fundamentos del controlador programable

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FUNDAMENTOS DEL CONTROLADOR PROGRAMABLE

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¿QUE ES UN CONTROLADOR

PROGRAMABLE?

PROGRAMMABLECONTROLLER

ENTRADAS

• A solid state device that controls output devices based on the status of the inputs, and a user developed program.

• Originally developed to directly replace relays used for discrete control.

OUTPUTS

CR

3

INPUT DEVICES

• Pushbuttons

• Selector Switches

• Limit Switches

• Level Switches

• Photoelectric Sensors

• Proximity Sensors

• Motor Starter Contacts

• Relay Contacts

• Thumbwheel Switches

• 120 VAC

• 240 VAC

• 12 VDC

• 24 VAC/VDC

• TTL

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OUTPUT DEVICES

• Valves

• Motor Starters

• Solenoids

• Control Relays

• Alarms

• Lights

• Fans

• Horns

Relays

• 120 VAC/VDC

• 240 VAC/VDC

• 24 VAC/VDC

Triac

• 120 VAC

MOSFET

• 24 VDC

5

CR

Isolation

BarrierIsolation

Barrier

Inside a PLC

CentralProcessor

MEMORY

program data

HighVoltage

HighVoltage

Low Voltage

AC Power Supply85-264 VAC, 50/60Hz

Circuits

DC Power Supplyor

Communications

Input

Circuits

Output

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PLC’s Come in a Variety of Sizes...

Micro– Typically less than 32 I/O

Small– Typically less than 128 I/O

Medium– Typically less than 1024 I/O

Large– Typically greater than 1024 I/O

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And a variety of shapes/configurations

Packaged

Packaged with expansion

Modular (rack less)

Modular (rack based)

Distributed

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Packaged PLC

INPUTSStop

Start

I/Ø I/1

Motor

M1 OUTPUTO/3

Power supply, Inputs, Outputs and Communication port are enclosed in a single package.INPUT and OUTPUT devices are wired individually to the packaged controller.

OOOOOOOOOOOO

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Packaged PLC with Expansion

Base is identical to the standard Packaged PLC, but it also has the ability to drive additional I/O.The most common form of expansion is a block of I/O that uses the same base, or makes use of different types of expansion “modules”.Connections between the base and the expansion device is either direct (mating connector), or by using a wired approach (ribbon connector is very common).

OOOOOOOOOOOO

2 Slot ExpansionChassis

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Modular PLC’s(The Ultimate in Flexibility)

OUT 0

IN 0

PROG

SLC 5/03 CPURUN

FLT

BATT

FORCE

RS232

DH485

RUN REM

DH-485 Port status indicator

RS-232 Port status indicator

Processor RUN indicatorProcessor FLT indicator

Battery status indicator

Force I/O indicator

Keyswitch RUN, REM, PROG

DH-485 Port connection for programming terminal

RS-232 Port for programming terminal

Power Supply

Input Modules

Output Modules

Mix N Match Components– Processors, Power Supplies and I/O are plugged into a rack or chassis– Available in Small, Medium, and Large platforms– Flexibility results in higher costs when compared to packaged

Modular PLC’s are either rack based or are rack-less

Allen-Bradley SLC-500 and PLC 5 are modular PLC’s

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Modular Rack-Less PLC’s(The Ultimate in Flexibility)

Identical in functionality to rack based PLC’s

Typically not as robust (packaging)

Typically found on “smaller” (small and medium) sized PLC’s.

Will likely become the prevalent form of packaging in the future.

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Distributed

Rely on communications for EVERYTHING

All I/O is connected to the processor through a “High Speed” data link.

Typically found on “larger” (medium and large) PLC’s.

For certain applications this type of form factor is very advantageous.

Usually higher cost for hardware, but much lower cost for system integration.

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Typical PLC Application

Motor

Solenoid 1 Solenoid 2

Solenoid 3

Sensor 1

Sensor 2

Ingredient A Ingredient B

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Operation of Mixer(Defining the Outputs)

Solenoid 1On = Sol 3 is off, and Motor is off, and Sensor 2 is off,

and Auto Switch is onOff = Sol 3 is on, or Motor is on, or Sensor 2 is on

Solenoid 2On = Sol 3 is off, and Motor is off, and Sensor 2 is onOff = Sol 3 is on, or Motor is on, or Sensor 1 is on

MotorOn = Sensor 1 is on, and Solenoid 2 is off, and

Solenoid 1 is offOff = Solenoid 3 on

Solenoid 3On = Sol 1 is off, and Sol 2 is off, and Motor has run

for 30 sec.Off = Solenoid 3 has been on for 60 sec.

