ti:M HNH TRM PLC S7-300 IU KHIN BIN TN

LI NI UTrong qu trnh cng nghip ho hin i t nc lnh vc khoa hc k thut ng vai tr ht sc quan trng. Trong lnh vc in -in T gp phn rt ng k t nhng thit b dn dng n cc dy chuyn cng ngh t ng ha nhm nng cao nng sut gim bt lao ng chn tay, vn lc hu khi t nc ta l thnh vin ca t chc thng mi th gii.Lnh vc t ng ha i vo hu ht cc nh my x nghip thay th dn nhng c my mc lc hu, thay th con ngi lm vic trong nhng lnh vc nguy him. c bit hn na vi s pht trin ca cng ngh thng tin mang n nhiu li ch to ln v thit thc hn. Kt hp vi t ng ha gip con ngi iu khin v gim st c cc qu trnh cng ngh tham gia trc tip iu khin i tng. khng nhng trong phm vi thu nh m trn c din rng. Gp phn lm gim chi ph sn sut, qun l sn xut d dng, theo di qu trnh n gin nng cao nng sut lao ng, hiu qu sn xut .Vi nhng ng dng thit thc nh vy nn em chn ti Xy dng m hnh iu khin gim st trm PLC iu khin bin tn. ti ny l c hi p dng nhng kin thc c s t trong nh trng vo m hnh thc t thu nh.

Tc gi :V Vn Phng

Chng 1 Tng quan v mng truyn thng PLC 300

1.1Mt s mng truyn thng trong cng nghip dng cho S7-3001.1.1 ModbusModbus l giao thc do hng Modicon pht trin. Theo m hnh ISO/OSI th Modbus thc cht l mt chun giao thc v dch v thuc lp ng dng, v vy c th c thc hin trn cc c ch vn chuyn cp thp nh TCP/IP, MAP (Manufactoring Message Protocol), v ngay c qua ng truyn ni tip RS-232. Modbus nh ngha mt tp hp rng cc dch v phc v trao i d liu qu trnh, d liu iu khin v chn on. Tt c cc b iu khin ca Modicon u s dng Modbus l ngn ng chung. Modbus m t qu trnh giao tip gia mt b iu khin vi cc thit b khc thng qua c ch yu cu/p ng. V l do n gin nn Modbus c nh hng tng i mnh i vi cc h PLC ca cc nh sn xut. C th , trong mi PLC ngi ta cng c th tm thy mt tp hp con cc dch v c a ra trong Modbus. c bit trong cc h thng thu thp d liu v iu khin gim st, Modbus hay c s dng trn cc ng truyn RS-232 ghp ni gia cc thit b d liu u cui (PLC, PC,...) vi thit b truyn d liu (Modem). C ch giao tipC ch giao tip Modbus ph thuc vo h thng truyn thng cp thp. C th, c th phn chia ra hai loi mng l Modbus chun v Modbus trn cc mng khc (v d TCP/IP, Modbus Plus, MAP)a. Mng Modbus chunCc cng Modbus chun trn cc b iu khin ca Modicon cng nh mt s nh sn xut khc s dng giao din ni tip RS-232. Cc b iu khin c th c ni mng trc tip hoc qua modem. Cc trm Modbus giao tip vi nhau qua c ch ch/ t (Master/Slave), trong ch mt thit b c th ch ng gi yu cu,

cn li cc thit b t s p ng bng d liu tr li hoc thc hin mt hnh ng nht nh theo nh yu cu. Cc thit b ch thng thng l cc my tnh iu khin trung tm v cc thit b lp trnh, trong khi cc thit b t c th l PLC hoc cc b iu khin s chuyn dng khc. Mt trm ch c th gi thng bo yu cu ti ring mt trm t nht nh hoc gi thng bo ng lot ti tt c cc trm t. Ch trong trng hp nhn c yu cu ring, cc trm t mi gi thng bo p ng tr li trm ch. Trong mt thng bo yu cu c cha a ch trm nhn, m hm dch v bn nhn cn thc hin, d liu i km v thng tin kim li.b. Modbus trn cc mng khcVi mt s mng nh Modbus Plus v MAP s dng Modbus l giao thc cho lp ng dng, cc thit b c th giao tip theo c ch ring ca mng , mi b iu khin c th ng vai tr l ch hoc t trong cc ln giao dch khc nhau. Nhn nhn mc giao tip thng bo, giao thc Modbus vn tun theo nguyn tc ch/ t mc d phng php giao tip mng cp thp c th l tay i. Khi mt b iu khin gi mt yu cu thng bo th n ng vai tr l ch v ch i p ng t thit b t. Ngc li, mt b iu khin s ng vai tr l t nu n nhn thng bo yu cu t mt trm khc v phi gi tr li p ng.c. Chu trnh yu cu p ngGiao thc Modbus nh ngha khun dng ca thng bo yu cu cng nh ca thng bo p ng, nh minh ha trn hnh v.Mt thng bo yu cu gm cc phn sau : a ch trm nhn yu cu (0-247), trong 0 l a ch gi ng lot. M hm gi ch th hnh ng trm t cn thc hin theo yu cu. V d, m hm 03 yu cu trm t c ni dung cc thanh ghi lu gi v tr li kt qu.

D liu cha cc thng tin b sung m trm t cn cho vic thc hin hm c gi. Trong trng hp c thanh ghi, d liu ny ch r thanh ghi u tin v s lng cc thanh ghi cn c. Thng tin kim li gip trm t kim tra ni dung thng bo nhn c. Thng bo p ng cng bao gm cc thnh phn ging nh thng bo yu cu. a ch y l a ch ca chnh trm t thc hin yu cu v gi li p ng. Trong trng hp bnh thng, m hm c gi nguyn nh trong thng bo yu cu v d liu cha kt qu thc hin hnh ng, v d ni dung hoc trng thi cc thanh ghi. Nu xy ra li, m hm quay li c sa ch th p ng l mt thng bo li, cn d liu m t chi tit li xy ra. Phn kim li gip trm ch xc nh chnh xc ca ni dung thng bo nhn c. Ch truyn Ch ASCIKhi cc thit b trong mt mng Modbus chun giao tip vi ch ASCII, mi byte trong thng bo c gi thnh hai k t ASCII 7 bit, trong mi k t biu din mt ch s Hex. u im ca ch truyn ny l n cho php mt khong thi gian trng ti a mt giy gia hai k t m khng gy ra li. Cu trc mt k t khung gi i c th hin nh sau :Mi k t khung bao gm : 1 bit khi u (Start bit) 7 bit biu din mt ch s hex ca byte cn gi di dng k t ASCII (0-9 v A-F), trong bit thp nht c gi i trc. 1 bit parity chn/l, nu s dng parity 1 bit kt thc (Stop bit) nu s dng parity hoc 2 bit kt thc nu khng sdng parity. Ch RTU

