GIAOTRINH HTCDT

MC LC

Bi ging H thng C in t 1

MC LC4CHNG 1: TNG QUAN V C IN T.

41.1. Cc khi nim c bn.

41.2. Lch s v xu th pht trin.

41.2.1. Lch s pht trin.

81.2.2. Xu th pht trin.

10CHNG 2: CC THNH PHN C BN CA H THNG C IN T

102.1. Mun mi trng.

102.2. Mun tp hp.

102.3. Mun o lng.

112.4. H thng kch truyn ng.

112.5. Mun truyn thng.

112.6. Mun x l.

122.6.1. ng truyn bus.

132.6.2. B x l trung tm CPU.

132.6.3. B nh.

132.7. Mun phn mm.

132.7.1. Ngn ng lp trnh.

142.7.2. Cc tp lnh.

142.7.3. Lp trnh.

142.8. Mun giao din.

15CHNG 3. CM BIN V C CU CHP HNH

153.1. Gii thiu v cm bin v c cu chp hnh.

153.1.1. Cm bin.

163.1.2. C cu chp hnh.

173.2. c tnh ca cm bin v c cu chp hnh

173.2.1. Di o.

173.2.2. phn gii.

173.2.3. nhy.

183.2.4. Sai s.

183.2.5. Kh nng lp li.

183.2.6. Vng cht.

203.2.7. Tnh n nh.

203.2.8. Thi gian p ng.

203.2.9. Nhit h thng.

213.3. Mt s loi cm bin thng gp.

213.3.1. Cm bin dch chuyn thng v quay.

213.3.1.1. Cng tc hnh trnh.

213.3.1.2. Tia hng ngoi.

223.3.1.3. Cc b m ha quang hc.

233.3.2. o lc.

243.3.3. Cm bin o khong cch.

263.4. C cu chp hnh.

263.4.1. Cc ng c in.

263.4.1.1. ng c DC.

283.4.1.2. ng c AC.

293.4.1.3. ng c bc.

323.4.2. H thng iu khin kh nn.

323.4.2.1. Phn t x l v iu khin.

323.4.2.1.1. Van o chiu.

363.4.2.1.2. Van chn.

363.4.2.1.3. Van tit lu:

383.4.2.1.4. Van p sut.

383.4.2.2. C cu chp hnh:

383.4.2.2.1. Xi lanh.

393.4.2.2.2. ng c kh nn:

40CHNG 4: IU KHIN LOGIC KH LP TRNH PLC

404.1. Gii thiu PLC.

404.1.1. Gii thiu chung.

404.1.2. Hnh dng bn ngoi.

434.1.3. Cc thnh vin h S7-200.

454.1.4. Modul m rng.

484.2. u ni PLC v modul m rng.

484.2.1. PLC s dng ngun nui mt chiu.

504.2.2. PLC s dng ngun nui xoay chiu.

524.2.3. u ni modul m rng.

564.3. Ngn ng lp trnh.

564.3.1. Cch thc hin chng trnh.

574.3.2. Cu trc chng trnh.

584.3.3. Phng php lp trnh.

594.4. Mt s lnh c bn.

594.4.1. Lnh vo ra.

604.4.2. Cc lnh ghi/xa gi tr cho tip im.

604.4.3. Cc lnh logic i s Boolean.

644.4.4. Cc lnh tip im c bit.

654.4.5. Cc lnh so snh.

674.4.6. Lnh nhy v lnh gi chng trnh con.

694.4.7. Cc lnh can thip vo thi gian vng qut.

694.4.8. Cc lnh iu khin Timer.

734.4.9. Cc lnh iu khin Counter.

764.4.10. Cc lnh s hc.

804.4.11. Lnh tng, gim mt n v v lnh o gi tr thanh ghi.

844.4.12. Cc lnh dch chuyn ni dung nh.

854.5. Son tho chng trnh v chng trnh m phng

854.5.1. Son tho chng trnh.

854.5.2. Chng trnh m phng.

CHNG 1: TNG QUAN V C IN T.1.1. Cc khi nim c bn.

Khi nim C in t c m ra t nh ngha ban u ca cng ty Yasakawa Electric. Trong cc ti liu xin bo h thng hiu ca mnh. Yasakawa nh ngha C in t nh sau:

Thut ng mechatronics c to thnh bi mecha trong mechanics v tronics trong electronics. Ni cch khc, cc cng ngh v sn phm c pht trin s ngy cng c kt hp cht ch v hu c thnh phn in t vo trong cc c cu v rt kh c th ch ra ranh gii gia chng.

Khi nim c in t tip tc pht trin sau khi Yasakawa a ra nh ngha u tin. Mt nh ngha khc v c in t thng hay c ni ti do Harashima, Tomizuko v Fukada a ra nm 1996 nh sau:

C in t l s kt hp cht ch ca k thut c kh vi in t v iu khin my tnh thng minh trong thit k, ch to cc sn phm v quy trnh cng nghip.

Nm 1997, Shetty v Kolk li quan nim:

C in t l mt phng php lun c dng thit k ti u cc sn phm c in.

V gn y, Bolton li xut nh ngha:

Mt h c in t khng ch l s kt hp cht ch cc h c kh, in v n cng khng ch n thun l mt h iu khin. N l s tch hp y cc h trn.

1.2. Lch s v xu th pht trin.

1.2.1. Lch s pht trin.Qu trnh pht trin CT trn th gii chnh thc bt u t nm 1969 vi s ra i thut ng C in t, sn phm CT ch l s kt hp gia c kh v in t. Sau , vi s pht trin ca CNTT, cc b vi x l c tch hp vo h thng C in t.V o to c in t trn th gii:

Nm 1983 Vin k thut Nht Bn Singapore a vo kha o to k thut c in t (mechatronics engineering) chng trnh o to 2 nm o to li k s c kh.

Kha ging u tin mang tn Mechatronics cho k s v hc vin cao hc c thc hin trng i hc Landcaster trong nm 1984/1985. K t kha o to v C in t pht trin mnh tt c cc nc cng nghip pht trin v ang pht trin.

Nhng nm u thp k 90 ca th k XX, 4 trng i hc Bch khoa ca Singapore c chng trnh o to 3 nm chnh quy k s c in t.

c cng c cc kha o to v cp bng k s theo chuyn ngnh C in t t nhng nm u 90. Tip theo khng lu l cc trng i hc Curtin v New South Weles.

chu u, t nm 1980 c cc hot ng c lin quan n o to C in t, nhng kha hc chnh thc v c in t trong trng i hc th ch bt u t chng trnh mt nm Cao hc ti trng i hc Katholieke (B) trong nm 1986. n nm 1989 trng ny m ngnh o to C in t.

Trong nm 1990 mt lot cc trng i hc CHLB c, an Mch, H Lan,(Chu u) a C in t vo ging dy. T nm 1992 n 1996 Lin minh chu u ti tr thc hin d n TEMOUS a kha hc C in t vo ging dy ti cc khoa C kh ca cc trng i hc: TU Brno, CTU, TU Plzeo, University College Dublin, Loughborough University of Technology,..

Cc trng i hc Anh ging dy C in t bt u t trng Lancaster, tip theo l trng i hc London, Survey, Dundee, Hull, Brunel, Loughborough, Manchester v Leeds.

Bc M mc d c rt nhiu trng hot ng trong lnh vc C in t, nhng cho n nm 1995 vn cha xut hin nhng kha ging dy mang tn C in t. n nay hu nh cc trng i hc k thut ca M u c khoa ny. Tnh n nm 1999 trn th gii c khong 90 trng i hc v vin nghin cu c o to ging dy v nghin cu v c in t

V o to c in t Vit Nam:Hin nay mt s Trng H tai Vit Nam ao tao chuyn nganh C in t h ai hoc:- T nm 1997 HBK TP H Chi Minh m Chuyn nganh C in t tai khoa C khi.- T nm 2001 HBK a nng m chuyn nganh C in t tai khoa C khi vi s lng 58 sinh vin. B mn C in t cng c thnh lp vo nm 2003.

- Nm 2001 H SPKT TP HCM cng m ngnh C in t kha u tin.

- Bt u t nm 2004, H Cng ngh thuc H Quc gia H ni m Chuyn ngnh C in t ti Khoa C k thut vi s lng ban u khong 20 SV/nm.Ngoai ra cac trng sau cung a m chuyn nganh C in t ao tao H Vin Cng ngh Chu (AIT) tai Ha ni H Cn th Mt s trng H Dn lp Phng ng, DL Thng Long vv... o to Cao hc: o to Cao hc trong nc ti trng H Bch khoa H Ni. H BK Ha Ni hp tac vi H Tng hp ky thut Hannover (CHLB c) va H Tng hp ky thut Dresden (CHLB c) m lp Cao hoc quc t.

