1. Th.S Chu Ch c K thut iu khin Thnh ph H Ch Minh 10-2008
2. LI NI U T ng ho cng nghip v dn dng ngy cng pht trin. B no
trong cc h thng t ng ho l cc b iu khin lp trnh. Vic hc v tm hiu v
cc b khin lp trnh cng nh vn hnh n cho tht tt ang l nhu cu cp thit i
vi hc sinh, sinh vin cc ngnh k thut. Hin nay ti liu ging dy v tham
kho v k thut iu khin lp trnh cn kh hn ch. Ti liu ''k thut iu khin
lp trnh PLC Simatic S7-200'', l quyn sch u tin trong b sch v k thut
iu khin lp trnh PLC h SIMATIC S7, c bin son vi mong mun gp mt phn
nh vo vic ging dy v t hc v k thut iu khin lp trnh ca gio vin, hc
sinh, sinh vin v c gi quan tm v PLC h SIMATIC S7-200 ca cng ty
Siemens. Ti liu c chia thnh 2 tp. Tp 1 bao gm cc phn c bn ph hp vi
cc bn mi bt u lm quen vi PLC, tuy nhin n cng c th l ti liu tham kho
cho cc bn c kin thc c bn v PLC. Tp 2 l phn nng cao tp trung v cc vn
iu khin s, truyn thng v mn hnh iu khin. Cu trc chung ca cc tp sch l
mi chng trong cc phn u c v d minh ha cho cc mc, ngoi ra cui mi chng
c thm mt s cu hi v bi tp c gi rn luyn thm. D c mt thi gian di lm
vic v ging dy v k thut iu khin lp trnh PLC h SIMATIC, mng truyn
thng cng nghip v truyn ng ca hng Siemens cho rt nhiu i tng khc nhau
cng nh rt c gng trong qu trnh bin son nhng ti liu khng trnh khi
thiu st. Rt mong c s gp chn thnh ca qu c gi gip ti liu c hon thin
hn. Th t gp xin gi v a ch: [email protected]. Xin cm n.
3. LI TM S Tp 1 ''k thut iu khin lp trnh PLC Simatic S7-200'' c
vit xong t rt lu. Nhng v ngh n vic in n v pht hnh qu nhiu kh, gi
thnh li cao v phi ch i thi gian rt lu tp sch ny mi n tay bn c, nn
tc gi hon li. Ngh rng cung cp cho c gi, cc bn hc sinh, sinh vin v
gio vin thm mt ti liu tham kho lm phong ph thm kin thc v t ng ha l
vic nn lm. V vy tc gi chn phng n pht hnh qua mng v truyn tay di dng
tp tin vi phng chm '' sch hu ch th mi c nhun bt''. Cc bn thn mn!
Vic bin son ti liu v k thut, nht l k thut mi, i hi ngi bin son ngoi
kinh nghim chuyn mn cn b rt nhiu thi gian v cng sc. Do s l mt nim
ng vin v cng to ln cho tc gi tip tc hon thnh tp 2, b sch v k thut
iu khin lp trnh PLC SIMATIC S7-300/400, cc ti liu khc lin quan n
PLC h SIMATIC, truyn thng cng nghip, truyn ng ca hng Siemens nu c s
ng vin t tinh thn n vt cht. Nu thy sch ny gip ch cho cc bn th khi
cc bn s hu n (c c t bt k phng tin no) dng tp tin hoc c in ra dng
sch, xin vui lng ng vin tc gi bng cch chuyn tin vo ti khon s
49809449 cho CHU CH C, ngn hng Thng mi Chu (ACB) chi nhnh Chu vn
Lim vi s tin ty theo ca cc bn. Nu cc bn c nhng ng vin khc xin gi
thng tin cho tc gi qua a ch mail [email protected]. Cm n s ng vin
ca c gi.
4. Mc lc Mc lc 1 Tng quan v iu
khin...................................................................1
1.1 Khi nim chung v iu
khin...................................................... 1 1.2 Cu
trc mt qui trnh iu
khin................................................... 2 1.3 Cc
loi iu
khin.......................................................................
3 1.4 H thng
s.................................................................................
4 1.5 Cc khi nim x l thng
tin........................................................ 5 1.5.1
Bit
.....................................................................................
5 1.5.2 Byte
..................................................................................
5 1.5.3 Word
.................................................................................
6 1.5.4 DoubleWord
.......................................................................
6 2 B iu khin lp trnh PLC Cu trc v phng thc hot ng 7 2.1 Gii
thiu.....................................................................................
7 2.2 S khc nhau gia h iu khin bng relay v h iu khin bng
PLC....................................................................8
2.3 Cu trc ca mt PLC
................................................................ 11
2.4 Cc khi ca PLC
......................................................................
13 2.4.1 Khi ngun cung
cp.........................................................13 2.4.2
B nh chng trnh
.........................................................14 2.4.3
Khi trung tm
(CPU).........................................................15
2.4.4 Khi
vo...........................................................................
15 2.4.5 Khi
ra.............................................................................
16 2.4.6 Cc khi c
bit..............................................................
16 2.5 Phng thc thc hin chng trnh trong PLC
...........................16 3 Cm bin v c cu chp hnh trong iu khin
logic.....................19 3.1 Cm
bin...................................................................................
19 3.1.1 Gii thiu
.........................................................................
19 3.1.2 Ni dy cho cm
bin.........................................................19
3.1.2.1 Switch
............................................................... 20
3.1.2.2 Ng ra
TTL..........................................................20
3.1.2.3 Ng ra
Sinking/Sourcing.......................................20 3.1.2.4
Ng ra Solid state relay........................................23
3.1.3 Pht hin i
tng...........................................................23
3.1.3.1 Chuyn mch tip xc
.........................................23 3.1.3.2 Reed Switches
....................................................23 3.1.3.3 Cm
bin quang (Optical Sensor) .........................23 3.1.3.4 Cm
bin in dung (Capacitive Sensor)...............25 3.1.3.5 Cm bin in
cm (Inductive Sensor) ..................26 3.1.3.6 Cm bin siu m
(Ultrasonic sensor)...................28 3.1.3.7 Hiu ng Hall (Hall
Effect)....................................28 3.1.3.8 Lu lng (Fluid
Flow).........................................28 3.1.4 Tm
tt............................................................................
29 3.2 C cu chp
hnh......................................................................
29 3.2.1 Gii
thiu.........................................................................
29 I
5. Mc lc 2 3.2.2
Solenoid............................................................................29
3.2.3 Van iu khin
(VALVE).....................................................30
3.2.4 Xy lanh
(CYLINDER)..........................................................32
3.2.5 ng c
...........................................................................33
3.2.6 Cc c cu chp hnh
khc...............................................34 4 B iu khin lp
trnh PLC Simatic S7-200......................................35 4.1
Cu hnh
cng............................................................................35
4.1.1 Khi x l trung
tm...........................................................35
4.1.2 Khi m rng
....................................................................39
4.1.2.1 Digital
module........................................................39
4.1.2.2 Analog module
......................................................40 4.1.2.3
Intelligent module
..................................................41 4.1.2.4
Function module
....................................................41 4.2 Mn hnh
iu
khin....................................................................42
4.3 Cc vng
nh.............................................................................43
4.4 Qui c a ch trong PLC
S7-200................................................46 4.4.1 Truy
xut theo
bit...............................................................46
4.4.2 Truy xut theo byte (8
bit)...................................................46 4.4.3
Truy xut theo word (16
bit)................................................46 4.4.4 Truy
xut theo 2 word (Double word = 32 bit).......................47 4.5
X l chng
trnh......................................................................48
5 Kt ni dy gia PLC v thit b ngoi vi
.........................................51 5.1 Kt ni dy gia PLC v
cc thit b ngoi vi.................................51 5.1.1 Gii thiu
CPU 224 v cch kt ni vi thit b ngoi vi......... 51 5.1.2 Kt ni vi my
tnh...........................................................52
5.1.3 Ni ngun cung cp cho
CPU............................................54 5.1.4 Kt ni vo/ra
s vi ngoi vi..............................................54
5.1.4.1 Kt ni cc ng vo s vi ngoi vi.......................55
5.1.4.2 Kt ni cc ng ra s vi ngoi vi .........................57 5.2
Kim tra vic kt ni dy bng phn mm
....................................60 5.2.1 Status Chart
......................................................................60
5.2.2 Gim st v thay i bin vi Status Chart
..........................60 5.2.3 Cng bc bin vi Status Chart
.......................................62 5.2.4 ng dng Status Chart
trong vic kim tra kt ni dy trong
S7-200................................................................................................63
5.3 Cu hi v bi
tp.......................................................................64
6 Phn mm Micro/Win v ngn ng lp
trnh..................................65 6.1 Ci t phn mm STEP
7-Micro/WIN..........................................65 6.1.1 Yu cu
h iu hnh v phn cng...................................65 6.1.2 Ci t
phn mm
.............................................................65 6.2
Cc phn t c bn trong chng trnh PLC S7-200.....................66
6.2.1 Chng trnh chnh OB1 (main
program).............................66 6.2.2 Chng trnh con SUB
(subroutine) ....................................66 6.2.3 Chng trnh
ngt INT(interrupt routine)..............................67 6.2.4
Khi h thng (system block)
.............................................67
6. Mc lc III 6.2.5 Khi d liu (data
block).....................................................67 6.3
Ngn ng lp trnh
......................................................................67
6.3.1 Dng hnh thang: LAD (Ladder
logic)...................................68 6.3.2 Dng khi chc nng:
FBD (Function Block Diagram) ............ 68 6.3.3 Dng lit k lnh:
STL (StaTement List)...............................69 6.4 Son tho
chng trnh vi phn mm STEP7-Micro/Win V4.0
SP6.........................................................69
6.4.1 M mn hnh son tho chng
trnh..................................69 6.4.1.1 Vng son tho chng
trnh................................70 6.4.1.2 Cy lnh
.............................................................70
6.4.1.3 Thanh chc nng
................................................70 6.4.2 Thanh cng
c (Toolbar) trong STEP7-Micro/WIN................. 75 6.4.3 To mt d
n STEP 7-Micro/WIN ......................................77 6.4.3.1
To d n mi.....................................................77
6.4.3.2 Lu d
n...........................................................77
6.4.3.3 M mt d n
.....................................................78 6.4.4 Th
vin
...........................................................................78
6.4.5 H thng tr gip trong STEP 7-Micro/WIN
..........................79 6.4.6 Xa b nh CPU
...............................................................80
6.4.7 M mt d n ang tn ti
sn............................................80 6.4.8 Kt ni truyn
thng S7-200 vi thit b lp trnh.................... 81 6.4.9 Ti d n t
PLC...............................................................82
6.4.9.1 Ti mt khi hoc ba khi
.....................................82 6.4.9.2 Ti vo mt d n mi hoc
d n rng.................. 82 6.4.9.3 Ti vo mt d n tn ti
......................................82 6.4.9.4 Th tc ti d n t PLC
v thit b lp trnh............. 82 6.4.10 Np (download) mt d n vo
PLC..................................83 6.4.11 Thit lp cu hnh chung
cho phn mm (menu option v
customize)......................................85 6.4.11.1 Menu
Option........................................................85
6.4.11.2 Menu
Custommize...............................................86 6.4.12
Son tho chng
trnh....................................................88 7 Cc php
ton logic
.........................................................................95
7.1 Ngn xp (logic stack) trong S7-200
.............................................95 7.2 Cc php ton
logic c
bn..........................................................96
7.2.1 Php ton AND
.................................................................96
7.2.2 Php ton OR
...................................................................97
7.2.3 T hp cc cng AND v
OR..............................................98 7.2.3.1 AND trc
OR ....................................................98 7.2.3.2
OR trc AND ....................................................98
7.2.4 Php ton
XOR.................................................................99
7.3 X l cc tip im, cm bin c ni vi ng vo PLC ................ 100
7.4 V d ng dng cc lin kt
logic................................................. 102 7.4.1
Mch t duy tr u tin m my.........................................
