Scada Systems for Distributed and Substation Automation (1)

8/2/2019 Scada Systems for Distributed and Substation Automation (1)

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SCADA SYSTEMS FOR DISTRIBUTED AND SUBSTATION

AUTOMATION

CHAPTER 1

INTRODUCTION

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1.1MOTIVATION

The motivation to our project SCADA SYSTEM FOR DISTRIBUTED AND

SUBSTATION AUTOMATION is designed and implements the wide area Remote

control using embedded Platform. To cut the traditional wires between sensors, wired slave

devices, and the microcontrollers and microprocessors the project is developed. This project

has three important modules; they are SCADA modem, Microcontroller unit and Driver units

of the appliances. The aim of the project is to monitor the power room electrical equipments

parameters like current, voltage and power. Display the all parameters in computer, and save all

values in that system by using embedded system technology. Such applications are motivated

us to do the Project successfully.

1.2 STATEMENT OF PROBLEM

Now a day the automation field gets a wide growth in the world wide. Under this

concept here the project is developed. To do this purposely the AT commands are developed,

by sending AT commands we can interact with PC modem. The microcontroller module

contains several controllable outlets to control.

RELATED WORK

To complete our project we studied about PIC 16f877A controller and its features. We

also studied about SCADA system, AT commands, Relays and Relay Drivers. Also we visited

sites how stuff works.com, www.Microchip.com, www.wikipedia.com.

1.4 SCOPE OF WORK

The project SCADA SYSTEM FOR DISTRIBUTED AND SUBSTATION

AUTOMATION is used in industrial electrical outlets for power control over the loads.

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THESIS OUTLINE

The report is divided into several sections and a brief overview of the section is described here.

Chapter 2- A Brief Review. This consists of Introduction and Motivation, preliminaries

Chapter 3- Approaches to the project.

Chapter 4- This consists of modules implemented. This consists of describing how to solve the

problem.

Chapter 5- This consists of software requirements of the project.

Chapter 6- This consists of Results obtained for the project.

Chapter 7- This describes conclusion part of the project.

Chapter 8- This contains Bibliography and list of web sites used.

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CHAPTER-2

BACK GROUND INFORMATION

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2.1 INTRODUCTION

The project report describes the design Development and Fabrication of One demo unit

of The project work SCADA SYSTEM FOR DISTRIBUTED AND

SUBSTATIONAUTOMATION

By using embedded systems.

Now a day, with the advancement technology, particularly in the field of

Microcontrollers, all the activities in our daily living have become a part of Information

technology and we find microcontrollers in each and every application. Thus, trend is directing

towards Microcontrollers based project works. However, in this project work SCADA Modem

used to Form the remote network. The microcontroller interacts with SCADA modem for

sending and receiving control message. Then the decisions are taken with the help of

microcontroller and associated software.

The microcontroller block is playing a major role in this project work. The micro

controller chip used in this project work is PIC 16F877A and this is like heart of the project

work. The PIC 16F877A microcontroller is a 40-pin IC.

The entire project was developed in embedded systems. A system is something that

maintains its existence and functions as a whole through the interaction of its parts. E.g. Body,

Mankind, Access Control, etc A system is a part of the world that a person or group of persons

during some time interval and for some purpose choose to regard as a whole, consisting of

interrelated components, each component characterized by properties that are selected as being

relevant to the purpose.

Embedded System is a combination of hardware and software used to achieve a single

specific task.

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Embedded systems are computer systems that monitor, respond to, or control an

external environment.

Environment connected to systems through sensors, actuators and other I/O interfaces.

Embedded system must meet timing & other constraints imposed on it by environment.

An embedded system is a microcontroller-based, software driven, reliable, real-time

control system, autonomous, or human or network interactive, operating on diverse

physical variables and in diverse environments and sold into a competitive and cost

conscious market.

An embedded system is not a computer system that is used primarily for processing, not

a software system on PC or UNIX, not a traditional business or scientific application. High-end

embedded & lower end embedded systems. High-end embedded system - Generally 32, 64 Bit

Controllers used with OS. Examples Personal Digital Assistant and Mobile phones etc. Lower

end embedded systems - Generally 8, 16 Bit Controllers used with a minimal operating systems

and hardware layout designed for the specific purpose. Examples Small controllers and devices

in our everyday life like Washing Machine, Microwave Ovens, where they are embedded in.

Microcontrollers are embedded inside some other device so that they can control the

features or actions of the project. Another name for a microcontroller therefore is Embedded

Controller. Microcontrollers are dedicated to one task and run one specific program. The

program is stored in ROM (read only memory) and generally does not change.

Microcontrollers are often low-price devices.

2.2 PRELIMINARIES

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2.2.1 INTRODUCTION TO EMBEDDEDSYSTEMS

EMBEDDED SYSTEM:

Embedded System is a combination of hardware and software used to achieve a

single specific task. An embedded system is a microcontroller-based, software driven, reliable,

real-time control system, autonomous, or human or network interactive, operating on diverse

physical variables and in diverse environments and sold into a competitive and cost conscious

market.

An embedded system is not a computer system that is used primarily for

processing, not a software system on PC or UNIX, not a traditional business or scientific

application. High-end embedded & lower end embedded systems. High-end embedded system -

Generally 32, 64 Bit Controllers used with OS. Examples Personal Digital Assistant and

Mobile phones etc .Lower end embedded systems - Generally 8,16 Bit Controllers used with an

minimal operating systems and hardware layout designed for the specific purpose. Examples

Small controllers and devices in our everyday life like Washing Machine, Microwave Ovens,

where they are embedded in.

SYSTEM DESIGN CALLS:

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THE EMBEDDED SYSTEM DESIGN CYCLE

V Diagram

In this place we need to discuss the role of simulation software, real-time systems and

data acquisition in dynamic test applications. Traditional testing is referred to as static

testing where functionality of components is tested by providing known inputs and measuring

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outputs. Today there is more pressure to get products to market faster and reduce design cycle

times.

This has led to a need for dynamic testing where components are tested while in use with the

entire system either real or simulated. Because of cost and safety concerns, simulating the

rest of the the system with real-time hardware is preferred to testing components in the actual

real system.

The diagram shown on this slide is the V Diagram that is often used to describe the

development cycle. Originally developed to encapsulate the design process of software

applications, many different versions of this diagram can be found to describe different product

design cycles. Here we have shown one example of such a diagram representing the design

cycle of embedded control applications common to automotive, aerospace and defense

applications.

In this diagram the general progression in time of the development stages is shown from left to

right. Note however that this is often an iterative process and the actual development will not

proceed linearly through these steps. The goal of rapid development is to make this cycle as

efficient as possible by minimizing the iterations required for a design. If the x-axis of the

diagram is thought of as time, the goal is to narrow the V as much as possible and thereby

reduce development time.