Hnh 1.1. C in t: s tch hp hu c ca nhiu ngnh khc nhau

Bng 1.1. Lch s pht trin ca cc h c hc, in, in t.

1.2.2. Xu th pht trin.

Nm 70 ca th k 20, cc sn phm c in t ch yu tch hp phn c kh vi cng ngh iu khin tr lc (servo) to nn cc sn phm nh ca t ng, my t ng bn hng, my nh t ng chnh tiu c (focus). n nhng nm 80, khi cng ngh thng tin c hnh thnh th cc chip vi x l c nhng vo trong cc h thng c kh nng cao cc cng nng h thng. Lc ny cc my cng c iu khin s v robot tr nn hon ho hn, cc t c phn iu khin s c s dng rng ri. Trong lnh vc qun s, cc h thng v kh thng minh c iu khin s ra i v pht trin mnh m.Vo nhng nm 90, khi a cc sn phm c in t vo cng ngh truyn thng to nn cc sn phm c kh nng kt ni mng. Cng trong giai on ny, cc vi cm bin v c cu chp hnh siu nh c pht trin v ng dng trong nhiu sn phm nh cc h thng vi c in t. C th ni rng, chc nng ca cc my mc v h thng c k thut hin nay ph thuc ch yu vo phn mm (c th l mt thut ton, mng nron, h m) trong my tnh ca sn phm. Ring iu ny l mt s khc bit v cht so vi cc sn phm c in cch y 25-30 nm.Xu th pht trin ca c in t l ngy cng tch hp trong n nhiu cng ngh cao hn, sn phm ngy cng "thng minh" hn ng thi kch thc cng ngy cng nh i.Chin lc pht trin khoa hc v cng ngh Vit Nam n nm 2010 xc nh mt s lnh vc c in t chuyn su: Robot lm vic trong cc mi trng c hi, nguy him, an ninh quc phng, mt s dy chuyn cng nghip cng ngh cao Cc sn phm CT trong mt s lnh vc c kh trng im nh my cng c, my ng lc, thit b in-in t, c kh t v cc thit b o lng iu khin... Nghin cu vi c in t v nano c in t...STTThit k truyn thngThit k C in t

Cc thnh phn thm voTch hp cc thnh phn (phn cng)

1.

2.

3.

4.To ln

Kt cu phc tp

Vn v dy dn

Cc thnh phn kt niNh gn

Kt cu n gin

Truyn thng khng dy hoc bus

Cc thit b t tr

iu khin n ginTch hp bi x l thng tin

5.

6.

7.

8.

9.

10.Cu trc cng nhc

iu khin truyn thng, tuyn tnh

chnh xc nh dung sai hp

Cc i lng khng o c thay i ty tin

Theo di n gin

Kh nng c nhCu trc mm do, phn hi

iu khin phn hi kh lp trnh

chnh xc nh o lng v phn hi

iu khin cc i lng khng o c bng cch c lng

Gim st vi chn on li

Kh nng t hc

Bng 1.2. Cc thuc tnh ca thit k truyn thng v thit k C in t.CHNG 2: CC THNH PHN C BN CA H THNG C IN T

2.1. Mun mi trng.Mun mi trng lin quan n cc thng s bn ngoi nh phm vi nhit , cc yu t ti trngs tc ng n hot ng ca sn phm ng b. Trong cc thit k tng th, cc tham s ny thit lp lot iu kin bin m sn phm phi tn ti v hot ng trong .

Mun mi trng hnh thnh t iu kin hoc cc tiu chun, quy tc thc t v chc nng thc hin ca h thng. Mun mi trng va ng vai tr u vo, va ng vai tr u ra ca c h thng buc h thng c cc chc nng thc hin, phc v mt mc ch c th no .Mun mi trng khng hin din trong sn phm c in t, tuy nhin v c in t lin quan c n vic thit k sn phm nn trong nghin cu sn phm c in t, mun mi trng cn c quan tm ng mc.

2.2. Mun tp hp.

Mun tp hp l ton b h thng c kh, th hin kt cu hnh dng c s cc sn phm. N bao gm chi tit, cm c kh, trong c bit l cc khung b lp rp cho cc mun khc, cc chi tit s dng lm vt lin kt, vt trung gian ghp niMi mt sn phm c mt cch th hin hnh dng khc nhau, lin quan n mc ch s dng sn phm. Thng cc chi tit thnh phn c thit k v ch to, sau c lp rp theo bn v lp ghp. Cng nh cc sn phm c kh khc, sn phm c in t cn c mt hnh dng mang tnh thm m.2.3. Mun o lng.

Mun o lng l h thng c s dng rt ph bin trong cc sn phm c in t v thng c cu to t 3 thnh phn:

Hnh 2.1. H thng o lng v cc thnh phn.

Cm bin: Cm nhn i lng ang c o bng cch sinh ti u ra ca n mt tn hiu tng ng.Gia cng tn hiu: y l khu thu thp, gia cng tn hiu sau cc chuyn i s cp. Tn hiu t cm bin ca mt h thng o thng c x l theo mt phng php ph hp vi giai on hot ng tip theo. Tn hiu c th c khuch i ln, loi nhiu, chnh lu, chuyn i t tn hiu s sang tng t v ngc liH thng hin th: Ni tn hiu ra t b gia cng tn hiu c th hin di dng con s (hin th s) hoc dng biu (hin th tng t).2.4. H thng kch truyn ng.

H thng kch truyn ng l thnh phn ca sn phm c in t, thc hin chuyn i u ra t mun x l thnh cc hnh ng iu khin trn mt my mc hoc thit b.

Phn ny s c tm hiu k chng 3.

2.5. Mun truyn thng.

Trong sn xut, ch to vi cc thit b c s iu khin, gi c nhp sn xut gia cc thit b, gia chng cn c s trao i thng tin. Cc thit b c th gi v c thng tin theo nhng cch khc nhau.S trao i, truyn thng tin, d liu gia cc my tnh ty theo phm vi s dng c yu cu c th l:iu khin trung tm: l s dng mt my tnh trung tm iu khin ton b dy chuyn. Trong trng hp ny, nu my tnh trung tm c s c, ton b dy chuyn s ngng hot ng. y l dng iu khin nhng nm 1970.

H iu khin phn cp: Cc my tnh thc hin cng vic thng nht b gim st bi cc my tnh c vai tr quyt nh ln hn. Cng vic c chia cho cc my tnh theo chc nng ca chng (chuyn mn ha).H thng iu khin phn quyn: Cc my tnh c thc hin cng vic tng t nhau. Trng hp c s c hoc mt my qu ti, cng vic c th c chuyn sang my khc. Cng vic c tri ra tt c cc my do vy mi my cn truy cp c tt c cc my trong h thng.2.6. Mun x l.

Mun x l, x l thng tin do mun giao din v mun o lng cung cp. Thnh phn chnh ca mun ny l b iu khin. Ngy nay cc b vi x l ng vai tr quan trng trong cc b iu khin.B vi x l c chia thnh 3 vng: B x l trung tm (CPU) nhn bit v thc hin cc lnh ca chng trnh.

Giao din nhp-xut qun l v truyn thng gia b x l v th gii bn ngoi.

B nh lu gi chng trnh v d liu.

Tn hiu s di chuyn t khu vc ny sang khu vc khc dc theo ng truyn bus. Bus l h thng dy ni truyn d liu t b phn ny n b phn khc trong my tnh. Ni mt cch v von, bus ging nh con ng cao tc, cng rng cng truyn c nhiu d liu i vi tc cao.

D liu lin quan n chc nng x l ca CPU c truyn bi ng truyn d liu (data bus). Thng tin v a ch ca mt v tr xc nh trn b nh truy cp cc d liu lu c ti bi bus a ch (address bus). Nhng tn hiu lin quan n hnh ng iu khin c ti bi bus iu khin (control bus).2.6.1. ng truyn bus.

Bus d liu (data bus): Dng mang thng tin gia CPU v b nh cng nh gia CPU v cc thit b nhp xut. Mi dy trong bus truyn mt tn hiu nh phn 0 hoc 1. Nh vy mt bus 4 dy ang truyn t 1010. Cc bit c truyn nh sau:TDy bus

0 (bit thp)Dy bus d liu u tin

1Dy bus d liu th 2

0Dy bus d liu th 3

1 (bt cao)Dy bus d liu th 4

Kch thc ca bus, c hiu nh rng ca ng cao tc, l yu t quan trng quyt nh lng d liu c chuyn i mi ln. V d: bus 4 bit, 8 bit, 16 bit, 32 bit c th truyn tng d liu mt ln.