Khi cc thit b trong mt mng Modbus chun c t ch RTU (Remote Terminal Unit), mi byte trong thng bo c gi thnh mt k t 8 bit. u im chnh ca ch truyn ny so vi ch ASCII l hiu sut cao hn. Tuy nhin , mi thng bo phi c truyn thnh mt dng lin tc. Cu trc mt k t khung gi i c th hin nh sauMi k t khung bao gm : 1 bit khi u (Start bit) 8 bit ca byte thng bo cn gi, trong bit thp nht c gi i trc 1 bit parity chn /l, nu s dng parity 1 bit kt thc (Stop bit) nu s dng parity hoc 2 bit kt thc nu khng sdng parity1.1.2 Mng Ethernet cng nghipIE (Industrial Ethernet) mng Ethernet cng nghip l mng phc v cho cp qun l v cp phn xng thc hin truyn thng gia my tnh v cc h thng t ng ho. N phc v cho vic trao i mt lng thng tin ln, truyn thng trn mt phm vi rng. Cc b x l truyn thng dng trong mng lun kim tra xem ng dn c b chim dng khng. Nu khng th mt trm no trong mng c th gi in tn i, khi xy ra xung t trn mng v c hai trm gi th ngng ngay li v qu trnh gi in tn c thc hin li sau mt thi gian nht nh, thi gian ny c xc nh theo lut ton hc ngu nhin. Mng Ethernet cng nghip c nhng tnh cht c trng sau: Mng Ethernet cng nghip s dng th tc truyn thng ISO v TCP/IP (Transmission Control Protocol / Internet Protocol). Theo phng php thm nhp ng dn chn (CSMA/CD Carrier Sense Multiple Access with Collision Detecion) th cc thnh vin trong mng Ethernet cng nghip u bnh ng vi nhau.

Theo tiu chun truyn thng ISO v ISO on TCP th cc trm khng phi ca SIEMENS cng c kh nng tch hp vo mng, ni mt cch khc Ethernet cng nghip l mng truyn thng m.Cc thng s ca mng Ethernet cng nghip: Chun truyn thng : IEEE 802.3 S lng trm : Max 1024 trm Phng php thm nhp ng dn : CSMA /CD (Carrier SenseMultiple Access with Collision Detection)Mi trng truyn thng : Dy dn :+ Cp ng trc+ Cp i dy xon Cp quang : Cp thu tinh hoc cht do Kiu ni : ng thng, cy, hnh sao v vng trn-Dch v truyn thng : S7-FunctionISO-TransportISO-on-TCP

Hnh 1.1 m hnh mng ETHERNET

1.1.3 Mng AS-iAS-i (Actuator Sensor Interface) giao din cm bin c cu chp hnh, mng ch c mt ch duy nht. Phng php thm nhp ng dn l phng php Master Slave, mt phng php hon ton ti u cho nhng mng ch c duy nht mt thit b l ch. AS-i s c cu trc tht l n gin nu nh cc c cu chp hnh v cc cm bin u l cc thit b kiu s (Digital Input/Digital Output DI/DO), khi thit b kiu analog phi s dng cc b chuyn i tn hiu chun ca SIEMENS. Trong mng ch c trm ch c quyn iu khin qu trnh trao i thng tin. Trm ch (Master) gi tun t tng trm t (Slave) ti mt v i hi cc trm ny gi d liu ln trn trm ch hoc nhn d liu t trm ch.Nhng tnh cht c trng ca AS-i: AS-i l mng ti u cho cc thit b chp hnh v cm bin s. Qu trnh trao i d liu c thc hin thng qua ng dn t c cu chp hnh/cm bin vi trm ch, ng dn ny ng thi l ng cung cp ngun cho cc cm bin. AS-i c th ghp ni vi cc c cu chp hnh c kch thc 1 bit n 8 bit theo tiu chun IP 65 v lin kt trc tip vi qu trnh. - Hot ng ca AS-i khng cn thit lp cu hnh trc. Cc thng s k thut ca AS-i: Chun : AS-i theo chun IEC TG 178 S lng trm cho php: 1 Master v max 31 Slave Phng php thm nhp ng dn : Master Slave Tc truyn: 167 Kbit/s Mi trng truyn thng: Dy dn thng khng bc Khong cch gia cc thit b trong mng : 300 m vi Repeater Kiu ni : ng thng, cy, sao Dch v truyn thng : AS-i Function

Hnh 1.2 Mng AS-I1.2 Gii thiu mng PROFIBUSProfiBus l mt h thng Bus trng chun m rng dng ni cc thit b trng vi cc thit b iu khin v gim st. ProfiBus l mt thit b nhiu ch, n cho php cc thit b iu khin t ng, cc trm k thut v hin th qu trnh cng nh cc ph kin phn tn cng lm vic trn mt ng truyn chung l Bus. ProfiBus thc hin chc nng ng dng hot ng theo chu k, c tin cy cao v c kh nng p ng cao v tnh nng thi gian thc.Mng PROFIBUS c cung cp theo ba chng loi tng thch nhau. PROFIBUS DP (Distributed Peripheral) phc v cho vic trao i thng tin nh nhng i hi tc truyn nhanh. PROFIBUS DP c xy dng ti u cho vic kt ni cc thit b trng vi my tnh iu khin. PROFIBUS DP pht trin nhm p ng yu cu cao v tnh nng thi gian trong trao i d liu, gia cp iu khin cng nh cc b PLC hoc cc my tnh cng nghip vi cc ngoi vi phn tn cp trng nh cc thit b o, truyn ng v van. Vic trao i ch yu c thc hin tun hon theo c ch Master/Slave. Vi s trm ti a trong mt mng l 126, PROFIBUS DP cho php s dng cu hnh mt trm ch (Mono Master) hoc nhiu trm ch