The y-axis of this diagram can be thought of as the level at which the system components are

considered. Early on in the development, the requirements of the overall system must be

considered. As the system is divided into sub-systems and components, the process becomes

very low-level down to the point of loading code onto individual processors. Afterwards

components are integrated and tested together until such time that the entire system can enter

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final production testing. Therefore the top of the diagram represents the high-level system

view and the bottom of the diagram represents a very low-level view.

Notes:

V diagram describes lots of applicationsderived from software development.

Reason for shape, every phase of design requires a complimentary test phase. High-

level to low-level view of application.

This is a simplified version.

Loop Back/ Iterative process, X-axis is time (sum up).

Characteristics of Embedded System:

An embedded system is any computer system hidden inside a product other than a

computer

There will encounter a number of difficulties when writing embedded system software

in addition to those we encounter when we write applications

Throughput Our system may need to handle a lot of data in a short period of

time.

ResponseOur system may need to react to events quickly

TestabilitySetting up equipment to test embedded software can be difficult

DebugabilityWithout a screen or a keyboard, finding out what the software is

doing wrong (other than not working) is a troublesome problem

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Reliability embedded systems must be able to handle any situation without

human intervention

Memory space Memory is limited on embedded systems, and you must make

the software and the data fit into whatever memory exists

Program installation you will need special tools to get your software into

embedded systems

Power consumption Portable systems must run on battery power, and the

software in these systems must conserve power

Processor hogs computing that requires large amounts of CPU time can

complicate the response problem

Cost Reducing the cost of the hardware is a concern in many embedded

system projects; software often operates on hardware that is barely adequate for

the job.

Embedded systems have a microprocessor/ microcontroller and a memory. Some have

a serial port or a network connection. They usually do not have keyboards, screens or

disk drives.

Applications:

1. Military and aerospace embedded software applications

2. Communicat ion Applicat ions

3. Industr ial automation and process control software

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CLASSIFICATION

Real Time Systems.

RTS is one which has to respond to events within a specified deadline.

A right answer after the dead line is a wrong answer

RTS CLASSIFICATION

Hard Real Time Systems

Soft Real Time System

HARD REAL TIME SYSTEM

"Hard" real-time systems have very narrow response time.

Example: Nuclear power system, Cardiac pacemaker.

SOFT REAL TIME SYSTEM

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"Soft" real-time systems have reduced constrains on"lateness" but still must operate very quickly and repeatable.

Example: Railway reservation system takes a few extra

seconds the data remains valid.

LANGUAGES USED

C

C++

Java

Linux

Ada

Assembly

MPLAB FEATURES

MPLAB Integrated Development Environment (IDE) is a free, integrated toolset for the

development of embedded applications employing Microchip's PIC and dsPIC

microcontrollers.


development of embedded applications employing Microchip's PIC and dsPIC

microcontrollers.

MPLAB IDE runs as a 32-bit application on MS Windows, is easy to use and

includes a host of free software components for fast application development and super-

charged debugging.

MPLAB IDE also serves as a single, unified graphical user interface for additional

Microchip and third party software and hardware development tools. Moving between tools is a

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snap, and upgrading from the free software simulator to hardware debug and programming

tools is done in a flash because MPLAB IDE has the same user interface for all tools.

MPLAB IDEs SIM, high speed software simulator for PIC and dsPIC (Digital Signal

Processing PIC Microcontroller) devices with peripheral simulation, complex stimulus

injection and register logging.

2.2.1 INTRODUCTION TO SCADA:

SCADA stands for Supervisory Control And Data Acquisition. It generally refers to an

industrial control system: a computer system monitoring and controlling a process. The process

can be industrial, infrastructure or facility based as described below:

Industrial processes include those of manufacturing, production, power

generation, fabrication, and refining, and may run in continuous, batch, repetitive, or discrete

modes.

Infrastructure processes may be public or private, and include water treatment

and distribution, wastewater collection and treatment, oil and gas pipelines, electrical power

transmission and distribution, and large communication systems.

Facility processes occur both in public facilities and private ones, including

buildings, airports, ships, and space stations. They monitor and control HVAC, access, andenergy consumption

The term SCADA usually refers to centralized systems which monitor and control entire sites, or

complexes of systems spread out over large areas (anything between an industrial plant and a

country). Most control actions are performed automatically by remote terminal units

("RTUs") or by programmable logic controllers ("PLCs"). Host control functions are usually

restricted to basic overriding orsupervisory level intervention. For example, a PLC may

control the flow of cooling water through part of an industrial process, but the SCADA

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system may allow operators to change the set points for the flow, and enable alarm

conditions, such as loss of flow and high temperature, to be displayed and recorded. The

feedback control loop passes through the RTU or PLC, while the SCADA system monitors

the overall performance of the loop.

Data acquisition begins at the RTU or PLC level and includes meter readings and equipment status

reports that are communicated to SCADA as required. Data is then compiled and formatted

in such a way that a control room operator using the HMI can make supervisory decisions to

adjust or override normal RTU (PLC) controls. Data may also be fed to a Historian, often

built on a commodity Database Management System, to allow trending and other analytical

auditing.

Data acquisition begins at the RTU or PLC level and includes meter readings and equipment status

reports that are communicated to SCADA as required. Data is then compiled and formatted in

such a way that a control room operator using the HMI can make supervisory decisions to

adjust or override normal RTU (PLC) controls. Data may also be fed to a Historian, often built

on a commodity Database Management System, to allow trending and other analytical auditing

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SCADA Architectures

SCADA systems have evolved through 3 generations as follows:

First Generation: "Monolithic"

In the first generation computing was done by Mainframe systems. Networks didnt

exist at the time SCADA was developed. Thus SCADA systems were independent systems

with no connectivity to other systems. Wide Area Networks were later designed by RTU

vendors to communicate with the RTU. The communication protocols used were often

proprietary at that time. The first generation SCADA System was redundant since a back-up

mainframe system was connected at the bus level and was used in the event of failure of the

main mainframe system.

Second Generation: "Distributed"

The processing was distributed across multiple stations which were connected through

LAN and they shared information in real time. Each station was responsible for a particular

task thus making the size and cost of each station less than the one used in First Generation.

The network protocols used were still mostly proprietary.

Third Generation: "Networked"

These are the current generation SCADA systems which use open system architecture

rather than a vendor controlled proprietary environment. The SCADA system utilizes open

standard and protocols thus distributing functionality across a WAN rather than a LAN. It is

easier to connect third party peripheral devices like printers, disk drives, tape drives due to the

use of open architecture. WAN protocols such as Internet Protocol (IP) are used for

communication between the master station and communications equipment. This on the other

hand has put a question on the security of SCADA system which seems to be vulnerable to

cyber-warfare and cyber terrorism attacks.

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2.2.3 INTRODUCTION TO RELAYS

A relay is usually an electromechanical device that is actuated by an electrical current.