Nu mt bus d liu c chiu di 4 bit, s lng cc gi tr s l 24 = 16. B vi x l 4 bit ngy nay hay s dng cho chi, my git. Loi ph thng hay dng cho cc h iu khin nht l loi 8, 16, 32 v 64 bit.

Bus a ch (address bus): Thng tin v a ch ca mt v tr xc nh trn b nh. Khi mt a ch c th c chn, th ch mi v tr ny c m thng vi CPU. Hu ht cc my tnh nh c t 16 n 32 ng a ch v c kh nng truy xut 2n v tr nh. Mt bus a ch 16 bit c kh nng truy xut 216 = 65536 = 64K v tr nh. Mt bus a ch 20 bit c kh nng truy xut 1M v tr nh, mt bus a ch 32 bit c kh nng truy xut n 4G v tr nh. B nh cng ln cha c nhiu d liu v s dng c cc chng trnh ln hn, phc tp hn.Bus iu khin (control bus): l mt hn hp cc tn hiu, mi mt tn hiu c mt vai tr ring trong vic iu khin c trt t hot ng ca h thng. Qua bus iu khin tn hiu c gi ng b cc thnh phn ring l.

2.6.2. B x l trung tm CPU.

CPU qun l tt c cc hot ng v thc hin tt c cc thao tc trn d liu. Hu ht cc CPU ch bao gm mt tp cc mch logic thc hin lin tc hai thao tc: tm np lnh v thc thi lnh. CPU c kh nng hiu v thc thi cc lnh da trn mt tp cc m nh phn, mi mt m nh phn biu th mt thao tc n gin. cc lnh ny thng l cc lnh s hc (cng, tr, nhn, chia), cc lnh logic (AND, OR, NOT), cc lnh di chuyn d liu hay cc lnh r nhnh c biu th bi mt tp cc m nh phn v c gi l tp lnh.2.6.3. B nh.B nh ROM (Read Only Memory): l b nh cha cc d liu vnh vin. Cc con ROM c lp trnh trong lc cc mch ny c ch to. Cc d liu ch c th c c v s dng cho cc chng trnh c nh.B nh EPROM (Erasable and Programable): Cc chip s dng loi b nh ny c th xa v lp trnh li c.

B nh RAM (Random Access Memory): c gi l b nh truy cp ngu nhin, n c nhim v lu d liu tm thi ang thc hin, n c th c v ghi d liu vo. Ton b d liu ca b nh RAM s b mt nu mt ngun cung cp in.2.7. Mun phn mm.

Cc mun phn mm c xy dng trn c s s dng cc ngn ng lp trnh lp thut ton ph hp theo nhim v ca cc thit b ngoi vi c iu khin. Mc ch sao cho b x l hiu, sau x l v a ra tn hiu iu khin ph hp mc tiu ra. mun phn mm tng thch vi b vi x l, chng ta phi tng thch vi m hnh lp trnh ca CPU tng ng.2.7.1. Ngn ng lp trnh.

Cc thng tin vo buc b vi x l thc hin mt hnh ng c th c gi l cc lnh (instruction), tp hp cc lnh m b vi x l nhn bit gi l b lnh (instruction set). Dng thc ca b lnh ph thuc vo b vi x l c lin quan. Lot cc lnh cn thit thc hin mt cng vic c th no ta gi l mt chng trnh (program).

B x l lm vic vi h nh phn. Cc chng trnh vit theo h nh phn c gi l m my. Vit chng trnh theo dng ny i hi k tht cao v thng b mc li nhiu. Mt ngn ng thng c s dng l hp ng (Assembly language). Tuy nhin trnh hp ng vn phi chuyn thnh m my nu mun b x l hiu c chng trnh trn. S chuyn i ny c th thc hin th cng khi s dng ti liu ca nh sn xut. Tuy nhin, thng c cc chng trnh my tnh thc hin chuyn i ny gi l chng trnh dch hp ng (assembler programs). Bn cnh ta cn dng cc ngn ng bc cao lp trnh nh: BASIC, C, C++, FORTRAN, PASCALTt c nhng ngn ng ny u phi chuyn sang ngn ng my th b vi x l mi c th s dng c.2.7.2. Cc tp lnh.

Tp lnh (instruction set) l danh sch t kha m t tt c cc hot ng hoc cc tc v m n v x l trung tm (CPU) c th thc hin c. Cc b vi x l khc nhau c cc lnh khc nhau nhng nhn chung cc lnh c th phn chia thnh nhng nhm lnh sau:

Chuyn d liu. Thc hin s hc.

Thc hin logic.

iu khin chng trnh.

2.7.3. Lp trnh.Thng phng php lp trnh c s dng pht trin chng trnh gm cc bc sau: Xc nh vn , bt u t vic lm r chng trnh phi thc hin nhng chc nng g, yu cu nhp xut, dung lng nh

Quyt nh thut ton s dng. Thut ton l tun t cc bc xc nh mt phng php gii quyt vn .

Th hin thut ton thng qua lu . Biu din cc biu tng chun th hin lu . Mi mt bc ca thut ton th hin bng mt hoc hn mt biu tng v ni vi nhau bi ng th hin lung chng trnh.

Chuyn i lu thut ton thnh cu lnh m b x l c th thc hin. Tc l vit cc cu lnh theo ngn ng lp trnh.

Chy th v sa li chng trnh.

2.8. Mun giao din.Mun giao din l mt phn quan trng trong h thng C in t. Cc thit b ngoi vi (b cm bin, bng iu khin) thng khng c ni trc tip vi h thng vi x l do thiu tng thch v mc v dng tn hiu. Do vy cn phi c mt mch ghp ni gi l mch giao din ni thit b ngoi vi v b vi x l.

Hnh 2.2. Giao din.CHNG 3. CM BIN V C CU CHP HNH

3.1. Gii thiu v cm bin v c cu chp hnh.

Cm bin v c cu chp hnh l hai thnh phn c bn ca mi h c in t. Mt h c in t in hnh nh trn hnh 3.1 gm mt khi cm bin, mt khi iu khin v mt khi c cu chp hnh.

Khi cm bin c th n gin l mt cm bin n l hoc c th gm cc thnh phn b sung nh b lc, b khuch i, b iu ch v cc b bin i tn hiu khc.

Khi iu khin nhn thng tin t khi cm bin, a ra quyt nh da trn thut ton iu khin v cc lnh ti khi c cu chp hnh.

Khi c cu chp hnh bao gm c cu chp hnh c th thm mt b ngun v mt c cu ghp ni.

Hnh 3.1. H C in t thng gp.3.1.1. Cm bin.

Cm bin l mt thit b m khi c mt hin tng vt l tc ng vo (nhit , lc, nh sng,) s to ra tn hiu u ra (in, c hc, t,) t l.

Cm bin c phn loi thnh 2 dng tng t hoc s da trn dng tn hiu u ra. Cm bin tng t cung cp tn hiu lin tc t l vi tham s cn o v cn s bin i tng t thnh s trc khi chuyn cho b iu khin s. Trong khi , cm bin s cung cp u ra s c th trc tip ghp ni vi b iu khin s.

Mt s loi cm bin thng gp:

Cm bin dch chuyn thng v quay.

Cm bin gia tc.

Cm bin lc.

Cm bin o mmen v cng sut.

Cm bin lu lng.

Cm bin nhit .

Cm bin o khong cch.

Cc cm bin nhn bit nh sng, hnh nh v nhn dng.

Tiu chun la chn.

Di o: Chnh lch gia gi tr ln nht v gi tr nh nht ca tham s cn o.

phn gii: Thay i nh nht m cm bin c th phn bit c.

chnh xc: Sai khc gia gi tr o c v gi tr thc.

Tnh chnh xc: Kh nng lp li kt qu o vi chnh xc cho trc.

nhy: L t s ca thay i u ra trn mt n v thay i ca u vo.

Thi gian p ng: tr gia u vo v u ra.

Nhit hot ng: Khong nhit m ti cm bin hot ng c.

Vng cht: Di u vo m trong di s khng c u ra.

Vic chn cm bin tha mn tt c cc c tnh k thut trn l khng thc t. V d vic tm cm bin v tr vi phn gii m trong khong mt mt gn nh khng p ng c vi hu ht cc loi cm bin. Do vy ty theo h C in t thit k m ta la chn cm bin cho ph hp.

Khi cc h s chc nng trn c tha mn, ngi ta c th a ra mt danh sch cm bin. S la chn cui cng s ph thuc vo kch c, tin cy, bn vng, kh nng bo dng v gi thnh cm bin.3.1.2. C cu chp hnh.

