WHAT THE PLC

2. http://fcbuy.ir / دش عارتخا یسک هچ طسوت و تسیچ یس لا یپ PLC دمآ یناف ار (Richard Dick Morley هب ناونع ردپ 1932 رد تسوچاسام اکیرما اکیرما رد 85 یگلاس راد تسوچ دنارذگ . رد و رد عادو ایند تعنص هب یلروم ( رد 2017 دوخ ار کید دوشیم دراچی هتخانش مهدفه ربتکا وا ر ایند لاس ربماسد تلایا وتیتسنا لوا هک لاس تلایصحت رشپمهوین ینف اسام رد رد . تفگ

3. What is PLC and by whom was it invented? Richard Dick Morley is known as the father of the PLC industry in the world. He was born on December 1, 1932 in Massachusetts, USA, and passed away on October 17, 2017 in New Hampshire, USA at the age of 85. He studied. He spent his time at the Massachusetts Institute of Technology. Prior to the invention of the PLC, mechanical relays were used to create logic systems. Due to the noise generated, as well as the high volume of breakdowns and depreciation, the need for an intermediate logic system was strongly felt. Morley as a mechanical engineer for the first time Modicon PLC, which itself is a combination of the three words Modular digital Controller, was later acquired by Schneider. Morley launched his company's first PLCs at General Motors. Morley's invention revolutionized the world industry, and later,

4. after Schneider, companies such as Alan Bradley and Siemens developed the equipment, and the current PLCs, which happens to be abbreviated. The three words Programmable Logic Controller are the result of their services. What is PLC? PLC stands for Programmable Logic Controller, which means programmable logic controller. What does programmable logic controller mean ?! Word by word, this sentence has an important meaning in its heart, which we will examine in the following controller From this word we learn that we are dealing with a device that can do all the control work for us, which is why PLC is also called automation, because an automation is a completely control system and of course pragmatic Be. Logical This may not seem like a big deal, but basically all the advantages of PLC can be summed up in this word, when it is a logical device, we can expect it from a rational person, to put it simply; If we understand his language, we can easily talk to him. So far we have a logic controller that can be very interesting to us, but a miracle happens when a third word is added to it…

5. Programmable Yes, exactly, if the above two are possible but we can not provide commands for it in some way, this device is practically useless, the programming of a PLC can be done in various ways. In the distant years, we have witnessed a lot of tastes in PLC programming languages, which fortunately, with the presence of the IEC standard, all these tastes were directed to a specific point, and today, learning and choosing a programming language to start or learn PLC is a very simple thing. PLC is a programming controller that belongs to the computer family; This controller is mainly used for industrial purposes. It receives the input of various digital or analog signals from the field and then converts them to the binary system logic signals for the cpu, and the cpu executes the commands according to the programs in which it is stored and outputs the output as logic signals. These signals can be sent in analog or digital form to equipment or operators. Before PLC The function of PLC in the past was the responsibility of relay control circuits, the use of which is obsolete today in industrial environments. It will follow the process. Electronic steering circuits were built to fix these problems, but many changes to the control system hardware needed to be made when there was a change in the process or operation of the machine. With PLC, minor changes in the process or operation of the machine are easy, because it is no longer necessary to change

6. the wiring and hardware of the control system, and it is enough to make changes in the program and send it to the PLC to achieve the intended purpose. The idea is realized. PLC is a controller like an electric steering circuit. PLC is logical unlike electric steering circuit. The above advantages along with the smaller dimensions of the control system, faster troubleshooting, less downtime, the ability to run more complex programs, the ability to exchange information with other systems, etc., made relay circuits quickly field for the presence of PLCs. To empty. PLCs were built instead of traditional control panels whose operation depended on logic electromagnetic relays based on timers for industrial control systems. The PLC is able to continuously monitor the inputs from the sensors and decide on the outputs. Contactor relay Contactor relays have always caused dissatisfaction among engineers. Circuits that not only do not have logic but can not be programmed in any way, let me explain the depth of the disaster with an example! Imagine we have a metropolis with 100 cities around it, all of which are located 900 km from our metropolis. We have to travel to one of these cities once a month and send them a letter. . In the relay model, it was like we had to build roads for all 100 cities, which in general required (900 * 100km) ninety million kilometers of roads, but this is only one part of the story, that you

