TRAINING REPORT

OF

SIX MONTHS INDUSTRIAL TRAINING, UNDERTAKEN

AT

“EUREKA ELECTROSOFT SOLUTIONS PVT LTD.”

IN

“PLC AND SCADA”

ON

“INDUSTRIAL AUTOMATION”

SUBMITTED IN PARTIAL FULFILLMENT OF THE DEGREE

OF

BACHELOR OF TECHNOLOGY

IN

ELECTRICAL ENGINEERING

ACKNOWLEDGEMENT

Words could never be enough to express our true regards to all those who in some or the other

way helped us in completing this training. I can’t in full measure, reciprocate the kindness shown

and contribution made by various persons on this endeavor of us. I shall always remember them

with gratitude and sincerity. I take this opportunity to thank all those who have been instrumental

in completion of my report.

PREFACE

CONTENTS

1. COMPANY PROFILE

EUREKA ELECTROSOFT SOLUTIONS PVT LTD (EEAST)

EEAST offers world-class software development and Embedded System Development from India to companies across the world. Focused to provide IT enabled services at lower costs without compromising on quality, EEAST has expertise in customized E-commerce website solution and software applications development with extensive functionality.

They have R&D Lab for Developing Embedded System Software based on Microprocessor, Microcontroller such PIC, AVR, MCS series etc. and having our own product on the market  

They also  develop effectual solutions in the fields of Web Application Development, Customized Application development, application integration; our solutions cover a range of industries including financial services, E-commerce, healthcare and medical transcription. We provide high quality work that complies with international standards.

We believe in providing superior quality to our clients, thereby enabling us to have an extremely illustrious client list. Our Expert Creative Team and Graphics specialists backed by Experienced Project Managers & Business Consultants facilitate our ability to undertake offshore projects of any size and complexity. Our competent and veteran team of professional web programmers, C/C++, Visual C++, C#, VB .Net Programmer, ASP .NET Programmers, etc ensures the delivery of solutions that work for our clients.

Our methodology allows you too quickly and seamlessly transitions your business requirements into effective solutions. Our solutions are developed after going through a “tried & tested” process that starts with gaining the knowledge about your existing systems. During this phase, our team delves into client business to get a better insight into the current end-users and the current application. This ensures that user requirements are based on facts. This phase is often combined with the simulation of clients’ environment at our development center.

The development, followed by testing and quality assurance leads to training of client team, and maintenance and enhancement requests by our project managers.

1.1 The advantages of Software Development with Eureka Electrosoft:

Skilled resources - that are either not available to customers or are currently engaged in existing critical deployments.

Reduced time to market - our clients benefit by having the extended offshore team work on regular development/maintenance operations, leaving them free to focus on core competencies and future requirements.

24x7 support - resulting in smooth and seamless flow of operations for clients.

1.2 HISTORY:

Eureka Electrosoft Solutions Pvt. Ltd. was established in year 2001 and since then they are

completely committed to provide customer based technology solutions. They are working as a

Registered Research and Development unit to provide technology solutions to other companies

in the field of Automation and Control. They also develop and sell more than 15 products by our

own brand name EEAST.

They are one of the leading Embedded & Telecom Product Development Company in the north

region. Eureka ElectroSoft Solutions Pvt. Ltd. is working as a registered R & D lab for

developing Advanced Automation related software and hardware solutions. They are mainly

concerned with complete design and development of Electronics Oriented Softwares Solutions &

Software Oriented Electronics Solutions i.e. “ElectroSoft Solutions” and in our field they are

completely committed for “Changing Ideas into Reality”.

EEAST is one of the main Telecom Service Provider and Product Development Company. They

are completely committed to provide customer based Technology Solutions and Staffing

Solutions.

1.3 SERVICES PROVIDED BY EEAST:

1.3.1 Design & Development of Embedded Applications

1.3.2 BTS Installation and Commissioning for Telecom Carriers

1.3.3 Windows & Web based Advanced Software Solutions

1.3.4 Device Programmers & Development Boards

1.3.5 Project & other Technical Kits Development

1.3.6 Industrial/Corporate training on Embedded, GSM & Advanced Software

Technologies.

1.3.7 Remote Automation based solutions (GSM/ IR/RF/INTERNET)

1.3.8 Message Display Boards / Token Number Displays / Digital Display Boards.

1.3.9 USB & Other PC ports based automation solutions.

1.3.10 Talking Embedded Solutions

 

INTRODUCTION

Control engineering has evolved over time. In the past humans were the

main method for controlling a system. More recently electricity has been

used for control and early electrical control was based on relays. These

relays allow power to be switched on and off without a mechanical switch. It

is common to use relays to make simple logical control decisions. The

development of low cost computer has brought the most recent revolution,

the Programmable Logic Controller (PLC). The advent of the PLC began in the

1970s, and has become the most common choice for manufacturing

controls. PLCs have been gaining popularity on the factory floor and will

probably remain predominant for some time to come. Most of this is because

of the advantages they offer.

• 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.

The term SCADA stands for Supervisory Control and Data Acquisition. A SCADA system is a

common process automation system which is used to gather data from sensors and instruments

located at remote sites and to transmit and display this data at a central site for either control or

monitoring purposes. The collected data is usually viewed on one or more SCADA Host

computers located at the central or master site.

A real world SCADA system can monitor and control hundreds to hundreds of thousands of I/O

points. A typical Water SCADA application would be to monitor water levels at various water

sources like reservoirs and tanks and when the water level exceeds a preset threshold, activate

the system of pumps to move water to tanks with low tank levels.

Common analog signals that SCADA systems monitor and control are levels, temperatures,

pressures, flow rate and motor speed. Typical digital signals to monitor and control are level

switches, pressure switches, generator status, relays & motors.

3. PROGRAMMABLE LOGIC CONTROLLER

Automation of many different processes, such as controlling machines, basic relay control, motion control, process control is done through the use of small computers called a programmable logic controller (PLC). This is actually a control device that consists of a programmable microprocessor, and is programmed using a specialized computer language.

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 lighting fixtures. PLC’s are used in many industries and machines, such as packaging and semiconductor 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 or non-volatile memory. A PLC is an example of a real time system since output results must be produced in response to input conditions within a bounded time, otherwise unintended operation will result.

A modern programmable logic controller is usually programmed in any one of several languages, ranging from ladder logic to Basic or C. Typically, the program is written in a development environment on a personal computer (PC), and then is downloaded onto the programmable logic controller directly through a cable connection. Programmable logic controllers contain a variable number of Input/Output (I/O) ports The programmable logic controller circuitry monitors the status of multiple sensor inputs, which control output.