V c bn, cc c cu chp hnh l phn pha sau mt h c in t, nhn lnh iu khin (hu ht l dng tn hiu in) v gy ra mt s thay i trong h vt l bng cch to lc, chuyn ng, nhit, dng chyThng thng cc c cu chp hnh c s dng kt hp vi ngun nui v mt c cu ghp ni nh trn hnh 3.2.

Hnh 3.2. Thit b chp hnh thng thng.Phn loi:

C cu chp hnh c th phn loi da trn dng nng lng.V c bn c cc dng: in, in c, in t, thy lc v kh nn.

C cu chp hnh cng c th phn loi thnh dng nh phn v lin tc da trn s lng u ra trng thi n nh. Mt rle vi hai trng thi n nh l mt v d in hnh ca c cu chp hnh dng nh phn. Tng t, mt ng c bc l mt v d in hnh cho c cu chp hnh dng lin tc.3.2. c tnh ca cm bin v c cu chp hnh

3.2.1. Di o.Chnh lch gia gi tr ln nht v gi tr nh nht ca tham s cn o. Di o thng c quy nh bi nh sn xut cm bin.

3.2.2. phn gii.

phn gii ca cm bin l khong nh nht ca u vo m cm bin c th o c. phn gii cng c th c hiu l s m nh nht ca cm bin. V d mt b m ha 1024 ppr (xung/vng) c phn gii l:

3.2.3. nhy.

nhy ca cm bin c nh ngha l t s gia thay i u ra trn mt n v thay i u vo. nhy ca cm bin thng lin quan mt thit n phn gii. Mt cm bin c c tnh tuyn tnh th c nhy khng i trn ton b di u vo. Cc cm bin c c tnh phi tuyn th c nhy tng hoc gim khi u vo thay i nh hnh 3.3.

Hnh 3.3. nhy ca cm bin.

3.2.4. Sai s.

Sai s l sai khc gia gi tr o c v gi tr thc ca u vo. C hai loi sai s l sai s h thng v sai s ngu nhin. Sai s h thng c tt c cc php o c thc hin vi cm bin. Cc dng ca sai s h thng:

Sai s lch khng: l dng ph bin ca sai s h thng khi gi tr u ra khc khng vi u vo bng khng.

Sai s ti: do thm cm bin vo h o lm thay i h.

Sai s do nhy ca cm bin thay i khng ging nh mong mun.3.2.5. Kh nng lp li.

Kh nng lp li l kh nng thu c u ra ging nhau vi u vo ging nhau ca mt cm bin. Sai s ngu nhin lm gim kh nng lp li. Sai s ngu nhin c th khc phc bng cch ly trung bnh ca mt s php o. Nhiu cng lm gim kh nng lp li.

3.2.6. Vng cht.

Vng cht l mt vng u vo gn im khng m u ra vn gi gi tr khng. Khi u vo dch ra khi vng cht th u ra s thay i theo u vo (hnh 3.4).

Hnh 3.4. Vng cht.Vng cht thng c dng trong b n nhit gia nh v cc b iu khin qu trnh.

Hnh 3.5. Vng cht ca b n nhit.

V d v b n nhit gia nh c m t trn hnh 3.5. Khi nhit t im t (gi tr mong mun) trn b n nhit, u ra vn gi trng thi tt. Ngay khi nhit trong phng tng ln ti gi tr im t cng mt na gi tr vng cht th u ra h thng lm mt s bt hon ton.

Khi phng lnh i, u ra s gi trng thi bt n khi nhit trong phng t im t tr i mt na gi tr vng cht, u ra h thng lm lnh s tt hon ton.

3.2.7. Tnh n nh.

Thut ng tnh n nh c nhiu nh ngha v cch dng khc nhau nhng nh ngha ph bin nht l nh ngha lin quan n cn bng. Mt h cn bng s gi c trng thi khng i khi khng c nhiu tc ng. Mt h n nh s tr li trng thi cn bng nu c nhiu nh lm dch chuyn h thng khi trng thi ban u. Mt h khng n nh s khng tr li v tr cn bng v thng dch chuyn xa v tr cn bng.

Hnh 3.6. Tnh n nh ca h thng.Hnh 3.6 cho thy ba iu kin n nh vi mt h n gin gm: qu bng v i. Trong mi trng hp, v tr cn bng c xc nh d dng trn nh i hoc di y. Trong trng hp n nh, mt dch chuyn nh ca qu bng ra khi v tr cn bng, n s quay tr v v tr cn bng, c th sau mt vi dao ng. Trong trng hp th ba, trng hp khng c ma st lm qu bng dao ng lin tc quanh v tr cn bng sau khi c mt chuyn ng nh. Trng hp c bit ny gi l bin n nh do h thng khng bao gi thc s tr li v tr cn bng.

Hu ht cc cm bin v c cu chp hnh vn n nh. Tuy nhin, vic thm cc h iu khin ch ng c th lm h cc thit b n nh tr thnh khng n nh. Cn phn tch v kim tra cn thn m bo rng mt h c in t hot ng trong trng thi n nh.

3.2.8. Thi gian p ng.

L thi gian tr gia u vo v u ra. Cm bin cng tt th thi gian p ng cng nh.3.2.9. Nhit h thng.

L khong nhit m ti cm bin cn c th hot ng c.3.3. Mt s loi cm bin thng gp.

3.3.1. Cm bin dch chuyn thng v quay.

Hu ht cc chuyn ng ph bin nht trong cc h thng c kh l chuyn ng thng dc theo mt trc c nh v quay mt gc quanh trc c nh. Nhng chuyn ng phc tp hn thng c to ra bi vic kt hp nhng chuyn ng n gin . Trong phn ny chng ta s gii thiu tm tt mt s cng ngh sn c o cc chuyn ng thng v chuyn ng quay quanh mt trc.

3.3.1.1. Cng tc hnh trnh.

Loi n gin nht ca cm bin dch chuyn l mt cng tc hnh trnh, n gi tr mt bit thng tin: chm hoc khng chm. Mt cng tc hnh trnh in hnh bao gm mt n by, khi n c tc ng n s to ra mt tip xc c kh bn trong cng tc, t to ra mt mch in kn (hnh 3.7). C th s dng cng tc ny nh l nhng cm bin va chm.

Hnh 3.7. Cng tc hnh trnh.

3.3.1.2. Tia hng ngoi.

Tia hng ngoi c th c s dng o cc dch chuyn thng hoc dch chuyn quay. Thng thng cc it pht tia hng ngoi (LED) hoc l n pht quang (Thit b pht) c dng nh mt ngun pht sng v mt thit b cm nhn hng ngoi c dng pht hin tia sng (thit b thu).

Nu thit b pht v thit b thu t i din nhau th chng c th c s dng nh mt b ngt tia pht hin bt k vt g i qua chng. Thit b ny c gi l thit b ngt quang (hnh 3.8).

Hnh 3.8. B ngt quang dn QVA11234

Nu thit b pht v thu di chuyn t do theo ng thng ni chng, th cng ca tn hiu nhn c c th c s dng o khong cch gia chng. Tuy nhin thit b thu tia hng ngoi cng c th nhy cm vi c nh sng ca mi trng xung quanh. Do vy trong qu trnh thit k ta phi n hin tng ny lm cho cm bin chng nhiu mt cch tt nht.

Mt b pht sng v b d t cng hng v mt pha c th o th khong cch ti mt b mt gn nh cng ca tia phn x sau khi va vo b mt. Thit b c gi l thit b phn x quang (hnh 3.9). Mt cm bin nh vy c th c dng cho cc robot di ng pht hin cc vt cn mt khong cch cho trc.

Hnh 3.9. Cm bin phn x quang bn dn QRB1114.

Cc thit b ngt quang v cc thit b phn x quang c th c ng gi sn hoc ch to ring bit t mt LED hng ngoi v mt it quang hoc tranzito quang, sau khi chc chn rng thit b thu nhy cm vi bc sng sinh ra bi LED pht hng ngoi.

3.3.1.3. Cc b m ha quang hc.

Mt b m ha quang s dng mt b ngt quang bin chuyn ng thnh mt chui xung in. Nhng chui xung ny m ha chuyn ng v cc xung c m hoc c gii m bi mt mch in a ra s o dch chuyn. Chuyn ng c th l thng hoc quay, nhng chng ta tp trung vo cc b m ha quang quay thng thng.

