Siemens PLC program

The development history of PLC
PLC can program the programmatic controller (logic, refers to a new type of industrial control device based on computer technology. In the PLC standard draft of the PLC standard issued by the International Electricity Commission (COMMITTEE) in 1987, the PLC defines the following definitions :
PLC English full name logic, the full name of Chinese name is programmable logic controller, definition is: an electronic system for digital operations, designed for the application of the industrial environment. Storage programs, implementing logical operations, sequential control, timing, counting and arithmetic instructions, etc., and control various types of mechanical or production processes through digital or simulation input/output .PLC is a programmable logic circuit It is also a very closely combined language with hardware. It has very important applications in semiconductors. It can be said that PLC
"PLC is a number specifically designed in the industrial environment. Electronic device for operation operation. It uses a memory that can prepares a program to store instructions to execute logic operations, sequential operations, timing, counting, and arithmetic operations in its internal storage. , Control various types of machinery or production processes. PLC and its related peripheral devices should be designed according to the principle of easy to form a whole with the industrial control system and easy to expand its functions. " The generation of PLC
1. Sui -Review of Control
The structure and principle of the student answering the relay (contactor), drawing the main circuit diagram of the three -phase difference motor, the control circuit diagram
Students summarize the lack of control of succession, thereby leading to the "PLC generation"
2.PLC generation
68 The Bidding Requirements for U.S. -National Train Auto Company (GM) Hard connection (2) convenient maintenance (3) higher reliability than relay control cabinets (4) The volume is less than the relay control cabinet (5) The cost is lower than the relay control cabinet (6) There is a data communication function (7) Enter 115V (8). When working in harsh environments (9) expansion, the original system changes less (10) User program storage capacity can be extended to 4K

Core thought:
n • Input/output level can be directly connected to the external device
• The structure is easy to expand

This is the prototype of PLC.
69 A PLC (PDP-14), and the birth of the car production line on the GM company was successful
PLC's birth:
• In 1969, the United States developed the world's first PDP-14
• 1971 , Japan developed the first DCS-8
• In 1973, Germany developed the first PLC
• In 1974, China developed the first one PLC

. The characteristics, current status and development of PLC
(1) Features
(1) Small volume (2) High reliability (3) Good flexibility, can be changed online to change Procedures (4) No requirements for environmental conditions (5) Low price ... All functions with bidding requirements
(2) Status
80%or more, more than 80%of equipment can use PLC
(3) Development

development history:
The first generation: 1969 ~ 1972, the representative products include
n • Japan's SCY-022
• HOSC-20
of Japan's Beichen Electric Company of Japan: From 1973 to 1975, the representative products include
• American GE Company LOGISTROT
• SIMATIC S3, S4 series
• Japanese Fuji Electric's SC series
from 1976 ~ 1983, the product is公司的M84、484、584、684、884 rn•德国SIEMENS公司的SIMATIC S5系列rn•日本三菱公司的MELPLAC-50、550 rn第四代：1983年~现在， Representative products are
• A5900
• S7 series of S7 series of Siemens Company in Germany

Processing simulation
• Pursue high reliability
• communication interface and smart module
• System operating station with high -resolution monitor
• Pursue soft and hardware standardization

three, the classification of PLC
• Press the structural division: r • overall
• Combination type
• Press I/O points and memory capacity points:
• Super small: less than 64 points, 256byet ~ 1kb
• Small: 65 ~ 128 points, 1 ~ 3.6kb
• medium: 129 ~ 512 points, 3.6 ~ 13KB
• Large: 513 ~ 896 points, greater than 13KB
• Super large: greater than 896 points, greater than 13kb

. The relationship between network PLC and DCS
DCS originated from the simulation quantity amount
PLC originated from the switching volume
The two people penetrate each other, take advantage of each other, and the function is getting closer, making the digital world and the simulation world more vague