The current flowing in one circuit causes the opening or closing of another circuit. Relays are

like remote control switches and are used in many applications because of their relative

simplicity, long life, and proven high reliability. Relays are used in a wide variety of

applications throughout industry, such as in telephone exchanges, digital computers and

automation systems. Highly sophisticated relays are utilized to protect electric power systems

against trouble and power blackouts as well as to regulate and control the generation and

distribution of power. In the home, relays are used in refrigerators, washing machines and

dishwashers, and heating and air-conditioning controls. Although relays are generally

associated with electrical circuitry, there are many other types, such as pneumatic and

hydraulic. Input may be electrical and output directly mechanical, or vice versa.

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CHAPTER-3

IMPORTANT APPROACHES TO THE PROJECT

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3.1 MICROCONTROLLER

3.1.1 INTRODUCTION TO MICROCONTROLLER

A computer-on-a-chip is a variation of a microprocessor which combines the processor

core (CPU), some memory, and I/O (input/output) lines, all on one chip. The computer-on-a-

chip is called the microcomputer whose proper meaning is a computer using a (number of)

microprocessor(s) as its CPUs, while the concept of the microcomputer is known to be a

microcontroller. A microcontroller can be viewed as a set of digital logic circuits integrated on

a single silicon chip. This chip is used for only specific applications.

Most microcontrollers do not require a substantial amount of time to learn how to

efficiently program them, although many of them, which have quirks, which you will have to

understand before you, attempt to develop your first application.

Along with microcontrollers getting faster, smaller and more power efficient they are

also getting more and more features. Often, the first version of microcontroller will just have

memory and digital I/O, but as the device family matures, more and more pat numbers with

varying features will be available.

In this project we used PIC 16f877A microcontroller. For most applications, we will be

able to find a device within the family that meets our specifications with a minimum of external

devices, or an external but which will make attaching external devices easier, both in terms of

wiring and programming.

For many microcontrollers, programmers can built very cheaply, or even built in to the

final application circuit eliminating the need for a separate circuit. Also simplifying this

requirement is the availability of micro-controllers wit SRAM and EEPROM for control store,

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which will allow program development without having to remove the micro controller for the

application circuit.

3.1.2 MICRO CONTROLLER CORE FEATURES

High-performance RISC CPU.

Only 35 single word instructions to learn.

All single cycle instructions except for program branches which are two cycle.

Operating speed: DC - 20 MHz clock input DC - 200 ns instruction cycle.

Up to 8K x 14 words of FLASH Program Memory, Up to 368 x 8 bytes of Data

Memory (RAM) Up to 256 x 8 bytes of EEPROM data memory.

Pin out compatible to the PIC16C73B/74B/76/77

Interrupt capability (up to 14 sources)

Eight level deep hardware stack

Direct, indirect and relative addressing modes.

Power-on Reset (POR).

Power-up Timer (PWRT) and Oscillator Start-up Timer (OST).

Watchdog Timer (WDT) with its own on-chip RC oscillator for reliable operation.

Programmable code-protection.

Power saving SLEEP mode.

Selectable oscillator options.

Low-power, high-speed CMOS FLASH/EEPROM technology.

Fully static design.

.

(ICSP)

In-Circuit Serial Programming

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Single 5V In-Circuit Serial Programming capability.

In-Circuit Debugging via two pins.

Processor read/write access to program memory.

Wide operating voltage range: 2.0V to 5.5V.

High Sink/Source Current: 25 mA.

Commercial and Industrial temperature ranges.

Low-power consumption.

In this project we used PIC 16f877A microcontroller. PIC means Peripheral Interface

Controller. The PIC family having different series, the series are 12- Series, 14- Series, 16-

Series, 18- Series, and 24- Series. We used 16 Series PIC microcontrollers.

3.1.3 ADVANTAGES OF USING A MICROCONTROLLER OVER

MICROPROCESSOR

A designer will use a Microcontroller to

Gather input from various sensors

Process this input into a set of actions

Use the output mechanisms on the Microcontroller to do something useful

RAM and ROM are inbuilt in the MC.

Cheap compared to MP.

Multi machine control is possible simultaneously.

Examples

The 8051 (ATMEL), PIC (Microchip), Motorola (Motorola), ARM Processor

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3.1.4 APPLICATIONS:

Cell phones.

Computers.

Robots.

Interfacing to two pcs.

3.3PIC MICROCONTROLLER 16F877A

3.3.1INTRODUCTION TO PIC MICROCONTROLLER 16F877A

The PIC 16f877A microcontroller is a 40-pin IC. The first pin of the controller is

MCLR pin and the 5V dc supply is given to this pin through 10K resistor. This supply is also

given to 11th pin directly. The 12th pin of the controller is grounded. A tank circuit consists of a

4 MHZ crystal oscillator and two 22pf capacitors is connected to 13th and 14th pins of the PIC.

3.2.1 FEATURES OF PIC MICROCONTROLLER 16F877A

Operating frequency: DC-20Mhz.

Flash program memory (14 bit words):8K

Data memory (in bytes): 368

EEPROM Data memory (in bytes):256

Interrupts: 15

I/o ports: A, B, C, D, E

Timers: 3

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Analog comparators: 2

Instructions: 35

3.2.3 PIN DIAGRAM OF PIC 16 F874A/877A

FIG 3.1 PIN DIAGRAM OF PIC 16 F874A/877A

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3.2.4 FUNCTIONAL BLOCK DIAGRAM OF PIC 16F877A

FIG 3.2 PIN DIAGRAM OF PIC 16F874A/877A

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POWER SUPPLY UNIT

CIRCUIT DIAGRAM

FIG 3.3 POWER SUPPLY UNIT

POWER SUPPLY UNIT COSISTS OF FOLLOWING UNITS

1) Step down transformer

2) Rectifier unit

3) Input filter

4) Regulator unit

v) Output filter

3.3.1 STEP DOWN TRANSFORMER

The Step down Transformer is used to step down the main supply voltage from 230V

AC to lower value. This 230 AC voltage cannot be used directly, thus it is stepped down. The

Transformer consists of primary and secondary coils. To reduce or step down the voltage, the

transformer is designed to contain less number of turns in its secondary core. The output from

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the secondary coil is also AC waveform. Thus the conversion from AC to DC is essential. This

conversion is achieved by using the Rectifier Circuit/Unit.

Step down transformers can step down incoming voltage, which enables you to have

the correct voltage input for your electrical needs. For example, if our equipment has been

specified for input voltage of 12 volts, and the main power supply is 230 volts, we will need a

step down transformer, which decreases the incoming electrical voltage to be compatible with

your 12 volt equipment.