Fig 3) Programmable logic controller (PLC)

3.1 HISTORY

3.1.1 Origin

The PLC was invented in response to the needs of the American automotive manufacturing industry. Programmable controllers were initially adopted by the automotive industry where software revision replaced the re-wiring of hard-wired control panels when production models changed.

Before the PLC, control, sequencing, and safety interlock logic for manufacturing automobiles was accomplished using hundreds or thousands of relays, cam timers, and drum sequencers and dedicated closed-loop controllers. The process for updating such facilities for the yearly model change-over was very time consuming and expensive, as the relay systems needed to be rewired by skilled electricians.

In 1968 GM Hydramatic (the automatic transmission division of General Motors) issued a request for proposal for an electronic replacement for hard-wired relay systems.

The winning proposal came from Bedford Associates of Bedford, Massachusetts. The first PLC, designated the 084 because it was Bedford Associates' eighty-fourth project, was the result. Bedford Associates started a new company dedicated to developing, manufacturing, selling, and servicing this new product: Modicon, which stood for MOdular DIgital CONtroller. One of the people who worked on that project was Dick Morley, who is considered to be the "father" of the PLC. The Modicon brand was sold in 1977 to Gould Electronics, and later acquired by German Company AEG and then by French Schneider Electric, the current owner.

One of the very first 084 models built is now on display at Modicon's headquarters in North Andover, Massachusetts. It was presented to Modicon by GM, when the unit was retired after nearly twenty years of uninterrupted service. Modicon used the 84 moniker at the end of its product range until the 984 made its appearance.

3.1.2 Development

Early PLCs were designed to replace relay logic systems. These PLCs were programmed in "ladder logic", which strongly resembles a schematic diagram of relay logic. Modern PLCs can be programmed in a variety of ways, from ladder logic to more traditional programming languages such as BASIC and C. Another method is State Logic, a very high-level programming language designed to program PLCs based on state transition diagrams.

Many of the earliest PLCs expressed all decision making logic in simple ladder logic which appeared similar to electrical schematic diagrams. This program notation was chosen to reduce training demands for the existing technicians. Other early PLCs used a form of instruction list programming, based on a stack-based logic solver.

3.1.3 Programming

Early PLCs, up to the mid-1980s, were programmed using proprietary programming panels or special-purpose programming terminals, which often had dedicated function keys representing the various logical elements of PLC programs. Programs were stored on cassette tape cartridges. Facilities for printing and documentation were very minimal due to lack of memory capacity. The very oldest PLCs used non-volatile magnetic core memory.

3.1.4 Functionality

The functionality of the PLC has evolved over the years to include sequential relay control, motion control, process control, distributed control systems and networking. The data handling, storage, processing power and communication capabilities of some modern PLCs are approximately equivalent to desktop computers. PLC-like programming combined with remote I/O hardware, allow a general-purpose desktop computer to overlap some PLCs in certain applications

3.2 ARCHITECTURE OF PLC

Fig 3.2) Architecture of PLC

3.2.1 PARTS OF PLC

3.2.1.1 POWER SUPPLY: PLC requires 24V switch mode power supply for its operation.

3.2.1.2 MCU: Its full form is microcontroller unit. It is the processor of PLC. It is basically the brain of PLC. It performs various control operations of PLC.

3.2.1.3 INPUTS AND OUTPUTS: PLC has a set of isolated inputs and isolated outputs. Different PLC’s have different number and different type of inputs and outputs. Like in Micrologix 1000 we have total number of 6 inputs and 4 outputs whereas in Micrologix 1100 we have 10 inputs and 6 outputs.

3.2.1.4 EXPANSION PORT: In PLC there is an expansion port which is used for the addition of any other equipment with PLC. For example analog cards.

3.2.1.5 MEMORY MODULE: The memory module in PLC is used for the storage of program in PLC for future use.

3.2.1.6 COMMUNICATION PORT: The communication ports are used in PLC to communicate with the computer. In PLC there are two types of communication ports i.e. RS 232 comport and Ethernet port.

3.2.1.7 DISPLAY: In some of the PLC’s there is display screen which is available on the PLC. This display screen is used as human machine interface i.e. it provides good visualization of operation running on PLC.

3.2.2 PIN DIAGRAM:-

Figure 3.2.2) PLC Pin Diagram.

3.3 INPUTS AND OUTPUTS OF PLC

PLC programs are made up of a combination of the "gates" together with inputs, outputs, timers, counters, internal memory bits, analog inputs, analog outputs, mathematical calculations, comparators etc.

3.3.1 INPUTS

These are the physical connections from the real world to the PLC. They can be limit switches, push buttons, sensors, anything that can "switch" a signal on or off. The voltage of these devices are usually, but not always,  24 Volt DC. Manufacturers make inputs that can accept a wide range of voltages both ac and dc. It should be remembered that an input will be ON, "status 1", when the voltage is present at the input connection and OFF, "status 0", when the voltage is no

longer present at the input connection.

3.3.1.1 TYPES OF INPUTS OF PLC

USER TYPE: These are the inputs and outputs that are physically present and are practical to the inputs and outputs of the PLC.

BIT TYPE: These are the inputs and outputs that are not physically present and are functional in the PLC only. These inputs/outputs are basically used to drive each other in the ladder logic programming.

XIC (Examine if closed):

XIO (Examine if open):

3.3.2 OUTPUTS

These are the connections from the PLC to the real world. They are used to switch solenoids, lamps, contactors etc on and off. Again they are usually 24 Volt DC, either relay or transistor, but can also be 115/220 Volt AC.

3.3.2.1 TYPES OF PLC OUTPUTS

Relay type output

Transistor type output High speed output

I/P O/P0 01 1

I/P O/P0 11 0

TRIAC type output

3.4) PLC MANUFACTURES

3.4.1) SIEMENS

3.4.2) ALLEN BRADLEY

3.4.3) GENERAL ELECTRICAL

3.4.4) MITSUBISHI

3.4.5) SCHENIDER

3.4.6) ABB

Here we have done programming of two PLC’s of Allen Bradley i.e. Micrologix 1000 and

Micrologix 1100.

3.4.2.1) Micrologix 1000 Controllers 1761

Micrologix 1000 brings high speed, powerful instructions and flexible communications to

applications that demand compact, cost-effective solutions.

The Micrologix 1000 programmable controller is available in 10-point, 16-point or 32-point

digital I/O versions. Analog versions are also available with 20 digital I/O points, with 4 analog

inputs (two voltage and two current) and 1 analog output (configurable for either voltage or

current).

