As we have selected ‘MILK PROCESS AUTOMATION IN DAIRY SYSTEM USING PLC and SCADA’ after observing a lot of projects, because we have observed that automation is widely used in most of the companies for various processes. In today’s generation it is needed in each field. Thus all the process needs a few operators to control automation.
Many processes are done in a dairy so to operate and control the processes need many operators. Our aim is to reduce operators and to save time and money. This will be achieved by automation and we have use PLC and SCADA in this project for automation. SCADA is the software for this process.
In dairy process, first of all raw milk will be collected in the tank. Then after filtration and clarification of milk will be done and collect into a balanced tank. After that pasteurization of milk will be done. Further, the process of separation of milk takes place and next standardization of milk will be done. In standardization, milk will standardize in different quality. Now after packing process will take place. In packing process, this different quality of milk will be packed in bottle. This all processes are done with automation using PLC and SCADA.
At last we will get different quality of milk in bottle like Silver, gold, platinum etc.
Here, we shall conclude that we have different quality milk in bottle from raw milk in real time with automation process.
1.1 Introduction
The first ideas about fully automating the milking process were generated in the mid seventies. Cost of labour in several countries was growing and this was one of the main reasons to start the development of automation around milking. The first applications were automatic concentrate feeders. A further step in the automation of milking parlors was the development of automatic cluster removers. In the early eighties, automation in milking parlors was expanded with the development of milk yield recording equipment and sensors to detect udder health problems. All these developments and new milking technology reduces the labour input during milking, resulting in a higher output per man-hour. The final step in the automation development seemed to be the development of automatic teat cup attachment systems. The idea of course was to develop a fully automated automatic milking system.
An Automatic milking system is in use for 24 hours per day, needs adjusted cleaning and cooling procedures, complicates visual control and the milking frequency varies from cow to cow and from day to day.
One of the aspects affected by automatic milking is milk quality. The quality of milk is a very important aspect of milk production. Milk payment systems and consumer acceptance are, to a great extent, based on it. Automatic milking is a fully automated process. Visual control of the milk is not possible as during conventional milking. Therefore, the milk quality needs to be managed in a different manner. Several devices such as sensors for conductivity, color and temperature of the milk, yield measurement and machine on time figures are integrated and inform the farmer on the status of the milk.
We only know that in India there are huge numbers of people depends on milk giving animals. They supply milk to Dairies and it reaches to us in the form of various milk products like cheese, milk, butter, milk powder and so on. Actually what happens to the milk, how it is processed? What makes the milk conducive to health? What treatment it receives? And how various milk products are prepared?
Even though with modern automation in place, the need to configure design process itself, specifically looking at methodologies for generating optimal dairy processing
Flow sheets over a range of scales, from raw milk to final product and packaging, are most sought after.
Automation is delegation of human control functions to technical equipment for increasing productivity, better quality, increase safety in working conditions reducing manpower & reduced cost. Manufacturing of products under the control of computers and programmable controllers, manufacturing assembly lines as well as stand-alone machine tools (CNC machines) and robotic devices can be used for dairy automation. Programmable Logic Controller (PLC) and Supervisory Control and Data Acquisition (SCADA) in combination attract the need of the project for its capability to provide over all fast and reliable control for large process automation needs.
Automation in various process industries using PLC and SCADA has gained high importance due to efficient & reliable control.
Dairy industry is one area in which automation plays an important role to control, automate and stream line the process. Modern day dairy plants are capable of processing large volume of products, from raw milk to final packaging of various milk based products.
The dairy industry is divided into two main production areas:
‘ Primary production of milk in farms
‘ Processing of milk The aim of this project is to study the dairy process automation, to suggest any scope of improvement in the milk processing and packaging and to implement them using PLC & SCADA
Brief History Of Work
‘
2.1 History Of PLC
The first PLC can be traced back to 1968 when Bedford Associates, a company in Bedford, MA, developed a device called a Modular Digital Controller for General Motors (GM). The MODICON, as it was known, was developed to help GM eliminate traditional relay-based machine control systems. Because relays are mechanical devices, they have limited lifetimes. They are also cumbersome, especially in large applications where thousands of them may exist. With so many relays to work with, wiring and troubleshooting could be quite complicated.
Since the MODICON was an electronic device, not a mechanical one, it was perfect for GM’s requirements, as well as for many other manufacturers and users of control equipment. With less wiring, simpler troubleshooting, and easy programming, PLC technology caught on quickly.
PLCs are often defined as miniature industrial computers that contain hardware and software that is used to perform control functions. A PLC consists of two basic sections: the central processing unit (CPU) and the input/output interface system. The CPU, which controls all PLC activity, can further be broken down into the processor and memory system. The input/output system is physically connected to field devices (e.g., switches, sensors, etc.) and provides the interface between the CPU and the information providers (inputs) and controllable devices (outputs).
PLCs can be divided into at least three categories:
‘ Full-size, for top level applications requiring fast program execution with very short instruction cycle times. They are capable of supporting several CPUs for multiprocessing to provide more processing power. They offer the TCP/IP communication capability over general purpose networks to the supervisory workstations, and support field bus data transmission with equipment controllers.
‘ Middle-size, intended for industrial automated systems of medium power. They offer a large choice of analog and digital input/output modules. They are usually connected to a field bus on one side and to the equipment on the other side; their speed is not an important parameter, the amount of data transferred is small and the average price per function is low
‘ Small or micro-size, for direct interface with sensors and actuators. They are very simple electrically and mechanically and are sometimes integrated with the intelligent sensor itself, they are characterized by short reaction times and they transfer a small amount of data.
To operate, the CPU "reads" input data from connected field devices through the use of its input interfaces, and then "executes", or performs the control program that has been stored in its memory system. Programs are typically created in ladder logic, a language that closely resembles a relay-based wiring schematic, and are entered into the CPU’s memory prior to operation. Finally, based on the program, the PLC "writes", or updates output devices via the output interfaces. This process, also known as scanning, continues in the same sequence without interruption, and changes only when a change is made to the control program.
As PLC technology has advanced, so have programming languages and communications capabilities, along with many other important features. Today’s PLCs offer faster scan times, space efficient high-density input/output systems, and special interfaces to allow non-traditional devices to be attached directly to the PLC. Not only can they communicate with other control systems, they can also perform reporting functions and diagnose their own failures, as well as the failure of a machine or process.
When you consider all of the advances PLCs have made and all the benefits they offer, it’s easy to see how they’ve become a standard in the industry, and why they will most likely continue their success in the future.
‘
2.1. (A) Interacting With PLCs
Occasionally, users will need to interact with the PLC to program or configure it. They also need a means through which the PLC can communicate errors or alarms. Users interface with PLCs in a number of ways. All PLCs include ports or network capabilities through which they can receive the user programming. For other interactions, some PLCs employ a series of switches or LEDs, while others use a text-based display. Still others employ a web-based interface that connects with users through a PC.