3.3.2 RECTIFIER UNIT

The Rectifier circuit is used to convert the AC voltage into its corresponding DC

voltage. There are Half-Wave, Full-Wave and bridge Rectifiers available for this specific

function. The most important and simple device used in Rectifier circuit is the diode. The

simple function of the diode is to conduct when forward biased and not to conduct in reverse

bias.

Bridge rectifier: A bridge rectifier makes use of four diodes in a bridge arrangement to

achieve full-wave rectification. This is a widely used configuration, both with individual diodes

wired as shown and with single component bridges where the diode bridge is wired internally.

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A diode bridge or bridge rectifier is an arrangement of fourdiodes in a bridge

configuration that provides the same polarity of output voltage for either polarity of input

voltage. When used in its most common application, for conversion ofalternating current (AC)

input into direct current (DC) output, it is known as a bridge rectifier. A bridge rectifier

providesfull-wave rectification from a two-wire AC input, resulting in lower cost and weight

as compared to a center-tappedtransformerdesign.

The Forward Bias is achieved by connecting the diodes positive with positive of the

battery and negative with batterys negative. The efficient circuit used is the Full wave Bridge

rectifier circuit. The output voltage of the rectifier is in rippled form, the ripples from the

obtained DC voltage are removed using other circuits available. The circuit used for removing

the ripples is called Filter circuit.

3.3.3 INPUT FILTER

Capacitors are used as filter. The ripples from the DC voltage are removed and pure DC

voltage is obtained. And also these capacitors are used to reduce the harmonics of the input

voltage. The primary action performed by capacitor is charging and discharging. It charges in

positive half cycle of the AC voltage and it will discharge in negative half cycle. So it allows

only AC voltage and does not allow the DC voltage. The 1000f capacitor serves as a

"reservoir" which maintains a reasonable input voltage to the 7805 throughout the entire cycle

of the ac line voltage. The four rectifier diodes keep recharging the reservoir capacitor on

alternate half-cycles of the line voltage, and the capacitor is quite capable of sustaining any

reasonable load in between charging pulses. This filter is fixed before the regulator. Thus the

output is free from ripples. Input side the low pass filter has been used.

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Low pass filter:

One simple electrical circuit that will serve as a low-pass filter consists of a resistorin

series with a load, and a capacitor in parallel with the load. The capacitor exhibits reactance,

and blocks low-frequency signals, causing them to go through the load instead. At higher

frequencies the reactance drops, and the capacitor effectively functions as a short circuit. The

combination of resistance and capacitance gives you the time constant of the filter = RC

(represented by the Greek letter tau). The break frequency, also called the turnover frequency

orcutoff frequency (in hertz), is determined by the time constant: or equivalently (in radians

per second):

One way to understand this circuit is to focus on the time the capacitor takes to charge.

It takes time to charge or discharge the capacitor through that resistor:

At low frequencies, there is plenty of time for the capacitor to charge up to

practically the same voltage as the input voltage.

At high frequencies, the capacitor only has time to charge up a small amount

before the input switches direction. The output goes up and down only a small fraction of the

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amount the input goes up and down. At double the frequency, there's only time for it to charge

up half the amount.

3.3.4 REGULATOR UNIT

FIG 3.4 7805 REGULATOR

Regulator regulates the output voltage to be always constant. The output voltage is

maintained irrespective of the fluctuations in the input AC voltage. As and then the AC voltage

changes, the DC voltage also changes. Thus to avoid this Regulators are used. Also when the

internal resistance of the power supply is greater than 30 ohms, the output gets affected. Thus

this can be successfully reduced here. Meanwhile it also contains current-limiting circuitry and

thermal overload protection, so that the IC won't be damaged in case of excessive load current;

it will reduce its output voltage instead. The regulators are mainly classified for low voltage

and for high voltage. Further they can also be classified as:

1) Positive regulator

Input pin

Ground pin

Output pin

It regulates the positive voltage.

2) Negative regulator

Ground pin

Input pin

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Output pin

It regulates the negative voltage.

7805 VOLTAGE REGULATOR:

The 7805 provides circuit designers with an easy way to regulate DC voltages to 5v.

Encapsulated in a single chip/package (IC), the 7805 is a positive voltage DC regulatorthat has

only 3 terminals. They are: Input voltage, Ground, Output Voltage.

7812 12V INTEGRATED CIRCUIT 3-TERMINAL POSITIVE VOLTAGE

REGULATOR:

The 7812 fixed voltage regulator is a monolithic integrated circuit in

a TO220 type package designed for use in a wide variety of applications

including local, onboard regulation. This regulator employs internal current

limiting, thermal shutdown, and safe area compensation.

With adequate heat-sinking it can deliver output currents in excess

of 1.0 ampere. Although designed primarily as a fixed voltage regulator,

this device can be used with external components to obtain adjustable

voltages and currents.

3.3.5 OUTPUT FILTER

The Filter circuit is often fixed after the Regulator circuit. Capacitor is most often used

as filter. The principle of the capacitor is to charge and discharge. It charges during the positive

half cycle of the AC voltage and discharges during the negative half cycle. The 10f and .01f

capacitors serve to help keep the power supply output voltage constant when load conditions

change. The electrolytic capacitor smooths out any long-term or low frequency variations.

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However, at high frequencies this capacitor is not very efficient. Therefore, the .01f is

included to bypass high-frequency changes, such as digital IC switching effects, to ground.

RELAY DRIVER

The ULN2001A, ULN2002A, ULN2003 and ULN2004Aare high Voltage, high current

Darlington arrays each containing seven open collector Darlington pairs with common emitters.

Each channel rated at 500mAand can withstand peak currents of 600mA.Suppressiondiodesare

included for inductive load driving and the inputs are pinned opposite the outputs to simplify

board layout.

These versatile devices are useful for driving a wide range of loads including solenoids,

relays DC motors; LED displays filament lamps, thermal print heads and high power buffers.

The ULN2001A/2002A/2003A and 2004A are supplied in 16pin plastic DIP packages with a

copper lead frame to reduce thermal resistance.

They are available also in small outline package (SO-16) as

ULN2001D/2002D/2003D/2004D.

3.4.1 FEATURES OF DRIVER

SEVENDARLINGTONS PER PACKAGE.

OUTPUT CURRENT 500mA PER DRIVER (600mA PEAK)

OUTPUT VOLTAGE 50V.

INTEGRATED SUPPRESSION DIODES FOR

INDUCTIVE LOADS.

OUTPUTS CAN BE PARALLELED FOR

HIGHERCURRENT.

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TTL/CMOS/PMOS/DTLCOMPATIBLE INPUTS.

INPUTS PINNED OPPOSITE OUTPUTS TO

SIMPLIFYLAYOUT

3.4.2 PIN CONNECTION

FIG 3.5PIN CONNECTIONS OF A RELAY

3.4.3 RELAYS

A relay is usually an electromechanical device that is actuated by an electrical current.

