report

Summer Internship Project Report
June 2014
Automatic FEEDING ,measuring temperature
& ejecting of components using plc
At
Central Institute of Tool & Design,Hyderabad
Under The Guidance of
Mr Babulal
Submitted by:-
Sai Shubhankar
Er no-A4717211003
7th
sem
B.tech-Aerospace +M.tech-Avionics
Amity Institute of Space Scince & Technology
Noida,U.P.

CERTIFICATE
This is to certify that Mr SAI SHUBHANKAR DUAN,a student
of B.Tech. in AEROSPACE+M.Tech. AVIONICS(DUAL DEGREE) has
carried out the work in the project of the summer internship
entitle "automatic feeding,measuring temperature
and ejecting of component using plc" as a part of
Third year programme of B.Tech in AEROSPACE+M.Tech In
AVIONICS from Amity Institute of Space Science and Technology,
Amity University, Noida, Uttar Pradesh under my supervision.
Name & signature of the industry guide
Uday bhaskar reddy
DIRECTOR TRAINING
CENTRAL INSTITUTE OF TOOL AND DESIGN,
HYDERABAD

Acknowledgement
I would like to take this opportunity to thank and express my deep
sense of gratitude to my industry guide Mr Babulal,engineer
grade-III. I am greatly indebted to him for providing me his valuable
guidance at all stages of study ,his advice, constructive suggestion,
positive and supportive attitude and continuous encouragement
without which it would have not possible to complete the project.
I would like to thanks MR Krishna swamy(Director,CITD) who in
spite of busy schedule has co-operated continuously and indeed,his
valuable contribution and guidance have been certainly
indispensable for my project work.
I owe my wholehearted thanks and appreciation to entire staffs of
the company for their cooperation and assistance during the course
of my project.
I hope that I can build upon the experience and knowledge I have
gained and make a valuable contribution towards this industry in
coming future.

Abstract
Mechatronics is “the synergistic integration of Mechanical Engineering with Electronics
and intelligent control algorithms in the design and manufacture of products process”.
This subject is invented by Japanese engineer in1969.Mechatronics is used in the design
and manufacturing of products in large industries. Mechatronics is more than a control
systems.
Automation is a technology dealing with application of ‘mechatronics’ and computers
for production of goods and services. In the scope of industrialization ,it is a step beyond
mechanization. Whereas mechanization provides human operators with machinery to
assist them with the physical requirements of work ,automation greatly reduces human
sensory and mental requirements as well specialised hardened computers referred to
as “Programmable Logic Controllers”(PLC’s), are used to synchronized the flow of
inputs from sensors and events with the flow of outputs to the actuators and events.
This leads to precisely controlled actions the permit a tight control of any industrial
process.
Under the mechatronics the systems available are pneumatics, electro-pneumatics,
hydraulics, electro-hydraulics, programmable logic control(PLC).Pneumatics deals with
the systems which work on air pressure. Hydraulics deals with the systems involving
fluids. Electro pneumatics and electro hydraulic system deal electrical systems to
control pneumatic and hydraulic systems. PLC is the hardware which can be
programmed , to define the relationships among inputs given to PLC and outputs taken
from the PLC.
Purpose of pneumatics, electro-pneumatics, hydraulics, electro-hydraulics and PLC is
same i.e. to automate the production and manufacturing. But every system has its own
advantages and disadvantages. System is chosen depending the advantages that suits
the requirement.
The project “Automatic feeding, measuring temperature and ejecting of components
using PLC” is used to measuring temperature of various components. The project is
being explained in Programmable Logic Controller which form the control unit of this
project.
Depending upon the inputs received from the sensors, the programmable controller
generates required actuating signals for the cylinders that help in placing components
at a specified position.
For this purpose we use proximity sensors, PLC software, power supply, solenoid valves
caps and containers which are required for setup. As it LCA(Low Cost Automation) this
process of sorting may increase the speed and meet the requirements with less manual
labour.