This little powerhouse is both inexpensive and compact, with footprints as small as 120mm x 80

mm x 40 mm (4.72" x 3.15" x 1.57"). The analog I/O circuitry is embedded into the base

controller, not accomplished through add-on modules, providing compact and cost-effective

analog performance

3.4.2.1.1) Features of Micrologix 1000

Preconfigured 1K programming and data memory — help ease configuration (bit, integer, timers, counters, etc)

Fast processing — allows for typical throughput time of 1.5 ms for a 500-instruction program

Built-in EEPROM memory — retains all of your ladder logic and data if the controller loses power, eliminating the need for battery back-up or separate memory module

RS-232 communication channel — allows for simple connectivity to a personal computer for program upload, download and monitoring using multiple protocols, including DF1 Full Duplex

RTU slave protocol support — use DF1 Half-Duplex Slave, which allows up to 254 notes to communicate with a single master using radio modems, leased-line modems or satellite uplinks

The Micrologix 1000 family provides small, economical programmable controllers. They are

available in configurations of 10 digital I/O (6 inputs and 4 outputs), 16 digital I/O (10 inputs and

6 outputs), 25 I/O (12 digital inputs, 4 analog inputs, 8 digital outputs, and 1 analog output), or

32 digital I/O (20 inputs and 12 outputs) in multiple electrical configurations of digital I/O. The

I/O options and electrical configurations make them ideal for many applications.

Fig 3.4.2.1) Micrologix 1000

3.4.2.2.2) Benefits

Compact design—Lets the MicroLogix 1000 controller thrive in limited panel space. Choice of communication networks—An RS-232-C communication port is

configurable for: DF1 protocol for direct connection to a programming device or operator interface; DH-485 networking through a 1761-NET-AIC converter; DeviceNet

networking through a 1761-NET-DNI interface; EtherNet/IP networking through a 1761-NET-ENI interface; or for half-duplex slave protocol in SCADA applications.

Simple programming with your choice of programming device—You can program these controllers in familiar ladder logic with MicroLogix 1000 A.I. Series Software®, PLC 500 A. I. Series Programming Software, RSLogix 500™ Windows Programming Software, or the MicroLogix Hand-Held Programmer (1761-HHP-B30). This symbolic programming language is based on relay ladder wiring diagrams that simplify the creation and troubleshooting of your control program.

Comprehensive instruction set—Over 65 instructions including simple bit, timer, and counter instructions, as well as instructions for powerful applications like sequencers, high-speed counter, and shift registers.

Fast—Execution time for a typical 500-instruction program is only 1.56 ms. Choice of languages—Software and documentation are available in 5 languages. The

hand-held programmer has 6 languages built in.

3.4.2.2) Micrologix 1100 Controllers

With online editing and a built-in 10/100 Mbps Ethernet/IP port for peer-to-peer messaging the

MicroLogix 1100 controller adds greater connectivity and application coverage to the

MicroLogix family of Allen-Bradley controllers. There are 10 digital inputs, 6 digital outputs,

and 2 analog inputs on every controller, with the ability to add digital, analog, RTD, and

thermocouple modules to customize the controller for your application. On versions of the

controller with DC inputs, there is a high-speed counter, and on the DC output version, two

PTO/PWM (pulse train outputs and pulse width modulated) outputs, enabling the controller to

support simple motion applications.

3.4.2.2.1) Features

The MicroLogix 1100 has 10 digital inputs, 2 analog inputs and 6 digital outputs, and supports

expansion I/O. Up to four 1762 I/O modules (also used on the MicroLogix 1200) may be added

to the embedded I/O, providing application flexibility and support of up to 80 digital I/O.

One embedded 20 kHz high-speed counter (on controllers with DC inputs)—The built-in independent high-speed counter uses 32-bit integers for extended range, features 8 modes of operation, and supports direct control of outputs independent of program scan.

Two 20 kHz high-speed PTO/PWM outputs (on controllers with DC outputs). Digital trim potentiometers—Allow quick and easy adjustments of timers, counters,

setpoints, and more. Program data security—Data file download protection lets a program be reloaded into

the controller without overwriting protected data. Floating Point Data Files—You can create data files that can contain up to 256 IEEE-

754 floating point values. Memory modules—Memory backup provides protection and transportability for

programs and data. Four interrupt inputs—Interrupt inputs let the controller scan a specific program file

(subroutine) when an input condition is detected from a sensor or field device. Real-Time Clock—embedded in every controller.

Fig 3.4.2.2) Micrologix 1100 with Analog Card

3.4.2.2.2) Benefits

Online Editing—modifications can be made to a program while it is running, making fine tuning of an operating control system possible, including PID loops. Not only does this feature reduce development time, but it aids in troubleshooting.

Built-in LCD—lets you monitor data within the controller, optionally modify that data and interact with the control program. The LCD displays status for embedded digital I/O and controller functions, and acts as a pair of digital trim pots to allow a user to tweak and tune a program.

Ethernet/IP Port—for peer-to-peer messaging offers users high-speed connectivity between controllers and the ability to access, monitor and program from the factory floor to anywhere an Ethernet connection is available.

Isolated RS-232/RS-485 combo port—provides a host of different point-to-point and network protocols.

Embedded Web Server—lets you custom configure data from the controller to be displayed as a web page.

3.4.2.2.3) Expansion I/O modules

If an application requires more I/O than the built-in I/O provided by the MicroLogix 1100

controller, you can connect up to four 1762 expansion I/O modules to the MicroLogix 1100 controller to

provide expanded I/O capacity. You can use digital and analog I/O modules in many combinations. The

current loading capacity of the controller’s built-in power supply may limit the number of I/O modules

that can be connected to the controller. MicroLogix 1100 expansion I/O modules include an integral high-

performance I/O bus. Software keying prevents incorrect positioning within the system.

You may install expansion I/O modules to the right of the MicroLogix 1100 controller either on a panel

with two mounting screws or on a DIN rail. Each expansion I/O module includes finger-safe terminal

blocks for I/O wiring and a label to record I/O terminal designations.

3.5) PROGRAMMING OF PLC

PLC programs are typically written in a special application on a personal computer, then

downloaded by a direct-connection cable or over a network to the PLC. The program is stored in

the PLC either in battery-backed-up RAM or some other non-volatile flash memory. Often, a

single PLC can be programmed to replace thousands of relays.

Under the IEC 61131-3 standard, PLCs can be programmed using standards-based programming

languages. A graphical programming notation called Sequential Function Charts is available on

certain programmable controllers.

