xe cu ti on.Th e s iz e of t h is m emor y va rie s w it h de vi

14、ce ty pe bu t it h as th e s ame c h ar ac te ri st ic wi dth (4,8,16 b its et c.)as t he pr oc es so r,S pe cia l f un ct io n re gi st e rs,su ch a s s tac k p oi nt er o r t i mer re gi st er ar e o ft en l og ic all y i nc or po ra te d i n to t he R AM ar ea.It is al so c ommon i n H ar ard ty

15、pe mi cr oc ompu t er s to tr ea t t h e RA M a re a as a co ll ec ti on of r egi st er;it is u nne ce ss ar y to ma ke d is ti nc ti on b et ween RA M a nd p r oc es so r re gi ste r a s i s d on e i n t he ca se of a mi cr op ro ce ss or sy s te m si nc e R AM a nd re gi st er s ar e no t us ua ll

16、 y p hys ic al ly s ep ara t ed i n a mi cr oco mpu te r.Central processing unit(CPU).The C PU is mu ch l i ke th at of a ny mi cr op ro ce s so r.Man y a pp li c at io ns o f mic ro c ompu te rs and mi cr oc on tr ol le rs i nv ol ve th e h and l in g of bi na ry-c o de d de ci mal(BCD)da t a(f or

17、n umeri ca l di sp lay s,fo r e xa mple),he nc e i t is c o mmon t o f in d t ha t t he CPU i s well ad ap te d t o h an dl i ng t hi s t ype of da ta.I t i s a ls o co mmon to fi nd go od fa ci li ti es f o r t es ti ng,s e tt in g and re se tt i ng in di vi du al bi t s o f memor y or I/O si nc e

18、many c o nt ro l l er ap pl ic ati on s i nv ol ve th e t ur ni n g on an d o ff of si ngle ou tp ut l in es o r t he re ad in g th e s i ng le l in e.T hes e l in es a re r e ad il y in te rf ace d t o tw o-st at e d evi ce s su ch a s s wit ch es,t h er most at s,s oli d-s ta te r el ay s,v al ve

19、s,m ot or,e t c.Parallel input/output.P ar al le l i np ut a nd o ut pu t s ch emes v a ry so mewhat i n di ff er en t mi cr oc omput er;i i s pr ov id ed t o at le as t al lo w so me fl ex ib il it pi ns ar e ou tp ut s a nd w hi ch a re in pu t s.Th is n mo st a m ec ha nism y of ch o os in g w hi

20、 ch may ap pl y to a ll or 3 s o me o f th e po rts.S ome I/O li nes ar e su it ab le fo r d ir ec t i n te rf ac in g to,f or ex ampl e,f luo r es ce nt d is pl ays,o r ca n pr ov id e su ff ic ien t c ur re nt to make in te rf ac in g o the r c ompo ne nt s s t ra ig ht fo rw ar d.Some dev ic es a

21、l lo w an I/O po rt to be c on f ig ur ed as a sy st em b us to a ll ow o ff-c hi p me mory an d I/O exp ans io n.Th is f a ci li ty i s po ten t ia ll y us ef ul as a pr od uc t ra nge de ve lo ps,s i nc e su cc es si ve enh an ce ment s may be co me t oo b ig f or o n-ch ip me mory a nd i t is und

22、 es ir ab le n ot t o bu il d on t he e xi st in g s o ft ware b as e.Serial input/output .S er i al co mmuni ca ti on wi th t erminal de vi ce s i s co mmon me an s of p ro vi din g a li nk u si ng a sm al l nu mber of l in es.T hi s so r t of co mmun ic at i on c an al so be e xp lo it ed fo r i n

23、 te rf ac in g sp eci al fu nc ti on c hip s o r li nk in g sev e ra l mi cr oc ompu te rs to get he r.B ot h the co mmon a sy nc hro n ou s s y nc hr on ou s co mmunic at io n sc he mes re qu ir e pr ot oco l s th at pr ov id e fr amin g(s ta rt a nd s to p)i nf or mati on.Thi s c an b e i mpl emen

24、 te d as a har dwar e fa ci lit y o r U(S)ART(Univ er sal(sy nc hr on ou s)as y nc hr on ou s r e ce iv er/t ra ns mit t er)re li ev in g t he pr oc es so r(an d t he ap pl ic at io ns p rog r ammer)o f th is l ow-l ev el,ti me-c on su mi ng,de ta il.t is m ere l y ne ce ss ar y to s el ec te d a ba

25、 ud-r at e an d po ss ib ly o th er op t io ns(nu mber of st op bi ts,p ari t y,e tc.)and l o ad(or re ad fr om)t he se ri al tr an s mi tt er(o r re c ei v er)b uf fer.Se ri al iz at io n of t he d at a in t he app ro pr ia te f orm at is t he n ha nd le d by t he ha r dwar e ci rc ui t.Timing/coun