102 7.4.2 Mch t duy tr u tin dng my
...................................... 103 7.4.3 iu khin ON/OFF ng
c c ch bo ............................. 104 7.4.4 iu khin o chiu
quay ng c ................................... 106 7.5 Bit nh M (bit
memory)
..............................................................109
7. Mc lc 4 9 B nh thi (Timer)
........................................................................
147 9.1 Gii thiu
.....................................................................................
147 9.2 Timer ng mch chm TON
...................................................... 148 9.3
Timer ng mch chm c nh TONR .......................................
149 9.4 Timer m mch chm TOF
......................................................... 150 9.5
ng dng Timer
..........................................................................
152 7.6 Cc lnh SET, RESET v mch nh
RS...................................... 111 7.6.1 Lnh SET
.......................................................................
111 7.6.2 Lnh RESET
(R)..............................................................
112 7.6.3 Mch nh R-S
.................................................................
112 7.6.3.1 u tin SET (khu SR)
...................................... 112 7.6.3.2 u tin RESET (khu
RS).................................. 113 7.6.4 Cc qui tc khi s dng
Set v Reset ................................. 114 7.6.5 V d ng dng
mch nh R-S .......................................... 114 7.7 Cc
lnh nhn bit cnh tn hiu v lnh NOT .............................. 118
7.7.1 Lnh
NOT.......................................................................
118 7.7.1 Cc lnh nhn bit cnh tn
hiu........................................ 118 7.8 Cc Bit nh c bit
(Special Memory bits).................................. 120 7.9 Cu
hi v bi tp
.....................................................................
121 8 Thitk theo logicBool & biu
Karnaugh.....................................................125
8.1 Gii
thiu.................................................................................
125 8.2 i s
BOOL............................................................................
125 8.3 Thit k
Logic...........................................................................
127 8.3.1 Cc k thut i s Bool
................................................... 131 8.4 Cc dng
logic
chung................................................................
132 8.4.1 Dng cng phc
.............................................................. 132
8.4.2
Multiplexers.....................................................................
132 8.5 Mt s v d thit k n gin vi i s bool
............................... 133 8.5.1 Cc chc nng logic c bn
............................................. 133 8.5.2 H thng an
ton xe hi ................................................... 134
8.5.3 Quay phi/tri ng
c..................................................... 134 8.5.4
Cnh bo trm
................................................................
135 8.6 Biu Karnaugh
.....................................................................
136 8.6.1 Gii
thiu........................................................................
136 8.7 Cu hi v bi tp
.....................................................................
139 9.5.1 To xung c tn s theo mong mun
................................ 152 9.5.2 To Timer xung v timer
xung c nh ................................ 152 9.5.2.1 Timer xung
(Pulse timer) .................................... 152 9.5.2.2
Timerxungcnh (ExtendedPulsetimer) .............153 9.5.3 o chiu
quay ng c c khng ch thi gian ...................154 9.5.4 Chiu sng
Garage..........................................................
155 9.5.5 Thit b rt cht lng vo thng
cha.................................. 156 9.6 Cu hi v bi
tp......................................................................
161 10 B m
(Counter)...........................................................................
170 10.1 Gii
thiu...............................................................................
170 10.2 B m ln CTU (Count Up)
.................................................... 171
8. Mc lc 5 10.3 B m xung CTD (Count
Down)............................................ 172 10.4 B m
ln-xung CTUD (Count Up/Down)............................... 173
10.5 ng dng b
m...................................................................
174 10.5.1 m sn phm c ng gi .....................................
174 10.5.2 Kim sot ch cho Garage ngm
.................................. 175 10.6 Cu hi v bi
tp...................................................................
178 11 iu khin trnh t
............................................................................
181 11.1 Cu trc chung ca mt chng trnh iu khin ....................
181 11.2 iu khin trnh t
...................................................................
182 11.2.1 Gii thiu
.....................................................................
182 11.2.2 Phng php lp trnh iu khin trnh t .................. 184
11.3 Cc th tc tng qut thit k bi ton trnh t .................... 186
11.4 Cu trc ca bi ton iu khin trnh t
.................................. 188 11.4.1 Chui trnh t
.............................................................. 188
11.4.2 Kiu hot ng
............................................................. 188
11.4.3 Cc thng bo
.............................................................. 190
11.4.4 Kch hot ng ra
........................................................... 190
11.5 Cc k hiu
...............................................................................
190 11.6 Bc trnh t
............................................................................
191 11.7 Cc lnh biu din trong s chc nng
............................... 193 11.8 Cc ch hot ng, cnh bo v xut
lnh .......................... 197 11.8.1 Bng iu khin
........................................................... 198
11.8.2 Cc khu ch hot ng c cnh bo ..................... 199 11.8.3
Hin th bc trnh t
................................................... 201 11.8.4 Xut
lnh
......................................................................
201 11.9 Cc v d ng dng
..................................................................
201 11.9.1 My phay n gin
...................................................... 201 11.9.2
Bng chuyn m to ..................................................
205 11.10 Cu hi v bi tp
........................................................ 210 12 An
ton trong PLC
.........................................................................218
12.1 Khi nim v mc
ch............................................................218
12.2 H hng
PLC......................................................................218
12.3 Cc quan im v k thut an ton PLC................................
219 12.3.1 Cc li nguy him v khng nguy him.........................
219 12.3.2 Cc cch gii quyt cho hot ng an ton ca thitb
iukhinPLC......................................................................220
12.4 Bo v cc ng ra PLC
...........................................................223
12.4.1 Bo v ng ra dng Transistor
.....................................224 12.4.2 Bo v ng ra Rle c
ngun iu khin DC................. 224 12.4.3 Bo v ng ra Rle v ng ra
AC c ngun iu khin
AC............................................................. 224
12.5 Cu hi v bi
tp...................................................................225
13 Chuyn iu khin kt ni cng sang iu khin bng PLC........... 226 13.1
Kt ni ng vo/ ra ca PLC t mt s iu khin c tip im
...........................................................................
226 13.2 Chuyn i iu khin t contactor thnh PLC
......................... 228
9. Mc lc V 13.2.1 iu khin thit b b cng sut phn
khng..................230 13.2.2 Thit b nghin
............................................................237
13.3 iu khin kh nn
..................................................................241
13.3.1 My un thanh kim
loi................................................242 13.3.2 My
doa ming ng kim loi.........................................246
13.4 Cu hi v bi
tp...................................................................253
14 Cc php ton c bn trong iu khin s
.................................... 257 14.1 Cc dng s trong PLC
............................................................ 257
14.1.1 Kiu d liu Integer (INT)
............................................. 257 14.1.2 Kiu d liu
Double Integer (DINT) .............................. 258 14.1.3 Kiu
d liu s thc (REAL) ........................................ 259
14.1.4 Kiu d liu s BCD (Binary Coded Decimal) .............. 260
14.2 Chc nng sao chp
................................................................
261 14.2.1 Cc lnh sao chp, trao i ni dung
........................... 261 14.2.2 Cc lnh sao chp mt mng ln d
liu .................... 263 14.3 Php ton so snh
....................................................................
264 14.4 Php ton s hc
......................................................................
266 14.4.1 Cng v tr
..................................................................
266 14.4.2 Nhn v chia
................................................................
267 14.4.3 V d php ton s hc
................................................ 268 14.5 Tng v gim
thanh ghi
........................................................... 269
14.6 Cc php tan logic s
............................................................. 271
14.6.1 Cc logic s trong S7-200
............................................ 271 14.6.2 ng dng
.....................................................................
272 14.6.2.1 Che v tr cc bit
............................................ 272 14.6.2.2 Chn thm
bit ................................................ 273 14.7 Chc
nng dch/quay thanh ghi
................................................ 273 14.7.1 Chc nng
dch chuyn thanh ghi ................................ 273 14.7.1.1
Dch tri .........................................................
273 14.7.1.2 Dch phi
....................................................... 274 14.7.2
Chc nng quay thanh ghi ...........................................
