Ngon ngfr l?p trinh su d1,1ng trong PLC c6 ba d<;1ng:
• Ladder
■ Boolean
• Graph
Ngon ngfr Ladder, Boolean v€ co ban th\fc hi~n theo cung m(>t each, nhung chung khac nhau v€ cu phap va each bi~u di~n khi vi~t chucrng trinh. Ngon ngfr Graph th\l'c hi~n theo each khac, d1,ra tren cac bu6c (Step) va hanh d(>ng (Action).
9.2. I Ngon ngfr ladder
PLC duqc phat triJn d~ don gian h6a vi~c l?p trinh khi su d1,mg cac ky hi~u m-le, d<;1ng gi6ng so d6 m<;1ch di~n d~ bi~u di~n chuong trinh di€u khi~n logic cho thi~t bi ho~c qua trinh. Chucrng trinh di€u khi~n duqc vi~t du6i d<;1ng nay duqc g9i la ngon ngfr Ladder. Hinh 9.1 mo ta m<;1ch dieu khi~n logic d<;1ng rcr-le va chuong trinh Ladder tucrng ung.
Ll PB3 L2
START PLI
_J_ LSI
' /
PB4 /
"
START
_L_
(a) M<;1ch kJt n6i bAng day
Psã LS PL
FS
(b) M<;1ch Ladder PLC
Hinhh hb 9.1 M<;1ch d§u day m-le va chuCYng trinh Ladder cua PLC
Ngon ngfr Ladder duqc phat tri~n thanh m(>t ngon ngfr l?p trlnh m<;1nh v6i nhi~u chuc nang duqc xay d1,mg nlm b(> dinh th<'ri (Timer), b(> d~m (Counter) ... Khai ni~m chuc nang duqc dung d~ mo ta cac t~p l~nh g6m: tu gqi nh6 cua t?p l~nh, ho<;1t d(>ng xu ly (thong tin du li~u ngu6n -dfch, qua trinh xfr ly va truy€n dfr li~u). Ti1t ca cac t?P l~nh mo r(>ng v~n d\l'a tren cac nguyen tic dcrn gian eua logic ti~p di~m. m?C du chung cho phep th\l'C hi~n cac tac Vl,l phuc t<;1p.
C'htrong 9: Ngan nxu ft;ip trinh 177
Cac b6 sung moi cho ngon ngfr Ladder cung bao g6m cac kh6i chuc nang. L?p trinh voi cac kh6i chuc nang lam tang sl'.rc m:;inh cua ngon ngfr Ladder ca ban va c6 th~ duqc g9i la ngon ngfr Ladder nang cao. Hinh 9.2 thJ hi~n each bi~u di~n chuang trinh Ladder ca ban va Ladder su dàng kh6i chuc nang.
Function Block
_ _ _ __,A..__ _ _ ....,
( MOVE 1
A B Re ister -to - Table Output
1---1 i--l ----1 1 - - - 1 Enable
A B
1---l 1-I ----ll i---l .._ Reset _____ __.
Functional Instruction
A B
, _ _ _ . . . , 1 - i - - - - l l i - - - MOVE register to table 1 - - - 1
Hinh 9.2 Dinh d,,mg kh6i chuc nang
Chu-c nang nang cao cua ngon ngfr Ladder duqc bi~u di~n theo nhi~u each khac nhau theo tlrng hang san xuAt. Tuy nhien, bAt ky dinh d{mg nao, tAt ca cac chuc nang cua ngon ngfr Ladder nang cao va co ban d~u ho<;1t d(mg theo cung m<)t each. Trang chuang nay. nhfrng l?P l~nh Ladder nang cao duqc bifu di~n du&i dinh d~ng la kh6i chuc nang.
Nhu da neu a tren. cac ngon ngfr Ladder cho PLC c6 the dugc chia thanh hai nh6m:
• Ngon nguã Ladder ca ban
• Ng6n ngfr Ladder nang cao
M6i nhom bao g6m nhi~u t?p l~nh t:;io d~ t:;io thanh hinh thuc cua ngon ngfr. Vi~c phan lo:;ii nhfrng t~p I?nh theo hai nh6m tren chl mang tinh tuang d6i va phà thu<)c vao nha san xm1t. Bang 9-1 th~ hi?n sv phan lo:;ii di~n hinh.