26、ter facilities.Many ap pl ic at io n of s i ng le-c hi p mi cro c ompu te rs r eq uir e a cc ur at e ev alu a ti on o f el ap se d re al ti me.T hi s c an be det erm in ed b y c ar ef u l as se ss ment of t he e xe cu ti on t i me of ea ch br anc h i n a p ro gr am but th is r ap id ly be co mes in

27、ef fi cie nt fo r all bu t sim p le st pro gr ams.T h e pr ef er re d ap pr oa ch i s t o us e t im er ci rc ui t t ha t c an i nd ep en den tl y co unt pr ec is e t im e in c re men ts a nd ge ne r at e an i nt er ru pt af t er a pr eset t i me h as el ap se d.This ty pe o f ti mer i s u su al ly a

28、 r ra ng ed t o be r e lo ad ab le wi th t he r eq ui re d co un t.T he t im er t he n de cr ements t h is v al ue p ro duc i ng a n in te rr upt or s et ti ng a fl a g when t he c o un te r re ac he s z ero.Be tt er t ime r s th en h av e the ab il it y to au to mati ca ll y rel o ad t he i ni ti a

29、l c oun t va lu e.T hi s r el ie ve s th e pr og ra mmer of t he r es po ns ib il it y of r el oa di ng t he c ou nt er and as se ss in g el ap sed ti me b ef or e the ti mer re st ar ted,w hi ch ot he rw is e woun d b e n ec es sa ry i f c ont in uo us p re cis e ly t im ed i n te rr up ts w er e r

30、e qui re d(a s in a c l oc k,f or e xa mple).S omet im es as so ci at ed w it h t i mer is an e ve nt co un te r.Wi th t his f ac il ity t h er e i s us ua ll y a s pe ci al i np ut pi n,t ha t ca n dr ive t he c ou nt er di re ct ly.4 Timing components.The c lo ck c ir c ui tr y of m os t mi cr oc

31、ompu te rs re qui re s on ly s imp l e ti mi n g c ompon e nt s.I f ma xi mum per fo rman c e is re qu ir ed,a c ry st al must be us ed t o ens ure t h e ma xi mum c lo c k f re qu en c y is ap pr o ac he d but not ex c ee de d.Many c l oc k ci rc ui ts al s o work w it h a r esi st or a nd c apa c

32、it or a s l o w-co st t im in g c ompon en ts o r can be d ri ve n fr om a n ex te rn al s o ur ce.This l att er ar ra ng emen t i s u se fu l is e xte r na l s y nc hr on iz at io n o f t he m ic ro co mput er i s re qu ir ed.WORDS AND TERMS culmination n.顶点 spilt adj.分离的 volatile n.易变的 commit v.保证

33、 albeit conj.虽然 custom adj.定制的 variant adj.不同的 piggy-back adj.背负式的 socket n.插座 B:PLC1 PL Cs(pr og ra mmabl e l og ic al c on tro l le r)f ac e ev er mor e c o mple x c ha ll en ge s t he se da ys .Where o nce t he y qui etl y r ep la ced r e la ys a nd ga ve a n o cc as io na l r ep ort t o a co rp

34、ora t e ma in fr ame,t h ey are no w gr oup e d in to ce ll s,gi v en new jo b an d ne w l an gu ag es,an d ar e fo rc ed to co mpet e ag ai nst a gr owin g ar ray of c on tr ol pr od uc ts.Fo r thi s y ea r s an nu al PLC t ec hn ol og y u p da te,we qu er ie d PLC maker s o n th es e to pic s a nd

35、 m or e.Programming languages Hi gh er l ev el P LC p r og ra mmin g la ngu age s ha v e b ee n ar oun d fo r s o me t im e,b ut la t el y th ei r po pul ari ty h as m us hro o mi ng.A s Ra ymon d Le ve il le,vi ce p re si de nt&g en er al m an age r,Si emen s En er gy&Auto matio n.in c;Pr og ra mma

36、bl e co nt ro ls ar e b ei ng used f o r more an d mor e s oph is ti ca te d ope r at io ns,la ng uag es ot he r t ha n l a dd er l og ic be come mor e pra ct ic al,ef fi ci en t,an d po werf ul.Fo r ex ampl e,i t s ver y d if fi cu lt t o w r it e a tr ig on omet ri c fu nc ti on us in g la dd er l

37、 ogi c.L an gu ag es ga i ni ng a cc ep ta nce in cl ud e Bo ol ea n,c on tr ol s ys te m f lo wcha rt i ng,an d s uc h fu n ct io n ch art l a ng ua ge s as Gra ph c et a nd i ts va ria t io n.A nd t he re s in cr ea si ng i n te re st i n la ngu age s li ke C a nd BASIC.PLCs in process control 5 T

38、h us f ar,PLCs h av e not be en us ed ex te ns iv el y f or co nti nu ous pr oc es s co nt ro l.Wil l th is c on tin ue?Th e fe el ing th at I v e go tt en,s ay s Ken J an no tt a,mang er,pr od uc t p la nn ing ,s er ie s One an d S er ie s Si x pro d uc t,at GE Fa nuc N or th A meri ca,i s t ha t P