Motor

Solenoid 1 Solenoid 2

Solenoid 3

Sensor 1

Sensor 2

Ingredient A

Ingredient B

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Input Wiring

Terminal Block

1

2

3

4

5

6

7

8

9

Input Devices

L1

L1

L210

COM

PLC

Isolation

Barrier

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Output Wiring

OUT 1

Output Devices

L2

L2

L1OUT 1

OUT 2

OUT 2

OUT 3

OUT 3

OUT 4

OUT 4

OUT 5

OUT 5

OUT 6

OUT 6

CR

L1PLC

Terminal Block

Isolation

Barrier

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PLC Operating Cycle

Input Scan

Program Scan

Output Scan

Housekeeping

START

Communications

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Ladder Logic Concepts

| | |/| ( )

Read / ConditionalInstructions

Write / ControlInstruction

| | |/| ( )

| | |/| ( )

| |

| | |/| ( )

| | ( )

| |

Start (Rung #1)

End (Rung #5)

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Logical AND Construction

| |I/4

| |I/5

( )O/0

IF input 004 AND input 005 have power

THEN energize output 0

Off

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Logical AND Construction

IF input 4 AND input 5 have power


| |I/4

| |I/5

( )O/0

Logical Continuity

T T T

On

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Logical OR Construction

| |I/4

| |I/5

IF input 4 OR input 5 have power


( )O/0 Off

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| |I/4

| |I/5

( )O/0

Logical Continuity

T

F

On

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| |I/4

| |I/5

( )O/0

Logical Continuity

T

F

On

| |I/4

| |I/5

( )O/0

Logical Continuity

F

T

Off

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Complex Construction

|/|I/11

| |I/5

|/|I/7

|/|I/1

| |I/3

| |I/2

| |I/4

|/|I/0

| |I/1

| |I/1

|/|I/8

| |I/9

( )O/0

| |I/10

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Input Instructions - XIC, XIO

False

The status of the instruction is If the data file bit is

Logic 0

Logic 1 False

True

True

XICExamine if Closed

-| |-

XIOExamine if Open

-|/|-

INPUT

Input Push Button

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Output Instruction - OTE

RungState

StatusBit

OutputTerminal

De-energized

ENERGIZEDTRUE

FALSE

ON

OFF

OTEOutput Energize

-( )-

| | |/| ( )

T T T

OUTPUT

Output Pilot Light

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Putting it all Together

| | ( )

OUT 0

IN 0

PROG

SLC 5/03 CPU

RUN

FLT

BATT

FORCE

RS232

DH485

RUN REM

INPUT OUTPUTINPUT

IN 0 OUT 0

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Addressing Example

L1 L2PB1 LS1 FS2 SOL6

DEVICE

PB1

LS1

FS2

SOL6

| | ( )| | | |I:1/1 I:1/2 O:3/1I:1/3

ADDRESS

L1 L2

I:1/1

I:1/2

I:1/3

O:3/1

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Relay Logic to Ladder Logic

INPUT Address Assignment:PB1- I:1/1 PB2- I:1/4LS1- I:1/2 LS2- I:1/3LS3- I:1/5 LS4- I:1/6

OUTPUT Address Assignment:SOL2- O:3/0 M1- O:3/1

I:1/1 I:1/2 O:3/0

|/|

CR3

CR3 M1

PB1 LS1 SOL2

PB2LS2

LS3

LS4O:3/1

| | | | ( )

I:1/4I:1/3

I:1/5

B3/0| | | | ( )

| |

|/|B3/0

( )| |I:1/6

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SOURCING vs. SINKING

The Mystery...

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DC Power Supply

+

-

DC COM

+VDC

SOURCING vs. SINKINGDC I/O (General)

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DC Power Supply

DC Power Supply

+

- DC COM

+

-

+VDC

SOURCING Pushbutton SINKING Pushbutton

SOURCING vs. SINKINGDC I/O (General)

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DC Power Supply

Field Device

DC Input Module

DC Input Module

Field Device

DC Power Supply

+

- DC COM

+

-

+VDC

IN1

IN1

SOURCING vs. SINKINGDC Inputs

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DC Power Supply

DC Power Supply

Field Device

Field Device

DC Output Module

DC Output Module

+

+

-

-

DC COMDC COM

+VDC +VDC

OUT1

OUT1

SOURCING vs. SINKINGDC Outputs

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RULES

Field devices on the positive side (+VDC) of the field power supply are sourcing field devices.

Field devices on the negative side (DC COM) of the field power supply are sinking field devices.

Sourcing field devices must be connected to sinking I/O cards and vice versa.

Sinking field devices must be connected to sourcing I/O cards and vice versa.

fundamentos del controlador programable

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