275 14.7.2.1 Quay tri
....................................................... 276
14.7.2.2 Quay phi
..................................................... 277
10. Chu Chc 1 Tng quan v iu khin 1 1 Tng quan v iu khin 1.1 Khi
nim chung v iu khin iu khin c nhim v thc hin cc chc nng ring ca mt
my mc hay thit b theo mt trnh t hot ng nh trc ph thuc vo trng thi
ca my hay b pht tn hiu. S iu khin c phn bit theo cc c im khc nhau:
* Theo loi biu din thng tin - iu khin nh phn: X l tn hiu u vo nh
phn (tn hiu 1-0) thnh cc tn hiu ra nh phn. - iu khin s: X l cc thng
tin s, c ngha cc thng tin c biu din di dng s. * Theo loi x l tn hiu
- iu khin lin kt: Cc trng thi tn hiu xc nh ca ng ra c iu khin bi cc
trng thi tn hiu ca ng vo tu thuc vo cc chc nng lin kt (AND, OR,
NOT). - iu khin trnh t: iu khin vi trnh t theo tng bc, s ng mch ca
mt bc sau xy ra ph thuc vo iu kin ng mch tip theo. iu kin ng mch
tip theo c th ph thuc vo qui trnh hay thi gian. - iu khin khng ng
b: Vic iu khin c x l s thay i trc tip ca tn hiu ng vo khng cn tn
hiu xung ph (iu khin chm). - iu khin ng b xung: Vic iu khin c x l
cc tn hiu ch ng b vi mt tn hiu xung (iu khin nhanh). * Theo loi thc
hin chng trnh - iu khin theo chng trnh kt ni cng: Loi iu khin ny c
th c lp trnh c nh, c ngha khng th thay i c v d nh lp t dy ni c nh
hay c th thay i chng trnh thng qua cc u ni (ma trn diode). - iu
khin kh trnh: Chc nng iu khin c lu gi trong mt b nh chng trnh. Nu s
dng b nh c/ghi (RAM), th c th thay i chng trnh m khng cn can thip n
phn c kh (iu khin c th lp trnh t do). Nu ngc li l mt b nh ch c
(ROM), th chng trnh c th
11. 1 Tng quan v iu khin Chu Chc 2 Datenflu Dateneingabe Signal
eingab e Anpas s u ng Verarb eit un g Verst rk un g Aus gab e
Datenverarbeitung Datenausgabe Stromversorgung c thay i bng cch
thay i b nh (iu khin c th thay i chng trnh). Hnh 1.1: S cc loi iu
khin 1.2 Cu trc mt qui trnh iu khin Mi s iu khin c chia ra lm 3 b
phn hp thnh: Ng vo d liu (ng vo tn hiu), X l d liu (x l tn hiu cng
nh cc lin kt) v ng ra d liu ( ng ra tn hiu). Dng d liu trong mt s
iu khin xy ra t u vo d liu qua phn x l d liu n ng ra d liu. Dong d
lieu Ngo vao d lieu X ly d lieu Ngo ra d lieu Ngo vao tn hieu Giao
tip X ly Khuech ai Ngo ra Ngun cung cp Hnh 1.2: Cu trc chung ca mt
qui trnh iu khin + Ng vo tn hiu: Bao gm cc loi tn hiu ca cc b pht
tn hiu nh nt nhn, cng tc hnh trnh, cm bin in dung, cm bin in cm
.v.v..
12. Chu Chc 1 Tng quan v iu khin 3 Tu thuc vo loi iu khin, cc
tn hiu c th l nh phn, s hay tn hiu tng t. + Giao tip: Phn ny cn
thit, nu tn hiu ca mt h thng l cn phi c x l. Mt b phn chuyn i t tn
hiu ng vo thnh tn hiu ph hp vi mc ca tn hiu x l c t phn giao tip. +
X l: Ton b cc lin kt, trnh t thi gian, cc chc nng nh, m .v.v.. c
thc hin trong phn ny. Phn x l l phn chnh ca tt c cc h thng iu khin.
Cc k thut iu khin c tip im nh khi ng t ph, relay thi gian, k thut
iu khin bng mch in t (nh AND, OR, NOT ...) c PLC hay my tnh iu khin
qu trnh tng hp ti y. + Khuch i: Cc tn hiu t phn x l c mc cng sut b
c khuch i ln ln nhiu ln y c th iu khin cc khi ng t, van t hay cc i
tng iu khin khc v cc n bo. + Ng ra: Phn ny c kt ni vi i tng iu khin
m c nh hng trc tip n qu trnh iu khin (v d: Khi ng t, van t,
thyristor, v.v..) 1.3 Cc loi iu khin Trong k thut iu khin cng nh t
ng ha, ngi ta chia ra lm hai loi iu khin: iu khin kt ni cng v iu
khin kh trnh. * iu khin kt ni cng iu khin kt ni cng l loi iu khin m
cc chc nng ca n c t c nh (ni dy). Nu mun thay i chc nng iu c ngha l
thay i kt ni dy. iu khin kt ni cng c th thc hin vi cc tip im
(Relay, khi ng t, v.v.) hay in t (mch in t). * iu khin kh trnh
(PLC) iu khin kh trnh l loi iu khin m chc nng ca n c t c nh thng
qua mt chng trnh cn gi l b nh chng trnh. S iu khin bao gm mt thit b
iu khin m tt c cc b pht tn hiu cn thit v i tng iu khin c kt ni cho
mt chc nng c th. Nu chc nng iu khin cn c thay i, th ch phi thay i
chng trnh bng thit b lp trnh i tng iu khin tng ng hay cm mt b nh
chng trnh lp trnh khc vo trong iu khin.
13. 1 Tng quan v iu khin Chu Chc 4 Elektrische Steuerungen v
erbindun gs program miert speicherprogram m iert Program m AUTOM
ATI SI ER U N G SG ER T Program m Speic her 23 22 21 20 8 4 2 1 ieu
khien ien Kt ni cng Kh trnh Chng trnh THIT B T NG HA B nh chng trnh
Hnh 1.3: Hai loi iu khin trong sn xut 1.4 H thng s Trong x l cc phn
t nh, cc ng vo, cc ng ra, thi gian, cc nh v.v... bng PLC th h thp
phn khng c s dng m l h thng s nh phn (h hai tr). * H nh phn H nh
phn ch c cc s 0 v 1, c th c c v biu din gi tr d dng trong k thut.
Gi tr nh v ca mt s nh phn l s m ca hai. ln ca s thng thng c biu din
dng m BCD (Binary-Code- Decimal). i vi mi s Decimal c vit vi s nh
phn 4 v tr. * S thp lc phn ( Hexadecimal) H thp lc phn c 16 k hiu
khc nhau t 0-9 v A-F. Gi tr nh v ca mt s thp lc phn s m ca 16. - H
nh phn: Ch s: 0,1 Gi tr nh v = S m ca c s 2
14. Chu Chc 1 Tng quan v iu khin 5 V d: 1 1 0 1 12 3 + 12 2 +
02 1 + 12 0 8 + 4 + 0 + 1 = 13D - H thp lc phn: ch s:
0,1,2,3,4,5,6,7,8,9,A,B,C,D,E;F Gi tr nh v = S m ca c s 16 16 3 16
2 16 1 16 0 4096 256 16 1 V d: 2 A B 216 2 + A16 1 + B16 0 512 +
160 + 11 = 683D 1.5 Cc khi nim x l thng tin Trong PLC, hu ht cc khi
nim trong x l thng tin cng nh d liu u c s dng nh Bit, Byte, Word v
doubleword. 1.5.1 Bit Bit l n v thng tin nh phn nh nht, c c th c gi
tr 0 hoc 1. 24 V 0 V 1 c in p 0 khng c in p Hnh 1.4: Mt bit c th c
trng thi tn hiu 1 hoc 0 1.5.2 Byte
15. 1 Tng quan v iu khin Chu Chc 6 0 1 0 1 1 0 0 1 0 1 0 1 1 0
0 1 0 1 0 1 1 0 0 1 0 1 0 1 1 0 0 1 0 1 0 1 1 0 0 1 0 1 0 1 1 0 0 1
0 1 0 1 1 0 0 1 1 doubleWord 1 Byte gm c 8 Bit BYTE 1.5.3 Word Trng
thi tn hiu 1 Word gom co 2 Byte hay 16 Bit. Vi Word co the bieu
dien cac dang: so nh phan, ky t hay cau lenh ieu khien. Trng thi tn
hiu WORD 1 Byte 1 Byte 1.5.4 DoubleWord 1 DoubleWord gom co 4 Byte
hay 32 Bit. Vi DoubleWord co the bieu dien cac dang: so nh phan, ky
t hay cau lenh ieu khien. 1 Word 1 Word Tom tat: 1 Bit Gi tr 0 hoc
1 1 Byte 1 Word 1 Byte 1 Byte 1 Word 1 Word
16. 7 2 B iu khin lp trnh PLC Chu Chc 2 B iu khin lp trnh PLC
Cu trc v phng thc hot ng 2.1 Gii thiu Cc thnh phn ca k thut iu khin
in v in t ngy cng ng mt vai tr v cng to ln trong lnh vc t ng ha ngy
cng cao. Trong nhng nm gn y, bn cnh vic iu khin bng Relay v khi ng
t th vic iu khin c th lp trnh c cng pht trin vi h thng ng mch in t
v thc hin lp trnh bng my tnh. Trong nhiu lnh vc, cc loi iu khin c c
thay i bi cc b iu khin c th lp trnh c, c th gi l cc b iu khin logic
kh trnh, vit tt trong ting Anh l PLC (Programmable Logic
Controller). S khc bit c bn gia iu khin logic kh trnh ( thay i c
qui trnh hot ng) v iu khin theo kt ni cng (khng thay i c qui trnh
hot ng) l: S kt ni dy khng cn na, thay vo l chng trnh. C th lp trnh
cho PLC nh vo cc ngn ng lp trnh n gin. c bit i vi ngi s dng khng cn
nh vo cc ngn ng lp trnh kh khn, cng c th lp trnh PLC c nh vo cc lin
kt logic c bn. Nh vy thit b PLC lm nhim v thay th phn mch in iu
khin trong khu x l s liu. Nhim v ca s mch iu khin s c xc nh bi mt s
hu hn cc bc thc hin xc nh gi l chng trnh. Chng trnh ny m t cc bc
thc hin gi mt tin trnh iu khin, tin trnh ny c lu vo b nh nn c gi l
iu khin theo lp trnh nh hay iu khin kh trnh. Trn c s khc nhau khu x
l s liu c th biu din hai h iu khin nh sau:
17. 8 Chu Chc 2 B iu khin lp trnh PLC Xc nh nhim v iu khin Thit
k thut gii San tho chng trnh Kim tra hot ng K1 K2 K1 K2 K3 Cc bc
thit lp h Cc bc thit lp h iu khin bng relay in iu khin bng PLC Xc
nh nhim v iu khin S mch in Chn phn t mch in Dy ni lin kt cc phn t
Kim tra hot ng Khi thay i nhim v iu khin th ngi ta thay i mch iu
khin: Lp li mch, thay i cc phn t mi h iu khin bng relay in. Trong
khi khi thay i nhim v iu khin h iu khin logic kh trnh (PLC) th ngi
ta ch thay i chng trnh son tho. 2.2 S khc nhau gia h iu khin bng
relay v h iu khin bng PLC S khc nhau gia h iu khin bng relay v h iu
khin bng PLC c th minh ho mt cch c th nh sau: iu khin h thng ca 3
my bm qua 3 khi ng t K1, K2, K3. Trnh t iu khin nh sau: Cc khi ng t
ch c php thc hin tun t, ngha l K1 ng trc, tip theo K2 ng v cui cng
K3 mi ng. thc hin nhim v theo yu cu trn mch iu khin c thit k nh
sau: F1 S1 S2 K1 S3 K2 S4 K3 Hnh 2.1: Mch iu khin trnh t 3 my
bm
18. 9 2 B iu khin lp trnh PLC Chu Chc Khi ng t K2 s ng khi cng
tc S3 ng vi iu kin l khi ng t K1 ng trc . Phng thc iu khin nh vy c
gi l iu khin trnh t. Tin trnh iu khin ny c thc hin mt cch cng bc. -
Bn nt nhn S1, S2, S3, S4: Cc phn t nhp tn hiu. - Cc tip im K1, K2,
K3 v cc mi ni lin kt l cc phn t x l. - Cc khi ng t K1, K2, K3 l kt
qu x l. Nu thay i mch in iu khin phn x l bng h PLC ta c th biu din
h thng nh sau: - Phn t vo: Cc nt nhn S1, S2, S3, S4 vn gi nguyn. -
Phn t ra: Ba khi ng t K1, K2, K3, ng v m ba my bm vn gi nguyn. -
Phn t x l: c thay th bng PLC. S kt ni vi PLC c cho nh hnh 2.3. Trnh
t ng m theo yu cu ra s c lp trnh, chng trnh s c np vo b nh. By gi
gi thit rng nhim v iu khin s thay i. H thng ba my bm vn gi nguyn,
nhng trnh t c thc hin nh sau: ch ng c hai trong ba my bm hoc mi my
bm c th hot ng mt cch c lp. Nh vy theo yu cu mi i vi h thng iu khin
bng relay in phi thit k li mch iu khin, s lp rp phi thc hin li hon
ton mi. S mch iu khin biu din nh hnh 2.4. Nh vy mch iu khin s thay
i rt nhiu nhng phn t a tn hiu vo v ra vn gi nguyn, chi ph cho nhim
v mi s cao hn. Nu ta thay i h iu khin trn bng h iu khin lp trnh
PLC, khi nhim v iu khin thay i th thc hin s nhanh hn v n gin hn bng
cch thay i li chng trnh. Hnh 2.2: S mch c chuyn thnh chng trnh
trong PLC
19. Chu Chc 2 B iu khin lp trnh PLC 11 S1 S2 S3 S4 24V 24V in1
in2 in3 in4 0V out1 out2 out3 K1 K2 K3 0V Hnh 2.3: S kt ni vi PLC
Hnh 2.4: S mch iu khin 3 ng c c thay i H iu khin lp trnh PLC c nhng
u im sau: - Thch ng vi nhng nhim v iu khin khc nhau. - Kh nng thay
i n gin trong qu trnh a thit b vo s dng. - Tit kim khng gian lp t.