Coã ban Relay contact Relay output Timer Counter Latch
Jump to/Go to Master control relay End
Addition SubtrACtion Multiplication Division
Compare(=.>.<) Go to Subroutine
Bang 9.1 Phan lo:;ii t?P l~nh PLC Nang cao
Double-precision arithmetic Square root
Sort
Move register
Move register to table First in - first out Shift register Rotate register Diagnostic block Block transfer (in/out) Sequencer
PIO Network Logic matrix
Doi khi. l?P I?nh Ladder ca ban dugc g9i la ngon ngfr dp thJp, trong khi cac chuc nang mo
178 Chuong 9: Ngan ngit /(Ip trinh
r(mg duqc g9i la ngon ngu dp cao. Tuy nhien, each dcm gian thuong duqc SU di,mg d~ phan loc;ti la d\fa tren nh6m chuc niing cua cac t?p l~nh. Nh6m t?p l~nh bao g6m:
• TiSp di~m
• Thai gian
• 0sm
• Chucmg trinh/di~u khi~n luu trinh
• Xu ly to.in h9c
• Xu ly dfr li~u
• Di chuy~n dfr li~u
• Chuc nang d~c bi~t
• Mc;tng truy~n thong
M~c du dcm gian, vi?c phan lo.;ii con mang tinh chu quan. Vi d\l, m<)t s6 nguoi cho r~ng cac t?p I?nh C(J ban bao gbm tiSp di€m, thm gian, dSm, chucmg trinh, XU ly toan h9c, va m<)t s6 t~p I?nh v~ XU ly du li?u. M<)t s6 khac l.;ii cho r~ng chi cac nh6m: tiSp di~m, thoi gian, va dSm m6i duqc xem la t~p l?nh co ban. ã
B~t ky SlJ phan lo.;ii nao, m<)t PLC h6 trq duqc nhi~u nh6m l~nh thi kha nang di~u khi~n cang du9c nang cao. Thong thuang, s6 luqng ciing nhu nh6m l~nh nang cao se duqc h6 trq tuy theo lo.;ii PLC. Tuy nhien, nhung tiSn b<) gfrn day trong phat tri€n phfrn m~m va phfrn cung 1/0 da lam tang sue m.;inh tinh toan cua cac PLC lo.;ii nho thong qua cac t?p l~nh nang cao. Xu hu6ng m6i nay da lam cho cac PLC nay tr& thanh m<)t thi~t bi d<)c l~p trong h~ th6ng di~u khi€n phan tan hay m9t s6 ung dt,mg.
9.2.2 Boolean
r---
1 LI L2 1
1 PBI: START ã PLl 1
1 _l_ LS I '\. / :
1----< ~ - ~ - - - < - - - ~ ~-- I
I / I
: PB2: ~TART '\. :
I ~ - ~ ~-~ I
: (a) Mc;tch.k~t nbi bitng day L
~---
\ I
L~p trinh d1,mg cau lenh LD30
OR31 .AND32
OtJT40 .
, ◊
Hien thi d.;ing Ladder
b~2
--- ---
--- ---
Chuong 9: Ngan ngu lcjp trinh 179
ani,m, : T.1:;le: 8 N•twork 2 : !.i.t.l•:
;.. A,,.. <
Q 0.0
C I O.Q ...,
0 -~ 0.0 :) Q 0.4
)
1,JI I O.l ,. I ').3
,.,_ 0. ,) • Q 0.4
...
Hinh 9.3 M?ch di~u khi~n logic va bi~u di~n du6i d?ng Boolean
M<)t s6 PLC su d\mg ng6n ngfr Boolean d~ l?P trinh. Ng6n ngfr Boolean su d\mg cu phap d?ng d?i s6 Boolean (tham khao Chu(Yilg 3) d~ l?p trinh va bi~u di~n chu(Yilg trinh di~u khi~n logic.