Recently, the International standard IEC 61131-3 has become popular. IEC 61131-3 currently

defines five programming languages for programmable control systems: FBD (Function block

diagram), LD (Ladder diagram), ST (Structured text, similar to the Pascal programming

language), IL (Instruction list, similar to assembly language) and SFC (Sequential function

chart). These techniques emphasize logical organization of operations.

While the fundamental concepts of PLC programming are common to all manufacturers,

differences in I/O addressing, memory organization and instruction sets mean that PLC programs

are never perfectly interchangeable between different makers. Even within the same product line

of a single manufacturer, different models may not be directly compatible.

In Allen Bradley PLC’s the logic used for the programming is ladder logic. Ladder logic is a

programming language that represents a program by a graphical diagram based on the circuit

diagrams of relay-based logic hardware. It is primarily used to develop software for

Programmable Logic Controllers (PLCs) used in industrial control applications. The name is

based on the observation that programs in this language resemble ladders, with two vertical rails

and a series of horizontal rungs between them.

An argument that aided the initial adoption of ladder logic was that a wide variety of engineers

and technicians would be able to understand and use it without much additional training, because

of the resemblance to familiar hardware systems. This argument has become less relevant given

that most ladder logic programmers have a software background in more conventional

programming languages, and in practice implementations of ladder logic have characteristics—

such as sequential execution and support for control flow features—that make the analogy to

hardware somewhat imprecise.

Ladder logic is widely used to program PLCs, where sequential control of a process or

manufacturing operation is required. Ladder logic is useful for simple but critical control

systems, or for reworking old hardwired relay circuits. As programmable logic controllers

became more sophisticated it has also been used in very complex automation systems.

Fig 3.5) Simple ladder logic

The language itself can be seen as a set of connections between logical checkers (contacts) and

actuators (coils). If a path can be traced between the left side of the rung and the output, through

asserted (true or "closed") contacts, the rung is true and the output coil storage bit is asserted (1)

or true. If no path can be traced, then the output is false (0) and the "coil" by analogy to

electromechanical relays is considered "de-energized". The analogy between logical propositions

and relay contact status is due to Claude Shannon.

Ladder logic has contacts that make or break circuits to control coils. Each coil or contact

corresponds to the status of a single bit in the programmable controller's memory. Unlike

electromechanical relays, a ladder program can refer any number of times to the status of a single

bit, equivalent to a relay with an indefinitely large number of contacts.

So-called "contacts" may refer to physical ("hard") inputs to the programmable controller from

physical devices such as pushbuttons and limit switches via an integrated or external input

module, or may represent the status of internal storage bits which may be generated elsewhere in

the program.

Each rung of ladder language typically has one coil at the far right. Some manufacturers may

allow more than one output coil on a rung.

--( )-- a regular coil, energized whenever its rung is closed

--(\)-- a "not" coil, energized whenever its rung is open

--[ ]-- A regular contact, closed whenever its corresponding coil is energized

--[\]-- A "not" contact, open whenever its corresponding coil is energized

The "coil" (output of a rung) may represent a physical output which operates some device

connected to the programmable controller, or may represent an internal storage bit for use

elsewhere in the program.

FIG 3.5.1) PLC TRAINER KIT

The above figure shows the view of PLC trainer kit. On this kit various operations are

performed. It has following components mounted:

3.5.1.1) PLC MicroLogix1000

3.5.1.2)) SMPS (220V AC-24V DC)

3.5.1.3) A Contactor Relay

3.5.1.4) An Electromechanical Relay

3.5.1.5) Normally open Switch (4)

3.5.1.6) Normally closed Switch (4)

3.5.1.7) Output LED’s (4)

3.5.1.8) RS 232 Comport for communication with PC

Fig 3.5.2) Trainer Board of micrologix1100 PLC

The above fig shows the trainer board of micrologix 1100 PLC. It has following components:

3.5.2.1) PLC micrologix 1100

3.5.2.2) SMPS (220V ac to 24V dc)

3.5.2.3) AC drive

3.5.2.4) Analog I/O card

3.5.2.5) A Contactor Relay

3.5.2.6) An Electromechanical Relay

3.5.2.7) Normally open Switch (4)

3.5.2.8) Normally closed Switch (4)

3.5.2.9) Output LED’s (4)

3.5.2.10) RS 232 Comport for communication with PC

Fig

3.5.1.1) Connections of trainer kit using micrologix 1000

Fig 3.5.2.1) Connections of trainer kit using micrologix 1100

3.5.3) COMMUNICATION OF PLC WITH PC

To make communication of PLC with PC following steps are noted down:

3.5.3.1) Connect PC and PLC via RS232 comport or Ethernet.

3.5.3.2) Then click on RS Linx icon, a window will appear as shown in fig below

Fig 3.4.3.2) RS Linx classic window

3.5.3.3) In this window add drivers i.e. whether it is RS232 comport or Ethernet and configure

the drivers and closes the window.

3.5.3.4) Then click on icon RS who on the RS Linx classic window, another window will appear

as shown in fig 3.5.3.4.

3.5.3.5) After opening the RS who window click on AB DF1-1 DH-485, the PLC is running is

shown on the window. Then close this window and double click on RS Logix 500 starter.

Fig 3.5.3.4) RS WHO window

3.5.3.6) When we double click on RS Logix 500 starter a window will appear as shown in fig

3.5.3.6.

Fig 3.5.3.6) RS Logix 500 window

3.5.4) PLC INSTRUCTIONS

There are various instructions which are useful for making ladder logic for PLC programming.

These are as follows:

3.5.4.1) XIC (Examine if closed):

Use the XIC instruction in your ladder program to determine if a bit is ON. When the instruction

is executed, if the bit addressed is on (1), then the instruction is evaluated as true. When the

instruction is executed, if the bit addressed is off (0), then the instruction is evaluated as false.

XIC (Examine if closed):

A push button wired to an input (addressed as I:0/4).

An output wired to a pilot light (addressed as O:0/2).

A timer controlling a light (addressed as T4:3/DN).

3.5.4.2) XIO (Examine if open):

Use the XIO instruction in your ladder program to determine if a bit is OFF. When the

instruction is executed, if the bit addressed is off (0), then the instruction is evaluated as true.

When the instruction is executed, if the bit addressed is on (1), then the instruction is evaluated

as false.

I/P O/P

0 0

1 1

I/P O/P0 11 0

Examples of devices that turn on or off include:

• Motor overload normally closed (N.C.) wired to an input (I:0/10).

• An output wired to a pilot light (addressed as O:0/4).

• A timer controlling a light (addressed as T4:3/DN).