- Tit kim thi gian trong qu trnh m rng v pht trin nhim v iu khin
bng cch copy cc chng trnh. - Cc thit b iu khin theo chun. - Khng cn
cc tip im. - v.v H thng iu khin lp trnh PLC c s rng rt rng ri trong
cc ngnh khc nhau: - iu khin thang my. - iu khin cc qu trnh sn xut
khc nhau: sn sut bia, sn xut xi mng v.v ....
20. 2 B iu khin lp trnh PLC Chu Chc 10 - H thng ra t t ng. -
Thit b khai thc . - Thit b ng gi bao b, t ng m v trng km v.v ... -
Thit b sy. - 2.3 Cu trc ca mt PLC Cc b iu khin PLC c sn xut theo
dng sn phm. Khi mi xut xng, chng cha c mt chng trnh cho mt ng dng
no c. Tt c cc cng logic c bn, chc nng nh, timer, counter .v.v... c
nh ch to tch hp trong chng v c kt ni vi nhau bng chng trnh c vit bi
ngi dng cho mt nhim v iu khin c th no . B iu khin PLC c nhiu loi
khc nhau v c phn bit vi nhau qua cc thnh phn sau: - Cc ng vo v ra -
Dung lng nh - B m (counter) - B nh thi (timer) - Bit nh - Cc chc
nng c bit - Tc x l - Loi x l chng trnh. - Kh nng truyn thng. Cc b
iu khin ln th cc thnh phn trn c lp thnh cc modul ring. i vi cc b iu
khin nh, chng c tch hp trong b iu khin. Cc b iu khin nh ny c s lng
ng vo/ra cho trc c nh. B iu khin c cung cp tn hiu bi cc tn hiu t cc
cm bin ng vo ca n. Tn hiu ny c x l tip tc thng qua chng trnh iu
khin t trong b nh chng trnh. Kt qu x l c a ra ng ra n i tng iu khin
hay khu iu khin dng tn hiu. Cu trc ca mt PLC c th c m t nh hnh v
sau:
21. Chu Chc 2 B iu khin lp trnh PLC 12 Hnh 2.5: Cu trc chung ca
b iu khin lp trnh PLC * B nh chng trnh B nh chng trnh trong PLC l
mt b nh in t c bit c th c c. Nu s dng b nh c-ghi c (RAM), th ni
dung ca n lun lun c thay i v d nh trong trng hp vn hnh iu khin.
Trong trng hp in p ngun b mt th ni dung trong RAM c th vn c gi li
nu nh c s dng Pin d phng. Nu chng trnh iu khin lm vic n nh, hp l, n
c th c np vo mt b nh c nh, v d nh EPROM, EEPROM. Ni dung chng trnh
EPROM c th b xa bng tia cc tm. * H iu hnh Sau khi bt ngun cung cp
cho b iu khin, h iu hnh ca n s t cc counter, timer, d liu v bit nh
vi thuc tnh non-retentive (khng c nh bi Pin d phng) cng nh ACCU v
0. x l chng trnh, h iu hnh c tng dng chng trnh t u n cui. Tng ng h
iu hnh thc hin chng trnh theo cc cu lnh. * Bit nh (Bit memoryt) Cc
bit memory l cc phn t nh, m h iu hnh ghi nh trng thi tn hiu. * B m
(Proccess Image) B m l mt vng nh, m h iu hnh ghi nh cc trng thi tn
hiu cc ng vo ra nh phn.
22. 2 B iu khin lp trnh PLC Chu Chc 13 * Accumulator
Accumulator l mt b nh trung gian m qua n timer hay counter c np vo
hay thc hin cc php ton s hc. * Counter, Timer Timer v counter cng l
cc vng nh, h iu hnh ghi nh cc gi tr m trong n. * H thng Bus B nh
chng trnh, h iu hnh v cc modul ngoi vi (cc ng vo v ng ra) c kt ni
vi PLC thng qua Bus ni. Mt Bus bao gm cc dy dn m cc d liu c trao i.
H iu hnh t chc vic truyn d liu trn cc dy dn ny. 2.4 Cc khi ca PLC
Cc khi khc nhau ca mt PLC c cho nh hnh 2.6. 2.4.1 Khi ngun cung cp
Khi ngun c nhim v bin i in p li (110V hay 220V ) thnh in p thp hn
cung cp cho cc khi ca thit b t ng. in p ny l 24VDC. Cc in p cho cm
bin, thit b iu chnh v cc n bo nm trong khong (24...220V) c th c
cung cp thm t cc ngun ph v d nh bin p. Hnh 2.6:Cc khi trong mt
PLC
23. Chu Chc 2 B iu khin lp trnh PLC 14 2.4.2 B nh chng trnh Cc
phn t nh l cc linh kin m thng tin c th c lu tr (c nh) trong n dng
tn hiu nh phn. Trong PLC cc b nh bn dn c s dng lm b nh chng trnh.
Mt b nh bao gm 512, 1024, 2048 . . .phn t nh, cc phn t nh ny sp t
theo cc a ch t 0 ti 511, 1023 hoc 2047 . . .. Thng thng s lng ca cc
phn t nh trong mt b nh cho bit dung lng ca n l bao nhiu kilobyte
(1kB = 1024 byte). Trong mi nh c th m t mt cu lnh iu khin nh thit b
lp trnh. Mi phn t nh phn ca mt nh c th c trng thi tn hiu "0" hoc
"1". S ca mt b nh chng trnh c cho nh hnh 2.7. * B nh c-ghi RAM
(random-access memory) B nh ghi-c c 1 s lng cc nh xc nh. Mi nh c 1
dung lng nh c nh v n ch tip nhn 1 lng thng tin nht nh. Cc nh c k
hiu bng cc a ch ring ca n. B nh ny cha cc chng trnh cn sa i hoc cc
d liu, kt qu tm thi trong qu trnh tnh ton, lp trnh. c im ca loi ny
l d liu s mt i khi h thng mt in. RAM c hnh dung nh mt t cha c nhiu
ngn ko. Mi ngn ko c nh s mt a ch v ngi ta c th ct vo hoc ly cc d
liu ra. Hnh 2.7: S mt b nh chng trnh * B nh c nh ROM (read-only
memory) B nh c nh (ROM) cha cc thng tin khng c kh nng xa c v khng
th thay i c. Cc thng tin ny do cc nh sn xut vit ra v khng th thay i
c. Chng trnh trong b nh ROM c nhim v sau: - iu khin v kim tra cc
chc nng hot ng ca CPU. c gi l h iu hnh. - Dch ngn ng lp trnh thnh
ngn ng my.
24. 2 B iu khin lp trnh PLC Chu Chc 15 Mt ROM c th so snh vi mt
quyn sch. Trong n cha cc thng tin c nh, khng th thay i c v ta ch c
cc thng tin m thi. c im ca loi ny l d liu vn tn ti khi mt in. *
EPROM (eraseable read-only memory) EPROM l mt b nh c nh c th lp
trnh v xa c. Ni dung ca EPROM c th xa bng tia cc tm v c th lp trnh
li. * EEPROM (electrically eraseable read-only memory) EEPROM l b
nh c nh c th lp trnh v xa bng in. Mi nh trong EEPROM cho php lp
trnh v xa bng in. 2.4.3 Khi trung tm (CPU) Khi CPU l loi khi c cha
b vi x l, h iu hnh, b nh, cc b thi gian, b m, cng truyn thng ... v
c th cn c mt vi cng vo ra s. Cc cng vo ra s c trn CPU c gi l cng
vo/ra onboard. 2.4.4 Khi vo Cc ng vo ca khi ny s c kt ni vi cc b
chuyn i tn hiu v bin i cc tn hiu ny thnh tn hiu ph hp vi tn hiu x l
ca CPU. Da vo loi tn hiu vo s c cc khi ng vo tng ng. Gm c hai loi
khi vo c bn sau: Khi vo s (DI: Digital Input): Cc ng vo ca khi ny c
kt ni vi cc b chuyn i to ra tn hiu nh phn nh nt nhn, cng tc, cm bin
to tn hiu nh phn .v.v... Do tn hiu ti ng vo c th c mc logic tng ng
vi cc in p khc nhau, do khi s dng cn phi ch n in p cn thit cung cp
cho khi vo phi ph hp vi in p tng ng m b chuyn i tn hiu nh phn to
ra. V d: Cc nt nhn, cng tc c ni vi ngun 24VDC th yu cu phi s dng
khi vo c ngun cung cp cho n l 24VDC. Khi vo tng t (AI: Analog
Input): Khi ny c nhim v bin i tn hiu tng t (hay cn gi l tn hiu
analog) thnh tn hiu s. Cc ng vo ca khi ny c kt ni vi cc b chuyn i
to ra tn hiu analog nh cm bin nhit (Thermocouple), cm bin lu lng,
ng ra analog ca bin tn .v.v...Khi s dng cc khi vo analog cn phi ch
n loi tn hiu analog c to ra t cc b chuyn i (cm bin) V d: Cc cm bin
to ra tn hiu analog l dng in (4..20 mA) th phi s dng ng vo analog l
loi nhn tn hiu dng in (4..20 mA). Nu cm bin to ra tn hiu analog l
in p (0..5V) th phi s dng ng vo analog nhn tn hiu l in p
(0..5V).