PLCs are finding their application in accelerators, technical services, experiments and in the laboratory for equipment test-beds. The technical requirements of the accelerators, the technical services and the experiments are mostly the same. Thus, a range of PLC products is needed for general purpose applications in a large diversity of fields such as electricity, water, gas, cryogenics, cooling, ventilation, process control, magnet control, machinery, personnel access and safety systems. It is planned to use PLCs for accelerator specific systems like: interlocks for main magnet power supplies, beam targets, dumps, stoppers, collimators, aperture limiters and beam extraction electronics.
‘
2.2 Diagram Of Process Flow Chart
Figure.2.0 Process Flow
‘
2.3 Process Flow
Milk is a white liquid produced by the mammary glands of mammals. It is the primary source of nutrition for young mammals before they are able to digest other types of food. Early-lactation milk contains colostrums, which carries the mother’s antibodies to the baby and can reduce the risk of many diseases in the baby. It also contains many other nutrients.
As an agricultural product, milk is extracted from mammals during or soon after pregnancy and used as food for humans. Worldwide, dairy farms produced about 730 million ton of milk in 2011. India is the world’s largest producer and consumer of milk, yet neither exports nor imports milk. New Zealand, the European Union’s 28 member states, Australia, and the United States are the world’s largest exporters of milk and milk products. China and Russia are the world’s largest importers of milk and milk products.
Throughout the world, there are more than 6 billion consumers of milk and milk products. Over 750 million people live within dairy farming households. Milk is a key contributor to improving nutrition and food security particularly in developing countries. Improvements in livestock and dairy technology offer significant promise in reducing poverty and malnutrition in the world.
Despite all the preventive hygiene measures, the raw milk delivered to dairies by agricultural businesses still contains unwanted foreign substances ‘ such as somatic cells and blood from the udders, contaminants from the air and dirt from contact with the milking machines, the milk lines and the transport vehicles.
The flow chart involves the various following processes:
1. Milk receipt tank
2. Filter and clarification
3. Pasteurization
4. Separation
5. Standardization
6. Packaging
‘
The each and every above process is briefly explained as follows:
1. Milk Receipt Tank:
This tank consists of the milk that is brought to the industry from source like farms. Here the milk is just stored and care is taken that the stored milk is safe and will then further it is taken for the further process.
2. Clarification:
Separation and clarification can be done at the same time in one centrifuge. Particles, which are more dense than the continuous milk phase, are thrown back to the perimeter. The solids that collect in the centrifuge consist of dirt, epithelial cells, leucocytes, corpuscles, bacteria sediment and sludge. The amount of solids that collect will vary, however, it must be removed from the centrifuge.
More modern centrifuges are self-cleaning allowing a continuous separation/clarification process. This type of centrifuge consists of a specially constructed bowl with peripheral discharge slots. These slots are kept closed under pressure. With a momentary release of pressure, for about 0.15 s, the contents of sediment space are evacuated. This can mean anywhere from 8 to 25 L are ejected at Intervals Of 60 Min. For One Dairy, Self-Cleaning Translated To A Loss Of 50 L/Hr Of Milk.
Filtration:
Filtered milk (UF milk) is a sub classification of milk protein concentrate that is produced by passing milk under pressure through a thin, porous membrane to separate the components of milk according to their size, permitting greater efficiency in cheese making. Specifically, filtration allows the smaller lactose, water, mineral, and vitamin molecules to pass through the membrane, while the larger protein and fat molecule are retained and concentrated. The removal of water and lactose reduces the volume of milk, and thereby lowers its transportation and storage costs. Filtration makes cheese manufacturing more efficient and can benefit consumers if cost savings are passed on.
3. Pasteurization
Pasteurization or pasteurization is a process of heating a food, which is usually a liquid, to a specific temperature for a predefined length of time and then immediately cooling it after it is removed from the heat. This process slows spoilage caused by microbial growth in the food.
Unlike sterilization, pasteurization is not intended to kill all micro-organisms in the food. Instead, it aims to reduce the number of viable pathogens so they are unlikely to cause disease (assuming the pasteurized product is stored as indicated and is consumed before its expiry date). Commercial-scale sterilization of food is not common because it adversely affects the taste and quality of the product. Certain foods, such as dairy products, may be superheated to ensure pathogenic microbes are destroyed.
4. Separation:
Milk should be clarified by separators to improve milk quality ‘ for good reason: As a basic food, milk is subject to national and international laws. The aim of these laws is to ensure that milk and dairy products are brought into circulation only in perfect condition which will not harm health. Centrifuges can be used to separate the cream from the skim milk. Under the influence of centrifugal force the fat globules (cream), which are less dense than the skim milk, move inwards through the separation channels toward the axis of rotation. The skim milk will move outwards and leaves through a separate outlet.
5. Standardization:
The streams of skim and cream after separation must be recombined to a specified fat content. This can be done by adjusting the throttling valve of the cream outlet; if the valve is completely closed, all milk will be discharged through the skim milk outlet. As the valve is progressively opened, larger amounts of cream with diminishing fat contents are discharged from the cream outlet. With direct standardization the cream and skim are automatically remixed at the separator to provide the desired fat content.
‘
Chapter 3
Literature Survey
‘
3.1 What Is Automation?
Automation is the use of various control system for operating equipment such as machinery, processes in factories, boilers and heat treating ovens, switching in telephone networks, steering and stabilization of ships or aircraft and other applications with minimal or reduced human intervention. Some processes have been completely automated.
The biggest benefit of automation is that it saves labor; however, it is also used to save energy and materials and to improve quality, accuracy and precision.
The term automation, inspired by the earlier word automatic was not widely used before 1947, when General Motors established the automation department. It was during this time that industry was rapidly adopting feedback controllers, which were introduced in the 1930s.
Automation has been achieved by various means including mechanical, hydraulic, pneumatic, electrical, and electronic and computers, usually in combination. Complicated systems, such as modern factories, airplanes and ships typically use all these combined techniques.
3.2 Types Of Automations
a. Feedback control.
b. Sequential control and logical sequence control.
c. Computer control.
a. Feedback Control
Feedback control is accomplished with a controller. To function properly a controller must provide correction in a manner that maintains stability. Maintaining stability is a principle objective of control theory.
As an example of feedback control, consider a steam coil air heater in which a temperature sensor measures the temperature of the heated air, which is the measured variable. This signal is constantly "fed back" to the controller, which compares it to the desired setting (set point). The controller calculates the difference (error) then calculates a correction and sends the correction signal to adjust the air pressure to a diaphragm that moves a positioned on the steam valve, opening or closing it by the calculated amount. All the elements constituting the measurement and control of a single variable are called a control loop.
The complexities of this are that the quantities involved are all of different physical types; the temperature sensor signal may be electrical or pressure from an enclosed fluid, the controller may employ pneumatic, hydraulic, mechanical or electronic techniques to sense the error and send a signal to adjust the air pressure. The first controllers used analog methods to perform their calculations.