(Multi Master). Mt c trng na ca PROFIBUS DP l tc truyn cao, c th ln ti 12 Mbit/s. PROFIBUS FMS (Fieldbus Message Specification) trao i lng thng tin trung bnh gia cc thnh vin bnh ng vi nhau trong mng. PROFIBUS FMS c dng ch yu cho vic ni mng cc my tnh iu khin v gim st. Mng ny ch thc hin cc lp 1, 2, 7 theo m hnh quy chiu OSI. Do c im ca cc ng dng trn cp iu khin v iu khin gim st, d liu ch yu c trao i vi tnh cht khng nh k. PROFIBUS PA (Process Automation) c thit k ring cho nhng khu vc nguy him. PROFIBUS PA l s m rng ca PROFIBUS DP v phng php truyn dn an ton trong mi trng d chy n theo chun IEC 61158-2. PROFIBUS PA l loi bus trng thch hp cho cc h thng iu khin phn tn trong cc ngnh cng nghip ho cht v ho du. Thit b chuyn i (DP/PA-Link) c s dng tch hp ng mng PA vi mng PROFIBUS DP. iu ny m bo cho ton b thng tin c th c truyn lin tc trn h thng mng PROFIBUS bao gm c DP v PA

Hnh 1.3 mng Profibus

ProfiBus l mt chun truyn thng trong cng nghip c s dng rt rng ri, c hai loi thit b thng gp trong mng truyn thng ProfiBus c phn bit l thit b ch (Master) v thit b t (Slave). Thit b ch (Master) c kh nng kim sot truyn thng trn Bus, mt trm ch c th gi thng tin khi n gi quyn truy nhp Bus. Trm ch cn c gi l trm tch cc. Thit b t (Slave) l cc thit b trng vo ra phn tn, cm bin v c cu chp hnh. Chng khng c quyn truy nhp Bus m ch c php xc nhn hoc tr li thng tin nhn c t trm ch khi c yu cu. Mt trm t cn c gi l trm th ng.Mt trm t thc hin t dch v hn, tc l x l giao thc n gin hn sovi trm ch.

1.2.1 c Tnh C Bn

Truyn d liu tc cao khng phi l iu kin cho s dng thnh cng mt h thng Bus. tha mn cc yu cu ca ngi dng th cc chc nng nh iu khin n gin, kh nng chun on tt v k thut truyn chng nhiu cn c p ng.Cc chc nng chun on m rng ca DP cho php tm ra v tr li nhanh chng, cc thng s chun on c truyn trn Bus v tp trung ti Master, cc thng s ny c chia lm 3 cp: Chun on cc trm lin quan. Chun on cc modul lin quan. Chun on cc knh lin quan.

1.2.2 Cu Hnh H Thng V Dng Thit B

DP cho php s dng cu hnh mt trm ch (Monomaster) hoc nhiu trm ch (Multimaster) vi s trm ti a trong mt on mng l 126 trm. Trong cu hnh nhiu ch, tt c cc trm ch u c th c d liu u vo/ra ca cc trm t nhng ch duy nht mt trm ch c quyn ghi d liu u ra.Cc quy nh cho cu hnh h thng bao gm s lng trm, gn a ch cho cc I/O phn tn, ng nht d liu I/O, dng thng bo chun on v thng s Bus s dng.Ty theo phm vi chc nng, kiu dch v thc hin ngi ta phn bit cc dngdch v sau: DP-Master cp 1 (DPM1), y l mt b iu khin trung tm trao i thng tin vi cc trm phn tn (DP-Slave) theo mt chu k thng bo xc nh. Cc thit b in hnh dng ny l cc b PLC, my CNC hoc iu khin Robot. DP-Master cp 2 (DPM2), cc thit b thuc dng ny l cc thit b lp trnh, thit b cu hnh hoc thit b chun on. Cc thit b ny c s dng trong qu trnh khi ng to ra cu hnh cho h thng DP. DP-Slave, mt DP-Slave l mt thit b I/O (Sensor-Actuator) c vo cc thng tin t Input hoc a ra thng tin ng ra ti qu trnh x l. Lng thng tin ng vo hoc ng ra ph thuc vo thit b.H thng Mono-Master, cu hnh h thng ny ch c duy nht mt Master v l h thng c thi gian chu k ngn nht.

Hnh 1.4 Cu hnh mng ProfiBus-DP Mono-Master.H thng Multi-Masterh thng ny c nhiu Master, chng hn nh cc thit b cu hnh, cc thit b chun on hoc mt s h thng con (subsystem) ph thuc ln nhau trn mt Bus.

Hnh 1.5 Cu hnh mng ProfiBus-DP Multi-Master.Vic t cu hnh h thng c thc hin bng phn mm, thng thng mt cng c cu hnh cho php ngi s dng b sung v tham s ha nhiu loi thit b ca cng mt nh sn xut mt cch tng i n gin bi cc thng tin tnh nng cn thit ca cc thit b ny c a vo c s d liu ca cng c cuhnh.

1.2.3 Cu trc mng (TOPOLOGY)

Topology l cu trc lin kt ca mt mng hay ni cch khc chnh l tng hp ca cc lin kt. Topology c th hiu l cch sp xp, t chc v mt vt l ca mng nhng cng c th l cch sp xp logic ca cc nt mng, cch t chc logic cc mi lin kt gia cc nt mng.C th phn bit cc dng cu trc c bn l Bus, mch vng tch cc v hnh sao. Mt s cu trc phc tp hn nh cu trc cy u c th xy dng trn c s phi hp ba cu trc c s ny.Trong cng nghip ngi ta phn cu trc mng Profibus ra lm nhiu dng cutrc theo cch sp xp cc thit b trn mt Bus, gm cc cu trc nh sau: Cu trc Bus. Cu trc mch vng tch cc. Cu trc hnh sao. Cu trc cy.

a, Cu Trc Bus

Trong cu trc ny, tt c cc thnh vin trong mng u c ni trc tip vi mt ng dn chung. c im c bn ca cu trc Bus l vic s dng chung mt ng dn lm cho tit kim c gi thnh v cng lp t. C ba loi cu hnh kiu Bus l Daisy-chain, Trunk-line/Drop-line v mch vng khng tch cc.Vi cu hnh dng Daisy-chain, mi trm c ni trc tip vi nhau ti giao imca hai on dy dn, khng qua mt on ni ph no:

Hnh 1.6 Kiu Daisy-chain.

