ie55103.ppt

8/17/2019 ie55103.ppt

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PROGRAMMABLE

LOGICCONTROLLERS Richard A. Wysk

IE450 - Manufacturing Systems

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PURPOSE OF Programmable

Logic Controllers (PLCs Initially designed to relace relay logic

!oards

" Se#uence de$ice actuation

" %oordinate acti$ities

Accets inut from a series of s&itches

Sends outut to de$ices or relays

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FUNCTIONS OFCONTROLLERS '( on-off control)

*( se#uential control)

+( feed!ack control) and

4( motion control.

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CONTROL !E"ICES

'( mechanical control - cam) go$ernor) etc.)

*( neumatic control - comressed air)

$al$es) etc.+( electromechanical control - s&itches)

relays) a timer) counters) etc)

4( electronics control - similar toelectromechanical control) e,cet useselectronic s&itches.

5( comuter control.

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PROGRAMMABLE LOGIC

CONTROLLERInvented in 1968 as a substitute for hardwired relay panels.

A digitally oerating electronic aaratus &hich uses a

rogramma!le memory for the internal storage ofinstructions !y imlementing secific functions such as

logic se#uencing) timing) counting) and arithmetic to

control) through digital or analog inutoutut modules)

$arious tyes of machines or rocesses. /he digital

comuter &hich is used to erform the functions of a

rogramma!le controller is considered to !e &ithin this

scoe. E,cluded are drum and other similar mechanical

se#uencing controllers.

National Electrical Manufacturing Association NEMA!

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"EN!ORS

Rock&ell

E1anuc

Schnieder

etc.

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PLC

"#$

%yste&

$ser 'adder (iagra&

)or*ing&e&oryregisters

Input

+lag

,utput

InputModule

,utput

Module

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PLC

Con#ig$ration

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%&at 'eices 'oes a PLC interact

)it&*

I23/ REA6S-7contacts(/hese are connected to the outside &orld. /hey hysically e,ist and recei$e signals from s&itches) sensors) etc. /yically theyare not relays !ut rather they are transistors.

I2/ER2A /II/6 REA6S-7contacts( /hese do not recei$e signals fromthe outside &orld nor do they hysically e,ist. /hey are simulated relays andare &hat ena!les a 3% to eliminate e,ternal relays. /here are also somesecial relays that are dedicated to erforming only one task. Some are al&ayson &hile some are al&ays off. Some are on only once during o&er-on and aretyically used for initiali8ing data that &as stored.

%92/ERS-/hese again do not hysically e,ist. /hey are simulated countersand they can !e rogrammed to count ulses. /yically these counters can

count u) do&n or !oth u and do&n. Since they are simulated they are limitedin their counting seed. Some manufacturers also include high-seed countersthat are hard&are !ased. We can think of these as hysically e,isting. Mosttimes these counters can count u) do&n or u and do&n.

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%&at 'eices 'oes a PLC interact

)it&*

Contin$e' /IMERS-/hese also do not hysically e,ist. /hey come in many

$arieties and increments. /he most common tye is an on-delay tye.9thers include off-delay and !oth retenti$e and non-retenti$e tyes.Increments $ary from 'ms through 's.

9/3/ REA6S-7coils(/hese are connected to the outside &orld./hey hysically e,ist and send onoff signals to solenoids) lights) etc./hey can !e transistors) relays) or triacs deending uon the modelchosen.

:A/A S/9RAE-/yically there are registers assigned to simly

store data. /hey are usually used as temorary storage for math or datamaniulation. /hey can also tyically !e used to store data &hen o&er is remo$ed from the 3%. on o&er-u they &ill still ha$ethe same contents as !efore o&er &as remo$ed. ;ery con$enient andnecessary<<

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S%ITC+E

S

(#%-%#(-

Non-locking Locking

Normally Open Normally Closed

Multiple Throw

P1

P2

Multiple Pole

Break-e!ore-make Make-e!ore-reak

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TERM

S /hro& - num!er of states

3ole - num!er of connecting mo$ing arts 7num!er of indi$idual circuits(.

SPDT

(#%-

A serial switch bo A/0 bo! hastwo 2 pin serial ports to switch fro&.