Cv th~, ng6n ngfr Boolean sfr d\lng cac ham logic AND, OR, NOT d~ tri~n khai m?ch di~u khi~n trong chu(Yilg trinh di~u khi~n. Hinh 9.3 th~ hi~n m<)t chu(Yilg trinh Boolean co ban.
Ng6n ngfr Boolean 1~ m<)t each thu~n tuy d~ nh~p chu(Yilg trinh di~u khi~n vao PLC chu khong phai la ng6n ngfr hu6ng t?P l~nh th1Jc & Khi dugc hi~n thi tren man hinh l~p trinh, ng6n ngfr Boolean thucmg dugc xem nhu la m<)t m?ch Ladder thay vi nhu cac l~nh Boolean da dugc djnh d?ng.
9.2.3 Graph
Graph hay Grafcet (Graphe Fonctionnel de Commande Etape Transition) la m<)t d?ng ng6n ngfr d6 h<;>a, co ngu6n g6c tir Phap. Graph bi~u di~n chu(Yilg trinh di~u khi~n cua m9t thi@t bi hay qua trinh theo tITTlg bu6c ho?c tr?ng thai. Th1Jc t@, ban djch ti@ng Anh cua Grafcet co nghia la "bi~u d6 chuc nang bu6c chuy~n ti@p".
Hinh 9.4 minh ho? m<)t m?ch d(Yil gian dugc bi~u di~n ng6n ngfr Graph. BiJu d6 Graph thJ hi~n m<)t ti@n trinh cac SIJ ki~n di~n ra qua m6i tr?ng thai cua chu(Yilg trinh di~u khiJn. Bi~u d6 nay su d\lng 3 thanh phin: Bu6c (Step), Chuy~n ti@p (Transitions), va hanh dc;mg (Action) d~ biJu di~n cac SIJ ki~n. T~p l~nh trong chu(Yilg trinh th1Jc hi~n & m6i bu6c co thJ dugc l?p trinh voi m9t ho?C nhi~u ng6n ngfr khac nhau, bao g6m ca ng6n ngfr Ladder.
PBl
__L_
CRl
CRl LS
LS2
L2
Ml
CR2
Grafcet
Step
C!J :.::=---T rans1t1on . .
1 If PBl Action
2 Ml IF LSI
2 LS2
Hinh 9.4 M?ch di~u khi~n rn-le va bi~u di~n du6i d?ng Graph
180
IF LSl AND
Software Translator
Grafcet
i I •
I ..
~ )1---;
Clnrong 9: Ngan ngaã l<Jp trinh
LSl LS2 CRI
1--1 - - -
PEl CR! SOLl
9 P E ~
PE3 LS4. TRMl M2
1:M2
PLC Ladder Language
Sl ã \tt'pl:
lnitt!O<k ('11<!111 O.,.U!k'r Al.lion
S-i -\h,p2:
lnliet1oU. tw.ni Qutltfier Mioo
'"-"!'1,; ,. "'' '
... :•) : __ :.. \ .-:. . ~
Hinh 9.5. Ngan ngfr Graph cua Siemens
Kha it PLC co th~ duqc l?p trinh tr\Ic ti~p bing each su dàng ngon ngfr Graph. Tuy nhien, m(>t s6 nha san xu:1t ph.1n m~m phat tri~n cong cà l?P trinh Graph su dàng tren may tinh ca nhan.
Sau khi l?p trinh tren PC, cac l~nh cua chuang trinh Graph co th~ duqc n?p vim PLC thong qua m◊t trinh bien djch ho?c b9 chuy~n d6i d~ djch chuong trinh Graph sang chuang trinh Ladder ho?C Boolean. Sfr d1,mg phuong phap nay, nha san xu:1t phfrn m~m Graph c6 th~ cung dp ph.1n m~m cho nhi~u lo?i PLC khac nhau. Hinh 9.5 minh h9a ban bien djch khi su di,mg ngon ngfr Graph.