39、L Cs wi ll b e us ed i n t he pr oc es s in dus t ry b ut n ot n ece s sa ri ly f or pr oc es s co nt ro l.Se ve ra l ve nd or s-obv io us ly b et tin g t ha t t he o pp os i te w ill ha pp en-ha ve i ntr odu ce d PLCs o pti miz ed f or p ro ces s ap pl ic at io n.R ich Ry an,mang er,c ommer ci al m

40、 ar ket i ng,Al le n-br ad le y Pro gra mmab le C on tro l s Di v.,ci te s P L Css i n cr ea si ng use suc h i nd us tr ie s a s f o od,ch emic al s,a n d pe tr ol eu m.Ry an f ee ls t he re a r e tw o ty pe s o f a ppl ic at io ns i n w hic h th ey r e ap pr op ri at e.one,he sa ys,is w he re th e

41、s iz e o f t he pr oc es s c o nt ro l sy st em th at s be in g au tom ate d do es n t jus t if y DCS di st ri bu te d c ont ro l sy st em.W i th t he st ar ti ng p ri ce ta gs of c h os e pr od uc ts bei ng re la ti ve ly hig h,a p ro gr ammable co nt ro ll er ma ke s se ns e f or s mal l,l ow lo o

42、p c oun t ap pl ic at ion .T he se co nd i s w he re y ou h ave to i nt eg ra te th e l oo p cl os el y w i th t he s e qu en ti al l og ica l .Batc h c on tr ol l er s ar e p ri me ex ample,where t h e se qu en ce a nd mai nt ai ni ng t he pro ce ss v ar ia ble ar e i n te rt wi ne d so cl ose ly t

43、 ha t th e b ene fi ts o f ha vin g a pr og ra mmab le c ont r ol le r to do t h e s eq ue nt ia l l og ic al ou tw ei ghs s o me o f t he d is ad v an ta ge s of no t h av in g a d is tr ib ute d co nt rol s y st em.Bi ll B ar ko vi tz,p r es id en t of Tr ic o ne x,p re di ct s t hat all f u tu re

44、 c on tr ol ler s t ha t c ome o ut i n t he pr oc es s co n tr ol s ys te m bu si ne ss wil l e mbr ace a lo t o f more PL C t ec hn ol og y a nd a l ot more PL C fu nc ti on al ity th an t he y ev er did b ef or e.Communications and MAP Co mmun ic at io ns ar e v it al to a n in d iv id ua l au to

45、 mat i on c el l an d t o be au to mate d fa ct or y as a wh ole.W e ve h ea rd a l ot ab out MAP in t he la st f ew ye ar s,an d a l ot o f c ompa ni es ha ve j umped on t he b an dwag on.2 Many,howev er,w er e di sa ppo i nt ed w he n a f u ll y-de fi ne d and co mple te d MAP s pec if ic at io n

46、did n t a pp ea r i mmedi at el y.S ays La rr y Komare k:Ri gh t no w,M AP i s st il l a mo vi ng t a rg et f or t he manu fa ct ur ers,a sp ec if ic at i on th at is not f i na l.P re se nt ly,fo r e xa mple.p eo ple a re in tr od uc i ng p ro du cts t o m ee t th e MAP2.1st an da rd .Yet2.1-bas ed

47、 p ro du cts wi ll b e ob so le te w he n the ne w st an da rd fo r M AP3.0 is i ntr odu ce d.Be ca us e o f t hi s,ma ny PL C ve nd ors a re ho ld in g off o n f ul l MAP im pl emen ta tio ns.O mr on,fo r e x ampl e,h as a n o n go in g MAP-co mpat ib il ity p ro gr am;3 bu t Fr an k Ne wbur n,vi c

48、 e p re si de nt of Omr on s In du s tr i al Div i si on,r ep ort s t h at be ca use of th e lack of a f ir m de fi nit i on,Omro n s PLCs d on t y et t alk to M AP.Si nc e it s u nl ike l y th at a n in div i du al P LC w ou ld t al k to 6 br oa d MAP an yway,make rs a re c onc ent ra ti ng o n pro

49、 p ri et ar y ne tw or ks.Ac co rdi ng to Sa l P ro van zan o,u se rs fe ar th at if th ey do ge t on b oa rd a nd v e nd or s wi thd r aw f ro m MAP,th ey ll b e t he on es l ef t ho ld ing a co mmun ic at ion s s tr uc tu re t hat s no t s u pp or te d.Universal I/O Wh il e th er e ar e c onc er n

50、s a bo ut th e l ac k of c ompat i bl e c o mmun ic at io ns be t ween P LCs fr om dif fe re nt v en dor s,th e c o nn ec ti on a t the ot he r en d-th e I/O-is e ve n more f r ag ment ed.Wi th r are e xc ep ti on s,I/O is s ti ll pr opr i et ar y.Y et t h er e a re th os e w ho f ee l t ha t I/O w