Analog methods were also used in solving differential equations of control theory. The electronic analog computer was developed to solve control type problems and electronic analog controllers were also developed. Analog computers were displaced by digital computers when they became widely available.
Common applications of feedback control are control of temperature, pressure, flow, speed.
B. Sequential Control And Logical Sequence Control
Sequential control may be either to a fixed sequence or to a logical one that will perform different actions depending on various system states. An example of a adjustable but otherwise fixed sequence is a timer on a lawn sprinkler. An elevator is an example that uses logic based on the system states.
A basic form of sequential control is relay logic by which electrical relays engage electrical contacts which either start or interrupt power to a device. Relay logic was developed when starting and stopping industrial sized electric motors, opening and closing solenoid valves and starting and stopping other devices was done with relays, timers and other electrical hardware.
More complicated examples involve start up and shut down sequences for equipment, in which a number of safety precautions can be taken by good design of control logic. The number of relays, cam timers and drum sequencers can number into the hundreds or even thousands in some factories. Special computers called programmable logic controllers were designed to replace many of these hardware items and to add a higher level of functionality.
In a typical hard wired motor start and stop circuit (called a control circuit) a motor is started by pushing a "Start" or "Run" button that activates a pair of electrical relays. The "lock-in" relay locks in contacts that keep the control circuit energized when the push button is released. (The start button is a normally open contact and the stop button is normally closed contact.). Another relay energizes a switch that powers the device that throws the motor starter switch (three sets of contacts for three phase industrial power) in the main power circuit. (Note: Large motors use high voltage and experience high in-rush current, making speed important in making and breaking contact. This can be dangerous for personnel and property with manual switches.). All contacts are held engaged by their respective electromagnets until a "stop" or "off" button is pressed that de-energizes the lock in relay. See diagram: Motor Starters Hand-Off-auto With Start-Stop.
c. Computer Control
Computers can perform both sequential control and feedback control, and typically a single computer will do both in an industrial application. Programmable logic controllers (PLCs) are a type of special purpose microprocessor that replaced many hardware components such as timers and drum sequencers used in relay logic.
General purpose process control computers have increasingly replaced stand alone controllers, with a single computer able to perform the operations of hundreds of controllers. Process control computers can process data from a network of PLCs, instruments and controllers in order to implement typical (such as PID) control of many individual variables or, in some cases, to implement complex control algorithms using multiple inputs and mathematical manipulations. They can also analyze data and create real time graphical displays for operators and run reports for engineers and management.
Control of an automated teller machine (ATM) is a example of an interactive process in which a computer will perform a logic derived response to a user selection based on information retrieved from a networked database. The ATM process has a lot of similarities to other online transaction processes. The different logical responses are called scenarios. Such processes are typically designed with the aid of use cases and flowcharts, which guide the writing of the software code.
‘
3.3 Different Control Systems Used In Automation
a. HMI Controller based control system.
b. DCS based Control system.
c. PC based control system.
d. PLC Based automation system.
a. Human Machine Interface (HMI)
In complex systems, the human-machine interface is typically computerized. The term Human-computer interface refers to this kind of systems.
The engineering of the human-machine interfaces is by considering ergonomics (Human Factors). The corresponding disciplines are Human Factors Engineering (HFE) and Usability Engineering (UE), which is part of Systems Engineering.
Tools used for incorporating the human factors in the interface design are developed based on knowledge of computer science, such as computer graphics, operating systems, programming languages. Nowadays, we use the expression Graphical User Interface for Human-Machine Interface on computers, as nearly all of them are now using graphics. Primary methods used in the interface design include prototyping and simulation.
b. Distributed Control System (DCS)
A distributed control system refers to a control system usually of a manufacturing system, process or any kind of dynamic system, in which the controller elements are not central in location (like the brain) but are distributed throughout the system with each component sub-system controlled by one or more controllers.
c. PC Based Control System
Compact, low-cost and yet advanced process-control engineering can be achieved based on Programmable Controllers.
‘
d. PLC Based Automation System
PLC Automation panels are used in Process Control application in industries such as … Steel / Aluminum / Wire and Cable / Tyre & Tube / Packaging / Plastic / Polyfilms / Pharmaceuticals / Defense / Automobile / Power Plant / Marine / LPG Gas & Oil / Cement / In fracture / Crane Automation etc.
‘
Chapter 4
Programmable Logic Controller
‘
4.1 What Is PLC?
A Programmable Logic Controller, PLC or Programmable Controller is a digital computer used for automation of electromechanical processes, such as control of machinery on factory assembly lines, amusement rides, or light fixtures.
The abbreviation "PLC" and the term "Programmable Logic Controller" are registered trademarks of the Allen-Bradley Company (Rockwell Automation). PLCs are used in many industries and machines. Unlike general-purpose computers, the PLC is designed for multiple inputs and output arrangements, extended temperature ranges, immunity to electrical noise, and resistance to vibration and impact.
In essence, a programmable logic controller reads its input signals and responds to them by turning the output modules on or off. It functions under the classic "if/then" scenario, only on a much more complicated scale since it controls multiple input and output devices, all of which must be responded to immediately and constantly as designated by the user program. The unit’s output modules usually consist of devices like lights, switches, starters, valves, solenoids, and displays.
Programs to control machine operation are typically stored in battery-backed-up or non-volatile memory. A PLC is an example of a hard real time system since output results must be produced in response to input conditions within a limited time, otherwise unintended operation will result.
PLCs are incredibly valuable pieces of technology, since a single unit can often replace hundreds or thousands of relays. Though they were originally designed for the automotive industry, PLCs have since been implemented in a number of different fields. In large part, the automation processes in most modern factories are facilitated by PLCs.
These devices are designed to follow their programming instructions precisely, which is especially vital in a factory assembly line setting where a small mistake or miscalculation can result in costly errors. Some PLCs function on a very basic level; others are capable of controlling higher-level, more complicated processes. They can be used for a wide variety of input/output functions and timing applications. They also offer motion control and complex networking capabilities.
‘
Figure-4.1 Multiple Inputs And Multiple Outputs PLC
(Source: www.plcedge.com/plc-scada.html’)
4.1. (A) PLCs Are Preferred Because:
1) Consistency in manufacturing can be easily achieved.
2) Complete control of the manufacturing process can be achieved.
3) Accuracy and quality can be improved.
4) Productivity can be improved.
5) Makes it easy to work in difficult or hazardous environment.
4.2 Why PLC Is Used In Automation?
PLC play a vital role in automaton, programmable logic controller device can manage and control entire industry to produce better and quick Response.
A PLC is a digital computer used for automation of industrial processes, like controlling machinery or factory assembly lines. Unlike desktop computers, PLCs are have multiple inputs and outputs, operate under extended temperature ranges, have immunity to electrical noise, and have resistance to vibration and impact. Programs to control machine operation are usually stored in battery-backed or non-volatile memory.
The main difference between PLC and other computer is that plc has multiple inputs and outputs then can do multiple works at moments, you can produce more output quickly.