7. have to keep these roads every year. The second challenge is the same. But with the PLC method, it was enough to use the Internet in the city of origin and destination! It may not be believable, but there was so much difference between a relay system and a PLC-style automation system. The problem of relays in industrial automation To modern factories f

8. Using PLC reduces the volume of control panels. 1 - Using PLC saves a lot of money. 2 -

9. PLC does not have mechanical depreciation, so in addition to longer life, it does not need periodic service and repairs. 3 - PLC power consumption is much less than relay circuits. 4 - PLC does not cause noise and electrical noise. 5 - Troubleshooting control circuits with PLC is quick and easy and usually the PLC itself has a troubleshooting program. 6 - PLC building block diagram A PLC with the ability to store programs has a structure similar to computers, except that the PLC is used as part of the processing and control of an industrial process. As shown in the figure below, the inputs transmit the necessary information to the PLC and the PLC controls the outputs according to the needs of the control system and based on the program written in it.

10. PLCs basically consist of a power supply, input signal receiving unit, central processing unit with microprocessor, program storage memory, output signal transmission unit, etc. رد In PLC, how to control the process as a program is stored in its memory. In the figure below, you can see the different units of a PLC, which we will describe in the following. It should be noted that PLCs available in the industry are available in compact, modular, network and also as industrial PCs. For PLCs with a small number of inputs and outputs, ie with a maximum About 100 DI / DO (digital inputs and outputs) compact or micro models are used as model PLCs (S7 200) and for PLCs with more than 100 inputs and outputs (DI / DO) from Modular model PLCs are used. Principles of operation and different parts of a PLC PLCs receive the inputs and, after reading the program written inside it, give the necessary command to the outputs. In general, PLC consists of the following three main parts. CPU - Input section -

11. Output section - The following figure describes the performance of each section Input section As mentioned, a series of inputs are connected to the PLC and give the necessary information to the PLC. These inputs may be sensors, switches, laminate switches, etc. In general, these inputs can be divided into two categories of analog that The same signal is continuous and digitally split. In the figure below you can see the types of inputs that are connected to the PLC. In this section, the ability to read and process values and variables should include: Limit values of switches Analog variables (such as values of heat and pressure sensors) Have positions in position finder systems, etc.

12. Output section In the PLC output section, various industrial devices such as motors, valves, displays, hydraulic valves, etc. can be connected. The output section can also be divided into two general modes, digital and analog. The following figure shows the types of outputs that are connected to the PLC. This section should also enable special devices, including: Electric motors Pneumatic or hydraulic cylinders Magnetic relays and coils Have analog outputs, etc. CPU The CPU is the mastermind of the PLC and is in fact responsible for all control processes. All the information collected from the inputs is processed in the CPU according to the written control program, then the outputs are controlled. It is worth mentioning that the CPU includes components such as Memory and microprocessor.

13. After getting acquainted with the three important parts of a PLC and for a better understanding of the subject, an example is given in the figure below to see the performance of all three parts. In this example, pushbuttons are connected to the PLC inputs and the motor to the output by the driver The PLC is connected, turned on and off according to the written program. This program can be left-right or a simple self-holding circuit. The push key can also be assumed as a sensor that senses hand pressure. Basic concepts in the operation of a PLC system In this section, we will introduce the topics that are the basis of PLC work, and in fact, we will introduce the process of working and reading the program by the CPU. Image Inputs Process Image Input)) Before execution, the CPU checks the status of all inputs and stores them in a part of the memory called PII. Except in exceptional cases and only in some types of PLCs, the CPU often does not refer to the inputs during the execution of the program. Information about the status of each input refers to the cell in PII. In some cases, this part of the memory (IITInput Image Table) is also called. Output Image (PIQ)

14. Whenever an output value is obtained during program execution, it is stored in this part of the memory. Except in exceptional cases and only in some types of PLCs, often the CPU does not refer to the outputs during program execution, but to record the latest status. Each output refers to the desired cell in the PIQ, and at the end of the program, the last state of the output from the PIQ is transferred to the physical output. In some cases, this part of the memory is called the PITPut Image Table. Scan cycle In a hardware circuit implemented by the PLC as shown below, which is programmed in the LADDER programming language, the input modes change the output state. In a PLC, the output of the output to the input states is not fast, but a PLC performs a three-step process to perform operations related to the designed process. This three-step process is called a CPU scan cycle. The following figure shows the three steps involved in performing a scan cycle. These three steps can be introduced as follows: Step 1: Determine the status of the input equipment