25. Chu Chc 2 B iu khin lp trnh PLC 16 2.4.5 Khi ra Khi ny c
nhim v khuch i cc tn hiu sau x l ca CPU (c gi n vng m ra) cung cp
cho i tng iu khin l cun dy, n bo, van t .v.v.. Ty thuc vo i tng iu
khin nhn tn hiu dng no m s c cc khi ra tng ng. Gm c hai loi khi ra
tiu biu: Khi ra s (DO: Digital Output): Cc ng ra ca khi ny c kt ni
vi cc i tng iu khin nhn tn hiu nh phn nh n bo, cun dy relay
.v.v...V i tng iu khin nhn tn hiu nh phn s dng nhiu cp in p khc
nhau nn khi s dng cc khi ra s cn phi ch n in p cung cp cho n c ph
hp vi in p cung cp cho i tng iu khin hay khng. Theo loi in p s dng,
ng ra s c phn thnh hai loi: - in p mt chiu (DC: Direct Current): Gm
c hai loi ng ra l Transistor v relay. Thng thng trong cng nghip in
p mt chiu c s dng l 24V. - in p xoay chiu (AC: Alternative
Current): Gm c hai loi ng ra l relay v TRIAC. Khi ra tng t (AO:
Analog Output): Khi ny c nhim v bin i tn hiu s c gi t CPU n i tng
iu khin thnh tn hiu tng t. Cc ng ra ca khi ny c kt ni vi cc i tng
iu khin nhn tn hiu tng t nh ng vo analog ca bin tn, van t l,
.v.v... Khi s dng cc ng ra tng t cn ch n loi tn hiu tng t cung cp
cho i tng iu khin c ph hp vi tn hiu tng t m i tng iu khin cn nhn
hay khng. V d: Ng vo analog ca bin tn nhn tn hiu l in p (0..10V) th
nht thit phi s dng ng ra tng t to ra tn hiu analog l in p (0..10V).
2.4.6 Cc khi c bit Ngoi ra cn c mt s khi khc m nhn cc chc nng c bit
nh x l truyn thng, thc hin cc chc nng c bit nh: iu khin v tr, iu
khin vng kn, m tc cao .v.v... Ty thuc vo tng loi PLC m cc khi trn c
th cc dng module ring hoc c tch hp chung trong khi x l trung tm
(CPU). 2.5 Phng thc thc hin chng trnh trong PLC Hnh v minh ha vic x
l chng trnh trong CPU c cho nh hnh 2.8
26. 2 B iu khin lp trnh PLC Chu Chc 17 Bt u chu k Ng vo PII =
Process-image input table (vng m vo) Chng trnh: - Bit memory -
Timer - Counter - . . . . Network 1 Motor on/off I0.0 Q0.0 Network
2 Dao chieu quay I0.1 Q0.1 PIQ = Process-image output table (vng m
ra) Ng ra Kt thc chu k Hnh 2.8: Chu k qut trong PLC PLC thc hin
chng trnh cheo chu trnh lp. Mi vng lp c gi l vng qut (scan). Mi vng
qut c bt u bng giai on chuyn d liu t cc cng vo s ti vng b m o ng vo
(I), tip theo l giai on thc hin chng trnh. Trong tng dng qut, chng
trnh c thc hin t lnh u tin n lnh kt thc. Sau giai on thc hin chng
trnh l giai on chuyn cc ni dung ca b m o ng ra (Q) ti cc cng ra s.
Vng qut c kt thc bng giai on truyn thng ni b v kim tra li. Thi gian
cn thit PLC thc hin c mt vng qut gi l thi gian vng qut (Scan time).
Thi gian vng qut khng c nh, tc l khng phi vng qut no cng c thc hin
trong mt khong thi gian nh nhau. C vng qut thc hin lu, c vng qut
thc hin nhanh ty thuc vo s lnh trong chng trnh c thc hin, vo khi
lng d liu truyn thng ... trong vng qut . Nh vy gia vic c d liu t i
tng x l, tnh ton v vic gi tn hiu iu khin ti i tng c mt khong thi
gian tr ng bng thi gian vng qut. Ni cch khc, thi gian vng qut quyt
nh tnh thi gian thc ca chng trnh iu khin trong PLC. Thi gian qut
cng ngn, tnh thi gian thc ca chng trnh cng cao. Ti thi im thc hin
lnh vo/ra, thng thng lnh khng lm vic trc tip vi cng vo/ra m ch thng
qua b m o ca cng trong vng
27. Chu Chc 2 B iu khin lp trnh PLC 18 nh tham s. Vic truyn
thng gia b m o vi ngoi vi do h iu hnh CPU qun l. mt s module CPU,
khi gp lnh vo/ra ngay lp tc, h thng s cho dng mi cng vic khc, ngay
c chng trnh x l ngt, thc hin lnh trc tip vi cng vo/ra.
28. 19 3 Cm bin v ccu chp hnh trong iu khin logic Chu Chc 3 Cm
bin v c cu chp hnh trong iu khin logic. Chng ny nhm gip cho bn c tm
hiu s lc v mt s cc thit b ngoi vi s c kt ni vi cc ng vo ra s ca PLC
v mt s k hiu v cc thit b ngoi vi. 3.1 Cm bin 3.1.1 Giithiu Cm bin
(sensor) cho php PLC pht hin trng thi ca mt qu trnh. Cc cm bin
logic ch c th pht hin trng thi ng hoc sai. Cc hin tng vt l tiu biu
cn c pht hin l: - Tip cn cm: cho bit mt i tng l kim loi c n gn v tr
cn nhn bit cha? - Tip cn dung: cho bit mt i tng l khng kim loi c n
gn v tr cn nhn bit cha? - S xut hin nh sng: Cho bit mt i tng c lm
ngt chm tia sng hay nh sng phn x? - Tip xc c hc: i tng c chm vo cng
tc? Gi thnh ca cm bin ngy cng gim thp v tr nn thng dng. Chng c nhiu
hnh dng khc nhau c sn xut bi nhiu cng ty khc nhau nh Siemens,
Omron, Pepperl+Fuch, Trong cc ng dng, cc cm bin c kt ni vi PLC ca
nhiu hng khc nhau, nhng mi cm bin s c cc yu cu giao tip ring. Phn
ny s trnh by cch thc ni dy cho cc cm bin v mt s tnh cht c bn ca n.
3.1.2 Ni dy cho cm bin Khi mt cm bin pht hin mt s thay i trng thi
logic th n phi truyn trng thi thay i ny n PLC. Tiu biu l vic ng hoc
ngt dng in hay in p. Trong mt vi trng hp, ng ra ca cm bin s dng ng
mch trc tip cho ti m khng thng qua PLC. Cc ng ra tiu biu ca cm bin
l: - Sinking/Sourcing: ng hoc ngt dng in - Switches: ng hoc ngt in
p
29. Chu Chc 3 Cm bin v ccu chp hnh trong iu khin logic 21 -
Solid State Relays: Chuyn mch AC - TTL (Transistor Transistor
Logic): S dng in p 0V v 5V ch th mc logic. 3.1.2.1 Switch Mt v d n
gin nht ca cc ng ra cm bin switch v relay c cho nh hnh 3.1. Hnh
3.1: Cm bin c ng ra l relay s dng ngun DC v AC . 3.1.2.2 Ng ra TTL
Ng ra TTL c hai mc in p: 0V tng ng l mc thp, 5V tng ng mc cao. in p
thc t c th ln hn 0V hoc nh hn 5V mt cht vn c th pht hin ng. Phng
php ny rt d b nhiu trong mi trng nh my cho nn n ch c s dng khi cn
thit. Cc ng ra TTL thng dng trong cc thit b in t v my tnh. Khi kt
ni vi cc thit b khc th mt mch Schmitt trigger thng c s dng ci thin
tn hiu (hnh 3.2). Hnh 3.2: Mch Schmitt trigger Mch Schmitt trigger
s nhn in p ng vo gia 0-5V v chuyn i n thnh 0V hoc 5V. Nu in p nm
trong khong 1.5-3.5V th khng chp nhn. Nu mt cm bin c ng ra TTL th
PLC phi s dng cc ng vo l TTL c cc gi tr ny. Nu cc cm bin TTL c s
dng cho cc ng dng khc th nn ch dng ng ra cc i ca cm bin (thng khong
20mA). 3.1.2.3 Ng ra Sinking/Sourcing Cc cm bin c ng ra Sinking (rt
dng) cho php dng in chy vo cm bin. Cn cc cm bin c ng ra sourcing
(ngun dng) cho php dng in chy t cm bin ra i tng c kt ni. hai ng ra
ny cn ch l dng in ch khng phi in p. Bng cch s dng dng in th nhiu c
loi tr bt.
30. 3 Cm bin v ccu chp hnh trong iu khin logic Chu Chc 20 Khi
gii thch v vn sinking hay sourcing th ta nn quy cc ng ra ca cm bin
tc ng nh cng tc. Trong thc t, cc ng ra ca cm bin thng l mt
transistor chuyn mch. Transistor PNP c s dng cho ng ra sourcing, v
transistor NPN c s dng cho ng vo sinking. Khi gii thch cc cm bin ny
th khi nim ngun dng thng c dng cho PNP, v rt dng vi NPN. V d cm bin
ng ra sinking c cho hnh 3.3. Hnh 3.3: Cm bin NPN (cm bin rt dng).