4.2.(A) Why PLCs?
1. Less cost to implement: For the cost of relays and timers to automate about 3 lines for conveying product from finishing machine to packaging machine, you could pay for a PLC to do the same job. In general, a PLC system would make production more flexible and responsive.
2. Reliability: Relays and Electro-mechanical timers (magnetic control), are susceptible to electrical / mechanical failure. With PLCs the control logic is non-mechanical, (solid state). And with the PLC, you can program extra logic to monitor and test itself for possible failure at no extra cost. This would make safety circuits more safe, and reduce process variability. With PLC control you could increase compatibility with existing equipment, scalability, improving ease of use, and providing a common look and feel.
3. Speed: The PLC can speed up operation of machines that you could not obtain with that old out dated relay logic. Control logic makes decisions more accurate and faster than a human operator could hope to achieve. Timers can be set to hundredths of a second to compensate for external variables, and enhance safety.
4. Greater functionality: PLCs have the ability to compare real-time values and make decisions based on that comparison. They can do complex mathematical functions, and adjust the machine accordingly. The greater functionality allows you to design logic that can automatically adjust for different machine products, there by reducing downtime for setups and machine change over.
5. Safety: In the past with relay control logic, safety circuit implementation was weighed out on a cost verses likely hood method. In other words, the basic emergency stop button, relying on operators to stop the machine before an accident occurred. Usually do to distractions and slow reaction time of humans, the button wasn’t pressed until after the damage was done. With PLCs, you can cover 99% of all the possible safety risk, and the only cost is the time it takes to add a few rungs of logic to your program. Safety curtains are about the most expensive item, but well under the cost of an accident. Using the PLC to monitor safety risks is equivalent to having a full time employee watching, but with quicker reaction time than any human.
6. Less downtime: Downtime can be broken down in to two separate areas. Scheduled and non scheduled. DuPont has been quoted as saying: "Maintenance is the single largest controllable cost opportunity, representing $100-$300 million per year corporate-wide."
Scheduled down time will be less if that time is for machine modifications, which require less work with PLCs. Some of the preventive maintenance can be automated through the PLC to even further reduce down time.
Unscheduled downtime can be broken down (no pun intended), further into two groups: Troubleshooting and repair. The more complex our systems become, the more beneficial it is to write logic that will not only isolate failures but also indicate potential failures that may occur in the near future.The trouble shooting down time can be reduced by 90%. This is accomplished by utilizing the sensors already in place, to do testing through PLC logic to isolate where trouble is originating.
Repair is usually only a fraction of the time it takes to find the problem. It’s not uncommon to spend hours tracking down a limit switch that is bent, or a dirty proximity sensor. The cost to find the problem is more expensive than the cost to repair it. With PLCs the cost to find the problem is greatly reduced.
A PLC has following sections and each section has unique job to perform.
1) The sensing section
This section consists of limit switches, photoelectric sensors, push buttons etc. These incoming hardware devices provides input signal to the PLC. These devices are also called as field input devices. The term ‘field input " is used because this device provides incoming signals that are tangible items that you physically connect to PLC.
Figure-4.2 Sensing Section Of PLC Source
(Source: www.industrialtext.com)
2) Input section
This section is majorly divided into 2 parts:
First, the physical screw terminals, where incoming signal (i.e. input), from the field input devices (e.g. limit switch) are connected to the PLC.
The second portion of the input section is the PLC’s internal conversion electronics. This section converts and isolates the high-voltage input level from field input devices. High-voltage signals from field input devices are converted to +5 volts direct current (VDC) for a valid ON input signal, and a 0 VDC for a valid OFF input signal. Incoming signal conversion and isolation is necessary because microprocessor components operate on +5 VDC, whereas an input signal may be of 24 VDC, 120 volts alternating current (VAC), or 220 VDC. If 120 VAC signal is inputted, for example, into 5 VDC, circuit will quickly destroy your PLC.
3) Controller
The controller is also known as central processing unit (CPU), or simply as the processor. Central processing unit controls or supervises the entire process. The central processing unit solves the user program and apparently updates the status of the outputs.
4) Programmer
The programmer is a device used by the programmer or operator to enter or edit program instructions or data. The programmer can be handheld unit, a personal computer, or an industrial computer programming terminal.
5) Output section
The ON or OFF status of the inputs are read and the information is used to solve the user ladder program and the updated signals is sent to the output section. The output section is simply a series of switches, one for each output point, that are controlled by CPU and are used to turn output field devices ON or OFF.
Figure-4.3 Input and output section
(Source: www.industrialtext.com
6) Field hardware devices
The devices that are controlled by the PLC’s output section screw terminals are the field hardware devices.
4.2.(b) How does a PLC work?
Microprocessor is the heart of any computer; it is also called as processor, or CPU. The central processing unit supervises system control through the user program. After reading the input signal, the CPU follows the instructions, that a programmer or operator has stored in the PLC’s memory. Depending upon the result of the solved program, the field control devices or outputs are turned ON or OFF. When the PLC is running and following the programmer’s instructions, it is called as solving the program.
4.2. (c) How can we register instructions into the PLC’s memory?
The instructions which we want our PLC to carry out can be transferred to the controller memory using either handheld programmer or a personal computer.
The first step is to develop the user ladder program. Once the user ladder program is verified for correctness, the next step is to download the program into the processor’s memory. The process of transferring the user defined PLC program from personal computer’s memory into PLC memory is called as downloading the program. But before downloading the user program, the processor must be in program mode.
Now, if all the inputs and outputs signals are wired to the correct screw terminals, the processor can be put in run mode. In run mode, the program will continuously run and solve the programmed instructions. The process of solving the programmed instruction is sometime called as solving the logic. This constant running of the program in a PLC is called as scanning.
4.2.(d) The PLC’s purpose
The PLC is primarily used to control machinery. A program is written for the PLC which turns on and off outputs based on input conditions and the internal program. In this aspect, a PLC is similar to a computer. However, a PLC is designed to be programmed once, and run repeatedly as needed. In fact, a crafty programmer could use a PLC to control not only simple devices such as a garage door opener, but their whole house, including switching lights on and off at certain times, monitoring a custom built security system, etc.
Most commonly, a PLC is found inside of a machine in an industrial environment. A PLC can run an automatic machine for years with little human intervention. They are designed to withstand most harsh environments.
4.3 Communication
PLCs have built in communications ports, usually 9-pin RS-232, but optionally EIA-485 or Ethernet. Modbus, BACnet or DF1 is usually included as one of the communications protocols. Other options include various field buses such as DeviceNet or Profibus. Other communications protocols that may be used are listed in the List of automation protocols.
Most modern PLCs can communicate over a network to some other system, such as a computer running a SCADA (Supervisory Control And Data Acquisition) system.
PLCs used in larger I/O systems may have peer-to-peer (P2P) communication between processors. This allows separate parts of a complex process to have individual control while allowing the subsystems to co-ordinate over the communication link. These communication links are also often used for HMI devices such as keypads or PC-type workstations.