3.5.4.3) Output Energize (OTE):

Use the OTE instruction in your ladder program to turn on a bit when rung conditions are

evaluated as true. An example of a device that turns on or off is an output wired to a pilot light

(addressed as O:0/4).

OTE instructions are reset when:

• The SLC enters or returns to the REM Run or REM Test mode or

Power is restored.

• The OTE is programmed within an inactive or false Master Control

Reset (MCR) zone.

3.5.4.4) Output Latch (OTL) and Output Unlatch (OTU):

OTL and OTU are retentive output instructions. OTL can only turn on a bit, while OTU can only

turn off a bit. These instructions are usually used in pairs, with both instructions addressing the

same bit. Your program can examine a bit controlled by OTL and OTU instructions as often as

necessary.

Fig 3.5.4.4) Latch output and Unlatch output

3.5.4.5) Timers:

Timers are used to perform the timing operations. Time base is the minimum value of time in

second that can be taken by the timer. Preset value is the total number of the seconds for which

the timing operation has to be done Accumulator starts increasing the time in seconds upto the

preset value. Upto the preset value of the accumulator the enable bit of timer is high & the timer

runs. When accumulator reaches the preset value then the timer stops and the done bit of the

timer becomes high.

The timer has following bits and these bits are useful in the operation of timer:

EN- Enable- This bit will high when the input is given to the timer

TT - Timer timing bit - This bit will be high during the timing process. It remains high till

accumulator value becomes equal to preset value

DN – Done – This bit will be high when the timing process is ended. It set to high when

the accumulator value becomes equal to preset value.

In Micrologix 1000 and 1100 PLC there are three types of timers i.e.

3.5.4.5.1 TON Timer

3.5.4.5.2 T-OFF Timer

3.5.4.5.3 Retentive timer ON (RTO)

3.5.4.5.1) TON Timer:

Use the TON instruction to turn an output on or off after the timer has been on for a preset time

interval. The TON instruction begins to count time-base intervals when rung conditions become

true. As long as rung conditions remain true, the timer adjusts its accumulated value (ACC) each

evaluation until it reaches the preset value (PRE). The accumulated value is reset when rung

conditions go false, regardless of whether the timer has timed out

Fig 3.5.4.5.1) TON timer

3.5.4.5.2) T-OFF Timer:

Use the TOF instruction to turn an output on or off after its rung has been off for a preset time

interval. The TOF instruction begins to count timebase intervals when the rung makes a true-to-

false transition. As long as rung conditions remain false, the timer increments its accumulated

value (ACC) based on the timebase for each scan until it reaches the preset value (PRE). The

accumulated value is reset when rung conditions go true regardless of whether the timer has

timed out.

Fig 3.5.4.5.2) T-OFF timer

3.5.4.5.3) Retentive Timer (RTO):

Use the RTO instruction to turn an output on or off after its timer has been on for a preset time

interval. The RTO instruction is a retentive instruction that begins to count timebase intervals

when rung conditions become true.

The RTO instruction retains its accumulated value when any of the following occurs:

• Rung conditions become false.

• You change processor operation from the REM Run or REM Test

mode to the REM Program mode

• The processor loses power (provided that battery backup is maintained)

• A fault occurs

When you return the processor to the REM Run or REM Test mode and/or rung conditions go

true, timing continues from the retained accumulated value. By retaining its accumulated value,

retentive timers measure the cumulative period during which rung conditions are true.

Fig 3.5.4.5.3) Retentive Timer (RTO)

3.5.4.6) Counters:

Counters are used to count the number of operations. Its function is same as the timer accepts

that the timer counts the number of seconds and the counter counts the number of operations or

pulses. At each operation the value of the accumulator increases and when the value of the

accumulator comes to the preset value of the counter then the counter stops.

Counter bits:

TT - Timer timing bit - This bit will be high during the counting process. It remains high

till accumulator value becomes equal to preset value

DN – Done – This bit will be high when the counting process is ended. It set to high

when the accumulator value becomes equal to preset value.

3.5.4.6.1) Counter UP (CTU):

The CTU is an instruction that counts false-to-true rung transitions. Rung transitions can be

caused by events occurring in the program (from internal logic or by external field devices) such

as parts traveling past a detector or actuating a limit switch. When rung conditions for a CTU

instruction have made a false-to-true transition, the accumulated value is incremented by one

count, provided that the rung containing the CTU instruction is evaluated between these

transitions. The ability of the counter to detect false-to-true transitions depends on the speed

(frequency) of the incoming signal. The accumulated value is retained when the rung conditions

again become false. The accumulated count is retained until cleared by a reset (RES) instruction

that has the same address as the counter reset.

Fig 3.5.4.6.1) Counter UP (CTU)

3.5.4.6.2) Counter Down (CTD):

The CTD is an instruction that counts false-to-true rung transitions. Rung transitions can be

caused by events occurring in the program such as parts traveling past a detector or actuating a

limit switch. When rung conditions for a CTD instruction have made a false-to-true transition,

the accumulated value is decremented by one count, provided that the rung containing the CTD

instruction is evaluated between these transitions. The accumulated counts are retained when the

rung conditions again become false. The accumulated count is retained until cleared by a reset

(RES) instruction that has the same address as the counter reset.

Fig 3.5.4.6.2) Counter Down (CTU)

3.5.4.7) EQU (equal to)

Fig 3.5.4.7) Equal to

This input instruction is true when source A becomes equal to source B. The EQU instruction

compares two user specified values if values are equal, it allows rung continuity. The rung goes

true and output energies.

3.5.4.8) GEQ (greater than equal to)

Fig 3.5.4.8) Greater than Equal to

This instruction compares two values and will be high when the counted value becomes equal to

or greater than the fixed value and will energize everything that is connected next to it.

3.5.4.9) LEQ(less than equal to)

Fig 3.5.4.9) Less than Equal to

This instruction compares two values and will be high when the counted value becomes equal to

or less than the fixed value and will energize everything that is connected next to it.

3.5.4.10) GRT (greater than)

Fig 3.5.4.10) Greater Than

Use of the GRT instruction to test whether one value (source A) is greater than another (source

B). If the value at source A is greater than the value at source B, the instruction is logically true.

If the value at source A is less than or equal to the value at source B, the instruction is logically

false. Source A must be an address. Source B can either be a program constant or an address.

Negative integers are stored in two’s complement form.

3.5.4.11) LES (less than)

Fig 3.5.4.11) Less than

Use of the LES instruction is to test whether one value (source A) is less than another (source B).