Cn trong cu hnh Trunk-line/Drop-line mi trm c ni vi nhau qua mt ng nhnh (drop-line) qua ng trc (Trunk-line):

Hnh 1.7 Kiu Trunk-line/Drop-line.V mch vng khng tch cc l mt cu hnh m ng truyn lin kt gia ccthit b trong mch c khp kn:

Hnh 1.8 Kiu mch vng khng tch cc.u im ca loi cu trc Bus l tit kim c dy dn, lp t thi cng n gin, d thc hin,. V vy, cu trc Bus c s dng rng ri trong mng cng nghip.Nguyn tc truyn thng l ti mt thi im nht nh ch c mt thnh vin trong mng c gi tn hiu, cn cc thnh vin khc ch c quyn nhn.Bn cnh nhng u im trn cu trc Bus c nhng nhc im khi s dng chung ng truyn l: Phi phn chia thi gian s dng Bus hp l.

Mt tn hiu gi i c th n nhiu trm khc nhau khng kim sot cnn cn phi gn a ch cho tng trm c th. S trm trong mt on mng b hn ch, mun m rng mng phi dng thm cc b lp. Vic s dng hai tr u cui thng lm cho ti ca h thng tng ln. Trong trng hp ng dn b t hoc do ngn mch trong phn kt ni Bus ca mt trm b hng u dn n ngng hot ng ca c h thng. Vic nh v li gp nhiu kh khn.b, Cu Trc Mch Vng Tch Cc

Cu trc mch vng tch cc l cu trc m cc trm trong cng mt mng c ni tun t t im ny n im kia to thnh mt mch vng khp kn gia cc trm.iu lm cho mi thnh vin trong mng u tham gia tch cc vic kim sot dng tn hiu trn ng truyn. Trong cu trc ny, mi trm c nhn tn hiu truyn t trm trc n v chuyn sang mt trm k sau n. Qu trnh truyn tn hiu theo mt chiu c tip tc cho n khi tn hiu c truyn quay v trm gi ban u, khi tn hiu s b hy b. Cu trc mch vng tch cc c chia lm hai dng: Dng mch vng c iu khin trung tm, mt trm ch s kim sot victruy nhp ng dn ca mng :

Hnh 1.9 Mch vng tch cc c iu khin trung tm.

Dng mch vng khng c iu khin trung tm, cc trm u bnh ng nh nhau trong vic gi v nhn d liu. Vic kim sot ng dn do cc trm t m nhn v phn chia:

Hnh 1.10 Mch vng tch cc khng c iu khin trung tm.u im ca cu trc ny l mi mt nt mng l mt b khuch i, nn khi thit k mng theo kiu cu trc vng c th thc hin vi khong cch v s trm ln. Mi trm c th va nhn v pht tn hiu cng mt lc. Vic lin kt im- im p ng c yu cu s dng cc phng tin truyn tin hin i nh cp quang, tia hng ngoi, truyn d liu. Cc kiu lin kt mch vng tch cc th vic gn a ch cho cc thnh vin trong mng c th c thc hin bi mt my ch mt cch t ng, cn c vo th t sp xp vt l ca cc trm trong mch vng.Mt u im khc ca cu trc mch vng l kh nng xc nh v tr xy ra s c v c lp v tr cc trm khc vn lm vic bnh thng bng mt dy d phng trong mng.Gi s, mt dy chnh lin kt gia cc trm b t th cc trm ln cn vi im xy ra s c s t pht hin li ng dy ri t ng chuyn qua ng dy ph v tn hiu c i vng qua ng dy ph:

Hnh 1.11 S c t dy gia hai trm.Trong trng hp khc, khi mt trm b hng th hai trm ln cn s b ni tt:

Hnh 1.12 Ni tt hai trm ln cn ca trm b s c.Kh nng x l li nh trn l nh vo mt thit b gi l thit b chuyn mch (by-pass) t ng, khi b s c th b chuyn mch t ng pht hin v ngn mch b qua thit b c ni qua n:Hnh 1.13 S dng b chuyn mch khi thit b lm vic bnh thng v lc s cc, Cu Trc Hnh Sao

Cu trc hnh sao l s dng mt trm trung tm lm nhim v truyn thng cho c mng, cc trm khc c ni gin tip vi nhau qua trm trung tm. V vy, trm trung tm c th l mt trm ch tch cc nu n kim sot ton b truyn thng ca mng hoc ch l mt b chuyn mch thng thng.S dng cu trc hnh sao c nhc im ln, l khi trm trung tm b s c th cc thit b c ni vi n s khng hot ng truyn thng c. Chnh v th m khi s dng cu trc hnh sao th trm trung tm phi c tin cy rt cao.

Hnh 1.14 Cu trc hnh sao

Mt nhc im na ca cu trc hnh sao l tn dy dn nu khong cch cc trm trong mng nh hn khong cch t chng ti trm trung tm. Tuy nhin, vn ny c th c khc phc bng phng php p dng k thut chuyn mch trong mng. Trong nhiu trng hp mt mng cu trc hnh sao v mt vt l li c cu trc logic nh mt h Bus bi cc trm c th t do lin lc nh khng c s tn ti ca trm trung tm.d, Cu Trc Cy

Cu trc cy khng phi l cu trc c bn m thc cht l s lin kt ca cc mng con c cu trc Bus, hnh sao, mch vng,. Cu trc cy l qu trnh phn chia ng trc ra cc ng nhnh bng cch s dng cc b ni tch cc hoc c th tng s trm cng nh phm vi ca mng ng nht bng cc b lp. Trng

hp cc mng con khc loi th phi dng cc b lin kt khc nh: Bridge, Router,Gateway,:

Hnh 1.15 M hnh cu trc cyV th cu trc hnh cy l s phn cp ng dn.1.2.4 Truy nhp BUSTrong mt mng c cu trc, cc thnh vin phi chia nhau s dng ng truyn. trnh s xung t v tn hiu gy ra sai lch v thng tin, mi thi im trn mt ng dn ch duy nht mt tn hiu c php truyn i. V vy, mch phi iu khin sao cho ti mt thi im nht nh th ch c mt thnh vin trong mng c gi thng tin, cn s lng thnh vin nhn thng tin trong mng th khng hn ch. Mt trong nhng vn quan trng hng u nh hng n cht lng ca mi h thng Bus l phng php phn chia thi gian gi thng tin trn ng dn hay cn gi l phng php truy nhp Bus.Trong mng truyn thng cng nghip, cc h thng c cu trc dng Bus haycc h thng Bus c vai tr quan trng nht do m bo c nhng l do: Lp t d dng. Chi ph dy dn thp. Lm vic linh hot. Khong cch truyn va v nh.

i vi mt s cu trc khc dng Bus, xung t tn hiu vn c th xy ra, tuy khng hin nhin nh h thng Bus. Nh vi cu trc mch vng, mi trm khng phi bao gi cng c kh nng khng ch hon ton tn hiu i qua n. Hay cu trc hnh sao c th trm trung tm khng c vai tr ch ng m ch l mt b phn chia tn hiu nn kh nng xung t tn hiu l khng th trnh khi. V th, trong cc h thng ny ta vn cn mt bin php phn chia quyn truy nhp, tuy c th n gin hn so vi cu trc Bus.Phng php truy nhp Bus l mt trong nhng vn c bn i vi cc h thng Bus, bi mi phng php c nhng nh hng khc nhau ti cc tnh nng k thut ca h thng. Nhng yu cu c th i vi mt phng php truy nhp Bus l tin cy, tnh nng thi gian thc v hiu sut s dng ng truyn.a s cc h thng Bus c s dng trong lnh vc t ng ha lm vic theo chu k. Ch c mt s hot ng xy ra bt thng nh thng tin cnh bo, d liu tham s,, cn phn ln cc d liu c trao i nh k theo chu k tun hon ca Bus. Vi chu k Bus l khong thi gian ti thiu m sau cc hot ng truyn thng chnh lp li nh c. Trong iu khin t ng, chu k qut l c s cho vic chn chu k ly mu tn hiu o hoc chu k vng qut cho cc PLC ng vai tr trm ch.Cc yu cu v iu khin truy cp Bus, c hai yu cu quan trng cn ch n l i vi truyn thng gia cc b PLC c cng trng thi (Master) phi m bo rng mi mt trm phi c thi gian thc hin xong nhim v truyn thng v i vi s truyn thng trao i d liu theo chu k gia Master v Slave c cng t yu cu cng tt.C th phn loi cch truy nhp Bus theo cc cp sau:

Hnh 1.16 Phn loi cc phng php truy nhp Busa, Phng Php Tin nh

Vi phng php ny, trnh t truy nhp Bus c quy nh r rng. Qu trnh truy nhp Bus c kim sot theo cch tp trung trm ch (phng php Master/Slave), theo quy nh trc v thi gian (phng php TDMA) hoc phn tn bi cc thnh vin (Phng php Token Passing). Nu mi hot ng truyn thng c hn ch bi mt khong thi gian hoc di d liu nht nh th thi gian p ng ti a cng nh chu k Bus c th tnh ton c. Cc h thng ny v th c gi l c kh nng thi gian thc.b, Phng Php Ngu Nhin

Ngc li, trong cc phng php ngu nhin trnh t truy nhp Bus khng c quy nh cht ch trc m xy ra hon ton theo nhu cu ca cc trm. Mi thnh vin trong mng u c th th truy nhp Bus gi thng tin i bt k lc no. loi tr tc hi ca vic xung t d liu gy nn ta c th s dng cc phngphp ph bin nhn bit xung t (CSMA/CD) hoc trnh xung t (CSMA/CA).

Nguyn tc hot ng ca cc phng php ny l khi c xung t tn hiu xyra th t nht mt trm phi ngng gi v ch mt khong thi gian no trckhi th li, mc d kh nng thnh cng k c lc ny cng khng c m bo.

Ngi ta thng xem cc h thng s dng phng php ny khng c kh nngthi gianthc. Tuy nhin, ty theo lnh vc ng dng c th m tnh nng thi gian thc camt hthng c nh gi khc nhau.

c, Phng Php Master/Slave

Theo phng php ny mt trm ch (Master) c trch nhim ch ng phn chia quyn truy nhp Bus cho cc trm t (Slave), cc trm t ng vai tr th ng, ch c quyn truy nhp Bus v gi thng tin i khi c yu cu. Trm ch c th dng phng php hi tun t theo chu k kim sot ton b hot ng giao tip ca c h thng. Nh vy cc trm t c th gi cc d liu thu thp t qu trnh k thut ti trm ch, cng nh nhn cc thng tin iu khin t trm ch. Trong mt s h thng, thm ch cc trm t khng c quyn giao tip vi nhau, m bt c d liu cn trao i no cng phi qua trm ch. Nu hot ng giao tip din ra theo chu k, trm ch s c trch nhim yu cu d liu t trm t cn gi v chuyn ti trm t cn nhn. Trng hp mt trm t cn trao i d liu bt thng vi mt trm khc th phi thng bo yu cu ca mnh khi c trm ch hi n v sau ch c p ng.

Hnh 1.17 Phng php truy nhp Master/SlaveTrnh t c hi ca cc trm t c th do ngi s dng quy nh trc bngcc cng c to lp cu hnh. Trong trng hp ch c mt trm duy nht, thi gian

trm ch kt thc vic hi tun t mt vng cng chnh l thi gian ti thiu ca chu k Bus, m chu k Bus ta c th tnh ton c mt cch chnh xc. y l mt yu t th hin tnh thi gian thc ca h thng.u im ca phng php Master/Slave l vic kt ni cc trm t n gin, tn km, ton b cc chc nng x l u tp trung trm ch. Ta cng c th tch hp thm mt s chc nng x l khc cho mng, m khng my kh khn do thit b ch thng l mt thit b iu khin.Nhc im ca phng php ny l hiu sut trao i thng tin gia cc trm t khng cao do phi i qua khu trung gian l trm ch nn hiu sut s dng ng truyn cng gim theo. ci thin nhc im ny l cho php cc trm t trao i d liu trc tip trong mt kh nng kim sot c.V d, trm t hai mun chuyn d liu v trm t mt trong khi trm t hai li c trm ch hi sau trm t mt. Sau khi trm ch yu cu trm t mt nhn d liu v trm t hai gi d liu th trm t hai gi trc tip n trm t mt. Sau khi trm t mt nhn c thng bo kt thc t trm t hai th trm t mt gi thng bo nhn xong d liu ngc v trm ch:

Hnh 1.18 Trao i d liu trc tip gia hai Slave

Mt nhc im na ca phng php ny l tin cy ca h thng truyn thng ph thuc vo mt trm ch duy nht, nn khi c s c xy ra trn trm ch th h thng truyn thng b t lit, cch khc phc l s dng mt trm t c vai tr gim st trm ch v c kh nng thay th trm ch khi cn thit.d, Phng Php Token Passing

Phng php Token Passing m bo quyn chuyn giao quyn truy cp. Token Passing l mt bc in c cu trc c bit chuyn giao quyn gi thng tin t mt Master ny n mt Master tip theo. Mt trm c quyn truy cp Bus v gi thng tin i ch trong thi gian n gi Token. Phng php Token Passing ch s dng ProfiBus gia cc Master vi nhau. Sau khi khng c nhu cu gi thng tin, trm ang c Token s chuyn quyn Token n mt trm khc theo mt trnh t nht nh. Nu trnh t ny ng vi trnh t sp xp vt l trong mt mch vng th ta dng khi nim Token Ring, cn nu trnh t quy nh ch c tnh cht logic nh cu trc Bus th c Token Bus. Trong mi trng hp u hnh thnh mt mch vng logic.

a,Token Bus

b,Token Ring.Hnh 1.19. Hai dng ca phng php Token Passing.

Mt trm ang gi Token khng nhng c quyn gi thng tin i m cn c th kim sot hot ng ca mt s trm khc. Cc trm khng c Token cng c kh nng tham gia gim st. V vy, Token Passing c xp vo phng php kim sot phn tn. Cc trm c th d tnh v thi gian s dng Token ca mnh, t tha thun mt chu k Bus thch hp tt c cc trm u c quyn tham gia gi thng tin v kim sot hot ng truyn thng ca mng, bao gm: Gim st Token m bo qu trnh truyn c chnh xc, nu Token b mt hoc gia bi th phi thng bo xa cc Token c v to ra mt Token mi. Khi to Token, sau khi khi ng mt trm c trch nhim to mt Token mi, mt trm c s c phi c pht hin v tch ra khi trnh t c nhn Token. B sung trm mi, mt trm mi c kt ni mng, mt trm c c thay th hoc a tr li s dng phi c b sung vo mch vng logic c quyn nhn Token.

Ngoi ra, Token Passing cng c th s dng kt hp vi phng php Master/Slave, phng php ny cn c gi l Multi-Master trong mi trm ch c quyn gi Token v c quyn truy nhp vo cc trm Slave:

Hnh 1.20. Truy nhp Bus kt hp Multi-Master

Chng 2. M hnh trm PLC iu khin Bin tn

2.1 Tng quan v bin tn Micromaster 420 v cch thc giao tip vi PLCqua PROFIBUS2.1.1 Tng quan v bin tn Micromaster 420 Cc c tnh c bn ca Micromaster D dng ci t, lp trnh v s dng Chu qu ti 200% trong 3s cho ti 150% trong 60s M men khi ng ln v iu chnh chnh xc tc motor bi iukhin vc t C th kt hp thm vi b lc iu chnh dng nhanh Khong nhit hot ng 0-50oC C sn cc hm iu khin chun P, I, D dng cho iu chnh vng kn (vng ngoi) . C sn ngun 15V, 50mA cp cho cc b bin i phn hi. iu khin t xa qua ng truyn ni tip RS485 s dng giao thc USS vi c tnh iu khin ti 31 b iu bin tn qua giao thc USS. Cc thng s c t t khi sn xut c th t li cho cc thit bca chu u, Asian v bc M. Tn s ra c th c iu khin bi Tn s t s dng bn phm Tn s t s dng tn hiu tng t vi phn gii cao (dng hoc p) B phn p m rng u vo nh phn

Chc nng thay i tc qua b phn p Giao din ni tip Ci sn hm mt chiu vi b hm phc hp c bit Ci sn phanh ngt cho in tr ngoi Tng/gim thi gian vi chng trnh san bng Hai chng trnh u ra r le (13 hm) Chng trnh u ra tng t (1 cho MMV, 2 Cho MDV) C th chn module Profibus DP hoc CANbus T ng phn tch 2,4,6 hoc 8 cc motor bi phn mm. Tch hp phn mm iu khin qut lm mt C th gn cnh nhau m khng cn iu kin v khong cch Tch hp mt s thnh phn bo v nh bo v qu dng, bo v qunhit, Bo v cao, thp p... Ch dn u dy Cn chc chn rng mi thit b trong t in c cha bin tn u c ni t. Dy ni t cn ngn, dn in tt v dy. im ni t c th l im trung tnh ca ngun hnh Y. Cn chc chn rng mi thit b c ni vi bin tn cng c ni t cng vi bin tn hoc ni vo im trung tnh hnh Y. Dy n dt thch hp hn v chng c tr khng thp tn s cao. im chung tnh ca ng c c iu khin bi bin tn c th c ni trc tip vi im t chung ca bin tn(PE). S dng cp c bc tt nu c th. i vi dy khng c bc cng ngn cng tt. Nn s dng dy cp c dy bo v khi ni vo u iu khin.