4.4 Programming
Technicians or other users write unique programs that direct the function of the PLC. The programs are written on a PC in one of the standard programming languages and then downloaded to the PLC directly through a cable or over a local network. The information is then stored in the PLC’s memory.
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.
PLCs can be programmed using standards-based programming languages. A graphical programming notation called Sequential Function Charts is available on certain programmable controllers. Initially most PLCs utilized Ladder Logic Diagram Programming, a model which emulated electromechanical control panel devices (such as the contact and coils of relays) which PLCs replaced. This model remains common today.
The most frequently used programming language for PLCs is ladder logic; however, other languages are also common. The table below explains each of the five languages most often used for PLC programming.
‘
Programming Language Description
Ladder Logic Ladder logic is a graphical language that includes math operations, timers, counters, and similar functions.
Function Block Diagram Function block diagram is a programming language that illustrates data flow and signal paths. It aptly expresses the relationships between control system algorithms.
Structured Text Structured text is a text language that is highly structured and supports a broad spectrum of functions. It is similar to the programming language PASCAL.
Instruction List Instruction list is a simple assembly language, and it is widely used in PLCs.
Sequential Function Chart Sequential function chart is a highly structured language and is best for complicated control systems. It manages complex tasks by dividing them into smaller tasks.
4.5 Basic PLC Operation
PLCs consist of input modules or points, a Central Processing Unit (CPU), and output modules or points. An input accepts a variety of digital or analog signals from various field devices (sensors) and converts them into a logic signal that can be used by the CPU. The CPU makes decisions and executes control instructions based on program instructions in memory. Output modules convert control instructions from the CPU into a digital or analog signal that can be used to control various field devices (actuators). A programming device is used to input the desired instructions. These instructions determine what the PLC will do for a specific input. An operator interface device allows process information to be displayed and new control parameters to be entered.
Figure-4.4 Scan cycle of PLC
(Source: www.software.inv ensys.com)
Power Supply
If input power fails and power supply can no longer deliver voltage to the system; power backup preserves any program that has been inserted into the CPU RAM.
Power Supply – This module can be built into the PLC processor module or be an external unit. Common voltage levels required by the PLC are 5Vdc, 24Vdc, 220Vac. The voltage lends are stabilized and often the PS monitors its own health.
The power supply gives the voltage required for electronics module (I/O Logic signals, CPU, memory unit and peripheral devices) of the PLC from the line supply.
The power supply provides isolation necessary to protect the solid state devices from most high voltage line spikes.
As I/O is expanded, some PLC may require additional power supplies in order to maintain proper power levels.
Figure- 4.5 Block Diagram of PLC
(Source: www. plc-scada.html)
‘
Pushbuttons (sensors), in this simple example, connected to PLC inputs, can be used to start and stop a motor connected to a PLC through a motor starter (actuator).
Figure-4.6 Motor Start/Stop Using PLC
(Source: www.plcedge.com/plc-scada.html’)’
ABB SIEMENS
SCHNEIDER MITSUBISHI
Figure- 4.7 Types of PLC
(Source: www.plc??-scada.html)
4.6 Advantages Of PLC
The same, as well as more complex tasks can be done with a PLC. Wiring between devices and relay contacts is done in the PLC program. Hard-wiring, though still required to connect field devices, is less intensive. Modifying the application and correcting errors are easier to handle. It is easier to create and change a program in a PLC than it is to wire and rewire a circuit.
Following are just a few of the advantages of PLCs:
‘ Smaller physical size than hard-wire solutions.
‘ Easier and faster to make changes.
‘ PLCs have integrated diagnostics and override functions.
‘ Diagnostics are centrally available.
‘ Applications can be immediately documented.
‘ Applications can be duplicated faster and less expensively.
‘ Reliability in operation.
‘ They are attractive on Cost-Per-Point Basis.
‘ Flexibility in control techniques.
‘ Flexibility in programming and reprogramming in the plant.
‘ Cost effective for controlling complex systems.
‘ Security.
‘ Expandability
4.7 Disadvantages Of Programmable Logic Controller
1. There’s too much work required in connecting wires.
2. There’s difficulty with changes or replacements.
3. It’s always difficult to find errors and require skillful work force.
4. When a problem occurs, hold-up time is indefinite, usually long.
4.8 PLC Vs Microcontroller
Microcontrollers (MCU) are complete computer systems on a chip. They combine an arithmetic logic unit (ALU), memory, timer/counters, serial port, input/output (I/O) ports and a clock oscillator.
Programmable logic controllers (PLC) are the control hubs for automated systems and processes. They contain multiple inputs and outputs that use transistors and other circuitry to simulate switches and relays to control equipment.They’re also programmable via standard computer interfaces and proprietary languages and network options.
Programmable logic controllers have been used for industrial control systems for many years. Their proven reliability in harsh environments and design to handle many inputs and outputs has made them the foundation of many factory automated systems. PLCs can be combined with most other technologies to provide a sophisticated control and monitoring system.
4.9 Difference Between PLC And Microcontroller
PLC is a special microcontroller designed for industrial application. It is for controlling machinery or processes. A microcontroller is a microprocessor that can be used for any type of application. The basic difference between PLC and microcontrollers is only the way of programming. Most common way of PLC programming is with graphical language Ladder logic programming which looks a little more similar to electrical schematics than a computer programming language.
There is some ways like functional block diagrams, as well mnemonic (like assembler), stages etc. Second significant characteristic is the infinite loop (cycling) through the ladder start-to-end and again from start. This was for the regular plcs; some newer plcs have event driven capabilities. Also plcs are more restricted in calculations.
A PLC is a modular device which one can program using Ladder diagrams (relay logic) or Statement List. It is optimized to handle several digital inputs and outputs, and is more rugged for use in industrial applications. Basically it scans the inputs, and determines the outputs based on the logical conditions programmed into it by the user. It internally uses a microcontroller to handle all input, output and logic scans. Application area is mostly industrial automation.
Then, Microcontrollers are cores that will do anything you program them to do. They probably can be used in each of the above applications, but with varying effectiveness. As always, your work is in discerning which option will work best in a given situation.
‘
Chapter 5
Ladder Diagram
‘
5.1 Introduction Of Ladder Diagram
Ladder diagrams are specialized schematics commonly used to document industrial control logic systems. They are called "ladder" diagrams because they resemble a ladder, with two vertical rails (supply power) and as many "rungs" (horizontal lines) as there are control circuits to represent. If we wanted to draw a simple ladder diagram showing a lamp that is controlled by a hand switch, it would look like this:
Figure-5.1 Lamp control by hand Switch
We can construct simply logic functions for our hypothetical lamp circuit, using multiple contacts, and document these circuits quite easily and understandably with additional rungs to our original "ladder." If we use standard binary notation for the status of the switches and lamp (0 for un-actuated or de-energized; 1 for actuated or energized), a truth table can be made to show how the logic works:
Figure-5.2 OR logic function
Now, the lamp will come on if either contact A or contact B is actuated, because all it takes for the lamp to be energized is to have at least one path for current from wire L1 to wire 1. What we have is a simple OR logic function, implemented with nothing more than contacts and a lamp.