If source A is less than the value at source B, the instruction is logically true. If the value at

source A is greater than or equal to the value at source B, the instruction is logically false. Source

A must be an address. Source B can either be a program constant or an address. Negative

integers are stored in two’s complement form.

3.5.4.12) LIM (Limit):

Fig 3.5.4.12) Limit

Use the LIM instruction to test for values within or outside a specified range, depending on how you set the limits.

3.5.4.13) SCP (Scale with parameter):

Fig 3.5.4.13) SCP (Scale with parameter)

Use the SCP instruction to produce a scaled output value that has a linear relationship between

the input and scaled values. This instruction supports integer and floating point values. Use this

instruction with SLC 5/03 (OS302), SLC 5/04 (OS401), and SLC 5/05 processors. The Input

Minimum, Input Maximum, Scaled Minimum, and Scaled Maximum are used to determine the

slope and offset values. The input value can go outside of the specified input limits and no

ordering is required. For example, the scaled output value is not necessarily clamped between the

scaled minimum and scaled maximum values.

3.5.4.14) RES (Reset):

Fig 3.5.4.14) Reset

Use a RES instruction to reset a timer or counter. When the RES instruction is enabled, it resets

the Timer ON Delay (TON), Retentive Timer (RTO), Count UP (CTU), or Count Down (CTD)

instruction having the same address as the RES instruction.

When resetting a counter, if the RES instruction is enabled and the counter rung is enabled, the

CU or CD bit is reset. If the counter preset value is negative, the RES instruction sets the

accumulated value to zero. This in turn causes the done bit to be set by a count down or count up

instruction.

3.5.5) PLC PROGRAMS

Program no. 1:

A bottle takes 7 sec to be completely filled, if the filling is interrupted then it should resume from

the same level. When the filling of one bottle is completed the motor should run for 2 sec for

changing the bottle.

Sol:

In this program we have used two inputs and two outputs of PLC i.e. I:0/0 & I:0/1 as inputs and

O:0/0 & O:0/1 as outputs. We have used a RTO as timer and compare instructions LEQ and

LIM. When input I:0/0 is ON the RTO will start and conveyor motor is started for 7 sec by using

LEQ instruction and after 7 sec conveyor motor is stopped and then the valve is operated for 2

sec using LIM instruction. Then after 2 sec the conveyor motor again starts automatically.

Fig 3.5.5.1) when RTO and conveyor motor runs by pressing start push button

Fig 3.5.5.2) when the valve operates and conveyor motor stops

Fig 3.5.5.3) after filling bottle the valve stops and conveyor starts again

Program no. 2:

When a momentary start push button is pressed, a lamp goes ON. If again same start push

button is pressed first lamp goes off and it remains off for the next 20 seconds. If start push

button is pressed again in between these 20 seconds, lamp should not go ON. It should go ON

again on pressing start push button only after completing 20 seconds.

Sol:

In this program one input and one output of PLC is used. A Counter, Timer and a Greater than

instructions are used.

Fig 3.5.5.4) program of controlling lamp by timer and counter

Fig 3.5.5.5) when lamp glows by pressing push button

Fig 3.5.5.6) when lamp goes off by pressing push button second time

Fig 3.5.5.7) lamp will not glow even if we press push button. The lamp will glow after 20 sec by pressing push button.

4) SCADA (Supervisory Control And Data Acquisition System)

4.1) Introduction

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, civil defense siren systems, 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, and energy

consumption.

A SCADA System usually consists of the following subsystems:

A Human-Machine Interface or HMI is the apparatus which presents process data to a

human operator, and through this, the human operator monitors and controls the process.

A supervisory (computer) system, gathering (acquiring) data on the process and sending

commands (control) to the process.

Remote Terminal Units (RTUs) connecting to sensors in the process, converting sensor

signals to digital data and sending digital data to the supervisory system.

Programmable Logic Controller (PLCs) used as field devices because they are more

economical, versatile, flexible, and configurable than special-purpose RTUs.

Communication infrastructure connecting the supervisory system to the Remote Terminal

Units

There is, in several industries, considerable confusion over the differences between SCADA

systems and Distributed control systems (DCS). Generally speaking, a SCADA system usually

refers to a system that coordinates, but does not control processes in real time. The discussion

on real-time control is muddied somewhat by newer telecommunications technology, enabling

reliable, low latency, high speed communications over wide areas. Most differences between

SCADA and DCS are culturally determined and can usually be ignored. As communication

infrastructures with higher capacity become available, the difference between SCADA and DCS

will fade

4.2) Systems concepts

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 or supervisory level intervention. For example, a PLC may control the flow of

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

Fig 4.2) SCADA SYSTEM

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.

SCADA systems typically implement a distributed database, commonly referred to as a tag

database, which contains data elements called tags or points. A point represents a single input or

output value monitored or controlled by the system. Points can be either "hard" or "soft". A hard

point represents an actual input or output within the system, while a soft point results from logic

and math operations applied to other points. (Most implementations conceptually remove the

distinction by making every property a "soft" point expression, which may, in the simplest case,

equal a single hard point.) Points are normally stored as value-timestamp pairs: a value and the

time stamp when it was recorded or calculated. A series of value-timestamp pairs gives the

history of that point. It's also common to store additional metadata with tags, such as the path to

a field device or PLC register, design time comments, and alarm information.

4.3) Hardware solutions

SCADA solutions often have Distributed Control System (DCS) components. Use of "smart"

RTUs or PLC’s, which are capable of autonomously executing simple logic processes without

involving the master computer, is increasing. A functional block programming language, IEC

61131-3 (Ladder Logic), is frequently used to create programs which run on these RTUs and

PLC’s. Unlike a procedural language such as the C programming language or FORTRAN, IEC

61131-3 has minimal training requirements by virtue of resembling historic physical control

arrays. This allows SCADA system engineers to perform both the design and implementation of

a program to be executed on an RTU or PLC. A Programmable automation controller (PAC) is a

compact controller that combines the features and capabilities of a PC-based control system with

that of a typical PLC. PACs are deployed in SCADA systems to provide RTU and PLC

functions. In many electrical substation SCADA applications, "distributed RTUs" use

information processors or station computers to communicate with protective relays, PACS, and

other devices for I/O, and communicate with the SCADA master in lieu of a traditional RTU.

Since about 1998, virtually all major PLC manufacturers have offered integrated HMI/SCADA

systems, many of them using open and non-proprietary communications protocols. Numerous

specialized third-party HMI/SCADA packages, offering built-in compatibility with most major

PLC’s, have also entered the market, allowing mechanical engineers, electrical engineers and

technicians to configure HMI’s themselves, without the need for a custom-made program written

by a software developer.