Cc cng tc t trong t in cn c kh nhiu. Vi loi xoay chiu dng R-C, vi loi mt chiu s dng iot. Vic ny rt quan trng c bit vi cc cng tc t c iu khin bi rle trong bin tn. S dng cp c v chng nhiu hoc v bc kim loi cho du ni vi ng c v 2 u ca dy dn cn c ni t Nu bin tn s dng trong mi trng c nhiu nhiu in t b lccn c s dng gim nhiu v tng s iu khin t bin tn. Hot ng vi ngun khng tip t.Micro Master c thit k hot ng c s dng dy t . Thit b u ra c th khng tip t, tuy nhin khng nn s dng nh vy. khi chng ta phi ch mt s vn sau: S dng ng dy c tr khng ph hp v in p nh nh nht. in p ngun ln nht l 500V Thit b s tt vi li qu dng nu mt hoc vi u ra c biu hinchm t. Ch s dng c cho cc thit b khng c b lc Tn s vng xung iu khin ti a 2KHz

S dng sau mt thi gian ct gi

Thi gian ct gi di 1 nm Khng c iu kin c bit Thi gian ct gi 1 n 2 nmCp ngun vo bin tn khong 1 h trc khi s dng lnh chy Thi gian ct gi 2 n 3 nm

Cp ngun xoay chiu 25%nh mc trong khong 30, 50% trong 30 tip theo, 75%trong 30 tip v 100% trong 30.Tng thi gian l 2h trc khi cho chy bin tn. 3 nm tr ln.Cp ngun nh bc trn tuy nhin thi gian l 2h cho mi bc. Tng thi gian khong 8h. Khi s dng dy cp di.Chiu di dy cp s dng ph thuc vo loi cp, tn s lm vic, di cng sut v di in p.Trong mt s trng hp c th di ti 200m m khng c iu kin g c bit

Mt s tham s c bn

Tn s u vo47Hz-63Hz

T s ngun vo> 0.7

Tn s u ra0Hz- 650Hz

phn gii0.01Hz

c tnh qu ti200% trong 3s v 150% trong 60s

Ch bo vQu p, thp p, qu nhit

Cc ch bo v thmNgn mch, chm t, khng ti(h mch)

u vo tng t/ PIDn cc :0-10V hoc 2-10V( nn dng bin tr 4,7K)0-20mA hoc 4-20mA Lng cc :-10 - +10V

phn gii u vo tng t10 bt

u ra tng t0-20mA/4-20mA, n nh 5%

n nh im tTng t PROFIBUS T th nht (PKE): 12BC s c ni dung T th 2 (IND): 0000T th 3 (PWE1): 0000T th 4 (PWE2): 0006iu c ngha l ngun lnh c la chn l CB trn ng truyn COMV d 2: c tham s P1082 ( tn s ln nht)AK = 1 yu cu c tham sPNU = 1082 dec = 43A hexDo t u tin c gi tr 143AV index = 0 v tham s ny nh hn 1999 nn t th 2 sx c gi tr 0000T th 3 v 4 cn c thit lp l 0Nh vy bn tin t PROFIBUS => MM4 s c ni dungT th nht (PKE): 143A

T th 2 (IND): 0000T th 3 (PWE1): 0000T th 4 (PWE2): 0000

Bn tin tr li t MM4 => PROFIBUS T th nht (PKE): 243A s c ni dung T th 2 (IND): 0000T th 3 (PWE1): 4248T th 4 (PWE2): 0000iu c ngha l ni dung bn tin tr li c di l 2 t c gi tr 4248 0000 Gi tr l s IEEE c chuyn sang s thc nh sauS IEEE gm 32 btBt th 31 l bt du 0 l dng 1 l mT bt 23 ti 30 l s mT bt s 0 ti bit 22 l gi tr thp phn (4248 0000 hex 50.0 dec)

(-1)VZ 1.M2Exp-127 = (-1)0 (1 + 9(1/16) + 0(1/162))2132-127 = 11.562525 = 50.0

V d 3: c tham s P2000 (tn s tham kho)AK = 1Do tham s ny ln hn 1999 v nh hn 3999 nn t th 2 IND = 0080Vy t th nht c gi tr 1000PNU = (2000 - 2000) dec = 0 dec = 0 hex T th 3 v th 4 c t l 0Nh vy bn tin t PROFIBUS => MM4 s c ni dungT th nht (PKE): 1000T th 2 (IND): 0080T th 3 (PWE1): 0000T th 4 (PWE2): 0000

Bn tin tr li t MM4 => PROFIBUS T th nht (PKE): 2000 s c ni dung T th 2 (IND): 0080T th 3 (PWE1): 4248T th 4 (PWE2): 0000iu c ngha l ni dung bn tin tr li c di l 2 t c gi tr 4248 0000 L 50HzV d 4: c tham s P2010 ( tc baud USS trn ng truyn BOP ) AK = 1PNU = 2010 2000 = 10 dec = A hexDo t th nht c gi tr 100ATham s ny ln hn 1999 v nh hn 3999 v c index 1 nn IND =0180 T th 3 v t th 4 phi c l 0

Nh vy bn tin t PROFIBUS => MM4 s c ni dungT th nht (PKE): 100AT th 2 (IND): 0180T th 3 (PWE1): 0000T th 4 (PWE2): 0000

Bn tin tr li t MM4 => PROFIBUS T th nht (PKE): 100A s c ni dung T th 2 (IND): 0180T th 3 (PWE1): 0000T th 4 (PWE2): 0006iu c ngha l ni dung bn tin tr li c di l 1 t c gi tr l 6 tng ng vi tc 9600 baud

V d 5: Thay i gi tr tham s P1082 ( tn s ln nht ) vit gi tr ti tham s ta cn phi bit c gi tr c di l 1 Word hay 1 double Word xc nh c gi tr cho tham s AK l 2 hay l 3, trong trng hp khng bit gi tr c di l 1 Word hay 1 double Word th ta nn gi 1 bn tin c tham s trc xc nh di ca tham s (tham kho v d 2) Nh vy bn tin t PROFIBUS => MM4 s c ni dungT th nht (PKE): 143AT th 2 (IND): 0000T th 3 (PWE1): 0000T th 4 (PWE2): 0000

Bn tin tr li t MM4 => PROFIBUS T th nht (PKE): 243A s c ni dung T th 2 (IND): 0000

T th 3 (PWE1): 4248T th 4 (PWE2): 0000Trong bn tin tr li vi AK = 2 do ta xc nh c gi tr ca tham s c di l 1 double Word iu ny c ngha l nu ta thay i gi tr ca tham s ny th trong bn tin gi ti bin tn AK cn c t bng 3, gi s ta chuyn gi tr tn s ln nht thnh 40 Hz (IEEE floating value = 4220 0000)T th 3 v th 4 cn c t gi tr 4220 v 0000Nh vy bn tin t PROFIBUS => MM4 s c ni dungT th nht (PKE): 343AT th 2 (IND): 0000T th 3 (PWE1): 4220T th 4 (PWE2): 0000