Hnh 3.4: Cm bin PNP (cm bin sourcing) cm bin hot ng cn phi c ngun
cung cp (chn L+ v L-). Khi cm bin pht hin i tng th c in p ti cc B
ca transistor NPN, transistor chuyn sang trng thi dn v cho php dng
chy vo cm bin xung mass (chn L-). Khi khng pht hin i tng th in p ti
cc B ca transistor mc thp (0V), transistor khng dn. iu ny c ngha ng
ra NPN s khng c dng vo/ra. Cc cm bin sourcing th ngc vi cc cm bin
sinking. N s dng transistor PNP (hnh 3.4). Khi cm bin khng c kch
hot th cc B ca transistor gi tr L+, v transistor trng thi ngng dn.
Khi cm bin c kch hot th cc B transistor s c t 0V, v transistor cho
php dng in chy t cm bin ra ngoi thit b c kt ni. Hu ht cc cm bin
NPN/PNP c kh nng dng n vi ampere, v chng c th c s dng ni trc tip vi
ti (lun lun kim tra s tay bit chnh xc dng in v in p nh mc). Ch : Cn
phi nh kim tra dng in v in p nh mc i vi cc cm bin. Khi ni dy cc cm
bin cn ch n cc chn ngun. Thng cc
31. Chu Chc 3 Cm bin v ccu chp hnh trong iu khin logic 22 chn
ngun c k hiu l L+ v COM(chn chung), nhng i khi khng c chn COM m c
chn L-. Trong trng hp ny L- l chn chung. Khi kt ni cc cm bin
sourcing vi cc ng PLC, th cn ch phi s dng cc modul ng vo loi
sinking. Thng thng cc ng vo PLC thng l loi sinking. Trong ng dng vi
PLC, gim lng dy ni, th cc cm bin hai dy thng c s dng. V d v s ni dy
cc cm bin s dng ngun 24VDC vi PLC c ch nh hnh 3.5. Cm bin hai dy c
th c s dng cho c hai loi ng vo sourcing hoc ng vo sinking ca PLC.
a. Ng vo PLC loi sourcing b. Ng vo PLC loi sinking Hnh 3.5: Kt ni
cm bin 2 dy vi ng vo PLC. Hu ht cc cm bin hin i c c hai ng ra PNP v
NPN. Thng thng cm bin loi PNP thng c s dng cho cc ng vo PLC. Trong
cc bn v th cc chn ca cc cm bin NPN v PNP c k hiu v mu sc nh sau: dy
mu nu l L+, dy mu xanh dng l L- v ng ra th mu trng i vi sinking v
mu en i vi sourcing. Cn lu l khi tip im trong cm bin sinking ng th
ng ra c ni vi COM hoc L-, tip im trong sourcing ng th ng ra ni vi
L+. a. Ng vo PLC loi sourcing b. Ng vo PLC loi sinking Hnh 3.6: Kt
ni cm bin NPN v PNP dy vi ng vo PLC.
32. 3 Cm bin v ccu chp hnh trong iu khin logic Chu Chc 23
3.1.2.4 Ng ra Solid state relay Cc ng ra Solid state relays ng mch
dng in AC. Cc cm bin ny c s dng vi ti ln. 3.1.3 Pht hin i tng C hai
cch c bn pht hin i tng: tip xc v tip cn (proximity). Tip xc c ngha
l tip im c kh cn mt lc tc ng gia cm bin v i tng. Tip cn ch bo rng
mt i tng ang gn nhng khng yu cu tip xc. Cc phn sau y s minh ha cc
kiu khc nhau ca cc cm bin pht hin s hin din ca cc i tng. Phn ny
khng i su vo cc cm bin m ch m t cc nguyn l trong lnh vc ng dng.
3.1.3.1 Chuyn mch tip xc Chuyn mch tip xc (contact switch ) thng c
hai dng l thng h (normally open) v thng ng (normally closed). V ca
chng c gia c c th chu c lc c tc ng nhiu ln. 3.1.3.2 Reed Switches
Reed switches th rt ging relay, ngoi tr mt nam chm vnh cu c s dng
thay th cun dy. Khi nam chm xa th tip im m, nhng khi nam chm n gn
th tip im ng li (hnh 3.7). Cc cm bin ny r tin v chng thng c s dng
cho cc mn chn v ca an ton. Hnh 3.7: Read switch 3.1.3.3 Cm bin
quang (Optical Sensor) Cm bin nh sng c s dng gn mt th k qua. Nguyn
thy l t bo quang c s dng cho cc ng dng nh c cc track m thanh trn cc
hnh nh chuyn ng. Nhng cc cm bin quang hin i th phc tp hn nhiu. Cc
cm bin quang yu cu c c hai b phn l ngun sng (pht) v u thu
(detector). Cc u pht (emitter) s pht ra cc tia sng trong vng ph nhn
thy v khng nhn thy c s dng LED v diode laser. u thu c cu to l cc
diode quang (photodidode) hoc transistor quang (phototransistor). u
pht v u thu c t vo v tr i tng khi
33. Chu Chc 3 Cm bin v ccu chp hnh trong iu khin logic 24 xut
hin s ct ngang hoc phn x li tia sng. Cm bin quang n gin cho hnh
3.8. Trong hnh, chm sng c to ra nm bn tri, c hi t qua mt thu knh. i
din l u thu, chm tia c hi t bng mt thu knh th hai. Nu chm tia b
ngt, th u thu s ch bo mt i tng xut hin. nh sng c to ra di dng xung
cm bin c th lc c nh sng bnh thng trong phng. nh sng t u pht c tt v
m ti mt tn s t. Khi u thu nhn nh sng, n kim tra m bo chc chn rng n
c cng tn s. Nu nh sng ang nhn c ti tn s ng th chm tia khng b ngt.
Tn s dao ng nm trong phm vi KHz. Ngoi ra vi phng php tn s th cc cm
bin c th c s dng vi cng sut thp hn v khong cch di hn. u pht c th bt
u t mt im trc tip ti u thu, y cn gi l ch t phn x. Khi tia sng b
ngt, th i tng c pht hin. Cm bin ny cn hai b phn ring (hnh 3.9a). S
xp t ny lm vic tt vi cc i tng chn sng v phn x vi u pht v u thu c
tch ring vi khong cch ln n c trm mt. Phn t thu Phn t pht Sensor
itng nhn bit nh sng phn x nh sng c truyn b. i tng nhn bit ngt nh
sng Gng phn x
34. 3 Cm bin v ccu chp hnh trong iu khin logic Chu Chc 25 Hnh
13.9: Cc loi cm bin quang khc nhau u thu v u pht tch ring lm tng vn
v bo tr v yu cu v s thng hng. Mt gii php khc l u pht v u thu c t
chung trn mt v. Nhng iu ny yu cu nh sng t phn x tr v (hnh 3.9b,c).
Cc cm bin ny ch tt cho cc i tng ln vi khong cch mt vi met. Trong
hnh, u pht pht mt chm tia sng. Nu nh sng b di tr v t gng phn x th
hu ht s tr v u thu. Khi mt i tng ngt chm tia gia u pht v gng phn x
th chm tia s khng t phn x tr v u thu v cm bin c tc ng. Mt vn ri ro
cho cc cm bin ny l cc i tng t phn x li chm tia sng tt. gii quyt th
s dng bin php phn cc nh sng ti u pht (bng b lc), v sau sau s dng mt
b lc phn cc ti u thu. 3.1.3.4 Cm bin in dung (Capacitive Sensor) Cc
cm bin in dung c th pht hin hu ht cc vt liu vi khong cch vi cm. Cng
thc biu din mi quan h in dung: C .A d vi C: in dung (Farads) : Hng
s in mi A: Din tch bn cc D: Khong cch gia cc bn cc. Trong cm bin,
din tch cc bn cc v khong cch gia chng l c nh. Nhng hng s in mi ca
khng gian xung quanh chng s thay i khi cc vt liu c mang n gn cm
bin. Minh ha hnh 3.10. B mt ca cm bin in dung c hnh thnh bi hai in
cc kim loi ng tm ca mt t in. Khi mt i tng n gn b mt nhn bit n i vo
vng in trng ca cc in cc v thay i in dung trong mch dao ng. Kt qu l
b to dao ng bt u dao ng. Mch trigger c bin ca b dao ng v khi t n mc
xc nh th trng thi ng ra s thay i. Khi i tng ri khi cm bin th bin ca
b dao ng gim, cm bin chuyn v trng thi bnh thng.
35. Chu Chc 3 Cm bin v ccu chp hnh trong iu khin logic 26 Khng
c C i tng Khng c i tng i tng Hnh 3.10: Cm bin in dung Cc cm bin ny
lm vic tt i vi cht cch in (nh cht do) c hng s in mi cao (lm tng in
dung). Hng s in mi cng ln th khong cch hot ng cng cao. V d khi hiu
chnh ng th cht lng trong thng cha c th c pht hin c d dng. Tuy nhin,
chng cng lm vic tt i vi kim loi. Cc cm bin thng c ch to vi cc vng
(khng phi bn cc) theo hnh 3.11. Trong hnh, hai vng kim loi nm bn
trong l cc in cc ca t in, nhng vng ngoi th ba c thm vo b s thay i.
Nu khng c vng b ny th cm bin s rt nhy cm vi bi bm, du v cc cht khc
dnh trn cm bin. in cc in cc b Hnh 3.11: B mt nhn bit ca cm bin in
dung Phm vi v chnh xc ca cc cm bin c xc nh bi kch thc ca chng. Cc
cm bin ln c th c ng knh vi centimeter. Ci nh c ng knh nh hn mt
centimeter v c phm vi nh hn nhng chnh xc hn. 3.1.3.5 Cm bin in cm
(Inductive Sensor) Cc cm bin in cm s dng dng in cm ng pht hin i tng
l kim loi. Cm bin in cm s dng mt cun dy to mt t trng tn s cao c cho
hnh 3.12. Nu c mt i tng l kim loi n gn lm thay i t trng, th s c dng
chy vo i tng. Dng chy ny to ra mt t trng mi ngc vi t trng ban u. Kt
qu l n lm thay
36. 3 Cm bin v ccu chp hnh trong iu khin logic Chu Chc 27 i t
cm ca cun dy trong cm bin. Bng cch o t cm, cm bin c th xc nh mt i
tng kim loi n gn. Cc cm bin ny s pht hin bt k kim loi no, khi cn
pht hin cc loi kim loi th cc cm bin a kim loi thng c s dng. Hnh
3.12: Cm bin tip cn in cm Khi i tng kim loi i vo vng in t trng, th
dng in xoy truyn vo i tng. iu ny lm tng ti trong cm bin, lm gim bin
ca in t trng. Mch trigger gim st bin dao ng khi t n mc nh trc th n
chuyn i trng thi ng ra ca cm bin. Khi i tng di chuyn khi cm bin, th
bin dao ng tng ln. Khi n gi tr nh trc th mch trigger chuyn i trng
thi ng ra tr v iu kin bnh thng. Khng c C i tng Khng c i tng i tng
Hnh 3.13: Cm bin tip cn in cm Cc cm bin c th pht hin cc i tng cch
xa vi centimeter. Nhng hng ca i tng c th l bt k nh hnh 3.14. T trng
ca cc cm bin khng bc bao ph xung quanh u ca cun dy ln hn. Bng cch
lp thm v bc kim loi th t trng s nh hn, nhng hng ca i tng nhn bit c
ci thin hn.