TABLE OF CONTENTS
PART 1: Training on Mechatronics
 CHAPTER 1 :AUTOMATION
1.1 Introduction
1.2 Types of Automation
1.3 Advantages of Automation
1.4 Disadvantages of Automation
 CHAPTER 2 :PNUEMATICS
2.1 Introduction
2.2 Gases used in Pnuematic system
2.3 Pnuematic Logics
2.4 CETOP Symbols
2.5 Valves
2.6 Applications of pneumatics
2.7 Advantages of Pnuematics
2.8 Disadvantages of Pneumatics
 CHAPTER 3 : ELECTRO-PNUEMATICS
3.1 Introduction
3.2 Types of valves in Electro-Pnuematics
3.3 Solenoid
3.4 Cylinder
3.5 Compressor
3.6 Ladder Diagram
3.7 Advantages of Electro-Pnuematics
3.8 Disadvantages of Electro-Pneumatics

 CHAPTER 4 : SENSORS
4.1 Introduction
4.2 Sensor Performance
4.3 Classification of Measurement errors
4.4 Sensor Deviations
4.5 Types of Sensors
 CHAPTER 5 : PROGRAMMABLE LOGIC CONTROLLERS
5.1 Introduction
5.2 Building block of PLC
5.3 Constituents of PLC
5.4 PLC Scan
5.5 How it differs from the Computers ?
5.6 Basic requirements
5.7 Programming a PLC
5.8 Program Structure
5.9 STEP 7 Programming
5.10 Advantages
5.11 Applications
PART 2 :
 CHAPTER 6 : PROJECT
Automatic feeding, measuring temperature and ejecting of
components using PLC.
 Bibliography & reference :

Chapter 1
Automation
1.1 INTRODUCTION:
Definition: It is process of replicating human efforts through the application of machines.
The word ―AUTOMATION‖ derived from the Greek words ―AUTO‖ and ―MATOS‖
means self -acting.
It is the technology dealing with the application of mechatronics and computers for
production of good and services.
The biggest benefit of automation is that it saves labour, however, it is also used to save
energy and materials and to improve quality, accuracy and precision.
Automation has been achieved by various means including mechanical, hydraulic,
pneumatic, electrical, electronic and computers, usually in combination. Complicated
systems, such as modern factories, airplanes and ships typically use all these combined
techniques.
 Automation Technology Includes:-
 Automation machine tools to process plans
 Automation assembly machines
 Industrial Robotics
 Automation material handling and storage system etc.
 MAIN COMPONENTS OF AUTOMATION:
1.ACTUATORS :- An actuator is a type of motor for moving or
controlling a mechanism or system. It is operated by a source of energy, typically
electric current, hydraulic fluid pressure or pneumatic pressure , and converts that
energy into motion.
2.CONTROLLERS :- Controllers are those components which take signals
from sensors and control the motion of the actuator.
3.SENSORS :- A sensor is a converter that measures a physical quantity
and converts it into a signal which can be read by an observer or by an instrument.
Every automated system has these 3 components. CETOP symbols are used to
denote or represent correctly the actuators and mainly controllers.

1.2 TYPES OF AUTOMATION:
Automation based on production is classified into 3 basic types:
1.Fixed Automation (Hard Automation)
2.Programmable Automation (Soft Automation)
3.Flexible Automation
1.2.1 FIXED AUTOMATION:
Fixed automation refers to the use of special purpose equipment to automate a
fixed sequence of processing or assembly operations. Each of the operation in the
sequence is usually simple, involving perhaps a plain linear or rotational motion
or an uncomplicated combination of two. It is relatively difficult to accomodate
changes in the product design. This is called hard automation.
 Advantages:
1. Low Unit cost
2. Automated material handling
3. High production rate
 Disadvantages :
1. High intial Investment
2. Relatively inflexible in accommodating product changes.
1.2.2 PROGRAMMABLE AUTOMATION :
In programmable automation, the production equipment is designed with the capability
to change the sequence of operations to accomodate different product configurations.
The operation sequence is controlled by a program, which is a set of instructions coded.
So that they can be read and interpreted by the system. New programs can be prepared
and entered into the equipment to produce new products. Examples: Numerical
controlled machine tools, industrial robots and programmable logic controller
 Advantages :
1. Flexible to deal with design variations.
2. Suitable for batch production.
 Disadvantages :
1. High investment in general purpose equipment.
2. Lower production rate than fixed automation.
Programmable automation can be further divided into 2 types according to the
investment required for the automation.
1. Low cost Automation 2. High cost Automation