Input

,utput

A 0

3nob

4ow is this switch classified5

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T,PES OF

S%ITC+ES '. =asic s&itch) oerated !y a mechanical le$el)

*. 3ush-!utton s&itch)

+. Slide s&itch)

4. /hum!&heel s&itch)

5. imit s&itch)

>. 3ro,imity s&itch) and

?. 3hotoelectric s&itch.

A-IN7 voltage current

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RELA,S A switch whose operation is activated by an electro&agnet is called a :relay:

contact

coil

input

elay coil ,utput contact

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COUNTE

R:igital counters outut in the form of a relay contact &hen a reassigned count $alue is reached.

6egister

Accu&ulator

contact

input

reset

output

Input

6eset

,utput

"ount ; 1 < = 2 ; 1

2

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TIME

RA timer consists of an internal clock) a count $alue register) and

an accumulator. It is used for or some timing urose.

"loc*

Accu&ulator

contact

reset

outpu

6egister

"ontact

-i&e 2 seconds.

"loc*

6eset

,utput

"ount 1 2 " #$ %

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AN E-AMPLE OF RELA, LOGIC

L1

L&1 PB1 L&2 '1

'1

'1T(M)'

'2

P'*%

1or rocess control) it is desired to ha$e the rocess start 7!y turning on a motor( fi$e

seconds after a art touches a limit s&itch. /he rocess is terminated automatically&hen the finished art touches a second limit s&itch. An emergency s&itch &ill stothe rocess any time &hen it is ushed.

L&1

PB1L&2

'1

T(M)'

%Motor'2

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PLC ARC+ITECTURE

3rogramma!le controllers relace most of the relay anel &iring !y soft&are rogramming.

#rocessor I>,

Modules

Me&ory#ower%upply

#rogra&

'oader

#rinter

"assette

'oader

E#6,M

'oader

%witches

Machines

#eripherals E.ternal (evices

#"

A typical #'"

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PLC

COMPONENTS '. 3rocessor Microrocessor !ased) may allo& arithmetic

oerations) logic oerators) !lock memory mo$es) comuter interface)local area net&ork) functions) etc.

*. Memory Measured in &ords.

R9M 7Read 9nly Memory()

RAM 7Random Access Memory()

3R9M 73rogramma!le Read 9nly Memory()

EE3R9M 7Electronically Erasa!le 3rogramma!le R9M()

E3R9M 7Erasa!le 3rogramma!le Read 9nly Memory()

EA3R9M 7Electronically Altera!le 3rogramma!le

Read 9nly Memory() and

=u!!le Memory.

PLC

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PLC

COMPONENTS +. I9 Modular lug-in erihery

A% $oltage inut and outut)

:% $oltage inut and outut)o& le$el analog inut)

@igh le$el analog inut and outut)

Secial urose modules) e.g..) high seed timers)

Steing motor controllers) etc. 3I:) Motion

4. 3o&er suly A% o&er

5. 3eriheral @and held rogrammer 7loader()

%R/ rogrammer)

9erator console)

3rinter)Simulator)

E3R9M loader)

%assette loader)

rahics rocessor) and

2et&ork communication interface. MA3) A2

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LA!!ER

!IAGRAM A ladder diagram 7also called contact sym!ology( is a means of

grahically reresenting the logic re#uired in a relay logic

system.

+

'1

PB1 PB2

'1

'1

start emergency stopail

ung

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La''er Re.resentation

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PLC %IRING

!IAGRAM

$1 $2 2$

2$

2$ 11

$1

$2

$"

11

12

+

PLC(nput Output

Eternalswitches

%tored progra&

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SCA

N

begin

Input

,utput

esolvelogic

Idle

A 3% resol$es the logic of a ladder diagram 7rogram( rung !y rung) from the to to

the !ottom. sually) all the oututs are udated !ased on the status of the internalregisters. /hen the inut states are checked and the corresonding inut registers are

udated. 9nly after the I9s ha$e !een resol$ed) is the rogram then e,ecuted. /his

rocess is run in a endless cycle. /he time it takes to finish one cycle is called the scan

time.

%can cycle

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PLC

INSTRUCTIONS '( Relay)

*( /imer and counter)

+( 3rogram control)

4( Arithmetic)

5( :ata maniulation)

>( :ata transfer) and

?( 9thers) such as se#uencers.

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LOGIC STATES

92 /RE) contact closure) energi8e) etc.

911 1ASE) contact oen ) de-energi8e)

etc.

In the notes we use the sy&bol :?: to represent

negation. AN( and , are logic operators. !