C hai b m ha quang quay c bn l: m ha tng i v b m ha tuyt i. Trong b m ha tng i, mt a (a chia vch) c gn vo mt trc quay trn gia hai b ngt quang hc (hnh 3.10). V vy khi trc quay th cc vch ny s ngn hoc cho tia sng hng ngoi ti thit b d quang hc. Cc dy xung thu c t cc b d ny c tn s tng ng vi vn tc gc ca a. Nhng tn hiu ny c k hiu l A v B. Hai tn hiu A v B ny lch pha nhau chu k.

Hnh 3.10. B m ha tng i.

Thng qua vic m s lng cc xung v s lng cc vch trn a bit, ta c th o c tc quay ca trc. Hng quay c xc nh da trn quan h pha ca cc chui xung A v B. V d A tng khi B = 1 ta c th ni rng chuyn ng ca a l chuyn ng quay ngc chiu kim ng h. Ngc li A tng khi B = 0 th chuyn ng ca a l chuyn ng quay cng chiu kim ng h.3.3.2. o lc.

Lc l mt i lng vect, c nh ngha nh l tc nhn gy ra gia tc hoc phn ng c th ca mt vt. Trong phn ny chng ta s gii thiu cc phng php c ng dng xc nh ln ca nhng lc ny.

Nhn xt chung: Nu cc lc tc dng ln mt vt m khng sinh ra gia tc, chng phi c mt dng h lc cn bng. H ny c xem nh l mt h cn bng tnh. Cc lc tc dng ln vt c th chia lm hai loi: ni lc do cc phn t ring bit ca vt tc dng ln nhau v ngoi lc.

Hnh 3.11. Vt b ko dc trc (a), nn dc trc (b), bin dng (c).

Trong k thut o hin c, mt nhm c gi l cm bin ti. Nhn chung cm bin ti gm mt khung cng, mt mi trng o cc lc t vo v mt u o. Cc cm bin ti c s dng o cc lc ln, tnh hoc bin thin chm vi lch rt t v tng i chnh xc. C th p dng cc phng php khc nhau o cc lc ty thuc vo thit k ca cm bin ti. V d hnh 3.12 minh ha cm bin ti thy lc. Cm bin ti dng o cc lc tng i ln vi gi thnh thp. Cm bin ti thy lc dng mt khung rt cng vi mt khoang trong cha y cht lng. Khi c ti, p lc ca du tng, v mt u o chnh xc s c gi tr ny.

Hnh 3.12. Cm bin ti thy lc.

3.3.3. Cm bin o khong cch.

Cm bin ny c s dng o khong cch t mt im tham chiu ti mt i tng. Rt nhiu cng ngh khc nhau c ng dng pht trin cc loi cm bin ny, tiu biu l nh sng/quang hc, hnh nh, vi sng v siu m. Cm bin o khong cch c th c phn lm hai loi: Tip xc v khng tip xc. Ta ch yu cp n loi khng tip xc.

Cm bin o khong cch khng tip xc l loi cm bin o khong cch thc t im tham chiu ti mt i tng khng qua tip xc vt l. C th c phn lm hai loi l: ch ng (pht mt s dng nng lng vo khu vc cn quan tm) v b ng (da trn nng lng pht ra t cc i tng trong khu vc quan tm).

Vi cc loi cm bin ch ng (phn x), khong cch o hiu qu ph thuc khng ch vo mc nng lng pht ra m cn ph thuc vo cc c tnh sau ca i tng:

Din tch tit din ngang: xc nh lng nng lng pht ra tc ng vo i tng.

H s phn x: xc nh lng nng lng truyn ti c phn x so vi lng nng lng b hp th hoc xuyn qua.

tp trung: xc nh kh nng phn b li ca nng lng phn x.

Rt nhiu cm bin khng tip xc hot ng da trn hin tng truyn sng. Sng c pht ra ti mt im tham chiu, khong cch c xc nh bng cch o thi gian truyn t im tham chiu ti vt hoc suy gim ca cng khi sng truyn ti vt v quay tr li im tham chiu. Thi gian truyn sng thng c o bng phng php thi gian truyn (TOF_Time of flight).

Phng php thi gian truyn:Phng php thi gian truyn c minh ha trong hnh 3.13 v 3.14. Mt b pht sng (pht ra vi chu k) c pht ra v phn x t vt v b thu c v tr gn b pht. B pht v b thu c th c tch hp trn cng mt cm bin. B thu cng c th c gn trn vt. TOF l thi gian t khi bt u pht n khi c tn hiu tr v. Khong cch c xc nh bng cng thc d = c.TOF/2 (khi b pht v b thu cng mt v tr ) v d = c.TOF (khi b thu c gn trn vt).

Hnh 3.13. Sng c pht v phn x li t vt

Hnh 3.14. nh ngha thi gian truyn sng.

chnh xc ca phng php ny c th c tng ln bng phng php d bin cc i (hnh 3.15)

Hnh 3.15. TOF tnh theo bin ln nht ca tn hiu phn x

Sai s ca phng php thi gian truyn c th do cc nguyn nhn sau:

S thay i tc truyn sng: c bit l vi cc h thng m thanh ta phi ch ti s thay i ny. V tc m thanh chu nh hng r rt ca nhit v m. Khng xc nh c chnh xc thi gian n ca xung phn x. Sai s ca mch nh thi s dng o thi gian truyn.

S tng tc ca sng ti b mt i tng cn o khong cch: Khi nh sng, m thanh hoc sng radio tc ng vo i tng, tn hiu phn hi o c ch th hin mt phn nh ca tn hiu ban u. Nng lng cn li phn x theo cc hng khc nhau v c th c hp th hoc xuyn qua i tng, ph thuc vo c tnh i tng v gc ti ca chm sng.3.4. C cu chp hnh.

3.4.1. Cc ng c in.

3.4.1.1. ng c DC.

Trn hnh 3.16 khi cho in p mt chiu U vo hai chi in A v B, trong dy qun phn ng c dng in chu lc tc dng tng h ln nhau to nn momen tc dng ln rto, lm rto quay. Chiu lc tc dng c xc nh theo qui tc bn tay tri (hnh 3.16a).

Hnh 3.16. Nguyn l lm vic ca ng c mt chiu.

Khi phn ng quay c na vng, v tr thanh dn ab, cd i ch nhau (hnh 3.16b), nh c phin gp i chiu dng in, nn dng in mt chiu bin i thnh dng in xoay chiu a vo dy qun phn ng, gi cho chiu lc tc dng khng i, do lc tc dng ln rto cng theo mt chiu nht nh, m bo ng c c chiu quay khng i.

IU CHNH TC :ng vi mi ti khc nhau ta cn c tc khc nhau. V vy ph hp vi ti, cn phi iu chnh tc ng c lc c ti.Ta c phng trnh in p mch phn ng l:

U = E + RIE = U - RI

Thay tr s E = KEn ta c phng trnh tc l:

n =

Nhn vo phng trnh trn, ta thy rng mun iu chnh tc ta c cc phng php sau:

a. Mc in tr iu chnh vo mch phn ng.

Khi mt thm in tr ph vo mch phn ng, in tr R tng ln c tnh c dc xung, tc ng c gim dn. Do dng in phn ng ln nn tn hao cng sut trn in tr iu chnh ln. Phng php ny ch s dng ng c cng sut nh.b. Thay i in p U.Dng ngun in mt chiu iu chnh in p cung cp cho ng c. Phng php ny c s dng nhiu.

c. Thay i t thng.Thay i t thng bng cch thay i dng in kch t.

Khi iu chnh tc , ta kt hp vi cc phng php trn. V d phng php thay i t thng, kt hp vi phng php thay i in p th phm vi iu chnh rt rng, y l u im ln ca ng c in mt chiu.

3.4.1.2. ng c AC.

a. ng c khng ng b.

Nguyn l lm vic:

Khi t in p xoay chiu ba pha c tn s f1 vo dy qun stato, trong dy qun stato s c h thng dng ba pha chy qua, dng in ny s to ra t trng quay p i cc, quay vi tc . T trng quay ct cc thanh dn ca dy qun rto v cm ng cc sc in ng. V dy qun rto ni ngn mch, nn sc in ng cm ng s sinh ra dng trong cc thanh dn rto. Lc tc dng tng h gia t trng quay ca my vi thanh dn mang dng in rto, ko rto quay theo chiu vi t trng quay vi tc n. minh ha, ta xt t trng quay B ca stato ang quay theo chiu kim ng h vi tc n1 (hnh 3.11).Khi xc nh chiu sc in ng cm ng theo quy tc bn tay phi, ta cn c vo chiu chuyn ng tng i ca thanh dn vi t trng. Nu coi t trng ng yn, th chiu chuyn ng tng i ca thanh dn ngc vi chiu n1, t p dng quy tc bn tay phi xc nh c chiu sc in ng nh hnh v.