1.2.3 FLEXIBLE AUTOMATION :
Flexible automation is an extension of programmable automation. A flexible
automation system is capable of producing a variety of parts with virtually no
time lost for changeovers from one part style to the next. There is no lost
production time while reprogramming the system and altering the physical set
up.
 ADVANTAGES :
1. Continuous production of variable mixtures of product.
2. Flexible to deal with product design variation.
 DISADVANTAGES :
1. Medium production rate
2. High investment
3. High ‘unit cost relative to fixed automation.
1.3 ADVANTAGES OF AUTOMATION :
 Increased through output or productivity.
 Improved quality or increased predictability of quality.
 Improved robustness (consistency), of processes or product.
 Increased consistency of output.
 Reduced direct human labour costs and expenses.
1.4 DISADVANTAGES OF AUTOMATION:
 Causing unemployment and poverty by replacing human labour.
 Security Threats/Vulnerability
 Unpredictable/excessive development costs
 High initial cost

CHAPTER 2
PNUEMATICS
2.1 INTRODUCTION:
Pnuematics is a section of technology which deals with study and
application of pressurized gas to produce mechanical motion. Pnuematic
systems that are used extensively in industries and factories are commonly
plumbed with compressed air or compressed inert gases.This is because a
centrally located and electrically powered compressor, that powers cylinders
and other pnuematic devices through solenoid valves, can often provide motive
power in a cheaper,safer,more flexible and more reliable.
Pnumatics also has applications in density, mining etc.
2.2 GASES USED IN PNUEMATIC SYSTEM:
Pnuematic system in fixed installments such as factories used compressed
air because a sustainable supply can made by compressing atmospheric air. The
air usually has moisture removed and a small quantity of oil is added at the
compressor to prevent corrosion and lubricate mechanical components.
In portable pnuematic tools such as Robot War machine compressed
carbon dioxide is used.
2.3 PNUEMATIC LOGICS:
Pnuematic logic systems sometimes called as air logic control are often
used to control industrial processes, consisting of primary logic units such as:
 AND logic

 OR logic
 Latching units
 Timer units
Pnuematic logic is reliable and functional method for industrial purposes. Now
a days these systems are replaced by analog electronic or digital control system
in new installation because of the smaller size,lower cost, highly accurate, and
more powerful features of digital control.
 Pnuematic system is an open system.
 Operating pressure is 4 to 6 bars.
 The basic principle behind the compression of air is "Boyle's law".
2.4 CETOP SYMBOLS:
Comité Européen des Transmissions Oléohydrauliques et Pneumatiques is the
full form of CETOP.
CETOP represents more than 1000 companies- mainly some manufactures but
also some dealers with almost 70,000 employees and market value is about 13
billion EUROS.
2.4.1 Symbol:
Symbol consists of a line, letter, abbrevation which identify the purpose and
method of operation of the component representation.
1. Line:
a) Straight or direct line: Working line,pilot supply.
b) Dotted or dashed line: Pilot line or pilot control.
c) Chain line: Envelop/casing.
2. Letters:
A,B-working ports.
P-Pressure port
Z,Y-pilot port
R,S-Exhaust port
3. Numbers:
2,4-working ports
1-pressure port
12,14-pilot ports
3,5-Exhaust port
4. Abbrevation:
a)FLR: Filter Regulator Lubricator
b)DCV: Direction Control Valve
c)NRV: Non Return Valve
d)FCV: Flow Control Valve
2.5 VALVES:
A valve is a mechanism either to control the flow of gas or a mechanism
operated by a gas control to control the flow of some or other fluid.
A valve which requires pressurized air to operate open or close is known as
pnuematic valve.The valves in the pnuematics are referred as "Pilots".

2.5.1 TYPES OF VALVES:
In general valves are divided into 5 depending on the no of ports and
positions.
1)2/2 valve
2)3/2 valve
3)4/2 valve
4)4/3 valve
5)5/2 valve
 2/2 valve:
A directional control valve with two ways,two ports and two positions.
Upper value represents the no of ports lower and lower value represents no
of positions.
 3/2 valve:
A directional control valve with 3 ways ,3ports,2 positions.
Out of 3 ports we have
a)1 input
b)1 output or working port
c)1 exhaust
 4/2 valve:
A directional control valve with 4 ways ,2 ports,2 positions.