4.4) Remote Terminal Unit (RTU)

The RTU connects to physical equipment. Typically, an RTU converts the electrical signals from

the equipment to digital values such as the open/closed status from a switch or a valve, or

measurements such as pressure, flow, voltage or current. By converting and sending these

electrical signals out to equipment the RTU can control equipment, such as opening or closing a

switch or a valve, or setting the speed of a pump.

4.5) Supervisory Station

The term "Supervisory Station" refers to the servers and software responsible for communicating

with the field equipment (RTUs, PLC’s, etc), and then to the HMI software running on

workstations in the control room, or elsewhere. In smaller SCADA systems, the master station

may be composed of a single PC. In larger SCADA systems, the master station may include

multiple servers, distributed software applications, and disaster recovery sites. To increase the

integrity of the system the multiple servers will often be configured in a dual-redundant or hot-

standby formation providing continuous control and monitoring in the event of a server failure.

Initially, more "open" platforms such as Linux were not as widely used due to the highly

dynamic development environment and because a SCADA customer that was able to afford the

field hardware and devices to be controlled could usually also purchase UNIX or OpenVMS

licenses. Today, all major operating systems are used for both master station servers and HMI

workstations.

4.6) Operational philosophy

For some installations, the costs that would result from the control system failing are extremely

high. Possibly even lives could be lost. Hardware for some SCADA systems is ruggedized to

withstand temperature, vibration, and voltage extremes, but in most critical installations

reliability is enhanced by having redundant hardware and communications channels, up to the

point of having multiple fully equipped control centres. A failing part can be quickly identified

and its functionality automatically taken over by backup hardware. A failed part can often be

replaced without interrupting the process. The reliability of such systems can be calculated

statistically and is stated as the mean time to failure, which is a variant of mean time between

failures. The calculated mean time to failure of such high reliability systems can be on the order

of centuries.

4.7) Communication infrastructure and methods

SCADA systems have traditionally used combinations of radio and direct serial or modem

connections to meet communication requirements, although Ethernet and IP over SONET / SDH

is also frequently used at large sites such as railways and power stations. The remote

management or monitoring function of a SCADA system is often referred to as telemetry.

This has also come under threat with some customers wanting SCADA data to travel over their

pre-established corporate networks or to share the network with other applications. The legacy of

the early low-bandwidth protocols remains, though. SCADA protocols are designed to be very

compact and many are designed to send information to the master station only when the master

station polls the RTU. Typical legacy SCADA protocols include Modbus RTU, RP-570,

Profibus and Conitel. These communication protocols are all SCADA-vendor specific but are

widely adopted and used. Standard protocols are IEC 60870-5-101 or 104, IEC 61850 and

DNP3. These communication protocols are standardized and recognized by all major SCADA

vendors. Many of these protocols now contain extensions to operate over TCP/IP. It is good

security engineering practice to avoid connecting SCADA systems to the Internet so the attack

surface is reduced.

RTUs and other automatic controller devices were being developed before the advent of industry

wide standards for interoperability. The result is that developers and their management created a

multitude of control protocols. Among the larger vendors, there was also the incentive to create

their own protocol to "lock in" their customer base. A list of automation protocols is being

compiled here.

Recently, OLE for Process Control (OPC) has become a widely accepted solution for

intercommunicating different hardware and software, allowing communication even between

devices originally not intended to be part of an industrial network.

4.8) SCADA Architecture

SCADA systems have evolved through 3 generations as follows:

4.8.1) First Generation: "Monolithic"

In the first generation computing was done by Mainframe systems. Networks didn’t 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.

4.8.2) 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, which led to significant security problems for any

SCADA system that received attention from a hacker. Since the protocols were proprietary, very

few people beyond the developers and hackers knew enough to determine how secure a SCADA

installation was. Since both parties had vested interests in keeping security issues quiet, the

security of a SCADA installation was often badly overestimated, if it was considered at all.

4.8.3) 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. Due to the usage of standard protocols and

the fact that many networked SCADA systems are accessible from the internet; the systems are

potentially vulnerable to remote cyber attacks. On the other hand, the usage of standard protocols

and security techniques means that standard security improvements are applicable to the SCADA

systems, assuming they receive timely maintenance and updates.

4.9) SCADA Programming

The SCADA system used by us is SCADA RSVIEW32. This SCADA system is created by

Rockwell Automation. It has variety of commands, tool library and many other features required

for programming. RSView®32™ is an integrated, component-based HMI for monitoring and

controlling automation machines and processes. RSView32 is available in English, Chinese,

French, German, Italian, Japanese, Portuguese, Korean, and Spanish. RSView32 expands your

view with open technologies that provide unprecedented connectivity to other Rockwell

Software products, Microsoft products, and third-party applications

RSView32 was the first HMI software to:

Open its graphic displays as OLE containers for ActiveX® controls — with thousands of

third-party ActiveX controls to choose from, you can drop ready-made solutions right

into your projects

Develop an object model to expose portions of its core functionality, allowing RSView32

to interoperate easily with other component-based software products

Integrate Microsoft's popular Visual Basic® for Applications (VBA) as a built-in

programming language allowing almost unlimited ways to customize your RSView32

projects

Support OPC standards as both a server and a client for fast, reliable communications

with a wide variety of hardware devices

Implement add-on architecture (AOA) technology to expand RSView32's functionality

and integrate new features directly into RSView32's core

4.9.1) Benefits of RSVIEW32

Interact with other Rockwell Software products

Share data with Microsoft products

Enjoy preferred compatibility with Rockwell Automation products

Maximize your hardware investments with OPC

Update projects online

4.9.2) Programming with RSVIEW32

4.9.2.1) Double click on RSVIEW32 icon and a window will appear named

‘RSVIEW32 show works’.

Fig 4.9.2.1 RSVIEW32 show works

4.9.2.2) Then click on ‘display’ and a display window will appear and on this window we

can do our programming.

Screenshots of SCADA programming

Fig no 4.9.2.2 to 4.9.5 SCADA programming

5) HMI (HUMAN MACHINE INTERFACE)

The user interface (also known as human computer interface or man-machine interface (MMI))

is the aggregate of means by which people—the users—interact with the system—a particular

machine, device, computer program or other complex tool. The user interface provides means of:

Input, allowing the users to manipulate a system

Output, allowing the system to indicate the effects of the users' manipulation.

The design of a user interface affects the amount of effort the user must expend to

provide input for the system and to interpret the output of the system, and how much

effort it takes to learn how to do this. Usability is the degree to which the design of a

particular user interface takes into account the human psychology and physiology of the

users, and makes the process of using the system effective, efficient and satisfying.