Figure-5.3 AND logic function
We can mimic the AND logic function by wiring the two contacts in series instead of
Parallel: Now, the lamp energizes only if contact A and contact B are simultaneously actuated. A path exists for current from wire L1 to the lamp (wire 2) if and only if both
switch contacts are closed.
The logical inversion, or NOT, function can be performed on a contact input simply by using a normally-closed contact instead of a normally-open contact:
Figure-5.4 NOT logic function
Parallel contacts are logically equivalent to an OR gate.
‘ Series contacts are logically equivalent to an AND gate.
‘ Normally closed (N.C.) contacts are logically equivalent to a NOT gate.
‘ A relay must be used to invert the output of a logic gate function, while simple normally-closed switch contacts are sufficient to represent inverted gate inputs.
‘ A rung of ladder diagram code can contain both input and output instructions
‘ Input instructions perform a comparison or test and set the rung state based on the outcome
‘ Normally left justified on the rung
‘ Output instructions examine the rung state and execute some operation or function
‘ In some cases output instructions can set the rung state
‘ Normally right justified on the rung
‘ This is a programming language, which expresses a program as a series of ‘coils’ and ‘contacts’, simulating the operation of electromechanical relays.
‘ The resultant program is the equivalent of an equation, which is executed continuously in a combinatorial manner.
‘ The advantage of this language is the familiarity many electricians have with the simple operation of relays.
‘
Chapter 6
Supervisory Control and Data Acquisition System (SCADA)
‘
6.1 What Is SCADA?
This acts as an operator station. The operator can monitor as well as control the process parameters from these stations. Apart from online process data the operator will have access to historical and real-time trends, alarms and reports. The operator can give commands to control hardware for opening the valve, change the set point, start the pump etc.
6.2 Features Of SCADA Software
The common features of SCADA include Dynamic process mimic, Trends, alarm, Connectivity with hardware, Recipe management etc.
6.3 Applications Of SCADA
SCADA systems have many applications right industrial automation, power distribution to water management. Basic dairy processes have changed little in the past decade. Specialized processes such as ultra filtration (UF), and modern drying processes, have increased the opportunity for the recovery of milk solids that were formerly discharged. In addition, all processes have become much more energy efficient and the use of electronic control systems has allowed improved processing effectiveness and cost savings.
‘
Chapter 7
Implementation of the Project / Simulation
‘
Working / Implementation of the Project work/ simulation
7.1 Work Done
Figure 7.1 Task For Heating An Element
Figure 7.2 Outcome And Working Of Heating An Element
7.2 Aim Of The Task
The aim of the task is that a can or says an object which is placed at left corner should move to the heating chamber automatically. It should be heated as per requirement and have to return on its place.
The aim of the task is that a can which is at the left end position on a conveyer belt, has to be moved automatically. We need the following components to complete the task:
‘ A switch
‘ Conveyer belt
‘ Four sensors
‘ Valve
‘ A door
‘ Motors
‘ Heater
‘ Heating chamber
At an instance the can is at zero position. When it is at zero position at that time the sensor 1 will be on. It will remain in the on state until the can doesn’t move along. A switch is provided to control the or say to on the whole system.
User input value is provided so that user finds flexibility in giving the desired temperature to the heating chamber. At the very starting of the system we have to provide the user value.
For example if we have given the user value as ’30’ then the heating chamber will heat the object for 30 seconds.
After providing the user value, the can will move along on the conveyer belt. As long as the can is moved the sensor1 will be turned off. The conveyer is provided with the value of 1000 in its properties. That means the length of the belt is 1000. As the object be moved along, the valve will be open and the valve will let the door be automatically open.
An object when reaching near the open door at that time the sensor 4 is on. The object will pass through the open door and the door is closed again. Sensor 2 will be on sensing the object inside the heating chamber. The heater will heat the object as per scheduled by the user value. Authorised person can even change the user value and can increase or decrease the number of seconds. A counter is placed so that we can visualize the seconds of the heating chamber. When the timer is done with the counting at that time sensor 3 is on. And after the object is moved away, that sensor will again turned off.
Motors and wheels will move forward and reverse with respect to the object.
As soon as the object is heated the door is opened again and the heated object moved out of the chamber and reverses in the direction to its original position. Whole the above process is implemented in the programming ahead.
‘
7.3 Programming
sw=0;
ob=0;
w1=0;
w2=0;
s1=0;
s2=0;
s3=0;
s4=0;
k=0;
d=0;
v=0;
h=0;
door=0;
x=0;
ui=0;