Out of 4ports we have
a) 1 input(p)
b) 2 outputs or working ports(A,B)
c) 1 exhaust
 4/3 valve:
A directional control valve with 4 ways,4 ports,3 positions.
 5/2 valve:
A directional control valve with 5 ways, 5 ports and 2 positions.
Out of 5 ports we have:

a)1 input or pressure(p)
b)2 working ports(A,B)
c)2 exhausts(R,S)
2.5.2 AND & OR LOGICS VALVE:
AND logic:
It is a two pressure valve.
OR logic:
It have two inputs,parallel connections.
2.6 APPLICATIONS OF PNEUMATICS:
 Industrial applications:
1)Clamping
2)Shifting
3)Positioning
4)Orientating
 General applications:
1)Packing
2)Feeding
3)Door control
4)Metering
5)Transfer of materials
6)Sorting of parts
7)Stocking of components
8)Stamping or embossing of components
 Machining and working operations:
1)Drillling

2)Turning
3)Milling
4)Measuring of components
2.7 ADVANTAGES:
 The availability of air is more this is the main advantage.
 Transportation is easy.
 Less temperature fluctuations.
 Components are relatively inexpensive.
 More speed and accuracy.
 Storage is easy and portable.
2.8 DISADVANTAGES:
 It requires good preparation. Dirt and condensate shouldn’t be present.
 Noise level is high .
 Force requirement is more .
 Compressed air is relatively expensive as conveying power.

CHAPTER 3
ELECTRO -PNUEMATICS
3.1 INTRODUCTION:
Electro-pnuematics is the control system of pipe organs where by air
pressure, controlled by electric current.The control of Pnuematics by electrical
impulses is known as Electro pnuematics.
This science is fast and expanding as it can make use of all electronic
development such as PLC'S and PC'S. However the electro pnuematics has
restrictions as it cannot be used in the places where electricity cannot be used
such as gas factories etc.
Here the actuator is pnuematic, controller is electric circuit.The solenoid are
used as inputs in this system.This works on the law of electro magnetic
induction.Many things can be done by using air pressure and remote control.
3.2 TYPES OF VALVES IN ELECTRO PNUEMATICS:
These are same as the pnuematic valves instead of pilots we use solenoids in
the electro pnumatics.
1. 2/2 valve

2. 3/2 valve
3. 4/2 valve
4. 5/2 valve.
In general we use 3/2 and 4/2 valves. For these valves we have normally
opened and normally closed positions depending up on the requirement.A 3/2
valve can be used as a push button valve or start button.
3.3 Solenoid:
A coil of wire that generates an electro magnetic force when a current is
applied.When activated,solenoids can open and close valves.There are two
types of operations of a electropnumatics:
 Single solenoid operation
 Double solenoid operation
 In electro pnumatics, the signal medium is electrical signal either AC or DC
source is used.
 Working medium is compressed air.
 Operating voltages are around 12V to 220V oftenly used.
 The final control valve is activated by solenoid actuation.
 The resetting of the valve is either by single solenoid or double solenoid.
Valves ,compressors and the cylinders plays a major role in the electro
pnuematics.
3.4 CYLINDER:
Electro pnuematic cylinders use air pressure differentials to produce force
and motion resulting in the work.
3.4.1 TYPES OF CYLINDERS:
 Single acting cylinder
 Double acting cylinder

 Double rod cylinder
 Diaphram cylinder
 Rotary cylinder
 Cushion cylinder
 Tander cylinder
 Telescopic cylinder
 Plunger cylinder
 Impact cylinder
 Duplex cylinder
 Cable cylinder
 Rod cylinder
 Muscle Cylinder
In general we use single acting and double acting cylinders. The rest of these
are used in the grinding mechanism, shoes manufacturing, garbage collecting,
pnuematic press, in buses for adjusting seats, automatic opening and closing the
doors in buses or malls etc..
5. Single acting cylinder:
It defined as a pneumatic actuator that directs energy in one direction.
a)It has only one opening and it acts as both the inlet and outlet depending
up on the situations.
b)It consists of a spring which is used for forward and backward movement of
the piston helps to return in the home position.
c)The single acting cylinder is controlled by one 3/2 valve.
Single acting cylinder is sub divided into
1)Spring to push
2)Spring to pull

Use: Used for clamping or holding purpose
6. Double acting cylinder:
It is defined as a pneumatic actuator that directs energy in two directions.
a)It has two ports one is inlet and the other is out let.
b)The double acting cylinder is controlled by two 3/2 valves.
c)When air sent though the in let the piston of the cylinder moves
forward, and when air is returned back the cylinder automatically moves in
reverse or back ward direction.