37. Chu Chc 3 Cm bin v ccu chp hnh trong iu khin logic 28 Hnh
3.14: Cm bin bc v khng bc v kim loi 3.1.3.6 Cm bin siu m
(Ultrasonic sensor) Cm bin siu m pht ra m thanh trn ngng nghe bnh
thng 16kHz. Thi gian c yu cu m thanh di chuyn n mc tiu v phn hi tr
v t l vi khong cch mc tiu. C hai loi cm bin l: - Tnh in
(electrostatic): S dng hiu ng in dung. Phm vi ln v bng thng rng hn
nhng nhy cao hn vi i tng m t. - p in (piezoelectric): Da vo phn t p
in thch anh. Cc cm bin ny c th rt hiu qu cho cc ng dng nh o mc cht
lng trong thng cha. 3.1.3.7 Hiu ng Hall (Hall Effect) Cc cng tc hiu
ng Hall c bn l cc transistor c th chuyn mch bi t trng. Cc ng dng ca
chng th rt ging vi reed switch, nhng v chng ch l cht bn dn nn chng
ph hp vi cc chuyn ng. Cc my mc t ng ha thng s dng chng thc hin khi
ng v pht hin v tr dng. 3.1.3.8 Lu lng (Fluid Flow) Hnh 3.15: xc nh
lu lng dng chy vi cm bin tip cn cm
38. 3 Cm bin v ccu chp hnh trong iu khin logic Chu Chc 29 Chng
ta c th thay th cc cm bin phc tp bng cc cm bin n gin. Hnh 3.15 cho
thy mt phao kim loi trong mt knh hnh nn. Tc dng chy tng p lc y phao
ln trn. Dng hnh nn ca phao m bo v tr ca cht lng t l vi tc dng chy.
Mt cm bin tip cn in cm c th c nh v n pht hin khi phao t n cao no ,
v h thng t n tc dng chy nh. 3.1.4 Tm tt Cm bin Sourcing cho php dng
in chy t cc L+ ca ngun. Cm bin Sinking cho php dng in chy t cc L-
ca ngun.. Cm bin quang c th s dng chm tia phn x, u pht v u thu v nh
sng phn x pht hin i tng. Cm bin in dung c th pht hin kim loi v cc
vt liu khc. Cm bin in cm pht hin c kim loi. Cm bin hiu ng Hall v
reed switch c th pht hin c nam chm. Cm bin siu m s dng sng m pht
hin cc phn t cch xa nhiu meter. 3.2 C cu chp hnh 3.2.1 Giithiu C cu
chp hnh c s dng bin i nng lng in thnh chuyn ng c hc. 3.2.2 Solenoid
Solenoid l c cu chp hnh thng dng nht. Nguyn l hot ng c bn l s di
chuyn li st (piston) trong cun dy (hnh 3.16). Bnh thng piston c gi
bn ngoi cun dy. Khi cun dy c cp in, cun dy sinh ra t trng ht piston
v ko n vo trung tm ca cun dy. ng dng quan trng nht ca solenoid l iu
khin cc van kh nn, thy lc v kha ca xe. Khng c in c in Hnh 3.16:
Solenoid Cn ch l cc cun cm c th to ra in p gai nhn v c th cn cc b
gim sc. Mc d vy hu ht trong cc ng dng cng nghip c in p thp v dng in
nh mc, chng c th c kt ni trc tip vi cc ng ra ca PLC. Hu ht cc
solenoid cng nghip s dng ngun cung cp 24Vdc v dng nh mc mt vi trm
mA.
39. Chu Chc 3 Cm bin v ccu chp hnh trong iu khin logic 31 3.2.3
Van iu khin (VALVE) Dng cht lng v kh c th c iu khin bng cc van iu
khin solenoid. V d van iu khin solenoid c cho hnh 3.17. solenoid Kh
ra Kh vo solenoid Kh vo Kh ra Hnh 3.17: Mt solenoid iu khin van 5
ca 2 v tr Cc loi van c lit k di y. Theo tiu chun, thut ng n-ca
(n-ca) ch nh s lng kt ni cc ng vo v ra ca van. Trong mt vi trng hp
c ca x kh ra. Vic thit k thng ng/thng m cho bit iu kin van khi mt
ngun cp. Van 2 ca, 2 v tr thng ng (van 2/2): Cc van ny c 1 ca vo v
mt ca ra. Khi mt ngun cung cp th v tr thng ng. Khi c ngun cung cp,
th van m cho php dng kh hay cht lng chy qua. Cc van ny c s dng cho
php dng chy. Van 2 ca, 2 v tr thng m (van 2/2): Cc van ny c mt ca
vo v mt ca ra. Khi mt ngun th m cho php dng chy. Khi c ngun, van
ng. Cc van ny c s dng ngt dng chy. Van 3 ca, 2 v tr thng ng (van
3/2): Cc van ny c ca vo, ca ra v ca x kh. Khi mt ngun th ca ra c ni
vi ca x kh. Khi c ngun th ca vo c ni vi ca ra. Cc van ny c s dng
cho cc cylinder tc ng n. Van 3 ca, 2 v tr thng m (van 3/2): Cc van
ny c ca vo, ca ra v ca x kh. Khi mt ngun th ca vo c ni vi ca ra.
Khi c ngun th van ni ca ra vi ca x kh. Cc van ny c s dng cho cc
cylinder tc ng n. Van 3 ca, 2 v tr a nng (van 3/2): Cc van ny c 3
ca. Mt trong cc ca hot ng nh l ca vo hoc ca ra, v c ni n mt trong
hai ca khc khi mt ngun hoc c ngun. Cc van ny c th
40. 3 Cm bin v ccu chp hnh trong iu khin logic Chu Chc 30 c s
dng lm chuyn hng dng chy, hoc chn ngun qua li. Van 4 ca, 2 v tr
(van 4/2): Cc van ny c 4 ca, 1 vo, 2 ra v 1 ca x kh. Khi c ngun van
ni cc ca vo vi cc ca ra v ngc li. Cc van ny c s dng vi cc cylinder
tc ng kp. Van 5 ca, 2 v tr (van 5/2): Cc van ny c 5 ca, 1 vo, 2 ra
v 2 ca x kh. Van 4 ca, 3 v tr (van 4/3): Cc van ny c 4 ca, 1 vo, 2
ra v 1 x. trng thi bnh thng (khng c ngun nng lng) th cc ca vo/ra u
b chn. Van ny c s dng iu khin v tr cc cylinder. Van 5 ca, 3 v tr
(van 5/3): Van ny c 5 ca, 1 vo, 2 ra v 2 ca x. Tng t nh van 4/3,
van ny c s dng iu khin v tr cc cylinder. K hiu ca cc van c cho hnh
3.18. Khi s dng trong cc bn v th v trng thi khng c cp ngun nng lng.
Mi tn ch ng dn dng chy n cc v tr khc. Biu tng tam gic nh ch ca x
kh. Loi van K hiu iu khin bng kh nn iu khin bng solenoid Van 2 ca,
2 v tr Thng ng Thng m Thng ng Thng m Van 3 ca, 2 v tr Thng ng Thng
m Thng ng Thng m
41. Chu Chc 3 Cm bin v ccu chp hnh trong iu khin logic 32 Van 4
ca, 2 v tr Hoc Van 5 ca, 2 v tr Hoc Van 4 ca, 3 v tr Van 5 ca, 3 v
tr Hnh 3.18 K hiu cc van iu khin bng kh v solenoid Khi chn la van,
cn ch mt s chi tit sau: - Kch thc ng: Ca vo v ra theo tiu chun NPT
(national pipe thread). - Tc dng chy: Tc dng chy cc i thng c cung
cp cho cc van thy lc. - p sut hot ng: p sut hot ng cc i phi c ch
bo. Mt vi van c yu cu p sut ti thiu hot ng. - Ngun in: Cc cun dy
solenoid yu cu c cung cp mt in p v dng in c nh (AC hoc DC). - Thi
gian p ng: y l thi gian van ng/m hon ton. Thi gian tiu biu cho cc
van nm trong phm vi t 5ms n 150ms. - V bc: V bc cho cc van c xp
theo loi: Loi 1 hoc 2: S dng trong nh, yu cu bo v chng nc. Loi 3: S
dng ngoi tri, chng bi bm v ma gi. Loi 3R hoc 3S hoc 4: Chng nc v
bi. Loi 4X: Chng nc, bi v s n mn. 3.2.4 Xy lanh (CYLINDER)
42. 3 Cm bin v ccu chp hnh trong iu khin logic Chu Chc 33
Cylinder s dng p lc kh hoc cht lng to lc/chuyn ng tuyn tnh (hnh
3.19). Trong hnh, dng cht lng c bm vo mt pha ca cylinder lm dch
chuyn piston v pha cn li. Cht lng pha ny c thot t do. Lc tc dng ln
cylinder t l vi din tch b mt ca piston. Cng thc tnh lc: F= P.A P F
A Vi P: p sut thy lc F: Lc y piston A: Din tch piston Hnh 3.19 Mt
ct ca mt cylinder thy lc Cylinder tc ng n yu cu cung cp lc khi dui
ra v s dng l xo co v. Cn cylinder tc ng kp th cung cp lc c hai pha.
Hnh 3.20 cylinder tc ng n v cylinder tc ng kp Cc cylinder t thng c
s dng trong iu khin kh nn. Trn u ca piston c mt mnh nam chm. Khi n
di chuyn n v tr gii hn th cc cng tc reed switch s pht hin ra. 3.2.5
ng c ng c l c cu chp hnh thng thng, nhng i vi ng dng cho iu khin nh
phn th c im ca n khng quan trng. iu khin logic tiu biu ca cc ng c l
ng ct in cho n. Cc ng c c dng
43. Chu Chc 3 Cm bin v ccu chp hnh trong iu khin logic 34 in nh
c th u trc tip vo cc ng ra ca PLC, cn i vi cc ng c cng sut ln th s
dng relay hay contactor hoc b khi ng ng c. Cc ng c s c kho st chi
tit hn chng cc cm bin v c cu chp hnh analog (tp 2). 3.2.6 Cc c cu
chp hnh khc Ngoi cc c cu chp hnh k trn cn c nhiu loi c cu chp hnh
khc nhau trong iu khin logic. Mt s c cu chp hnh thng c s dng relay
v contactor. Ngoi ra c mt s c cu chp hnh khc: - L nhit: Thng c iu
khin bng relay, ng v ct in gi nhit nm trong mt phm vi no . - n bo:
n bo c s dng cho hu ht cc my mc ch bo trng thi my v cung cp thng
tin cho ngi vn hnh. Hu ht cc n bo c dng in thp v c kt ni trc tip n
PLC. - Ci/chung bo: Ci hay chung bo c th c s dng cho cc my mc khng
c gim st hoc ang b nguy him. Chng thng c ni trc tip vi cc ng ra ca
PLC.
