I, R2=LR 4, Nhu v~y mQt cau can bang la cau co:
2.5.MOOUN TRUYEN THONG
a) Thyristor ra kf Ill/h.1 b) Dt;k tfnl! Clia thyristor
2.5.MOOUN TRUYEN THONG
Trong san xuat ehe' t~a voi cae thie't bj eo SI! dieu khien, M gifr duqe nh~p
san xU<lt gi[i:a cae thiet bi, gifra ehung can eo Sl! trao d6i thong tin. Oie thiet b~ eo the gui va dQe thong tin thea nhitng eaeh khae nhau. M~e du nen san xullt tl! d¢ng bao gam mQt s610~i may voi eae bQ dieu khien khae nhau, tuy nhien da so cae bQ Jieu khien nay eo ehung di).e diem la tren co sO bQ vi xu Ii eo the tich hgp mQt h¢ truyen thong. SI! lUll thong dfr li~u tu: mQt bQ dieu khien ella thiet b~ nay sang b¢ dieu khien ella thiet bi khae hlnh thanh modun truyen thong eua m~ng.
Tuy thu¢e vaa quy mo san pham, modun truyen thong eo the ehi eo trang ph~m tru m¢t thiet b~ ha~e trang m¢t h~ thong thiet bi. Di).e trung ella M thong eo di~n tu la eo the co cac vimg tl! tr~ duoi slJ ket hqp ella h¢ thong trung tam, Vi.
d~, trong may cat laser co the co nhiing h~ th60g "to" dieu khhin cOng suat laser, lam mat M thong , h~ th6ng "chu" cl,lc bt) dieu khien ph6i hqp 2 ho~t dQng nay Va lren ta't ca 130 b¢ dieu khien CNe trung tam dieu khien vi trio t6e dQ va laser. Trang h¢ th6ng nay, thong tin/dfr li¢u duqe traa d6i gifra "to" -"ehU." va "ehu"- trung tam. Vi dl,l khac 1;1 trang m¢t h¢ th6ng san xuat linh ha~t (FMS), diI li¢u can thiet duqe truyen khong nhililg giua cac b¢ dieu khien logie khi trloh (PLC), man hlnh, senso va cae b¢ kich truyen dt)ng, eha phep nguai v~n himh nMp du li¢u va chuang tdnh van M, rna eon can co sl! trao d6i thong tin gifra may Hnh dieu khien nay vOl eac may tfnh dieu khien kMe. Trang nhU'ng nam gan day, ky thu~t m~ng nQi bQ (LAN) dff trd nen nit quen thu¢c trong ca van phong Ian trang san xuat tl,l d¢ng. Ngoai ra xu huO'ng "gia eong qua m~ng phan tan" thong qua sU: dl,lng m<;tng ta~m cau Internet dff va dang hlnh thanh. SI! trao d6i, truyen thong tin, dfr li¢u giiIa cae may tfnh (gam d. cae h~ dieu khien) tuy thea ph~m vi sil dl,lng duqc yeu cau e6 the 13.:
Diiu khie'n trung tam (centralised computer control) Ia Slr dl,lng mQt may tmh trung tam de dieu khien toi:1fl b¢ day chuyen. TruOng hqp fiy, neu may trung Him e6 sl! eo, toan bt) day chuyen SI! nglrng ho~t d¢ng. Day lit d<p1g dieu khien m<;lng trong nhfrng nam 1970.
rna:, tfnh thlfc hi~n coog vi~c thuang nh~t bj giam sat b6i cac may tfnh co val tr'- (;uyet Jinh J6n hem (vf dl;!, may tinh dieu h3nh h¢ thong dieu khi~n so phai eh> gi~m sat h6i may tfoh dieu khi~n toan b¢ h¢ thong). Cong vi¢c duqe ehia ella cae may tfnh thea ehCre nang cua chung (chuyen man hmi).
J/¢ diiu khien phdn qu)'c'n (distrihuted system): cae may tfnh thlfc hi~n eang .~~c tucmg tl! nhau. Truang hqp c6 sl! co hoi!.c m(lt may qua tai, cbng vi~c co th~ chuy~n sang may khac. Cong vi~c trai fa tat d cac may do v~y moi may can truy c:)p dlfqc tat d thbng tin trong h~ thong.
Da so cae h~ thong truyen thong hi~n d~i Iii sl! pha trQn cua cae h~ thong phan cap va phan quyen, vf dl;!, cong vi¢c do va truyen dQng co the phfin quyen giiIa dc bQ vi xU W mOt so cae may tfnh noi vai nhau va eung cap co sO' du li¢u cho day ehuyen san xuaL Tat cii cae h~ nay co the duqe kiem soat bOi. mQt may tinh dicu khi6n so ho~e dicu khieo lUAn tlf va no c6 the b~ giam sat boi mOt h¢ thong dieu khien toan bO day chuyen.
2.S.1. CO" sa truy~n thOng dii li~u 2.5.1.1. GiOi th!~u: 2.5.1.1. GiOi th!~u:
H¢ thong truycn thong d~e tTung thuang bao gam: nguan sinh/ngu6n phat; moi truang twyen, bO ph~n nh~n (nh~n va chue)n bj thong tin de cap eho dich); dieh nh~n va su dl;!ng thong tin theo yeu cau.Thong lin truyen c6 the a d~ng tucmg tl! (analog) ho~c s6 (digital). Sl! truyen!trao dai/chia se thong tin trang m<:J.ng cbng tae may tfnh co nhfmg d~c diem chung va nhung diem dij.c bi¢t 50 vai truyen! trao dai thong tin qua h¢ di¢n tho~i. Sau day Iii. nhfmg co sa truyen thong du li¢u trong che t~o may.