Use: Used for feeding purpose.
3.5 COMPRESSOR:
It is defined as a component that pressurizes the ambient air and directs into
a electro pneumatics.
3.5.1 TYPES:
 Centrifugal type
 Piston type
 Gear type axial type
 Pressure regulation type
 Screw type.
3.6 LADDER DIAGRAM :
Ladder diagrams are specialized schematics commonly used to document
industrial control logic system .They are called "Ladder Diagrams" because they
resemble a ladder.
It has two vertical rails (Supply power) and as many "rugs"(horizontal
lines )as they are control units.
Ladder diagram includes
1)Coils
2)Timers
3)Monostable Vibrators.
 —( )— :A regular coil energized when the rug is closed.
 —()— : A "not"coil energized when rug is opened.

3.6.1 SYMBOLS:
3.6.2 Advantages of ladder diagram:
 It is a simple graphical technique which is easy to understand.
 Used in a part of documentation file.
Disadvantages of ladder diagram:
 Complexity is more.
3.7 ADVANTAGES ELECTRO PNUEMATICS:
 Better adaptability and flexibility.
 Easy automation.
 Temperature is flexible.
 Higher reliability.
 Lower planning and commissioning
 Lower installation effort.

 Simpler exchange information between several controllers.
 Equipment cost is less compared to pnuematics.
3.8 DISADVANTAGES OF ELECTRO PNUEMATICS:
 System use two supply units (pnuematic and electric).
 Hazard of electrocution.

CHAPTER 4
SENSORS
4.1 INTRODUCTION:
 To be useful ,system must be interact with their environment.To do this they
use sensors and actuators.
 Sensors and actuators are the examples of transducers.
 A transducr is a device that converts one physical quantity into another.
Almost any physical property of a material that changes in a response to
some excitation can be used to produce a sensor.
-Widely used sensors includes those that are:
Inductive Sensors
Capacitive Sensors
Elastic Sensors
Thermal Sensors
Photoresistive Sensors
Piezoelectric Sensors
 Thermal Sensors
4.2 SENSOR PERFORMANCE:
 Range: Maximum and minimum values that can be measured.
 Resolution: Smallest indiscrinable change in measured values.
 Errors: Difference between measured and critical values.
 Accuracy,uncertainity,inaccuracy:Accuracy is a measure of
maximum expected error.
4.3 Classification of measurement errors:
 Is sensitive to measure the property only.
 Is insensitive to the any other property likely to be encountered in its
application.
 Does not influence the measured property.
Ideal sensors are to be linear to some simple mathematical function of

measurement, typically logarithmic. The output of such sensors is an analog
signal and linearly proportional to the value or simple function of the measured
property.
The sensitivity is then defined as the ratio between output signal and
measured property.
4.4 SENSOR DEVIATIONS:
If sensor is not ideal several types of deviations are observed:
 The sensitivity may in practice differ from the value specified. This is called
sensitivity error,but the sensor is still linear.
 Noise is a random deviation of a signal that varies in time.
 Hysterisis is an error caused by when the measured property is in reverse
direction, but there is some finite lag in the time for the sensor to respond,
creating a different offset error in one direction than in the other.
 Long term drift usuallly indicates a slow degradation of sensor properties
over a long period of time.
 If the sensor has a digital output,the output essentially an approximation of
measured property.The approximation error is also called as"Digitization
error".
CLASSIFICATION OF SENSORS:
The sensors are classified into the following criteria:
 Primary input quantity.
 Transduction principles.
 Materials and technology.
 Property.
 Applications.
4.5 TYPES OF SENSORS:
 Temperature sensors
 IR sensor
 UV sensor
 Touch sensor
 Proxmity sensor
1) Temperature Sensor: This device collects the information about the
temperature from a source and converts into the form that is understandable
by a person or a device. The outside temperature is source element for the
temperature measurement. The position of the mercury is observed by the
viewer to measure the temperature.
Temperature sensors are basically divided into two types:
a)Contact Sensor:This requires direct physical contact with object.
b)Noncontact Sensor: This does not require any physical contact.
Eg: Thermocouple, Resistant Temperature Detectors (RTD), Thermisters.