The current flowing in one circuit causes the opening or closing of another circuit. Relays are

like remote control switches and are used in many applications because of their relative

simplicity, long life, and proven high reliability. Relays are used in a wide variety of

applications throughout industry, such as in telephone exchanges, digital computers and

automation systems. Highly sophisticated relays are utilized to protect electric power systems

against trouble and power blackouts as well as to regulate and control the generation and

distribution of power. In the home, relays are used in refrigerators, washing machines and

dishwashers, and heating and air-conditioning controls. Although relays are generally

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associated with electrical circuitry, there are many other types, such as pneumatic and

hydraulic. Input may be electrical and output directly mechanical, or vice versa.

All relays contain a sensing unit, the electric coil, which is powered by AC or DC

current. When the applied current or voltage exceeds a threshold value, the coil activates the

armature, which operates either to close the open contacts or to open the closed contacts. When

a power is supplied to the coil, it generates a magnetic force that actuates the switch

mechanism. The magnetic force is, in effect, relaying the action from one circuit to another.

The first circuit is called the control circuit; the second is called the load circuit.

On/Off Control: Example: Air conditioning control, used to limit and control a high

power load, such as a compressor Limit Control:

Example: Motor Speed Control, used to disconnect a motor if it runs slower or faster

than the desired speed

Logic Operation: Example: Test Equipment, used to connect the instrument to a

number of testing points on the device under test.

3.4.4 ELECTROMECHANICAL RELAYS

In our project we will be using an electromechanical relay, which will be a 5 pin relay

and the working of the relay will be like as.The general-purpose relay is rated by the amount of

current its switch contacts can handle. Most versions of the general-purpose relay have one to

eight poles and can be single or double throw. These are found in computers, copy machines,

and other consumer electronic equipment and appliances.

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FIG 3.6 MECHANICAL RELAY

3.4.4.1 INTERNAL OPERATION OF MECHANICAL RELAYS

Standard: Single Side Stable with any of the following three different methods for

closing contacts:

1. Flexure Type: The armature actuates the contact spring directly, and the contact is

driven into a stationary contact, closing the circuit.

2. Lift-off Type: The moveable piece is energized by the armature, and the contact

closes

3. Plunger Type: The lever action caused by the energization of the armature produces

a long stroke action. Reed: A Single Side Stable Contact that involves low contact pressure and

a simple contact point.

4. Polarized: Can be either a single side stable or dual-winding. A permanent magnet is

used to either attract or repel the armature that controls the contact. A definite polarity (+ or -)

is required

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By the relay coil. The latching option makes a polarized relay dual-winding, meaning it

remains in the current state after the coil is de-energized.

3.4.4.5 LOAD TYPES

Load parameters include the maximum permissible voltage and the maximum

permissible current. The relay can handle both volts and amps. Both the size of the load and its

type are important. There are four types of loads:

1) Resistive, 2) Inductive, 3) AC or DC, and 4) High or Low Inrush

3.4.5.1 RESISTIVE LOAD

It is the one that primarily offers resistance to the flow of current. Examples of resistive

loads include electric heaters, ranges and ovens, toasters and irons.

3.4.5.2 INDUCTIVE LOADS

It include power drills, electric mixers, fans, sewing machines and vacuum cleaners.

Relays that are going to be subjected to high-inrush inductive loads, such as an AC motor, will

often be rated in horsepower, rather than in volts and amps. This rating reflects the amount of

power the relay contacts can handle at the moment the device is turned on (or switched).

3.4.5.3 AC OR DC

This affects the contacts circuit of the relay (due to EMF) and the timing sequencing. It

may result in performance issues in the switching capacity of the relay for different load types

(I.e. resistive, inductive, etc.).

3.4.5.4 HIGH OR LOW IN RUSH

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Some load types draw significantly higher amounts of current (amperage) when first

turned then they do when the circuit later stabilizes (loads may also pulsate as the circuit

continues operating, thus increasing and decreasing the current). An example of a high inrush

load is a light bulb, which may draw 10 or more times its normal operating current when first

turned on (some manufacturers refer to this as lamp load).

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CHAPTER-4

DESCRIBING ABOUT PROJECT IMPLEMENTATION

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4.1 BLOCK DIAGRAME OF SCADA SYSTEM FOR DISTRIBUTED AND

SUBSTATION AUTOMATION

FIG 4.1.1BLOCK DIAGRAM

38

Microcontroller

unit

Key-board

SCADA unitPC

Electrical

equipments &

loads

Current

transformer

Potential

transformer

Signal

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Driver unit


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4.2 DESCRIPTION OF THE BLOCK DIAGRAM

The entire project is powered with the power supply unit, the project needs two

different dc power supply one is dc +12v supply it is maintained through LM7812 positive 12v

regulator and one more dc +5v supply it is maintained through LM7805 positive 5v regulator.

The project is separated by three parts, first one is parameters sensing part, second one is

parameter calculation and display part, third one is save all values in computer. In this first part

the current and voltage values are sensed by the current transformers and voltage transformers

at RTU(Remote Terminal Unit, i.e., Remote Terminal Units (RTUs) connecting to sensors in

the process, converting sensor signals to digital data and sending digital data to the supervisory

system.). In that second part the sensing values are calculated by microcontroller.

The block diagram consists of mainly five parts; they are controller unit, SCADA unit

with keypad, driver unit, signal conditioning unit with current transformer and potential

transformer and power supply unit. Only one relay is connected to the driver circuit.

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4.3 CIRCUIT DIAGRAM

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4.4 POWER SUPPLY DIAGRAM

FIG 4.3 POWER SUPPLY DIAGRAM

4.5 CIRCUIT DESCRIPTION

4.5.1 POWER SUPPLY

Power supply unit consists of Step down transformer, Rectifier, Input filter,

Regulator unit, Output filter.

The Step down Transformer is used to step down the main supply voltage from

230V AC to lower value. This 230 AC voltage cannot be used directly, thus it is stepped down.

The Transformer consists of primary and secondary coils. To reduce or step down the voltage,

the transformer is designed to contain less number of turns in its secondary core. The output

from the secondary coil is also AC waveform. Thus the conversion from AC to DC is essential.

This conversion is achieved by using the Rectifier Circuit/Unit.

The Rectifier circuit is used to convert the AC voltage into its corresponding DC

voltage. There are Half-Wave, Full-Wave and bridge Rectifiers available for this specific

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function. The most important and simple device used in Rectifier circuit is the diode. The

simple function of the diode is to conduct when forward biased and not to conduct in reverse

bias.

The Forward Bias is achieved by connecting the diodes positive with positive of the

battery and negative with batterys negative. The efficient circuit used is the Full wave Bridge

rectifier circuit. The output voltage of the rectifier is in rippled form, the ripples from the

obtained DC voltage are removed using other circuits available. The circuit used for removing

the ripples is called Filter circuit.