2.5.1.2. Khai ni~m ca so trong truyen thong
Truycn thong du li¢u la co 51.! hru chuyen du li¢u tu thiet bj nay sang thiet bi khac. Ben {rong nQi bO, thiet bj tren co sa may tfoh so hru du li¢u tren cae thanh ghi hoij.c trong bQ nh6 RAM (hloh 2.80). Du li¢u duqc trao dai giua dc vi tff bQ nha va thanh ghi qua mQt buyt diI li¢u. Phl;! thuQc vao cau truc Clla may tinh, bus du li~u co the iiI 8,16, 32 ho~c 64 bit. Khi dn thiet co giao tiep vai thiet bi ngoai, philn cUug xuat/nh~p (I/O) duqe sir dl;!ng. Xuilt/ nMp co the duqe thl.!c hi¢n qua 1/0 philo l<;tp (isolated I/O) ho~c I/O anh X<;l -ki tIc (memory-mapped 110). JlO phan l~p sir dl,lng cac cang I/O philn nhi¢m chuyen dl;!ng va eac vi tf!
dU'qc gan cho cac m\lc di'ch lIO. Nhltng chi thi I/O d~c hi~t cho phep dil li~u dau va~ va dau ra qua cac cong nay dU'gc l~p san trang hi) chi thi clla CPU.
Trudng hqp memory-mapped 110: mot thiet bi I/O s6 (Ie chip) dl1Q"c gan
mot dia chi bO nhd va hO<;lt dong nhU' bat cu vi tri nhd nao trong computer. De (hinh d~a chi mot vi tri nhd. dia chi dU'qc d~t tren buyt dja chi. BQ giai rna, giaj rna dia chi va cho phep thiet bi (ho~c buyt memory) thu dU'Q"c du li~u. Chi co thiet bi dl1Q"c pbep cua bO giai rna tra lai tin hi~u dieu khien, nhltng tln hi¢u den tit buyt dieu khien. Cac tin hi~u dieu khien co th~ daqc dQc ho~c viet.
Thiet hi I/O co the lil mot bg d¢m (huffer). mgt chat (latch) • mot dieu khitn (driver) 2 chicu • m¢t bQ dieu hqp (adapter) giao di¢n song song ho~c giao di~n n6i tiep nha UART (Universal Asynchromous Receiverrrransmitter). USRT (Universal Synchromous Receiverrrransmitter).
PhU'oog phap truyen d~t dO li¢u thaoog dagc sa dl,lllg nhat la truyen song song ho~c lien tl,lc.
2.5.1.3. Ma hoa di1li~u
cac may Hnh hIll du li~u dl161 d~g nhi phan, tuy nhien chi nhltng s6 nguyen moi hru dagc dU'di d~ng nay, cac d1.lng du li¢u kh:ic, vi dl,l text (ki tl,l', chu s6) va do thi dn dagc rna hoa sao cho cac may trnh trong h¢ c6 th~ nh~n d<;lng chung. Da s6 cac may tfnh hru dO li¢u chu s6 thea ASCII (American Standard Code for Information Interchange). Mgt s6 nha san xuat thiet bi Slt dl,lng d1.lng thuc EIA (Electronic Industries Association). lUng IBM thU'oog sa dl,lng EBCDIC (Expanded Binary- Coded Dccimallnterchange Code). Cac rna nay hao gam cac ki tl,l', so, dau va cac ki tl,l' dieu khitn. Cac ki t\I dieu khitn kh6ng hien th~ khi in dlIqC su dl,lng d6 dieu khien may in, man hlnh, truyen dc du li~u to~ dQ va danh dj"u dc dU'Cmg gian dO<;ln va ket thuc t¢p. DO li¢u de truyen co the duqc rna hoa thea m¢t trang cac d~ng thuc tren. tuy nhien khong dl1Q"c trQn 1<1n, ASCII dlIqC su dl,lng phd bien nhat.
Nhung du li¢u khac d1.lng chu so thi co nhung chu&n chuycn doi khac. Du Ii?u dq.ng anh ~ bitmap. tuy thea s6 mau daQ"c sa dl,lng, moi mot pixel (phan tu anh) dUQ"c tht hi~n bdi mot s6 hits, nhU' v~y anh bitmap co tht dUQ"c rna hoa ha~c dudi d~ng nh! phan ho~c daoi d<;lng ASCI1. Ngoai fa, con co m¢t so ung dl,lng phat tri~n d~ng thuc rieng nha Posl Scrip, GIF, JPEG va TIF Slr dl,lng cha tfuyen dO li¢u. D6i vdi cac (mg dl,lng CAD, cac hlnh ve va mo hlnh hlnh hQC co th~
dUQ'c th~ hi~n thea khu6n thuc IGES, POES/STEP va OXF, H:(t ca cac khu6n thuc
nay c6 th~ dUQ'C rna hoa thea ASCII.