2) IR Sensor: This device emits AND/OR detects infrared radiation to
sense a particular phase in the environment.
Generally thermal radiation is emitted by all the objects in the infrared
spectrum.
Infrared Sensors detects the radiations which are not visible to the
human eye.
Advantages:
1)Easy for interfacing.
2)Readily available in the market.
Disadvantages:
Disturbed by the noises in the surroundings such as radiations,etc.
Applications:
*Thermography
*Heating
*Spectroscopy
*Meteorology
*Photo-biomodulation
*Climatology
*Communication
3) UV Sensor: These sensors measure the power or intensity of the
ultraviolet radiation. This form of electromagnetic radiation has longer wave
lengths compared to x-rays but still shorter than the visible radiation. UV
sensors discover the exposure environment to ultraviolet radiation.
Eg: ultraviolet light detectors, photo stability sensors.
Applications:
1)Measures the portion of UV spectrum which sunburns human skin.
2)Pharmacy
4)Robotics
4)Printing industry for solvent handiling and dyeing process.
5)Chemical industry for the storage,production and transportation.
4) Touch Sensors: Touch sensor acts as a variable resistor as per the
location where it is touched.
The touch sensor is made of:
*Fully conductive substance such as copper.
*Insulated spacing material such as foam or plastic.
*Partially conductive material.
Applications:
 Commercial-Medical, vending, fitness and gaming.
 Appliances-Oven, Refrigerators.

 Transportation-Cockpit fabrication.
 Industrial automation-Position and liquid level sensing.
 Proximity Sensor:
A proximity sensor detects the presence of objects that are nearly placed
without any point of contact. Since there no contact between the sensor and
the sensed objects and lack of mechanical parts, these sensors have long
functional life and high reliablility.
Different types of proximity sensors are:
a)Inductive Proximity Sensors
b)Capacitive Proximity Sensors
c)Ultrasonic Proxmity Sensors
Working: The proximity sensor emits an electromagnetic radiation
And waits for the return signal or changes in the field. The object which is
being sensed known as "Proximity Sensor's Target".
a) Inductive proximity sensors: They have an oscillator as input to
change the loss resistance by proximity of an electrically conductive
medium.These sensors are preferred for metal targets.
b) Capacitive Proximity Sensors: They convert the electrostatic
capacitance variation flanked by the detecting electrode and ground electrode.
This occurs by approaching the near by object with a variation in the oscillation

frequency.
c) Ultrasonic Sensors: These works on the principle similar to radars
which evaluate attributes of a target by interrupting the echoes from the radio or
sound waves respectively. These sensors generate high frequency sound waves.
Applications:
*Conveyor systems
*Roller coasters
*Parking Sensors
*Used in automation engineering
*Used in windows, the alarm is activated to when the window opens.
*Used in machine vibration monitoring.

CHAPTER 5
PROGRAMMABLE LOGIC CONTROLLER
5.1 INTRODUCTION
A Programmable Logic Controller, PLC or Programmable Controller is
a digital computer used for automation of electromechanical processes, such as control of
machinery on factory assembly lines, amusement rides, or light fixtures. PLCs are used in
many industries and machines. Unlike general-purpose computers, the PLC is designed for
multiple inputs and output arrangements, extended temperature ranges, immunity to electrical
noise, and resistance to vibration and impact. Programs to control machine operation are
typically stored in battery-backed-up or non-volatile memory. A PLC is an example of
a hard real-time system since output results must be produced in response to input conditions
within a limited time.
5.1.1 DEFINITION :
As per NEMA Standards a programmable controller is defined as a “DIGITALLY
OPERATING ELECTRONIC APPARATUS” which uses a Programmable memory
for the storage of instructions for specific functions such as logic sequencing, timing,
counting, and arithmetic control through digital or analog input/output modules, various types
of machines or processes. A digital computer which is used to performed the function of a
programmable controller is considered to be within this scope. Excluded are drum and similar
mechanical type sequencing controller.
Fig 5.1 PLC S7 300

5.2 BUILDING BLOCK OF PLC :
Fig 5.2 Building block of PLC
5.3 CONSTITUENTS OF PLC :
The programmable controller has three main units.
 PROCESSOR OR CENTRAL PROCESSING UNIT(CPU) AND
MEMORY: The processor reads input signals in response to them it generates
output commands by interpreting the instructions from the program which is stored in
the memory.
 INPUT/OUTPUT RACK OR INTERFACE:
This is the interface between the application devices and the processor. The I/O rack
receives information signals from the input devices and transmits action signals to the
controlled devices.