Capacitors are used as filter. The ripples from the DC voltage are removed and

pure DC voltage is obtained. And also these capacitors are used to reduce the harmonics of the

input voltage. The primary action performed by capacitor is charging and discharging. It

charges in positive half cycle of the AC voltage and it will discharge in negative half cycle.

Here we used 1000F capacitor. So it allows only AC voltage and does not allow the DC

voltage. This filter is fixed before the regulator. Thus the output is free from ripples.

Regulator regulates the output voltage to be always constant. The output voltage is

maintained irrespective of the fluctuations in the input AC voltage. As and then the AC voltage

changes, the DC voltage also changes. Thus to avoid this Regulators are used. Also when the

internal resistance of the power supply is greater than 30 ohms, the output gets affected. Thus

this can be successfully reduced here. The regulators are mainly classified for low voltage and

for high voltage. Here we used 7805 positive regulator. It reduces the 6V dc voltage to 5V dc

Voltage.

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The Filter circuit is often fixed after the Regulator circuit. Capacitor is most often used

as filter. The principle of the capacitor is to charge and discharge. It charges during the positive

half cycle of the AC voltage and discharges during the negative half cycle. So it allows only

AC voltage and does not allow the DC voltage. This filter is fixed after the Regulator circuit to

filter any of the possibly found ripples in the output received finally. Here we used 0.1F

capacitor. The output at this stage is 5V and is given to the Microcontroller

In the power supply circuit two regulators are used. 7805 regulator is used to

produce positive 5V dc and 7812 regulator produces positive 12V dc voltage. Relays and ULN

2003 drivers operates at 12V dc and microcontroller and sensors are operated at 5V dc voltage.

The output of the 7805 regulator is connected to PIC 16f877A microcontroller, sensors and the

output of the 7812 regulator is connected to driver ICs and relays.

4.5.2 CONTROLLER CIRCUIT

The PIC 16f877A microcontroller is a 40-pin IC. The first pin of the controller is

MCLR pin and the 5V dc supply is given to this pin through 10K resistor. This supply is also

given to 11th pin directly. The 12th pin of the controller is grounded. A tank circuit consists of a

4 MHZ crystal oscillator and two 22pf capacitors are connected to 13th and 14th pins of the PIC.

The circuit consists one driver IC. IC ULN 2003 is acts as driver. It is a 16- pin IC. This

is of NPN transistor type. And this IC is a combination of 7 transistors. At a time we can

connect seven loads to each IC. In this project we used 4 relays and connected four relays to

driver. These relays act as switches also. The 8th pin of driver ICs is grounded and the 9 th pin is

connected to 12V dc voltage which is from 7812 regulator.

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First to fourth pins of driver IC are connected to RB0 to RB3 pins of the controller

respectively. Similarly 13

th

to 16

th

pins are connected to Relays R4, R3, R2, and R1

respectively. The relays used in this project are of Single pole Single throw type.

The Relay Driver Circuit is the main circuit that enables the actual control over the

applications. As per the project designed, the Relay Driver circuit signals the appliances to be

used if the user is valid or authenticated. Here we are using transistor as the relay driver circuit.

Relay is connected with the transistor, which generally contains five pins totally. The first two

pins are connected with the transistor and contain the magnetic coil wound between them. The

rest of the pins are common point, Normally Open (NO) point and Normally Close (NC) point.

Initially common point is in contact with Normally Close point. The magnetic coil also

contains an arrangement very similar to that of a hook. When supply is given at the supply

point, the magnetic coil of the relay gets energized or activated. Due to this a magnetic field is

created that lifts the hook upwards. Thus the arrangement that was initially closed gets opened

now. The status of the relay point gets changed (i.e. common point gets connected with

normally open point).

The status of the relay is depends upon the conduction of the transistor. The transistor

configuration used here is that of common emitter mode. The conduction of the transistor

depends on the base voltage of the transistor. The supply to the transistor is given from the

regulator of the power supply board. Normally transistor acts as a switch. The switch then gets

activated by the Microcontroller.

The output of the relay driver circuit is given to any of the port pins. The Microcontroller is

programmed to respond corresponding to the relay signal obtained. Thus the transistor acts as a

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switch to control the relay and indirectly controls the appliances. The output pins of the relays

are connected to the load, here only the phase of load is coming through relays the neutral is

connected directly to the load. This connection is actually as manual switch.

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CHAPTER-5

SOFTWARE REQUIREMENTS

SOFTWARE REQUIREMENTS

5.1 SOFTWARE TOOLS

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MPLAB

Protel

Propic

HI-Tech PIC C Compiler

5.2 MPLAB INTEGRATION


development of embedded applications employing Microchip's PIC micro and dsPIC

microcontrollers. MPLAB IDE runs as a 32-bit application on MS Windows, is easy to use and

includes a host of free software components for fast application development and super-

charged debugging. MPLAB IDE also serves as a single, unified graphical user interface for

additional Microchip and third party software and hardware development tools. Moving

between tools is a snap, and upgrading from the free simulator to MPLAB ICD 2 or the

MPLAB ICE emulator is done in a flash because MPLAB IDE has the same user interface for

all tools.

Choose MPLAB C18, the highly optimized compiler for the PIC18 series

microcontrollers, or try the newest Microchip's language tools compiler, MPLAB C30, targeted

at the high performance PIC24 and dsPIC digital signal controllers. Or, use one of the many

products from third party language tools vendors. They integrate into MPLAB IDE to function

transparently from the MPLAB project manager, editor and compiler.

5.3INTRODUCTION TO EMBEDDED C:

Ex: Hitec c, Keil c

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HI-TECH Software makes industrial-strength software development tools and C

compilers that help software developers write compact, efficient embedded processor code.

For over two decades HI-TECH Software has delivered the industry's most reliable

embedded software development tools and compilers for writing efficient and compact code to

run on the most popular embedded processors. Used by tens of thousands of customers

including General Motors, Whirlpool, Qualcomm, John Deere and many others, HI-TECH's

reliable development tools and C compilers, combined with world-class support have helped

serious embedded software programmers to create hundreds of breakthrough new solutions.

Whichever embedded processor family you are targeting with your software, whether it

is the ARM, PICC or 8051 series, HI-TECH tools and C compilers can help you write better

code and bring it to market faster.

HI-TECH PICC is a high-performance C compiler for the Microchip PIC micro

10/12/14/16/17 series of microcontrollers. HI-TECH PICC is an industrial-strength ANSI C

compiler - not a subset implementation like some other PIC compilers. The PICC compiler

implements full ISO/ANSI C, with the exception of recursion. All data types are supported

including 24 and 32 bit IEEE standard floating point. HI-TECH PICC makes full use of

specific PIC features and using an intelligent optimizer, can generate high-quality code easily

rivaling hand-written assembler. Automatic handling of page and bank selection frees the

programmer from the trivial details of assembler code.