(o not confuse the internal relay and progra& with the eternalswitch and relay. Internal sy&bols are used for progra&&ing.Eternal devices provide actual interface.

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AN! an' OR

LOGIC PB1 '1PB2

'2

'1 * PB1,+N-,PB2

'2 * PB2,+N-,.PB#

PB" PB#

PB1 '1

PB2

'1 * PB1 ,O', PB2

AN(

,

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COMBINE! AN! / OR

1 @ #01 .,. #0 .AN(. #0<!

PB1 '1

PB2 p"

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RELA, A elay consists of two parts the coil and the contacts!.

%ontacts

a. 2ormally oen -B B-

!. 2ormally closed -BB-

c. 9ff-on transitional -B↑B-

d. 9n-off transitional -B↓ B-

%oil

a. Energi8e %oil -7 (-

!. :e-energi8e -7(-

c. atch -7(-

d. nlatch -7(-

!

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TIMERS AN! COUNTERS

/imers

a. Retenti$e on delay -7R/9(-

!. Retenti$e off delay -7R/1(-

c. Reset -7RS/(-

%ounter

a. %ounter u -7%/(-

!. %ounter do&n -7%/:(-

c. %ounter reset -7%/R(-

-, counting stop countingresu&e

-+ stop counting stop

-rue +alse -rue

Input

-, reach # value output ,N-+ reach # value output ,++

# value in ;.1 second

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SE0UENCE

R%euencers are used with &achines or processes involving

repeating operating cycles which can be seg&ented intosteps.

9utut

Ste A = % :&ell time

' 92 911 911 5 sec.

* 92 92 911 '0 sec.

+ 911 911 92 + sec.

4 911 92 911 C sec.

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A1B

PLC I9 oints are num!ered) they corresond to the I9 slot on

the 3%.

1or A-= controller used in our la!I9 uses '-+*

Internal relays use 0++ - 0CD

Internal timerscountersse#uencers use C0'-C+*Status C5'-CD*

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Programming a PLC

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La''er Logic #or Tan2

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Logic #or La''er Sol$tion

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+o) 'oes it )or2*

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PROGRAMMING E-AMPLE

3Part

microswitch

Bar code reader

&topper

Con/eyor

Machine'oot

id descrition state e,lanation

MSI micros&itch ' art arri$e

R' outut to !ar code reader ' scan the art

%' inut from !ar code reader ' right art

R* outut ro!ot ' loading cycle

R+ outut ro!ot ' unloading cycle

%* inut from ro!ot ' ro!ot !usy

R4 outut to stoer ' stoer u

%+ inut from machine ' machine !usy

%4 inut from machine ' task comlete

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SOLUTIO

N $1$2

$"

$#

$%

1112

1"

1#

1%

(nputOutput

ProgrammaleControllerPLC

M&1

C1

C2

C"

C#

'1

'2

'"

'#

$1 1# 11

$2

1# $# $"

1#

12

1"$% $"

Rung '. If art arri$es and no

art is stoed) trigger the !ar code reader.

Rung *. If it is a right art)acti$ate the stoer.

Rung +. If the stoer is u) themachine is not !usy and the

ro!ot is not !usy) load the art onto the machine.

Rung 4. If the task is comletedand the ro!ot is not !usy)unload the machine.

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%IRING !IAGRAM

0#

0%

00

0

$

1

#rogra&&able"ontroller

input output

e!!erson 'ed

e!!erson 3ellow

e!!erson 4reen

Main 4reen

Main 3ellow

Main 'ed

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PROGRAM

(3RUNG1

RUNG2

RUNG3

RUNG4

RUNG5

RUNG6

RUNG7

RUNG8

RUNG9

RUNG10

RUNG11

RUNG12

20

67

RTO

903 66

RTO

901

80

RTO

902

30

901 902 67 M. Red

901 903 66 J. Green

902 904 71 M. Green

904 905 70 M. Yellow

RST

RST901 904

RTO

904

40

71

RST901 903

RST901 902

901 901

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PROGRAM

(4 RUNG13

64RTO

907

50

65

RTO

906

10

70RTO

905

10

903 906 65 J. Yellow

902 64

907 J. Red

RST901 907

RST901 906

RST901 905

RUNG14

RUNG15

RUNG16 RUNG17

RUNG18

RUNG19

RUNG 20

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ie55103.ppt