IF sw==1 AND x==1 THEN v=1;ELSE v=0;ENDIF;
IF sw==1 AND door==0 THEN s4=1;ELSE s4=0;ENDIF;
IF sw==1 AND ob==0 AND h==0 THEN x=1; ENDIF;
IF v==1 AND door<120 THEN door=door+5;ENDIF;
IF sw==1 AND ob==0 THEN s1=1; ELSE s1=0;ENDIF;
IF sw==1 AND door==120 THEN s2=1;ELSE s2=0; ENDIF;
IF sw==1 AND ob<620 AND h==0 AND door==120 THEN k=1;ELSE k=0;ENDIF;
IF sw==1 AND k==1 AND ob>0 THEN w1=w1+5;ELSE w1=0;ENDIF;
IF sw==1 AND ob<620 AND k==1 THEN ob=ob+10;ENDIF;
IF sw==1 AND ob==620 AND h==0 THEN x=0;ENDIF;
IF v==0 AND door>0 THEN door=door – 5 ;ENDIF;
IF sw==1 AND ob==620 THEN s3=1;ELSE s3=0;ENDIF;
IF sw==1 AND door == 0 AND s3==1 AND h<ui THEN h=h+5;ENDIF;
IF sw==1 AND ob==620 AND h==ui THEN x=1;ENDIF;
IF sw==1 AND ob==0 AND h==ui THEN x=0; ENDIF;
IF sw==1 AND door==120 AND h==ui AND ob<=620 THEN d=1;k=0;ELSE d=0;ENDIF;
IF sw==1 AND d==1 AND k==0 THEN w2=w2+5; ELSE w2=0;ENDIF;
IF sw==1 AND ob>0 AND d==1 THEN ob=ob – 10;ENDIF;
IF sw==1 AND ob==0 THEN d=0;ENDIF;
IF sw==1 AND door==0 AND ob==0 THEN h=0;ENDIF;
‘
7.4 Outcome Of Task
Figure 7.4.(A) Outcome Of Heating An Element(When Switch Is Off)
Figure 7.4.(b) outcome of heating an element(when switch is on)
Figure 7.4.(C) Outcome Of Heating An Element(Process While Heating An Element)
‘
7.5 Milk Process Automation in Dairy system
Figure 7.5 Milk Process Automation In Dairy System
7.6 Programming For The Milk Process Automation
sw=0;
k1=0;
k2=0;
k3=0;
k4=0;
k5=0;
k6=0;
k7=0;
k8=0;
k9=0;
k10=0;
k11=0;
t=0;
tm=0;
tm4=0;
t1=0;
t2=0;
t3=0;
t4=0;
t5=0;
t6=0;
t7=0;
v1=0;
v2=0;
v3=0;
v4=0;
v5=0;
p1=0;
p1=0;
p2=0;
p3=0;
p4=0;
h1=0;
h2=0;
c1=0;
c2=0;
sp=0;
tm1=0;
tm2=0;
tm3=0;
t61=0;
IF sw==1 AND t<100 THEN p1=1;t=t+5;ENDIF;
IF sw==1 AND p1==1 AND k1<100 THEN k1=k1 + 5;ENDIF;
IF sw==1 AND k1==100 AND t1<1000 THEN t1=t1+20;ENDIF;
IF sw==1 AND t1>900 THEN l=1;ENDIF;
IF sw==1 AND t1==1000 THEN k1=0;p1=0;v2=1;l=1;ENDIF;
IF sw==1 AND v2==1 AND k2<100 THEN k2 = k2+5;l=0;ENDIF;
IF sw==1 AND k2==100 AND t2<1000 THEN t2=t2+20;ENDIF;
IF sw==1 AND k2==100 AND k1==0 AND p1==0 AND t1>0 THEN t1 = t1 – 20;ENDIF;
IF sw==1 AND t2==1000 THEN k2=0;v2=0;ENDIF;
IF sw==1 AND t2==1000 AND v2==0 AND k2==0 THEN h2=1;ENDIF;
IF sw==1 AND h2==1 AND tm<80 THEN tm=tm+1;h2=1;v1=1;p2=1;ENDIF;
IF sw==1 AND v1==1 AND p2==1 AND k3<100 THEN k3=k3+5;ENDIF;
IF sw==1 AND k3==100 AND k4<100 THEN k4=k4+5;h1=1;ENDIF;
IF sw==1 AND k4==100 AND h1==1 AND k5<100 THEN k5=k5+5;ENDIF;
IF sw==1 AND k5==100 AND k6<100 THEN k6=k6+5;h1=1;ENDIF;
IF sw==1 AND k6==100 THEN p2=0;v1=0;h1=0;ENDIF;
IF sw==1 AND k6==100 AND tm==80 THEN p2=0;h1=0;h2=0;ENDIF;
IF sw==1 AND k6==100 AND h2==0 THEN p3=1;ENDIF;
IF sw==1 AND k6==100 AND p3==1 THEN tm=0;h2=0;ENDIF;
IF sw==1 AND k6==100 AND h2==0 AND k7<100 THEN k7=k7+5;ENDIF;
IF sw==1 AND k7==100 AND k2==0 AND t2>0 THEN t2=t2 – 20;ENDIF;
IF sw==1 AND k7==100 AND t3<1000 THEN t3=t3+20;k3 =0;k4=0;k5=0;k6=0;ENDIF;
IF sw==1 AND t2==0 AND h2==0 THEN k7=0;p3=0;ENDIF;
IF sw==1 AND t3==1000 THEN c1=1;ENDIF;
IF sw==1 AND t3==1000 AND c1==1 AND tm1<50 THEN tm1=tm1+2;ENDIF;
IF sw==1 AND t3==1000 AND tm1==50 THEN p4=1;ENDIF;
IF sw==1 AND p4==1 THEN tm1=0;c1=0;ENDIF;
IF sw==1 AND p4==1 AND k8<100 THEN k8=k8+5;ENDIF;
IF sw==1 AND k8==100 AND k7==0 AND p3==0 AND t3>0 THEN t3=t3 – 20;ENDIF;
IF sw==1 AND k8==100 AND t4<1000 THEN t4=t4+20;ENDIF;
IF sw==1 AND t4==1000 THEN k8=0;p4=0;ENDIF;
IF sw==1 AND t4==1000 AND tm2<50 THEN tm2=tm2+2;sp=1;ENDIF;
IF sw==1 AND tm2==50 AND t4==1000 THEN v3=1;ENDIF;
IF sw==1 AND v3==1 THEN tm2=0;sp=0;ENDIF;
IF sw==1 AND v3==1 AND k9<100 THEN k9=k9+5;ENDIF;
IF sw==1 AND k9==100 AND k8==0 AND p4==0 AND t4>0 THEN t4=t4 – 20;ENDIF;
IF sw==1 AND k9==100 AND v3==1 AND t6<1000 THEN t6=t6+20;ENDIF;
IF sw==1 AND t6==1000 THEN k9=0;v3=0;ENDIF;
IF sw==1 AND v3==1 AND t5<100 THEN t5=t5+5;ENDIF;
IF sw==1 AND t5==100 AND k9==0 THEN v4=1;ENDIF;
IF sw==1 AND v4==1 AND k10<100 THEN k10=k10+5;ENDIF;
IF sw==1 AND v4==1 AND k10>1 AND t5>0 THEN t5=t5 – 5;ENDIF;
IF sw==1 AND t5==0 THEN v4=0;k10=0;ENDIF;
IF sw==1 AND t6==1000 AND k10==0 AND tm3<50 THEN t61=1;tm3=tm3+2;ENDIF;
IF sw==1 AND k10==0 AND tm3==50 THEN t61=0;ENDIF;
IF sw==1 AND t6==1000 AND k10==0 AND t61==0 THEN v5=1;ENDIF;
IF sw==1 AND v5==1 THEN tm3=0;t61=0;ENDIF;
IF sw==1 AND t6==1000 AND tm3==0 AND v5==1 AND k11<100 THEN k11=k11+5;ENDIF;
IF sw==1 AND v5==1 AND k11==100 AND t6>0 THEN t6=t6 – 20;ENDIF;
IF sw==1 AND v5==1 AND k11==100 AND t7<1000 THEN t7=t7+20;ENDIF;
IF sw==1 AND t7==1000 THEN v5=0;k11=0;ENDIF;
IF sw==1 AND t7==1000 AND v5==0 THEN c2=1;ENDIF;
IF sw==1 AND t7==1000 AND c2==1 AND tm4<50 THEN tm4=tm4+2;ENDIF;
IF sw==1 AND t7==1000 AND tm4==50 THEN c2=0;ENDIF;
IF sw==1 AND tm4==50 AND t7>0 THEN t7=t7 – 20;p1=1;ENDIF;
IF sw==1 AND t7==0 THEN tm4=0;ENDIF;
‘
Chapter 8
Supported Software
‘
8.1 Wonderware
Wonderware is the global leader in Human Machine Interface (HMI), SCADA and real-time operations management software. Wonderware solutions enable production and industrial operations to synchronize with business objectives to achieve speed,flexibility and sustained profitability. Wonderware software delivers significant cost benefits for designing, building, deploying and maintaining robust applications for manufacturing and infrastructure operations. Wonderware Supervisory HMI Software brings an empowering simplicity to managing plant operations through legendary ease of use, unparalleled scalability, matchless capabilities and standards-based, secure integration.