5.1 How to connect HMI with PC

The terminal of HMI can be connected with PC either by USB or Ethernet port. You

must have to enter the panel address of your HMI in your browser (Internet Explore, mozila

firebox etc.). You can also transfer programme by pen drive.

5.1.1 For USB

The panel view component have a USB port to support communication with USB. You

must first install ALLEN BRADLEY Panel view USB remote NDIS network device driver on

your computer. The default address of Allen Bradley HMI is 169.254.2542.

5.1.2 For Ethernet

For Ethernet first install the drivers. The default address of single Allen Bradley HMI is

169.254.2542. If you install more than one HMI in the circuit then the address start from

169.254.0.0 to 169.254.255.255.

5.1.3 After connecting

After connecting the HMI with PC. Fill the default IP address in the web browser

software. Then panel view component is shown as shown in fig.

Fig 5.1.3.1 Panel view component screen

5.2.1 OPEN A NEW APPLICATION

Applications are created with default file names that you can change when saving the

application. The default file name is PVcApplication1. The number automatically increments as

you create new applications.

1. Click the Create & Edit button in the Panel View Explorer Startup window

2. Review areas of screen. This is where you will spend most of your time

5.2.2 Different toolbars

1. Navigation tabs Provides access to the different functional areas of an application

2. Application toolbar Provides common tools that are available to all views of the

application. Drag your mouse over each tool

3. Cursor controls Hides or shows the Controls or Properties panel to increase the

workspace area

4. Screen list Contains a list of screens in the application including the alarm banner and

diagnostics banner

5. Screen workspace Contains objects that you drag to the screen from the object palette

6 Object palette Contains panels of objects that you can drag to the screen workspace. Click the

cursor on a tab to open or close a panel of objects. The palette can occupy 25, 50 or 75% of the

Controls panel. Right-click on the object palette heading to resize it. The object palette and

screen list are resized accordingly

7 Screen toolbar Contains tools that operate on selected objects in the screen workspace. Also

contains a tool for turning the screen grid on or off

8. Properties panel Contains panels of properties to configure the appearance, navigation,

common properties, or connection tags of a selected object. Panels vary for each object. Click the

cursor on a tab to open orclose a panel You can also change the screen properties by clicking a

blank area of a screen. Screen properties include name, description, grid spacing, and the screen

background color9 Status bar Provides information about the terminal type, current actions, and

Validation Report link after a validation is performed.

Table no;- 5.2.2

Tag nameData type Tag

addressController

description

 Motor_Start

 Boolean

 B3:0/0

 PLC_1

 Starts the motor.

 Motor_Stop

 Boolean

 B3:0/1

 PLC_1

 Stops the motor.

 Change_Speed

 16 bit integer

 N7:1

 PLC_1

Changes the motor speed to a value between 0 and 1000 rpm.

 Motor_Status_Ind

 Boolean

 B3:0/2

 PLC_1

Reads the running or stopped status of the motor.

  Motor_Speed

  16 bit integer

  N7:0

  PLC_1

Reads the current motor speed. Also used to trigger an alarm if the speed rises above 850 or 900 rpm.

  Motor_AutoManual

  Boolean

  B3:0/3

  PLC_1

Changes the motor to auto or manual mode and also used to read the current mode of the motor.

6. DRIVES

A variable-frequency drive (VFD) is a system for controlling the rotational speed of an

alternating current (AC) electric motor by controlling the frequency of the electrical power

supplied to the motor. A variable frequency drive is a specific type of adjustable-speed drive.

Variable-frequency drives are also known as adjustable-frequency drives (AFD), variable-speed

drives (VSD), AC drives, microdrives or inverter drives. Since the voltage is varied along with

frequency, these are sometimes also called VVVF (variable voltage variable frequency)

drives.Variable-frequency drives are widely used. For example, in ventilations systems for large

buildings, variable-frequency motors on fans save energy by allowing the volume of air moved

to match the system demand. Variable frequency drives are also used on pumps, conveyor and

machine tool drives.

Fig 6.1 Powerflex 4M drive

Variable frequency drive controllers are solid state electronic power conversion devices.

The usual design first converts AC input power to DC intermediate power using a rectifier

bridge. The DC intermediate power is then converted to quasi-sinusoidal AC power using an

inverter switching circuit. The rectifier is usually a three-phase diode bridge, but controlled

rectifier circuits are also used. Since incoming power is converted to DC, many units will

accept single-phase as well as three-phase input power (acting as a phase converter as well as a

speed controller); however the unit must be derated when using single phase input as only part

of the rectifier bridge is carrying the connected load

6.1 Volts per Hertz (v/f) Ratio 

Flux should remain constant in order to produce full load torque which is achieved by

maintaining a constant magnetic flux in the motor. This method of magnetic flux control is

called the volts-per-hertz ratio. With this method, the frequency and voltage must increase in

the same proportion to maintain good torque production at the motor.  For example, if the

frequency is 60 Hz and the voltage is 460 V, then the volts per Hertz ratio(460 divided by 60)

would be 7.6 V/Hz. So, at half speed on a 460 V supplied system, the frequency would be 30

Hertz and the voltage applied to the motor would be 230 V and the ratio would still be

maintained at 7.6 V/Hz.  This ratio pattern saves energy going to the motor, but it is also very

critical to performance. The variable-frequency drive tries to maintain this ratio because if the

ratio increases or decreases as motor speed changes, motor current can become unstable and

torque can diminish. On the other hand, excessive current could damage or destroy the motor.   

In a PWM drive the voltage change required to maintain a constant Volts-per-Hertz ratio as the

frequency is changed is controlled by increasing or decreasing the widths of the pulses created

by the inverter. And, a PWM drive can develop rated torque in the range of about 0.5 Hz and

up. Multiple motors can be operated within the amperage rating of the drive (All motors will

operate at the same frequency). This can be an advantage because all of the motors will change

speed together and the control will be greater.  

6.2 Catalog no. explanation

The catalog explanation of drives is given below

Fig no.6.2 Catalog explanation

6.3.1 Drive connection

Fig no 6.3 Drive connection

6.3.2 Installation connection

Fig no 6.3 showing I/O connection

6.4 Program for speed control

For speed control we have to given three input, one is for forward run, one for reverse run & one

for speed control. The forward run & reverse run are of digital type while speed control in analog

type that is 0 – 10 V. The program is shown below.

Fig no:6.4 Snap shot of drive program (PLC ladder logic)

Fig no 6.4.1 Drive control by SCADA