Chiu lc in t xc nh theo quy tc bn tay tri, trng vi chiu quay n1. chnh lch gia tc t trng quay v tc ca my gi l tc trt n2:

n2 = n1 n

H s trt ca tc l

S =

Khi roto ng yn (n = 0), h s trt s = 1. Khi roto quay nh mc s = 0,02 0,06. Tc ng c l:

n = n1 (1 - s) = vg/pb. ng c ng b.

Nguyn l lm vic:

Khi cho dng in ba pha vo dy qun stato, dng in ba pha dy qun stato s sinh ra t trng quay vi tc :

Nu rto ang ng yn (hnh 3.12), cc Nam S ca rto b cc Bc N stato ko v n c xu hng quay theo chiu kim ng h. Nhng do qun tnh v cc Bc stato qut qua n qu nhanh, trong khi n cha quay ti th sau na chu k n i din vi cc Nam stato v b y li, ngha l rto c xu hng quay theo chiu ngc li. Kt qu l moment (m my) trung bnh bng khng v rto khng quay c.

Tuy nhin nu chng ta quay trc rto vi tc ng b cc cc t rto b kha cht vo cc t stato tri du. Khi khng ti, t trng stato v rto cng quay vi tc ng b n1 v trc ca chng trng nhau ( = 0). Lc c ti trc t trng rto i chm sau trc t trng stato mt gc , ti cng nng gc cng ln, nhng c hai vn cng quay vi tc ng b n1.3.4.1.3. ng c bc.

a. Gii thiu v ng c bc.ng c bc c bn l mt ng c in khng c b phn o mch (chi than). Thng thng ng c bc c nhiu hn 2 cun dy ng vai tr stator (phn tnh). Rotor (phn ng) vn l mt nam chm vnh cu hoc l nhng khi c rng (kha) lm bng vt liu nh c t tnh (trng hp ng c bc bin t tr). S o mch cho dng in trong cun dy c thc hin bng mch in iu khin bn ngoi. Thng thng, mch iu khin ny cn c thm chc nng iu khin ng c quay ti, lui hoc gi nguyn v tr xc nh.

Hnh 3.17. Phn bit ng c bc v ng c in thng thng.

Hnh 3.18. Cu to bn trong ng c bc.

Hnh 3.19. Hnh dng bn ngoi ca ng c bc.

ng c bc thuc loi ng c ng b, chng khng th quay t do, lin tc m hot ng theo nguyn l quay tng bc, mi bc ng c s quay c mt gc (v d 1,80/bc). Mt vng quay ca n gm nhiu bc ni tip nhau. Khi kt hp vi mch iu khin bn ngoi, chng c th quay n v dng li ti mt v tr xc nh mt cch chnh xc.

b. Cc loi ng c bc.

Da vo cu to, ta c ba loi ng c bc chnh l: ng c bc nam chm vnh cu, ng c bc bin t tr v ng c bc hn hp (ng c lai). Ngoi ra cn c cch phn loi da vo mch iu khin nh ng c bc n cc, lng cc.

ng c bc nam chm vnh cu.

ng c bc nam chm vnh cu c rotor l mt nam chm vnh cu, khng chia thnh nhiu rng, cng c nhiu cun dy nh loi bin t tr. C hai loi thng dng l ng c bc n cc (cn gi l c cc unipolar) v lng cc (bipolar).

ng c bc bin t tr:ng c bc bin t tr (hay cn gi l ng c bc phn khng) khng dng nam chm vnh cu lm rotor m dng mt khi c rng lm bng vt liu nh c t tnh. Phn stator l 3 n 5 cun dy c ni chung vi nhau.

Hnh 3.20. ng c bin t tr.

ng c bc hn hp.

ng c bc hn hp (hay cn gi l ng c bc cm ng) kt hp u im ca hai loi ng c trn, ngha l chng c rotor l nam chm vnh cu, c nhiu rng, stator l nhng cun dy. ng c hn hp thng dng l loi c 200 rng v c bc 1,80.

Hnh 3.21. ng c bc hn hp.

Nh ta thy trong hnh, rotor ca ng c bc hn hp gm hai a b tr so le nhau. Mi a c nhiu rng ng vi cc cc.

3.4.2. H thng iu khin kh nn.

iu khin l qu trnh ca mt h thng, trong di tc dng ca mt hay nhiu i lng vo, cc i lng ra thay i theo mt quy lut nht nh ca h thng .

Mt h thng iu khin bao gm:

Trong phn ny ta ch xt n 2 phn: Phn t x l v iu khin v c cu chp hnh. 3.4.2.1. Phn t x l v iu khin.

3.4.2.1.1. Van o chiu.

Van o chiu c nhim v iu khin dng nng lng bng cch ng m hay thay i v tr cc ca van thay i hng ca dng kh nn.a. K hiu ca van o chiu.TN THIT BK HIU

Van o chiu 2/2

Van o chiu 4/2

Van o chiu 5/2

b. Tn hiu tc ng:Tn hiu tc ng vo van o chiu c 4 loi l: tc ng bng tay, tc ng bng c hc, tc ng bng kh nn v tc ng bng nam chm in.

Tn hiu tc ng t 2 pha (i vi van o chiu khng c v tr khng) hay ch t 1 pha (i vi van o chiu c v tr khng).

Tc ng bng tay:

TN THIT BK HIU

K hiu nt nhn tng qut

Nt bm

Tay gt

Bn p

Tc ng bng kh nn:TN THIT BK HIU

Trc tip bng dng kh nn vo

Trc tip bng dng kh nn ra

Trc tip bng dng kh nn vo vi ng knh 2 u nng van khc nhau

Gin tip bng dng kh nn vo qua van ph tr

Tc ng bng c.

TN THIT BK HIU

u d

C chn bng con ln, tc ng 2 chiu

C chn bng con ln, tc ng 1 chiu

L xo

Nt nhn c rnh nh v

Tc ng bng nam chm in

TN THIT BK HIU

Trc tip

Bng nam chm in v van ph tr

Tc ng theo cch hng dn c th

c. Van o chiu c v tr khng.Van o chiu c v tr khng l loi van tc ng bng c l xo ln nng van v k hiu l xo nm ngay v tr bn cnh vung pha bn phi ca k hiu van. Tc ng ln pha i din nng van l tn hiu tc ng bng c, kh nn hay bng in. Khi cha c tn hiu tc ng, v tr ca cc ca ni c biu din trong vung pha bn phi i vi van o chiu 2 v tr. Cn i vi van o chiu 3 v tr th v tr khng nm gia.V d: Van o chiu 2/2 tc ng bng nam chm in.Van c 2 ca P v R, 2 v tr 0 v 1. Ti v tr 0, ca P v R b chn. Khi cun Y c in, t v tr 0 van chuyn sang v tr 1, ca P ni vi ca R. Khi cun Y mt in, do tc ng ca l xo pha i din, van s quay tr v v tr ban u.d. Van o chiu khng c v tr khng.

Khi khng c tn hiu tc ng ln u nng van na, th v tr ca van vn c gi nguyn i tn hiu tc ng t pha nng van i din. V tr tc ng k hiu a , b, c,

Tn hiu tc ng c th l:

Tc ng bng tay hay bn p. Tc ng bng dng kh nn iu khin vo hay ra t 2 pha nng van.

tc ng trc tip bng in t hay gin tip bng dng kh nn i qua van ph tr.V d: Van o chiu 3/2 tc ng bng nam chm in.

Khi cun Y1 c in th ca P ni vi ca A, ca R b chn. Khi cun Y2 c in th ca A ni vi ca R cn ca P b chn.3.4.2.1.2. Van chn.Van chn l loi van ch cho dng kh nn i qua mt chiu, chiu cn li b chn. Van chn gm c cc loi sau:

Van 1 chiu. Van Logic OR. Van Logic AND.

Van x kh nhanh.TN THIT BK HIU

Van mt chiu.

Van mt chiu c tc dng ch cho dng kh nn i qua mt chiu (t A qua B), chiu ngc li b chn.

Van logic OR.Khi c dng kh nn vo t P1 th ca P2 b chn v ca P1 ni vi ca A. Ngc li khi dng kh nn vo P2 th ca P1 b chn, ca P2 ni vi ca A.

Van logic AND. Khi c dng kh nn vo P1 th P1 b chn, v ngc li khi c dng kh nn vo P2 th P2 b chn. Ch khi no c P1 v P2 c dng kh nn vo th mi c kh nn qua ca A.

Van x kh nhanh.Khi dng kh nn vo ca P, chn ca R, ca P ni vi ca A. Khi dng kh nn vo t A, ca P b chn, ca A ni vi ca R, kh c x nhanh ra ngoi.

