plc_scada d2 final v1

7/28/2019 Plc_scada d2 Final v1

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Sofcon India Pvt. Ltd. C-87, Sector 88, Noida, U.P.

Enriching Skills

INDUSTRIALAUTOMATION ENGINEER

TRAINING

PLC/SCADA

Day 2


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Enriching Skills

Contents

Introduction of PLC Block Diagram of PLC and Role of each module

Types of I/O Modules

I/O configuration types

Scan cycle of PLC

PLC wiring

PLC programming S/W Introduction

Basic Instructions


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Enriching Skills

Introduction of PLC


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Enriching SkillsCOMPARISON

MICROPROCESSOR A multipurpose,

programmable device

that accepts digital data

as input, processes it

according toinstructions stored in its

memory, and provides

results as output.

It is only one

component of anelectronic device and

requires additional

circuits, memory and

firmware or software

before it can function.

MICROCONTROLLER Microcontroller has a

microprocessor, in

addition with a fixed

amount of RAM, ROM

and other peripheralsall embedded on a

single chip.

A microcontroller is a

specialized form of

microprocessor thatis designed to be self-

sufficient and cost-

effective.

PLC

A PLC is a special

microcontroller

designed for industrial

use, that is forcontrolling machinery

or processes.

A PLC is a system that

uses a microprocessor

or microcontroller as

one of the components


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Enriching Skills

PROGRAMMABLE LOGIC

CONTROLLER

A PLC is a microprocessor based, mini-computer

specifically tailored specifically for certain control

tasks

It uses programmable memory to store instructions

and specific functions that include On/Off control,

timing, counting, sequencing, arithmetic and data

handling to control machines and processes


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Enriching Skills

PROGRAMMABLE LOGIC

CONTROLLER

Extensive use of PLCs because of:

Flexible

Faster Response time

Less and simpler wiring

Modular design easy to repair and troubleshoot

Rugged can withstand harsh industrial

surroundings


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Enriching SkillsHISTORY OF PLC

The first PLC systems evolved from conventional computers in

the late 1960s and early 1970s.

Programmable logic controllers were initially adopted by the

automotive industry where software revision replaced the re-

wiring of hard-wired control panels when production models

changed.

The plants had to be shutdown for up to a month at model

changeover time but the early PLCs when used along with

other new automation techniques shortened the changeovertime.



Enriching SkillsHISTORY OF PLC

The earliest PLCs were developed to offer the same

functionality as the existing relay logic systems.

The PLCs:

Could start in seconds

Could bear tough plant environment

Had battery backup



Enriching Skills

GENERAL FEATURES OF A PLC

General characteristics of a programmable controller

include:

Withstands rugged industrial environment, such as

temperature and humidity

Easily installed and maintained

Reusable (i.e., can be moved and reprogrammed)

Modular (i.e., parts can be replaced easily for

maintenance or repair)

Easy transition for people who worked with relays



Enriching Skills

TYPICAL PLC APPLICATION

Here we can see an example of a typical PLC (Programmable LogicController) application. This application could be production of any

liquid product, such as the brewing of a batch of beer. What we see

are several devices that can detect information about the beer. The

sensors are an example of this-- they can detect whether the tank isfilled too much, or too little. We call these devices Input Devices.



Enriching Skills

We can also see devices that can create actions to the batch of beer,

such as the motor, that can turn on and mix the beer, or the valves

that can open or close, to either allow beer ingredients to fill the tank,

or to allow the batch of beer out of the tank to the next stage of the

system. We call these devices Output Devices.

TYPICAL PLC APPLICATION



Enriching SkillsTYPICAL PLC APPLICATION

The instructions that tell the output devices what to do based on

the conditions returned by the input devices are written in

programs that are stored and run by the PLC (Programmable

Logic Controller).


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Enriching SkillsADVANTAGES OF PLCs

FLEXIBILITY

It is easier to create and change a

program in a PLC than to wire and

rewire a circuit.

The program can be modified by

the end-user on field.

Moreover, one model of a PLC can

be used to run numerous

machines with distinct programfor each machine.


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LOWER COST

With day-by-day

improving technology, it is

possible to get morefunctions (relays, timers,

counters, sequencers ) into

smaller and less expensive

packages.


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CAPABILITY OF

COMMUNICATION

PLCs can be communicated to

perform functions such as:supervisory control, data

gathering, monitoring devices

and process parameters, and

downloading and uploading of

programs.


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QUICK RESPONSE TIME

PLCs have real-time operation

which implies that they react

immediately on the input theyobtain.

Real-time operation is a relative

concept that means any task is

guaranteed to be handled within acertain time.


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Enriching Skills

Block Diagram of PLC & Role of

each Module


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Enriching SkillsCOMPONENTS OF PLC


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Enriching SkillsCOMPONENTS OF PLC

There are five basic components in a PLC system:

The PLC processor, or controller

I/O (Input /Output) modules

Chassis or backplane Powersupply

Programming software that runs in a PC

In addition to these 5, most PLCs also have:

A network interface


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Enriching Skills

Stores the control program anddata in its memory

Reads the status of connectedinput devices

Executes the control program

Commands connected outputs tochange state based on programexecution

For example: Turn a light on,start a fan, adjust a speed, ortemperature

Comes in various physical forms

PROCESSOR, CONTROLLER,

OR CPU


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Enriching Skills

Comes in various physical forms:

PROCESSOR, CONTROLLER,

OR CPU


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Enriching SkillsI/O MODULES

Physically connect to field devices

Input modules convert electrical signals coming in frominput field devices such as pushbuttons, to electricalsignals that the PLC can understand.

