title of presentation - srm university - industrial... · before the plc, control, sequencing, and...

Title of presentation

1

PLC TRAINING

PLC

BASIC

CONCEPTS

2

Basics Concepts of PLC

CPU/ RAM/ Hard disk

Key board, Mouse,Remote station (LAN)

CPU/Memory

Inputs

Monitor, Printer, Projector Etc.,

Outputs

Power Supply

OS: Windows XP /SW: MS OfficeSoftware

220V AC, 1 Ph.

PLCComputer

Calculator etc.,Internal

CPU/ RAM/ Flash Card

Push Button, Selector, Limit Switch, PxS, Bus Interface

Solenoids, Relays, Lamps, Motors, HMI

OS: Firmware / SW: Machine Logic

220V AC / 24V DC

Markers, Timers, Counters, FBs

PLC & PC In Comparison

3


Inputs

Outputs

ControllerMachine

Relays, Solenoids, Power contactors

Actuators: Motors, Cylinders, Heaters, Lamps etc.,

Push Buttons, Selector Switches

Limit Switch, Proximity,Reed Switch etc.,

Command Signals Status Signals

HMI

Machine Automation Over View


4


Push Button Selector Switch

Inputs – Sample Pictures

5


Power Contactor

Over Load Relay

Aux. Contactor

Relays

Relay Boards

Outputs ‐ Switch Gear Products Over View

6


Cylinders Servo Motor

Manifold Block

Solenoid Coils

Outputs ‐ Actuators

9


Before the PLC, control, sequencing, and safety interlock logic for manufacturing automobiles was accomplished using hundreds or thousands of relays, cam timers, and drum

sequencers and dedicated closed‐loop controllers. The process for updating such facilities for the yearly model change‐over

was very time consuming and expensive, as electricians needed to individually rewire each and every relay.

History of PLC

10


The PLC is an industrial computer.

It is capable of storing instructions to implement control functions such as

sequencing, timing, counting, arithmetic, data manipulation and communication.

The I/O interfaces provide the connection between the PLC and the

information providers (inputs like pushbuttons, sensors,…) and the controllable

devices (outputs like valves, relays, lamps,…).

What is a PLC ?

11


The PLC controls industrial machines and processes. In different areas of the

industry PLC are being applied, e.g.: materials handling, packaging, palletizing,

milling, boring, grinding, filling,

sorting, weighing,...etc.

Where is the PLC used ?

12


In the past the movements of industrial machines were controlled by relay

circuits. These relay-controlled systems were replaced by PLC.

The primary function of the PLC was to perform the sequential operations that

were previously implemented with relays.

Before we can talk about the working method of an PLC, we must

understand the function of relay circuits.

How does PLC work ?

13


A relay is an electrical switch.

It contains:

a iron core

a coil a switch

and a iron bar connected to the switch

What is a Relay ?

14


When a current goes through the coil...

I

How does a Relay work ?

15


… a magnetic field is produced in the coil and the iron core in the coil

becomes magnetic.

I


16


The electromagnetic force pulls in the switch and...

I


17


…a current can go through the switch.

I I


18


The answer to this question shall be shown with the following example

circuits, A, B, C, and D.

L1

S1

24V

0V

K1K1

technical symbol of a relay

coil

electro magn. connection

internal switch

A).

How does the PLC replace Relay in an electric circuit ?

19


The answer of this question shall be shown with a little example circuit.

K1 L1

S1

24V

0V

Function of the electrical circuit:

When the user presses button S1, the relay

K1 pulls in its internal switch and the lamp

L1 turns on.

B).


20



K1 L1

S1

24V

0V

24V

S1

0V

L1

PLCInput

Output

Power

Power

C).


21



K1 L1

S1

24V

0V

S1

24V

0V

L1

PLC logic

D).


22


S1

24V

0V

L1

SPS logic

The PLC logic is not a mechanical part of the controller.

The PLC logic is a software program, which runs on the

processor in the PLC. This program has to be created with a

special programming tool on a PC. After downloading the

the program into the PLC, the control

automatically starts the program.

What is PLC logic ?

23


START PB STOP PB PC

PC

TMR1

TMR1

Ph. N220V AC SUPPLY

LADDER PROGRAMI1 I2

Q1

Q1

M1TMR1

En

M1

Trig

Time

Q

T#5s

Q1

RELAY LOGIC

24


Communication module

Power supply Input modules

Output modules

RAM E-EPROMnetwork

power cord

Machine

Programming tool CPU

PLCHow a PLC works: internal

25




Output modules

RAM E-EPROMnetwork

power cord

Machine


Central processing unit


26




Output modules

RAM E-EPROMnetwork

power cord

Machine


Working- and program memory


27




Output modules

RAM E-EPROMnetwork

power cord

Machine


Program editor and monitoring


28




Output modules

RAM E-EPROMnetwork

power cord

Machine


Sensor signal input


29




Output modules

RAM E-EPROMnetwork

power cord

Machine


Actuator command output


30




Output modules

RAM E-EPROMnetwork

power cord

Machine


Control communication


31


Read input signals, store in table

Determine new output state of output module

Write output commands in table

Set output values on output module

Read user program & Copy to RAM

Start PLC from E-EPROMpr

oces

sing

cyc

le

How PLC works: processing cycle

32


Schematic:

Starting position: vac. off, slide right, up; swivel not used (front position)

Sequence of movements:1) slide left 5) move down

2) move down & switch on vacuum 6) switch off vacuum

3) move up 7) move up

4) slide right

pick

place

shuttlecylinder

swiveldevice

up/down cylindersuction

pad

Pick & Place Unit

33


Animation:

Sequence of movements:

slide leftmove down & vacuum onmove upslide rightmove downvacuum offmove up

title of presentation - srm university - industrial... · before the plc, control, sequencing, and...

Documents