3.4.2.1.3. Van tit lu:

Van tit lu c nhim v thay i lu lng dng kh nn, c ngha l thay i vn tc ca c cu chp hnh.TN THIT BK HIU

Van tit lu c tit din khng i:

Khe h ca van c tit din khng thay i, do lu lng dng chy khng thay i.

Van tit lu c tit din thay i:

Lu lng dng chy qua van thay i c nh vo mt vt iu chnh lm thay i tit din ca khe h.

Van tit lu mt chiu iu chnh bng tay:

Tit din Az thay i bng cch iu chnh vt bng tay. Khi dng kh nn t A sang B, l xo y mng chn v dng kh nn ch qua tit din Az. Khi dng kh nn t B sang A, mng chn b y ln v dng kh i qua khong h gia mng chn v mt ta mng chn, lu lng khng c iu chnh.

Van tit lu mt chiu iu chnh bng c chn:

Nguyn l hot ng tng t nh van tit lu mt chiu iu chnh bng tay. Dng kh nn ch c th i mt chiu t A sang B, ty vo v tr ca c chn m tit din ca khe h ca van thay i, lm cho lu lng dng chy thay i.

3.4.2.1.4. Van p sut.TN THIT BK HIU

Van an ton.Bnh thng khi p sut nh hn hoc bng p sut cho php, ca R b chn, nhng khi p sut ln hn p sut cho php, ca R m ra, kh nn t ca P theo ca R thot ra ngoi.

Van trn.Nguyn tc hat ng tng t nh van an ton, nhng ch khc ch l khi p sut bng hoc ln hn p sut cho php th ca P ni vi ca A, ni vi h thng iu khin.

Van p sut iu chnh t xa :

Khi c tn hiu p sut tc ng, th ca P ni vi ca A. Tn hiu tc ng c th trc tip ln van o chiu, hay tn hiu gin tip qua van trn.

3.4.2.2. C cu chp hnh:

C cu chp hnh c nhim v bin i nng lng kh nn thnh nng lng c hc. C cu chp hnh c th thc hin chuyn ng thng (xilanh) hoc chuyn ng quay (ng c kh nn).3.4.2.2.1. Xi lanh.TN THIT BK HIU

Xilanh tc dng n (xilanh tc dng mt chiu).

p lc kh nn ch tc dng vo mt pha ca xilanh, pha cn li l do ngoi lc hay l xo tc dng.

Xilanh tc dng 2 chiu (xilanh tc dng kp).

p sut kh nn c dn vo 2 pha ca xilanh, do yu cu iu khin m xilanh s i vo hay i ra ty thuc vo p lc kh nn vo pha no.

3.4.2.2.2. ng c kh nn:

ng c kh nn c nhim v bin i nng lng ca kh nn thnh nng lng c hc (chuyn ng quay).

ng c kh nn c nhng u im sau:

iu chnh c momen quay v s vng quay. S vng quay cao v iu chnh v cp Khng h hng khi qu ti Gi thnh bo dng thpNhc im. Gi thnh nng lng cao. S vng quay thay i theo ti trng. Gy ting n ln khi x kh.CHNG 4: IU KHIN LOGIC KH LP TRNH PLC

4.1. Gii thiu PLC.

4.1.1. Gii thiu chung.

PLC vit tt ca Programmable Logic Controllers. L thit b iu khin logic lp trnh c, cho php thc hin linh hot cc thut ton iu khin logic thng qua mt ngn ng lp trnh.

S pht trin ca PLC em li nhiu thun li v lm cho cc thao tc my tr nn nhanh, nhy, d dng v tin cy hn. N c kh nng thay th hon ton cho cc phng php iu khin truyn thng dng rle (loi thit b phc tp v cng knh); kh nng iu khin thit b d dng v linh hot da trn vic lp trnh trn cc lnh logic c bn; kh nng nh thi, m, gii quyt cc vn ton hc v cng ngh, kh nng to lp gi i, tip nhn nhng tn hiu nhm mc ch kim sot s kch hot hoc nh ch nhng chc nng ca my hoc mt dy chuyn cng ngh.

Nh vy nhng c im lm cho PLC c tnh nng u vit v thch hp trong mi trng cng nghip: Kh nng khng nhiu rt tt. Cu trc dng modul rt thun tin cho vic thit k, m rng, ci to nng cp... C nhng modul chuyn dng thc hin nhng chc nng c bit hay nhng modul truyn thng kt ni PLC vi mng cng nghip hoc mng Internet... Kh nng lp trnh c, lp trnh d dng. Yu cu ca ngi lp trnh khng cn gii v kin thc in t m ch cn nm vng cng ngh sn xut v bit chn thit b thch hp l c th lp trnh c. Thuc vo h sn xut linh hot do tnh thay i c chng trnh hoc thay i trc tip cc thng s m khng cn thay i li chng trnh.

4.1.2. Hnh dng bn ngoi.

Hnh 4.1. Hnh dng bn ngoi ca mt PLC

M t cc n bo trn S7-200:

SF: n SF bo hiu h thng b hng. n SF sng ln khi PLC c hng hc.

RUN: n xanh RUN ch PLC ang ch lm vic v thc hin chng c np vo trong PLC.

STOP: n vng STOP ch nh rng PLC ang ch dng. Dng chng trnh ang thc hin li.

Ix.x: n xanh cng vo ch nh trng thi tc thi ca cng Ix.x . n ny bo hiu trng thi ca tn hiu theo gi tr logic ca cng.

Qy.y: n xanh cng ra bo hiu trng thi tc thi ca cng Qy.y. n ny bo hiu trng thi ca tn hiu theo gi tr logic ca cng.

Cng truyn thng:

S7-200 s dng cng truyn thng ni tip RS485 vi phch ni 9 chn phc v cho vic ghp ni vi thit b lp trnh hoc vi cc trm PLC khc.

Ch thch:

1. t

2. 24 VDC

3. Truyn v nhn d liu

4. Khng s dng

5. t

6. 5 VDC

7. 24 VDC

8. Truyn v nhn d liu

9. Khng s dng.

Hnh 4.2. S chn ca cng truyn thng

Ghp ni S7-200 vi my tnh PC qua cng RS232 cn c cp ni PC/PPI vi b chuyn i RS232/RS485.

Hnh 4.3. S kt ni gia PLC v my tnh thng qua cp PC/PPI

Hnh 4.4. Hnh dng v kch thc ca cp PC/PPI

Cng tc chn ch lm vic cho PLC

RUN: Cho php PLC thc hin chng trnh trong b nh, khi chng trnh gp li hoc gp lnh STOP th PLC s t ng chuyn sang ch STOP mc d cng tc vn ch RUN (nn quan st trng thi thc ti ca PLC theo n bo).

STOP: Khi chuyn sang ch STOP, dng cng bc chng trnh ang chy, cc tn hiu ra lc ny u v off. ch STOP PLC cho php hiu chnh li chng trnh hoc np mt chng trnh mi.

TERM: cho php my lp trnh t quyt nh chn mt trong hai ch lm vic cho PLC RUN hoc STOP.

Vt chnh nh tng t: Mi CPU c t 1 n 2 vt chnh nh tng t, c th xoay c mt gc 270, dng thay i gi tr ca bin s dng trong chng trnh.

Pin v ngun nui b nh: Khi nng lng ca t b cn kit, ngun pin t ng chuyn sang trng thi tch cc, PLC s s dng nng lng t pin. Vic thay th ny lm cho d liu trong b nh khng b mt i.

4.1.3. Cc thnh vin h S7-200.

Cc thng s c bn ca cc thnh vin h S7-200 c m t tm tt bng sau:Thng sCPU221CPU222CPU224CPU226CPU226XM

Kch thc90x80x6290x80x62120.5x80x62190x80x62190x80x62

B nh chng trnh4096 bytes4096 bytes8912 bytes8912 bytes1634 bytes

B nh

D liu2048 bytes2048 bytes5120 bytes5120 bytes1024 bytes

Cng vo68142424

Cng ra46101616

Modul m rng02 Modules7 Modules7 Modules7 Modules

Cng truyn thngRS-485RS-485RS-485RS-485RS-485

D tr b nh (gi)5050190190190

B nh thi256 b nh thi: 4 b 1ms, 16 b 10 ms, 236 b 100ms

Cc loiDC/DC/DC

AC/DC/RLDC/DC/DC

AC/DC/RLDC/DC/DC

AC/DC/RLDC/DC/DC

AC/DC/RLDC/DC/DC

AC/DC/RL

B mC0-C255C0-C255C0-C255C0-C255C0-C255

Bng 4.1. Cc thng s c bn ca cc thnh vin h S7-200Bng 4.2. Cc loi CPU S7-200.