 PROGRAMMABLE PANEL OR PROGRAMMING,EDITING AND
MONITORING DEVICE:
Individual instructions which form the programmable controller program are entered
into the memory through the keyboard or program panel. These instructions are shown in the
program panel display in the from of individual ladder diagram type rungs. The program
panel provides a reading of the programmable controller program for verification. It permits
changes (editing) of existing programs and also aids in machines or process start –ups and in
trouble shooting.
5.4 PLC SCAN :
A PLC program is generally executed repeatedly as long as the controlled system is running
referred to as a scan. A PLC scan starts with the CPU reading the status of inputs. The status
of physical input points is copied to an area of memory accessible to the processor,
sometimes called the "I/O Image Table". The program is then run from its first instruction
rung down to the last rung. It takes some time for the processor of the PLC to evaluate all the
rungs and update the I/O image table with the status of outputs. As PLCs became more
advanced, methods were developed to change the sequence of ladder execution, and
subroutines were implemented.
5.5 HOW IT DIFFER FROM THE COMPUTERS ?
The memory unit of the processor sequentially scans input (sensors, limit switches, push
buttons, photo cells) in cyclical fashion to determine which output (contacts, motors, starters,
solenoids, pilot lamps, converters etc.) it should be turned ON or OFF. The programmable
controller processes instructions in a fixed cycle. The instructions can be skipped or not
performed, but they are all at least examined on every scan. Computers, on the other hand
operate on an interrupt system where by changing events can alter the order in which the
instructions are performed. This speeds response time in relation to programmable controllers
but acts complexity to programming.
The second difference between computers and programmable controllers is in the manner by
which the controller is programmed. Ladder diagram the same used program electro-
mechanical relays, is also used in programmable controller. Control engineers working with
relays are familiar with relay ladder diagram logic and this makes the programmable
controller a shop tool and not a data process system.
The other distinguishing character of programmable controllers are their rugged construction,
equipment is designed to withstand jarring and freezing and elevated temperature, highly
humidity, corrosive atmosphere and electrical interference. While all PC’s are computers, by
definition, not all computers are PC’s. the difference is in environmental considerations,
programming methods and maintenance.

5.6 BASIC REQUIREMENTS :
In order to create a PLC program, the following items are needed :
 PLC
 Programming Device
 Programming Software
 Connector Cable
5.6.1 Programming Device :
The program is created in a programming device and then transferred to PLC. The program
for the S7 can be created using dedicated Siemens SIMANTIC S7 programming device, such
as a PG 720,A personal computer, with STEP 7 micro/lite installed, can be used as a
programming device with the S7.
Fig 5.6 Firmware
5.6.2 Programming Software:
A software program is required in order to tell the PLC what instructions it must follow. A
software package of one PLC , or one family of PLC’s ,such as the S7 family,would not be
useful on other PLC’s. A software based PLC requires a computer with an interface card, but
allows the PLC to be connected to sensors and other PLCs across a network.
5.6.3 Connector Cables :
A special cable is needed when a personal computer is used as a programming device. Two
versions of this cable are available. One is RS-585/PPI Multi –Master Cable ,and other is
USB/PPI Multi –Master Cable.

5.7 PROGRAMMING A PLC :
5.7.1 Ladder Logic :
Ladder logic is the main programming method used for PLCs. It is one programming
language used with PLC’s .Ladder logic uses components that resembles elements used in a
line diagram format to describe hard-wired control. The left of vertical line of a ladder logic
diagram represents the power or energized conductor. The output element represents the
neutral or return path of the circuit. Ladder logic diagrams are read from left to right ,top to
bottom. As mentioned before, ladder logic has been developed to mimic relay logic. The
decision to use the relay logic diagrams was a strategic one. By selecting ladder logic as the
main programming method, the amount of retraining needed for engineers and tradespeople
was greatly reduced.
5.7.2 Statement List :
A statement list provides another view of a set of instructions. The operation, what is to be
done, is shown on left. The operand ,the item to be operated by the operation ,is shown on the
right. A comparison between the statement list shown below, and the ladder logic shown on
the similar structure is terminated.
5.8 PROGRAM STRUCTURE :
The programs of the PLC can either be linear or structured.
5.8.1 LINEAR PROGRAMMING :
Programming individual operations in one section (block) is sufficient for handling simple
automation jobs. This is organization block1 (OB1). The PLC scans this block cyclically (i.e.,
after it scans last statements it goes back to the first statement and begins scanning again.
5.8.2 STRUCTURED PROGRAMMING :
To solve complex tasks, it is advisable to divide a program into individual, self-contained
program parts (blocks).
The procedure has the following advantages:-
 Simple and clear programming even for large program
 Easy alteration
 Simple program test
 Simple startup
 Subroutine techniques (block call from different locations)
 Lower scan time extensions through STATUS PLC function
5.9 STEP 7 PROGRAMMING :
STEP 7-Micro/Lite is the program software used with the S7 PLC to create the PLC
operating program. Step 7 consists of a number of instructions that must be arranged in a
logical order to obtain the desired PLC operation. These instructions are divided into 3
groups : Standard instructions, Special instructions, High –speed instructions.