15. The stage

17. Power supply (AC power supply) is responsible for the AC voltage in the system from the system power supply, which causes safety against noise and fluctuations of the input voltage 1 - in industrial environments. CPU The microprocessor executes the program stored in the PLC, taking into account the status of the inputs. And accordingly instructs the output to activate the desired output. . 2 Memory is used to store programs and information. 3 - The programmer relation is used by the user to write the program and transfer it to the PLC memory and they are divided into two categories in terms of appearance: 4 - A small keyboard with a screen 1 - Using personal computers and installing software required for 2 - special programming. I / O unit that connects the PLC to the outside world. 5 - Types of PLCs In the PLC industry, there are more than one hundred factories with a great variety in designing and manufacturing different types of PLCs. PLCs can be categorized in terms of size, memory, number of inputs / outputs, scope of operation (local or

18. large) and.. It should be noted that to evaluate the capability of a PLC, other features such as processor, runtime, simplicity of programming language, scalability, etc. PLCs with local application Application: Control of systems with small volume (limited number of inputs and outputs) and for simultaneous control of a smaller number of processes or control of separate industrial devices (due to more limited capabilities), most manufacturers offer this type of PLCs along with other PLCs, but Some manufacturers offer it under the name of micro PLC. Among these types of PLCs, the following examples can be mentioned: ZEN Made by Omron Japan LOGO made by SIEMENS Germany Zelio Made by Telemecanique France Moeller Germany LG Korea Wide application PLCs Application: Factory site control. In large industries, PLCs are usually present in different parts of the factory site and exercise local control over the parts they cover. The required information is then transferred to the central control room using various data transfer methods, where the information is converted to graphic form and displayed on the monitor screen using various industrial monitoring methods. However, the operator can control the system only by knowing

19. how to work with the computer and without the need for specialized information. Among the most famous PLCs of this family that can be named are: S7 and SIMATIC S5 of the German company SIEMENS OMRON Japan Company French Telemecanique Company Mitsubishi Japan LG Korea Allen-Bradley USA ABB Switzerland-Sweden Having a complete view of the variety of PLCs is the most important issue in choosing and buying a suitable PLC; Therefore, when buying, you should pay attention to the following points: Number of entries Number of outputs Number of flags Number of counters Number of timers Types of flags and timers

20. Memory size SCAN TIME program execution speed Classification of types of plc brands In general, plc brands are divided into four different categories, which we will introduce in the following mini plc Compact plc Modular plc Rack plc Mini PLC Mini plc . 1 Mini PLCs are among the small types of PLC. Less output and input restrictions are among the features of this type of PLC. Due to the benefit of this type of PLC with less output and input (up to 40 output inputs), mini PLCs are often used for small projects. Compact PLC Compact plc Other types of plc include compact or integrated PLC. In this type of plc, all parts such as outputs and inputs, processor and power supply are designed in one box. Having more outputs and inputs

21. (up to 300 output inputs), has made it possible to use integrated plc in medium projects. This type of PLC is commonly used for smart and factory automation projects. Modular PLC In this type of plc, the main parts such as inputs, outputs, processor and power supply modules are separated from each other, but it is possible to put these parts next to each other in order to form a plc. Enables a large number of outputs and inputs commensurate with the power of the CPU (it is possible to add up to 2,000 output inputs to this PLC). Note that to work with this type of PLC, the frame at the end must be closed and the PLC completed. RAC plc PLC rack is another example of a type of plc that is very similar to modular PLC. In this plc, all inputs and outputs are connected to the central module that is located behind it. So the LC rack is installed vertically and due to having a lot of outputs and inputs (you can get 5000 output inputs with this PLC), this type of plc is considered one of the best options for large projects, such as refinery and petrochemical projects.

22. Application of PLC Today, the use of PLC in industries in various industrial processes is abundant. Automotive industry: 1 - Automatic drilling operations, connecting parts, as well as testing car parts and equipment, spray systems and shaping the body by automatic presses, etc. Plastic manufacturing industries: 2 - Injection molding and molding machines, air blowers, plastic production and analysis systems. Heavy industries: 3 - Industrial furnaces, automatic temperature control systems, appliances, etc. www.fcbuy.ir