Bng 4.3. Kch thc v trng lng.

Bng 4.4. Mt s thng s k thut.

4.1.4. Modul m rng.

Cu trc modul ca S7-200 to s linh hot ti a gii quyt cc bi ton, n cho php chng ta chn s u vo ra ti u v mt kinh t. Chng ta c th tng thm s cng vo ra cho bng cch ni thm cc modul m rng.

Cc modul m rng ny c cm ni tip nhau vo bn phi CPU lm thnh mt mc xch.. a ch cc u vo ra trn cc modul m rng c xc nh bng kiu vo, ra v v tr ca modul trong mc xch.

Hnh 4.5. Ghp ni CPU 224 vi cc modul m rng

Bng 4.5. Cc loi modul m rng

Bng 4.6. Cc thng s c bn ca modul m rng s

Bng 4.6. Cc loi modul m rng s.

Bng 4.7. Cc thng s c bn ca cc loi modul m rng analog.

Hnh 4.6. Kch thc ca cc loi PLC v modul m rng4.2. u ni PLC v modul m rng.

4.2.1. PLC s dng ngun nui mt chiu.

Hnh 4.7. Cch u dy CPU 221 DC/DC/DC




4.2.2. PLC s dng ngun nui xoay chiu.

Hnh 4.11. Cch u dy CPU 221 AC/DC/RELAY




4.2.3. u ni modul m rng.

Hnh 4.15. Cch u modul m rng EM 221 Digital Input 8x24 VDC

Hnh 4.16. Cch u modul m rng EM 222 Digital Output 8

Hnh 4.17. Cch u modul m rng EM 223 24VDC 4 Inputs/4 Outputs

Hnh 4.18. Cch u modul m rng EM 223 24VDC 4 Inputs/4 Relay Outputs





4.3. Ngn ng lp trnh.

4.3.1. Cch thc hin chng trnh.

PLC thc hin chng trnh theo chu trnh lp. Mi vng lp c gi l vng qut (scan). Mi vng qut c bt u bng giai on c d liu t cc cng vo vng m o, tip theo l giai on thc hin chng trnh. Trong tng vng qut, chng trnh c thc hin bng lnh u tin v kt thc ti lnh kt thc. Sau giai on thc hin chng trnh l giai on truyn thng ni b v kim tra li. Vng qut c kt thc bng giai on chuyn cc ni dung ca b m o ti cc cng ra.

Hnh 4.23. Cu trc mt vng qut trong PLC

Nh vy ti thi im thc hin lnh vo/ra, thng thng lnh khng thc hin hin lnh trc tip vi cng vo/ra m ch thng qua b m o ca cng trong vng nh tham s. Vic truyn thng gia b m o vi ngoi vi do CPU qun l. Khi gp lnh vo/ra th ngay lp tc h thng s cho dng mi cng vic khc, ngay c chng trnh x l ngt, thc hin lnh ny mt cch trc tip vi cng vo/ra.

Chng trnh x l ngt ch c thc hin trong vng qut khi xut hin tnh hiu bo ngt v c th xy ra bt c im no trong vng qut.4.3.2. Cu trc chng trnh.

Cu trc ca mt chng trnh c to thnh t 3 thnh phn c bn: 1 chng trnh chnh (main Program), c th c mt hay nhiu chng trnh con (subroutines), cc chng trnh con x l ngt (interrupt routines) c th c hoc khng.

Chng trnh chnh bao gm cc lnh iu khin ng dng. Cc lnh ny c thc hin tun t mt cch lin tc, c mi vng qut mt ln. Chng trnh chnh c kt thc bng lnh kt thc chng trnh (MEND hoc END).

Chng trnh con l mt b phn ca chng trnh. N c th c hoc khng, ch c thc hin khi c lnh gi n t chng trnh chnh. Cc chng trnh con phi c vit sau lnh kt thc chng trnh chnh (MEND hoc END).

Cc chng trnh con x l ngt (c th c hoc khng) khi xy ra s kin ngt tng ng. S kin c th l s thay i mc mt u vo, b nh thi m hay nhn c d liu trn cng truyn thng.Chng trnh x l ngt cng phi c vit sau lnh kt thc chng trnh chnh (MEND hoc END).

Cc chng trnh con thng c nhm li thnh mt nhm ngay sau chng trnh chnh. Sau n ngay cc chng trnh x l ngt. Bng cch vit nh vy, cu trc chng trnh c r rng v thun tin hn trong vic c chng trnh sau ny. Cng c th t do trn ln cc chng trnh con v chng trnh x l ngt ng sau chng trnh chnh.

Hnh 4.24. Cu trc mt chng trnh ca PLC

4.3.3. Phng php lp trnh.

Lp trnh cho S7 200 v cc PLC khc ca hng Siemens da trn 3 phng php c bn:

Phng php hnh thang (Ladder logic _ LAD).

Phng php khi hm (Function Block Diagram _ FBD).

Phng php lit k cu lnh (Statement List _ STL).

Thng thng chng ta ch dng 2 phng php l LAD v STL. Nu chng trnh c vit theo kiu LAD, thit b lp trnh s t to theo kiu STL tng ng. Ngc li khng phi mi chng trnh c vit theo kiu STL cng u c th chuyn sang c dng LAD.

nh ngha v LAD: LAD l ngn ng lp trnh bng ha. Nhnh thnh phn c bn dng trong LAD tng ng vi nhng thnh phn c bn dng trong bng mch rle. Trong chng trnh LAD cc phn t c bn dng biu din lnh logic nh sau:- Tip im c hai loi: Thng ng ; thng h

- Cun dy (coil):

- Hp (box): M t cc hm khc nhau, n lm vic khi c dng in a n hp. C cc nhm hp sau: hp cc b nh thi, hp cc b m, hp di chuyn d liu, hp cc hm ton hc....

- Mng LAD: L ng ni cc phn t thnh mt mch hon chnh, i t ng ngun bn tri sang ng ngun bn phi. Ngun in c hai ng chnh, mt ng bn tri th hin dy nng, mt ng bn phi l dy trung ha (neutral) hay l ng tr v ngun cung cp. ng ngun bn phi khng c th hin trn giao din lp trnh.

nh ngha v STL: L phng php th hin chng trnh di dng tp hp cc cu lnh. Khc vi hai ngn ng kia l dng ha. Chnh v th trong STL c th vit nhng chng trnh m trong hai ngn ng cn li khng th vit c. Bi v n st vi ngn ng my hn, khng b gii hn bi cc quy tc ha. STL thng dnh cho lp trnh vin giu kinh nghim.

STL c th gii quyt c mt s vn khng th gii quyt d dng trong Lad v FBD, STL ch c th s dng tp lnh SIMATIC, mi chng trnh vit bng LAD hay FBD c th xem v sa trong STL nhng khng phi tt c nhng chng trnh vit trong STL u c th xem bng LAD hay FBD.

to ra mt chng trnh bng STL, ngi lp trnh cn phi hiu r phng thc s dng 9 bit trong ngn xp (stack) logic ca S7-200.

Ngn xp l mt khi 9 bit chng ln nhau t S0 n S8, nhng tt c cc thut ton lin quan n ngn xp u lm vic vi bit u tin v bit th hai (S0 v S1) ca ngn xp. Gi tr logic mi c th c gi hoc ni thm vo ngn xp. Hai bit S0 v S1 phi hp vi nhau th ngn xp c ko ln mt bit.4.4. Mt s lnh c bn.

4.4.1. Lnh vo ra.STLLADM tTon hng

LD

A

OTip im thng m s c ng khi bit = 1.bit: I, Q, M, SM, T, C, V.

LDNANONTip im thng ng s c m khi bit = 1.bit: I, Q, M, SM, T, C, V.

LDI

AIOITip im thng m s ng tc thi khi bit = 1.bit: I

LDNIAINOINTip im thng ng s m tc thi khi bit = 1.

bit: I

= bit

Cun dy u ra trng thi ON khi c dng in iu khin i qua.bit: I, Q, M, SM, T, C, V.

=I bit

Cun dy u ra trng thi ON tc khi c dng in iu khin i qua.bit: Q

4.4.2. Cc lnh ghi/xa gi tr cho tip im.

Lnh ny dng ng v ngt cc im gin on c thit k. Khi dng iu khin n cc cun dy th cc cun dy ng hoc m cc tip im (hoc mt dy cc tip im).

STLLADM tTon hng

S bit, nSet 1 mng gm n tip im, tnh t tip im "bit" (n

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