Output modules take information coming from the PLCand convert it to electrical signals the output fielddevices can understand, such as a motor starter, or ahydraulic solenoid valve.

I/O modules form the interface by which input field devicesare connected to the controller.


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Enriching SkillsI/O MODULES

I/O comes in various forms:


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Enriching Skills

I/O Configuration types


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Enriching SkillsI/O CONFIGURATION: TYPES

Local, Extended-local, and Remote I/O are terms used for

different types of I/O configurations. I/O configurations are

differentiated by the following:

The number and type of modules present in the chassis

The distance of each chassis and module from the processor

The required speed of communications


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Enriching SkillsLOCAL I/O

Local I/O: I/O modules

connected to a processor

across a backplane, thus

limiting their distance from

the processor.

Resident I/O Chassis:

Chassis that houses the

processor.


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Enriching SkillsINPUT MODULES

Input modules interface directly to devices such as switches

and temperature sensors. Input modules convert many different types of electrical

signals such as 120VAC, 24VDC, or 4-20mA, to signals whichthe controller can understand.


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Enriching SkillsINPUT MODULES

Input modules convert real world voltage and currents to

signals the PLC can understand.

Since there are different types of input devices, there is a

wide variety of input modules available, including both digital

and analog modules.


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Enriching SkillsOUTPUT MODULES

Output modules take a signal from a PLC and convert it to a

signal that a field device needs to operate. Since there are different types of output devices, there is a

wide variety of output cards available, including both digital

and analog cards.


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Enriching SkillsCHASSIS/BACKPLANE

All PLCs need some method of communicating between thecontroller, I/O and communications modules.

A chassis provides the following:

Communication pathways between I/O modules and

processor (or other communications adapter) via a circuitboard called the backplane

Power supply connections


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Enriching Skills

SCAN CYCLE OF PLC PLC

OPERATIONA PLC works by continually scanning a program. We can think ofthis scan cycle as consisting of 3 important steps.

The Scan Time, the time required for one full cycle, provides a

measure of the speed of response of the PLC.


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Enriching Skills

BASIC TERMINOLOGY Scan Time: The time required for the controller to read all inputs,

execute the program, and update all outputs.

Program Scan Time: The time required for the controller to

execute the instructions in the program.

I/O Scan Time: The time required for the processor to scan all I/O

modules, writing output data and reading input data.

The following graphic shows both the program and I/O scan time:


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Enriching Skills

Allen Bradley : Micrologix


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Enriching Skills

Allen Bradley : SLC

All B dl PLC


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Enriching Skills

Allen Bradley : PLC

All B dl C t L i


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Enriching Skills

Allen Bradley : Compact Logix

All B dl Fl L i


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Enriching Skills

Allen Bradley : FlexLogix


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Enriching Skills

Wiring of plc- SINK & SOURCE


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Input wiring of plc as sinking


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Enriching Skills

Input wiring of plc as sinkinginput

Opto-coupler


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Enriching Skills

Data files and addressing


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PLC programming S/W

introduction


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RSLinx 2 41Overview


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Enriching Skills

RSLinx 2.41Overview

1784-PCC driver enhanced to increase browsingperformance. The node table object on the card now

determines valid nodes instead of RSLinx browsing for

them.

Support added for a new item property (I.D. is 5000).

This property exists only for ControlLogix items and

will test an item to determine if it is boolean.

New DeviceNet error code added for better addressparsing of parameter errors

RSLinx 2 41Overview


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Enriching Skills

RSLinx 2.41Overview

More support added for OPC 2.05 compliancy.Specific support includes:

Date and Currency

Returning errors when values out of range

Failing the add Items when requested data

type is invalid


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Enriching Skills

Basic Instructions

BASIC INSTRUCTIONS


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Enriching SkillsBASIC INSTRUCTIONS

One organizes ladder logic as rungs on a ladder and put

instructions on each rung. There are two basic types ofinstructions:

Input instruction: An instruction that checks, compares, or

examines specific conditions in the machine or process.

Output instruction: An instruction that takes some action,such as turn on a device, turn off a device, copy data, or

calculate a value.

BASIC INSTRUCTIONS


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Enriching SkillsBASIC INSTRUCTIONS


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PLC PROGRAMMING LADDER


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Enriching Skills

PLC PROGRAMMING LADDER

LOGIC

Each line of code is known as a rung. In this example there are 4 rungs,

numbered 0, 1 and 2, and the end rung marking the end of the program.

The PLC executes the program 1 rung at a time, starting with the first rung andthen working down.

Ladder logic rungs are basically IF-THEN statements. Each individual rung is

executed from the left to the right

OTHER PROGRAMMING


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Enriching Skills

OTHER PROGRAMMING

LANGUAGES

While ladder logic is the oldest and most popularlanguage used in PLCs today, many other languages arewidely in use. Examples are:

Sequential Function Chart (SFC)

Function Block

Structured Text

Higher level languages such as C

REALIZATION OF BASIC GATES


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Enriching SkillsUSING BASIC

PLC INSTRUCTIONS The logical AND function is constructed by series combinations of

digital (discrete) inputs

Two (or more) series components

The logical OR function is constructed by parallel combinations of

digital (discrete) inputs

Two (or more) parallel components

The logical NOT function is constructed by referencing the input

signal with a normally closed contact (XIO instruction)

More complex Boolean expressions can be formulated with various

serial-parallel combinations of XIC and XIO instructions

NAND, NOR, XOR, XNOR


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Enriching Skills

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