The STEP 7 programming language has the following 5 block types:-
 Organization blocks(OBs)
Organization blocks manage the control program
 Program blocks (PBs)
Program blocks arrange the control program according to functional or technical aspects.
 Sequence blocks (SBs)
Sequence blocks are special blocks that program sequence controls. They are handled like
program blocks.
 Function blocks (FBs)
Function blocks are special blocks for programming frequently recurring or especially
complex program parts (e.g., reporting and arithmetic functions). The parameters can be
assigned. They have an extended set of operation (e.g., Jump operation within a block)
 Data blocks (DBs)
Data blocks store data needed to process a control program. Actual values, limiting values
and texts are examples of data.
Blocks can be nested upto 16 levels in this particular controller.
5.10 ADVANTAGES :
 Cost effective for controlling complex systems.
 Flexible and can be reapplied to control other systems quickly and easily.
 Computational abilities allow more sophisticated control.
 Trouble shooting aids make programming easier and reduce downtime.
 Reliable components make these likely to operate for years before failure.
 Ease of programming using ladder circuits.
 Ability to withstand rugged and adverse conditions of the factory floor.
 They can withstand vibrations ,transients, noises etc.
 They can withstand temperatures ranging from 0 to 50 degree centigrade.
5.11 APPLICATIONS :
 Factory Automation
 Machine Control
 Instrumentation
 Process Control
 Data Acquisition and control
 Manufacturing systems like CNC.

PROJECT
AUTOMATIC FEEDING, MEASURING
TEMPERATURE AND EJECTING OF COMPONENTS
USING PLC
AIM :- Automatic feeding, measuring temperature and ejecting of components using PLC.
EQUIPMENTS REQUIRED :-
1. Double Acting Cylinder
2. Directional Control Valves
3. Compressor
4. Tubes,banana cables
5. PLC
6. Sensors
 Optical Sensors
 Capacitive Sensors
7. Relays
8.PC.
INTRODUCTION :-
The project is to feed a component , measure temperature and eject the component
automatically. Automation used in this process for measuring temperature. Therefore in many
industries where temperature measuring of components is required , automation is used.
STEP IN THE PROCESS :-
1. The component is placed.
2. The feeder will measure temperature of the component.
3. The ejecting cylinder will eject the component.
4. The ejecting cylinder deactivates (come back).
5. Then the temperature measuring cylinder deactivates.

PROCEDURE :-
In this process we take 3 double acting cylinders (named A,B,C ) control valves and
connecting tubes as many as required.
Consider Cylinder A as Feeding Cylinder
Cylinder B as Temperature measuring Cylinder
Cylinder C as Ejecting cylinder
Here the forward stroke of the cylinder A is called as A+ and the backward stroke of
the cylinder is called A-. In this similar way B+,B- and C+,C-.
Here two optical sensors are used namely Optical sensor 1(S1) and Optical sensor 2(S2).
At first the components whose temperature has be measured has to be fed , this done by
forward stroke of the cylinder(A+) then after feeding the component the cylinder A has to
undergo the backward stroke(A-),then cylinder B has to undergo the forward stroke (B+) to
measure the temperature of the component and after the operation it performs the backward
stroke(B-). After B-, the cylinder C has to undergo forward stroke(C+) to eject the
component and the backward stroke (C-). i.e, A+A-B+B -C+C-.
All the actions are performed by connecting the components.

RESULTS AND CONCLUSIONS :-
The system has worked successfully by PLC. A minute change in the program causes the
total system to work differently.
Adding PLC to the electro pneumatic systems gives more flexible automation of
the system. Because the sequence of the operations by using PLC’s is very easy i.e. to change
the program, whereas it is much more difficult in pure pneumatic and electro pneumatic as
for every different sequence we need to rewire the connections.

Biblography & Reference
1.citdindia.org
2. google.com
3. wikipedia.com
4. vigorplc.com
5. hydraulicspneumatics.com
6. numatics.com
7. rotork.com

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