Achieve improved operator awareness and productivity and reduce operational risks, response time and system downtime. Wonderware InTouch brings real-time visibility to a new level and transforms the way industrial user interfaces and Human Machine Interfaces (HMIs) are de’ned, moving from merely presenting data to the next evolution of displaying information in context. Instead of developing a library of ‘symbols’, the new features of InTouch enable application developers to focus on creating highly contextualized and interpretive visual content and assembling the most effective HMI applications and user interfaces for operational excellence and abnormal situation management. With InTouch 2014, the success rate of exception handling can be improved by 37% and the total time required to complete tasks can be reduced by 41%.
‘
8.2 KEPServerEX
KEPServerEX is an server which provides direct connectivity between hundreds of different PLCs, devices, and systems, and a wide variety of client applications, including HMI, SCADA, Historian, MES, ERP, and countless custom applications.
Employing the universally accepted standard, KEPServerEX maximizes the promise of expedites project development through the use of a single server interface, regardless of the control system in use. Multiple device drivers can be ‘plugged in’ to one application which centralizes communications and greatly reduces user learning curves.
Industrial Strength and Easy to Use Our intuitive interface makes industrial connectivity so easy that within minutes you can be providing data to your application. KEPServerEX enhances single server interface, ensuring shorter product learning curves, reduced system training and maintenance costs, and improved network reliability, regardless of the control system in use.
Methods used to manage and configure 3rd party OPC servers may vary from one
manufacturer to the next. This results in a continuous process of learning each new
OPC server when a new PLC or device is used. If the goal of OPC technology is to
provide a single, well defined and reliable interface to share data, then it would seem only natural that this goal should be matched with a single user interface to simplify configuration. Experience High Performance Communications.
KEPServerEX is designed for efficient operation throughout the entire product. Each driver plug-in is developed to take advantage of any operational gain that a given PLC or device offers for enhanced communication speed. Kepware’s development team has written drivers on nearly every Microsoft platform dating all the way back to DOS. This depth of development experience keeps us keenly aware of how to develop and maintain high performance connectivity without sacrificing quality.
Figure-8.2 Image Of Kepserverex V4.0
Minimum Effort ‘ Maximum Throughput
KEPServerEX is a truly multi-threaded application where drivers support up to 100 channels of communication and each channel isa separate task running inside the server application. By distributing the communication load across multiple channels, maximum throughput can be achieved. The use of multiple tasks to improve communication performance may immediately raise the concern aboutpotential negative impacts on the host PC. Rest assured, KEPServerEX has been real-world tested in applications actively polling over onehundred-thousand tags, producing only a negligible effect on the host PC’s CPU usage and memory.
‘
8.3 Wpl Software
WPLSoft is a software for PLC ( Programmable logic controller). PLC is a control system using electronic operations.When PLC is in operation, use WPLSoft to monitor the set value or temporarily saved value in timer (T), counter (C), and register (D) and force On/Off of output contacts.
Using Mouse and F1 ~ F12 function keys.
1. Click ‘File’ > ‘New’ to create a new document and enter the ladder diagram mode shown below
Figure-8.3(A) Create A New Document In WPL
2. Click the Normally Open (NO) contact icon on toolbar or press F1 function key.
Figure-8.3(B) F1 Function Key In WPL
3. The ‘Input Device Instruction’ dialog box will appear. You can select device name (e.g. M) and number (e.g. 10), and enter comments (e.g. Internal Relay). Then, click ‘OK’ to save the setting
Figure-8.3(C) Input Device Instruction
4. Click the Output Coil icon on toolbar or press F7 function key. The ‘Input Device Instruction’ dialog box will appear. You can select device name (e.g. Y) and number (e.g. 0), and enter comments (e.g. Output Coil). Then, click ‘OK’ to save the setting.
Figure- 8.3(D) Output Device Instruction
5. Click Application Instructions icon or press F6 function key. Choose ‘All Application Instructions’ in the Instruction Type box and select ‘END’ instruction from the pull-down menu or type the ‘END’ instruction in the Application Instruction list box. Then, click ‘OK’ to save the setting.
Figure- 8.3(E) Application Instruction
6. Click the compiler icon to convert the ladder diagram to instructions. After compiler action is completed, the numbers of steps will be displayed on the left side of the start of the ladder diagram.
Figure-8.3(F) Convert The Ladder Diagram To Instruction
7. If the ladder diagram is not correct, a Ladder Diagram Error message will appear and point out the exact erroneous rows and addresses after the compiler action is completed.
Figure-8.3(G) Ladder Diagram Error Message
‘
8.4 Intouch
‘
Chapter 9
Result And Analysis
‘
The outcome of our project includes Standardization Of milk Production, Quality Improvement, Improve Commissioning Time, Reduced Production Time, Improved Quantity of Product, and reduced Manufacturing Cost.
Dairy industry is one area in which automation plays an important role to control, automate and stream line the process. Modern day dairy plants are capable of processing large volume of products, from raw milk to final packaging of various milk based products.
This objective is typically achieved by
‘ Heat treatment to ensure that milk is safe for human consumption and has an extended keeping quality, and
‘ Preparing a variety of dairy products in a semi-dehydrated or dehydrated form (butter, hard cheese and milk powders), which can be stored. The focus of this document is on the processing of milk and the production of milk-derived products butter, cheese and milk powder at dairy processing plants.
‘ Our project includes processes taking place at a typical milk plant include:
‘ Receipt and filtration/clarification of the raw milk
‘ Separation of all or part of the milk fat (for standardization of market milk, production of cream and butter and other fat-based products, and production of milk powders)
‘ Pasteurization
‘ Homogenization (if required)
‘ Deodorization (if required)
‘ Further product-specific processing
‘ Packaging and storage, including cold storage for perishable products
‘ Distribution of final product.
‘
Chapter 10
Conclusion
‘
Supervisory Control and Data Acquisition is real time industrial process control systems used to centrally monitor and control remote or local industrial equipment such as motors, valves, pumps, relays, etc’ A SCADA system gathers
SCADA is used in power plants as well as in oil and gas refining, telecommunications, transportation, and water and waste control.
Main advantage SCADA is Saves Time and Money , Less traveling for workers (e.g. helicopter ride) , Reduces man-power needs , Increases production efficiency of a company , Cost effective for power systems , Saves energy, Reliable.
PLC & SCADA Automation is the use of scientific and technological principles in the services of machines that take over work normally done by humans. Applications manufacturing companies in virtually every industry are achieving rapid increases in productivity by taking advantage of automation technologies.
‘
References
‘ www.industrialtext.com
‘ Programmable logic control systema version2 EE IIt Kharagpur.
‘ Basic of PLC Programming,industrial control systems fall 2006