5.4 EMBEDDED C COMPILER

ANSI C - full featured and portable

Reliable - mature, field-proven technology

Multiple C optimization levels

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An optimizing assembler

Full linker, with overlaying of local variables to minimize RAM usage

Comprehensive C library with all source code provided

Includes support for 24-bit and 32-bit IEEE floating point and 32-bit long data types

Mixed C and assembler programming

Unlimited number of source files

Listings showing generated assembler

Compatible - integrates into the MPLAB IDE, MPLAB ICD and most 3rd-party

development tools

Runs on multiple platforms: Windows, Linux, UNIX, Mac OS X, Solaris

5.5 EMBEDDED DEVELOPMENT ENVIRONMENT

This environment allows you to manage all of your PIC projects. You can compile,

assemble and link your embedded application with a single step.

Optionally, the compiler may be run directly from the command line, allowing you to

compile, assemble and link using one command. This enables the compiler to be integrated into

third party development environments, such as Microchip's MPLAB IDE.

5.6 EMBEDDED SYSTEM TOOLS

5.6.1 ASSEMBLER

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An assembler is a computer program for translating assembly language essentially, a

mnemonic representation of machine language into object code. A cross assembler (see

cross compiler) produces code for one type of processor, but runs on another. The

computational step where an assembler is run is known as assembly time. Translating assembly

instruction mnemonics into opcodes, assemblers provide the ability to use symbolic names for

memory locations (saving tedious calculations and manually updating addresses when a

program is slightly modified), and macro facilities for performing textual substitution

typically used to encode common short sequences of instructions to run inline instead of in a

subroutine. Assemblers are far simpler to write than compilers forhigh-level languages.

5.6.2 ASSEMBLY LANGUAGE HAS SEVERAL BENEFITS

Speed: Assembly language programs are generally the fastest programs around.

Space: Assembly language programs are often the smallest.

Capability: You can do things in assembly which are difficult or impossible in High

level languages.

Knowledge: Your knowledge of assembly language will help you write better

programs, even when using High level languages. An example of an assembler we use in our

project is RAD 51.

5.6.3 SIMULATOR

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Simulator is a machine that simulates an environment for the purpose of training or

research. We use a UMPS simulator for this purpose in our project.

5.6.4 UMPS

Universal microprocessor program simulator simulates a microcontroller with its

external environment. UMPS is able to simulate external components connected to the

microcontroller. Then, debug step is dramatically reduced. UMPS is not dedicated to only one

microcontroller family, it can simulate all kind of microcontrollers. The main limitation is to

have less than 64K-Bytes of RAM and ROM space and the good microcontroller library.

UMPS provide all the facilities other low-cost simulator does not have. It offers the user to see

the "real effect" of a program and a way to change the microcontroller family without changing

IDE. UMPS provide a low-cost solution to the problems. UMPS is really the best solution to

your evaluation.

5.6.5 UMPS KEY FEATURES

The speed, UMPS can run as fast as 1/5 the real microcontroller speed. No need to wait

2 days to see the result of a LCD routine access. All the microcontroller parts are

simulated, interrupts, communication protocol, parallel handshake, timer and so on.

UMPS have an integrated assembler/disassembler and debugger. It is able to accept an

external assembler or compiler. It has a text editor which is not limited to 64K-bytes

and shows keyword with color. It can also communicate with an external compiler to

integrate all the debug facilities you need.

UMPS is universal, it can easily be extended to other microcontroller with a library.

Ask us for toolkit development.

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External resource simulation is not limited. It can be extended to your proper needs by

writing your own DLL.

UMPS allows you to evaluate at the lowest cost the possibility to build a

microcontroller project without any cable. - UMPS include a complete documentation

on each microcontroller which describe special registers and each instruction

5.6.6COMPILER

A compiler is a program that reads a program in one language, the source language and

translates into an equivalent program in another language, the target language. The translation

process should also report the presence of errors in the source program.

Source

Program Compiler

Target

Program

Error

Messages

There are two parts of compilation. The analysis part breaks up the source program into

constant piece and creates an intermediate representation of the source program. The synthesis

part constructs the desired target program from the intermediate representation.

5.6.7 COUSINS OF THE COMPILER ARE

1. Preprocessor.

2. Assembler.

3. Loader and Link-editor.

A naive approach to that front end might run the phases serially.

1. Lexical analyzer takes the source program as an input and produces a long string

of tokens.

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2. Syntax Analyzer takes an out of lexical analyzer and produces a large tree.

Semantic analyzer takes the output of syntax analyzer and produces another tree.

Similarly, intermediate code generator takes a tree as an input produced by semantic analyzer

and produces intermediate code

5.6.8 PHASES OF COMPILER

The compiler has a number of phases plus symbol table manager and an error handler.

Input Source

Program

Lexical

Analyzer

Syntax

Analyzer

Symbol

Table

Manager

Semantic

Analyzer

Error

Handler

Intermediate

Code

Generator

Code

Optimizer

Code

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Generator

Out Target

Program

FABRICATION DETAILS

The fabrication of one demonstration unit is carried out in the following sequence.

Finalizing the total circuit diagram, listing out the components and sources of

procurement.

Procuring the components, testing the components and screening the components.

Making layout, repairing the interconnection diagram as per the circuit diagram.

Assembling the components as per the component layout and circuit diagram and

soldering components.

Integrating the total unit, interwiring the unit and final testing the unit.

5.7 DESIGN OF EMBEDDED SYSTEM

Like every other system development design cycle embedded system too have a design

cycle. The flow of the system will be like as given below. For any design cycle these will be

the implementation steps. From the initial state of the project to the final fabrication the design

considerations will be taken like the software consideration and the hardware components,

sensor, input and output. The electronics usually uses either a microprocessor or a

microcontroller. Some large or old systems use general-purpose mainframe computers or

minicomputers.

USER INTERFACES

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User interfaces for embedded systems vary widely, and thus deserve some special

comment. User interface is the ultimate aim for an embedded module as to the user to check the

output with complete convenience. One standard interface, widely used in embedded systems,

uses two buttons (the absolute minimum) to control a menu system (just to be clear, one button

should be "next menu entry" the other button should be "select this menu entry").

Another basic trick is to minimize and simplify the type of output. Designs sometimes

use a status light for each interface plug, or failure condition, to tell what failed. A cheap

variation is to have two light bars with a printed matrix of errors that they select- the user can

glue on the labels for the language that he speaks. For example, most small computer printers

use lights labeled with stick-on labels that can be printed in any language. In some markets,

these are delivered with several sets of labels, so customers can pick the most comfortable

language.

In many organizations, one person approves the user interface. Often this is a

customer, the major distributor or someone directly responsible for selling the system.