Bn tin tr li t MM4 => PROFIBUST th nht (PKE): 243AT th 2 (IND): 0000T th 3 (PWE1): 4248T th 4 (PWE2): 0000V d 6: nh gi li trong bn tin tr liTrong v d 5 vic vit gi tr tham s c thc hin khi bin tn ang dng (khng chy) nu vic sa i thc hin khi bin tn ang chy th bin tn s bo khng th thc hin c yu cu tc l tham s P1082 khng th thay i khi bin tn ang chy, s ca li c ch ra trong t th 4 PKE2 tra bng di y bit c tn liBng 2.6 li trong bn tin tr li

Li sTn li

0Tn tham s khng hp lTham s khng tn ti

1Tham s khng th thay iTham s ny ch c khng s

2Gi tr khng hp lGi tr khng nm trong gii hn

3Faulty subindex-

4No arraySingle parameter has been accessed with array request and subindex > 0

5Incorrect data typeMix-up between word and double word

6Settingnot only)allowed(resetting-

7Descriptive modifiedelementcannotbeDescription can never be modified

11No status as master controlModification request without statusasmastercontrol(see P0927

12Key word missing-

17Request cannot be processed due to operating stateCurrent inverter status is not compatible with the received request

101Parameter number currently deactivatedDependent on inverter status

102Channel not wide enoughCommunication channel too small for response

104Illegal parameter valueParameter permits only certain values

106Request not implementedAfter request identifier 5, 10, 15

200/201Modified minimum/maximum notMinimum/maximum can be

reached/exceededfurther limited in operation

204Available access authorization does not cover modification of parameters-

Request PROFIBUS => MM4T th nht (PKE): 343AT th 2 (IND): 0000T th 3 (PWE1): 4220T th 4 (PWE2): 0000- an attempt to change the value of P1082 to 40.00.Response MM4 => PROFIBUST th 1 (PKE): 743A (7: khng thc hin c yu cu) T th 2 (IND): 0000T th 3 (PWE1): 0000T th 4 (PWE2): 0011 (li s)

2.2.3 Xy dng giao din iu khin t Wincca, To cc Tag lien kt vi PLCKhi ng Wincc bng cch chon StartSIMATICWincc ca s sau xut hinchn OK

Ca s sau xut hin

Trong mc Project Name t tn TruyenthongbientanCreateCa s sau xut hin

Click chut phi ln Tag ManagementAdd New Driver

SIMATIC S7 Protocol Suite.chnOpen

Click chut phi ln MPINew Driver connection

Trong mc Name t tn PLC1Click properties

Mc Slot Number t l 2OKOK

Trong mc PLC click chut phi chn New TagTrong mc Name t tn l bat_tatbt1

Mc Data Type chn l Binary tagClick Seclect la chn a ch lin kt vi PLC

Chn Data l Bit memory Address l M200.0OKOK Tng t to ra Tag o chiu

click seclect chn a ch lin kt vi PLC

Chn Data l Bit memory Address l M200.1OKOK To Tag tansodatbatData type : Floating-point number 32 bit IEEE 754

Click seclect chn a ch lin kt vi PLC

Chn Data l Bit memory Address l MD202OKOK To Tag tansothuctebt1Data type : Floating-point number 32 bit IEEE 754

Click seclect chn a ch lin kt vi PLCChn Data l Bit memory Address l MD206OKOK

Tng t cc bc nh trn ta s to ra cc Tag sau

b, Xy dng iao din iu khinclick chut phi ln Graphic Designer New pictureclick chut phi chn Rename t tn CaiDatThamSo

Tng t ta to ra bc tranh qu trnh vi tn DieuKhien

Click chut vo bc tranh vi tn DieuKhien ta c giao din sau

Ly 1 i tng l button trong Object Palte Windows bject button

t tn l bat_bt1tng t ta s to ra cc nt n bat_bt2, daochieubt1, daochieubt2, tatbt1, tatbt2

to nt n chuyn ti mn hnh ci t tham s bng cch ly 1 i tng l button trong Object Palte Windows Object button t tn l caidatthamso

Trong mc Change Picture Mouse Click la chn bc tranh cn chuyn ti riOK

Ta to c cc nt n nh sau

Tip theo ta s ly i tng l Static Text trong ca s Object PalteStandard ObjectStatic Text c giao din nh sau

Tip tc ly i tng l I/O Field trong ca s Object PalteSmart Object I/O FieldTrong mc update chon Upon change

Mc Tag chn ti Tag lin kt

Chn Tag tansodatbt1 OK

Tip theo ta s chnh sa cc thuc tnh cho I/O Field bng cch Click chut phichn Properties

Trong mc Limits chn gi tr thp nht v cao nht ca i tng l t -60 ti 60

Trong mc output/input chn dang DecimalTng t ta s to ra 4 ca s I/O Field c ca s nh sau

Tip theo ta s to ra 1 n bo khi ng c chy th n s hin th mu xanh khi dng th n s hin th mu

Ly 1 i tng l hnh trn Object PalteStandard ObjectCircle

Click chut phi chn PropertiesColors

Trong mc Background Colors click chut phi chn Dynamic DialogXut hin ca x

Data Type: chn Boolean tin hnh chn mu Trong mc Expression/Formula chn Tag lin kt

Tng t ta s to ra n bo cho ng c th 2ViewlibraryGlobalPlantElementsMotor

Ly 1 ng cTng t ly ng c th 2

Tin hnh vit code cho cc nt n bat_tatbt1 bng cch Click chut phi chnProperties

Ca s sau xut hin chn Tag EventMousepress leftC-Action

Xut hin ca s sau vit code cho nt n

Tin hnh vit on code sau sau OK

Tng t ta s vit code cho cc nt n khcVic xy dng giao din cho mn hnh ci t tham s cng tin hnh tng t

Ci t tham s khi chay Runtime nh sau Click p vo Computer

Click chut phi vo Computer Name chn Properties

Ca s sau xut hinChn Tag Graphic RuntimeStart Picture chn mn hnh iu khinWindow Attributes chn Title, Maximize, Minisize, Adapt Picture.