44. 35 Chu Chc 4 B iu khin lp trnh PLC Simatic S7-200 4 B iu
khin lp trnh PLC Simatic S7-200 4.1 Cu hnh cng 4.1.1 Khi x l trung
tm PLC S7-200 l thit b iu khin lp trnh loi nh (micro PLC) ca hng
Siemens (CHLB c) c cu trc theo kiu modul v c cc modul m rng. Thnh
phn c bn ca S7 - 200 l khi x l trung tm (CPU: Central Processing
Unit) bao gm hai chng loi: CPU 21x v CPU 22x. Mi chng loi c nhiu
CPU. Loi CPU 21x ngy nay khng cn sn xut na, tuy nhin hin vn cn s
dng rt nhiu trong cc trng hc v trong sn xut. Tiu biu cho loi ny l
CPU 214. CPU 214 c cc c tnh nh sau: - B nh chng trnh (cha trong
EEPROM): 4096 Byte (4 kByte) - B nh d liu (Vng nh V): 4096 Byte
(trong 512 Byte cha trong EEPROM) - S lng ng vo:14 , v - S lng ng
ra: 10 ng ra digital tch hp trong CPU - S module m rng: 7 gm c
module analog - S lng vo/ra s cc i: 64 - S lng Timer :128 Timer
chia lm 3 loi theo phn gii khc nhau: 4 Timer 1ms, 16 Timer 10 ms v
108 Timer c phn gii 100ms. - S lng Counter: 128 b m chia lm hai
loi: 96 Counter Up v 32 Counter Up/Down. - Bit memory (Vng nh M):
256 bit - Special memory (SM) : 688 bit dng thng bo trng thi v t ch
lm vic. - C php tnh s hc
45. 36 4 B iu khin lp trnh PLC Simatic S7-200 - B m tc cao
(High-speed counters): 2 counter 2 KHz v 1 counter 7 KHz - Ng vo
analog tch hp sn (bin tr): 2. - Cc ch ngt v x l ngt gm: ngt truyn
thng, ngt theo sn ln hoc xung, ngt thi gian, ngt ca b m tc cao v
ngt truyn xung. Ton b vng nh khng b mt d liu trong khong thi gian
190 gi khi PLC b mt ngun nui. S b mt ca b iu khin logic kh trnh
S7-200 CPU 214 c cho nh hnh 4.1. Ng ra Card nh Kiu hotng Bin tr
SIEMENS SIMATIC S7-200 SF RUN STOP I0.0 I0.1 I0.2 I0.3 I0.4 I0.5
I0.6 I0.7 I1.0 I1.1 I1.2 I1.3 I1.4 I1.5 Q0.0 Q0.1 Q0.2 Q0.3 Q0.4
Q0.5 Q0.6 Q0.7 Q1.0 Q1.1 CPU 214 Cng PPI Ni n thit b lp trnh Ng vo
Bo trng thi CPU Bo trng thi ng vo/ra Hnh 4.1: B iu khin lp trnh
S7-200 CPU 214 * M t cc n bo trn CPU 214: - SF (n ): n SF bo hiu h
thng b li. n SF sng ln khi PLC c li. - RUN ( n xanh): cho bit PLC
ang ch lm vic v thc hin chng trnh c np vo trong b nh chng trnh ca
PLC. - STOP (n vng): n vng STOP ch nh PLC ang ch dng. Dng chng trnh
ang thc hin li. - I x.x (n xanh): n xanh cng vo ch nh trng thi tc
thi ca cng ( x.x = 0.0 - 1.5). n ny bo hiu trng thi ca tn hiu theo
gi tr logic ca cng.
46. 37 4 B iu khin lp trnh PLC Simatic S7-200 Chu Chc - Qy.y (n
xanh): n xanh cng ra ch nh trng thi tc thi ca cng ( y.y = 0.0 -
1.1). n ny bo hiu trng thi ca tn hiu theo gi tr logic ca cng. Hin
nay, CPU 22x vi nhiu tnh nng vt tri thay th loi CPU 21x v hin ang c
s dng rt nhiu. Tiu biu cho loi ny l CPU 224. Thng tinv CPU 22x c
chonh bng 4.1v hnh dng CPU 224 hnh 4.2. c im CPU 221 CPU 222 CPU
224 CPU 224XP CPU 226 I/O trn CPU Digital Analog 6DI/4DO - 8DI/6DO
- 14DI/10DO - 14DI/10DO 2AI/1AO 24DI/16DO - S module m rng max. 0 2
7 7 7 B nh chng trnh 4KB 4KB 8KB 12KB 16KB B nh d liu 2KB 2KB 8KB
10KB 10KB Thi gian x l 0,37 s 0,37 s 0,37 s 0,37 s 0,37 s Memory
bits/counters/timers 256/256/256 256/256/256 256/256/256
256/256/256 256/256/256 High-speed counters 4 x 30 kHz 4 x 30 kHz 6
x 30 kHz 4 x 30 kHz 2x 200 kHz 6 x 30 kHz Real-time clock card card
Tch hp Tch hp Tch hp Ng ra xung 2 x 20 kHz 2 x 20 kHz 2 x 20 kHz 2
x 100 kHz 2 x 20 kHz Cng giao tip 1x RS-485 1x RS-485 1x RS-485 2x
RS-485 2x RS-485 Bin tr analog trn CPU 1 1 2 2 2 Bng 4.1: Bng d liu
v CPU h 22x * Chn ch lm vic cho PLC Cng tc chn ch lm vic nm pha
trn, c ba v tr cho php chn cc ch lm vic khc nhau ca PLC: - RUN: Cho
php PLC thc hin chng trnh trong b nh. PLC S7-200 s ri khi ch RUN v
chuyn sang ch STOP nu trong my c s c, hoc trong chng trnh gp lnh
STOP.
47. 38 4 B iu khin lp trnh PLC Simatic S7-200 - STOP: Cng bc
PLC dng chng trnh ang chy v chuyn sang ch STOP. ch STOP, PLC cho
php hiu chnh, np, xa mt chng trnh. - TERM: Cho php ngi dng t my tnh
quyt nh chn mt trong hai ch lm vic cho PLC hoc RUN hoc STOP. LED bo
trng thi I/O LED bo trng thi CPU Khe cm - Memory Module - Battery
Module, - Clock Module (221, 222) Bin tr chnh gi tr analog Cng
truyn thng L bt cht vo vch u ni c th tho ri (trn 224,226) Chtkha
module trn gi Hnh 4.2: B iu khin lp trnh CPU 224 * 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. Tc truyn cho my
lp trnh kiu PPI l 9600 baud. Tc truyn cung cp ca PLC theo kiu t do
l t 300 baud n 38400 baud. ghp ni S7-200 vi my lp trnh PG720 (hng
Siemens) hoc vi cc loi my lp trnh thuc h PG7xx c th s dng mt cp ni
thng qua MPI. Cp i km theo my lp trnh. Ghp ni S7-200 vi my tnh PC
qua cng RS-232 cn c cp ni PC/PPI vi b chuyn i RS232/RS485, v qua
cng USB ta c cp USB/PPI. * Card nh, pin, clock (CPU 221, CPU222)
S7-200 cung cp nhiu bin php m bo cho chng trnh ngi dng, d liu chng
trnh v cu hnh d liu c duy tr sau:
48. 39 4 B iu khin lp trnh PLC Simatic S7-200 Chu Chc Mt t in
vi in dung ln cho php nui b nh RAM sau khi b mt ngun in cung cp. Ty
theo loi CPU m thi gian lu tr c th ko di nhiu ngy. Chng hn CPU 224
l khong 100 gi Vng nh EEPROM cho php lu chng trnh, cc vng nh c ngi
dng chn cha vo EEPROM v cu hnh d liu. Cho php gn thm Pin nui RAM v
cho php ko di thm thi gian lu tr d liu, c th ln n 200 ngy k t khi
mt ngun in. Ngun ca Pin s c ly sau khi t in x ht. - Card nh: c s
dng lu tr chng trnh. Chng trnh cha trong card nh bao gm: program
block, data Battery module Clock/ Battery module memory module
block, system block, cng thc (recipes), d liu o (data logs), v cc
gi tr cng bc (force values). - Card pin: Dng m rng thi gian lu tr
cc d liu c trong b nh. Ngun pin c t ng chuyn sang Hnh 4.3: Hnh dng
cc module khi t trong PLC cn. Pin c th s dng n 200 ngy. - Card
Clock / Battery module: ng h thi gian thc (Real-time clock) cho CPU
221, 222 v ngun pin nui ng h v lu d liu. Thi gian s dng n 200 ngy.
* Bin tr chnh gi tr analog: Hai bin tr ny c s dng nh hai ng vo
analog cho php iu chnh cc bin cn phi thay i v s dng trong chng
trnh. 4.1.2 Khi m rng Trn cc CPU tch hp sn mt s cc ng vo v ng ra s,
chng hn nh CPU 224 DC/DC/DC c sn 16 ng vo v 14 ng ra. Tuy nhin
trong thc t , xut pht t yu cu iu khin nh: cn nhiu hn s ng vo/ra c
sn, c s dng tn hiu analog hay c cc yu cu v truyn thng, ni mng cc
PLCm ta phi gn thm vo CPU cc khi m rng (Expansion module) c cc chc
nng khc nhau (bng 4.2). 4.1.2.1 Digital module Cc module s gn thm
vo khi CPU m rng s lng cc ng vo/ra s. Khi ng vo s DI (Digital
Input): Siemens sn xut cc khi ng vo s nh: DI8 x 24VDC, DI8 x
AC120/230V, DI16 x 24VDC. Khi ng ra s (Digital Output): Cc ng ra ny
c chia ra lm 3 loi l ng ra DC, ng ra AC v ng ra relay. in p ng ra c
th l 24Vdc hoc 230Vac ty loi, vi s lng ng ra c th l 4 hoc 8.
49. 4 B iu khin lp trnh PLC Simatic S7-200 41 Ngoi ra cn c s kt
hp cc ng vo vP