PLATFORM

There are many different CPU architectures used in embedded designs such as ARM,

MIPS, Coldfire/68k, PowerPC, X86, PIC,8051, Atmel AVR, H8, SH, V850, FR-V, M32Retc.

This in contrast to the desktop computer market, which as of this writing (2003) is

limited to just a few competing architectures, mainly the Intel/AMD x86, and the

Apple/Motorola/IBM PowerPC, used in the Apple Macintosh. With the growing acceptance of

Java in this field, there is a tendency to even further eliminate the dependency on specific

CPU/hardware (and OS) requirements.

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Standard PC/104 is a typical base for small, low-volume embedded and ruggedized system

design. These often use DOS,Linux or an embedded real-time operating system such as QNX

orInferno.

A common configuration for very-high-volume embedded systems is the system on a

chip, an application-specific integrated circuit, for which the CPU was purchased as intellectual

property to add to the IC's design. A related common scheme is to use a field-programmable

gate array, and program it with all the logic, including the CPU. Most modern FPGAs are

designed for this purpose.

TOOLS

Like typical computer programmers, embedded system designers use compilers,

assemblers, and debuggers to develop embedded system software. However, they also use a

few tools that are unfamiliar to most programmers.

Software tools can come from several sources:

Software companies that specialize in the embedded market.

Ported from the GNU software development tools.

Sometimes, development tools for a personal computer can be used if the embedded

processor is a close relative to a common PC processor. Embedded system designers also use a

few software tools rarely used by typical computer programmers.

One common tool is an "in-circuit emulator" (ICE) or, in more modern designs, an

embedded debugger. This debugging tool is the fundamental trick used to develop embedded

code. It replaces or plugs into the microprocessor, and provides facilities to quickly load and

debug experimental code in the system. A small pod usually provides the special electronics to

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plug into the system. Often a personal computer with special software attaches to the pod to

provide the debugging interface.

Another common tool is a utility program (often home-grown) to add a checksum or

CRC to a program, so it can check its program data before executing it.

An embedded programmer that develops software fordigital signal processing often has

a math workbench such as MathCad orMathematica to simulate the mathematics.

Less common are utility programs to turn data files into code, so one can include any

kind of data in a program. A few projects use Synchronous programming languages for extra

reliability ordigital signal processing.

DEBUGGING

Debugging is usually performed with an in-circuit emulator, or some type of debugger

that can interrupt the microcontroller's internal microcode. The microcode interrupt lets the

debugger operate in hardware in which only the CPU works. The CPU-based debugger can be

used to test and debug the electronics of the computer from the viewpoint of the CPU. This

feature was pioneered on the PDP-11.

As the complexity of embedded systems grows, higher level tools and operating

systems are migrating into machinery where it makes sense. For example, cell phones, personal

digital assistants and other consumer computers often need significant software that is

purchased or provided by a person other than the manufacturer of the electronics. In these

systems, an open programming environment such as Linux, OSGi or Embedded Java is

required so that the third-party software provider can sell to a large market.

OPERATING SYSTEM

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Embedded systems often have no operating system, or a specialized embedded

operating system (often a real-time operating system), or the programmer is assigned to port

one of these to the new system.

BUILT- IN SELF- TEST

Most embedded systems have some degree or amount of built-in self-test.

There are several basic types.

1. Testing the computer.

2. Test of peripherals.

3. Tests of power.

4. Communication tests.

5. Cabling tests.

6. Rigging tests.

7. Consumables test.

8. Operational test.

9. Safety test.

START UP

All embedded systems have start-up code. Usually it disables interrupts, sets up the

electronics, tests the computer (RAM, CPU and software), and then starts the application code.

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Many embedded systems recover from short-term power failures by restarting (without recent

self-tests). Restart times under a tenth of a second are common.

Many designers have found a few LEDs useful to indicate errors (they help

troubleshooting). A common scheme is to have the electronics turn on all of the LED(s) at reset

(thereby proving that power is applied and the LEDs themselves work), whereupon the

software changes the LED pattern as the Power-On Self Test executes. After that, the software

may blink the LED(s) or set up light patterns during normal operation to indicate program

execution progress or errors. This serves to reassure most technicians/engineers and some

users. An interesting exception is that on electric power meters and other items on the street,

blinking lights are known to attract attention and vandalism.

5.8 COMPONENTS USED

1. Step Down Transformer :(230/12V) 2 No.

2. Diodes :(1N4007) 4 No

3. Capacitors :1000F 1 No, 22pF- 2Nos

4. Regulators :7812 1 No, 7805 1 No

5. Light Emitting Diodes :LED`s 6Nos

6. TEMPERATURE SENSOR :LM-35-1 NOS

7. Driver ICs :ULN 2003 1No

8. PIC microcontroller :16f877A 1 No

9. Relays :Single Pole Single Throw Type 4Nos

10. Crystal Oscillator :4MHz 1Nos

11. Resistors :330 1Nos,10 K- 1 No

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:1 K 4os

12. Loads :4Nos

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CHAPTER-6

RESULTS

RESULT

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The below figure shows the hardware circuit for SCADA system for distributed and

substation automation fitted on a wooden board.

PUT YOUR PROJECT PHOTOS

FIG x

The below figure y shows that the circuit in ON position, it is identified by

PUT YOUR PROJECT PHOTOS

FIG y

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CHAPTER-7

CONCLUSION

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APPLICATIONS

1. Power plants

2. Power station

3. Textile mills

4. In Any kind of factory

CONCLUSION

The System operated successfully. By using the SCADA system we can monitoring and

control the substation.

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CHAPTER-8

BIBLIOGRAPHY

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BIBLIOGRAPHY

BOOKS

Customizing and programming ur pic microcontroller- Myke Predcko

Complete guide to pic microcontroller -e-book

C programming for embedded systems- Kirk Zurell

Teach yourself electronics and electricity- Stan Giblisco

Embedded Microcomputer system-onathan w.Valvano(2000)

Embedded PIC microcontroller- John Peatman

WEB SITIES:

Microchips.com

http://www.mikroelektronika.co.yu/english/product/books/PICbook/0_Uvod.ht

m

how stuff works.com

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APPENDIX-A

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CODING:

#include

void delay();

unsigned int i=0;

signed int count=0;

#define ir1 RB7

#define ir2 RB6

#define dc_for RD7

#define dc_rev RD6

#define light RD5

#define fan RD4

void main()

{

TRISC=0x06;

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TRISD=0x00;

TRISA=0x00;

TRISB=0xFF;

TRISE=0x00;

PORTC=0X00;

PORTD=0X00;

PORTA=0X00;

PORTB=0X00;

PORTE=0X00;

while(1)

{

if(ir1==1)

{

dc_for=1;

count++;

delay();

delay();

delay();

dc_for=0;

delay();

dc_rev=1;

delay();

Documents

Scada Systems for Distributed and Substation Automation (1)