1, PLC to programming the controller (logic, refers to a new type of industrial control device based on computer technology Essence In the PLC standard draft of the PLC standard issued by the International Electricity Commission (Committee) in 1987, the PLC defines the following definitions:
PLC English full name Logic, the full name of Chinese name is programmable logic controller, and the definition is: an electronic system for digital operations operation operation operation operations operation. , Designed for the application of the industrial environment. It adopts a type of programmable memory for its internal storage program, performing logical operations, sequential control, regular, counting and arithmetic operations, etc. Or the production process.PLC is a programmable logic circuit, and it is also a very closely combined language. It has very important applications in semiconductor. It can be said that PLC
Electronic devices designed for digital operations designed in the industrial environment. It uses a memory that can prepares a program to store instructions such as logical operations, sequential operations, timing, counting, and arithmetic operations in its internal storage, and can be able to operate. Through the input and output of digital or analog, controlling various types of mechanical or production processes. PLC and its related peripheral devices should be designed in accordance with the principle of easy to form a whole with the industrial control system and easy to expand its functions. " The characteristics of
PLC
2.1 High reliability, strong anti -interference ability
The high reliability is the key performance of electrical control equipment. Due to the use of modern large -scale integrated circuit technology, PLC uses strict production technology manufacturing, and the internal circuit adopts advanced anti -interference technology, which has high reliability. For example, the F series PLC produced by Mitsubishi is as high as 300,000 hours without failure. The average failure working time of some PLCs that use redundant CPUs is longer. From the PLC's off -machine circuit, the use of PLC to form a control system. Compared with the same -scale relay contact system, electrical wiring and switching contacts have been reduced to hundreds or even thousands of tenths, and the faults are greatly reduced. In addition, PLC has a hardware failure self -detection function, which can issue alert information in time when faulty. In the application software, the application can also be incorporated into the fault self -diagnostic program of the peripheral device, so that the circuits and devices in the system are also obtained from the fault self -diagnosis and protection. In this way, it is not surprising that the entire system has extremely high reliability.
2.2 has complete supporting facilities, complete functions, and strong applicability
PLC has developed to this day, and large, medium and small -scale series of products have been formed today. Can be used for industrial control occasions of various scale. In addition to logical processing functions, most modern PLCs have comprehensive data computing capabilities and can be used in various digital control areas. In recent years, a large number of functional units of PLC have emerged, causing PLC to penetrate into various industrial controls such as position control, temperature control, and CNC. Coupled with the enhancement of PLC communication capabilities and the development of human -machine interface technology, it is very easy to use PLC to form various control systems.
2.3 Easy to learn and easy to use. It is welcomed by engineering and technical personnel
PLC as the general industrial control computer, which is an industrial control equipment for industrial and mining enterprises. It is easy to interface, and the programming language is easy to accept for engineering and technical personnel. The graphics symbol of the trapezoidal diagram language is quite close to the expression method as the expression. It can easily achieve the function of the relay circuit with only a small amount of logic control instructions of PLC. Those who are not familiar with electronic circuits, do not understand computer principles and assembly languages ​​use computer to engage in industrial control.
2.4 The design and construction workload of the system is small, convenient to maintain, and it is easy to transform
PLC with storage logic instead of wiring logic, which greatly reduces the external wiring of the control device, and the cycle of the control system design and construction is large. Shorten, while maintenance becomes easy. More importantly, it is possible to change the process of the same device to change the production process. This is very suitable for multi -variety and small batch of production occasions.
2.5 is small in size, light weight, low energy consumption
Taking ultra -small PLC as an example, the bottom size of the newly produced variety is less than 100mm, the weight is less than 150g, and the power consumption is only countless. Because small volume is easy to install the interior of the machine, it is an ideal control device to achieve mechanical and electrical integration.
3. PLC basic knowledge
1.1 PLC's development process In the process of industrial production, a large number of switching sequence control is controlled. data collection. Traditionally, these functions are achieved through pneumatic or electrical control systems.
4. The application field of PLC
At present, PLC has been widely used at home and abroad in steel, petroleum, chemical, electricity, building materials, machinery manufacturing, automotive, light textiles, transportation, environmental protection, cultural and entertainment and other various various them The industry can be summarized as the following categories.
4.1 The logical control of the switch volume
This is the most basic and wider application field of PLC. It replaces the traditional relay circuit and achieves logical control and order control. It can also be used for multi -machine group control and automated assembly line. Such as injection molding machines, printing machines, booking machinery, combined machine tools, grinding machines, packaging production lines, electroplating assembly lines, etc.
4.2 Simulation control
It in the industrial production process, there are many continuous changes, such as temperature, pressure, flow, liquid level, and speed. In order to make the programmable controller processing the simulation, the A/D conversion and D/A conversion between the analog quantity (Analog) and the digital volume must be achieved. PLC manufacturers all produce supporting A/D and D/A conversion modules for programming controllers for simulation control.
4.3 Movement control
PLC can be used for control of circular or straight movements. From the perspective of the configuration of the control agency, it is directly used to connect the position sensor and execution agency directly in the connection of the I/O module in the I/O module. If you can drive a single or multi -axis position control module of a step motor or servo motor. The products of major PLC manufacturers in the world have motion control functions, which are widely used in various machinery, machine tools, robots, elevators, etc.
4.4 Process control
The process control refers to a closed -loop control of simulation such as temperature, pressure, and flow. As an industrial control computer, PLC can compile a variety of control algorithm programs to complete closed -loop control. PID adjustment is a regulatory method used in general closed -loop control systems. Large and medium -sized PLCs have PID modules. At present, many small PLCs also have this function module. PID processing is generally a special PID subroutine. The process control is very widely used in metallurgical, chemical, heat treatment, boiler control, etc.
4.5 Data processing
HP PLC has mathematical operations (including matrix operations, function operations, logical operations), data transmission, data conversion, sorting, table check, bit operation and other functions. , Analysis and processing. These data can be compared with the reference value stored in the memory, completing a certain control operation, and can also use the communication function to transfer to other smart devices, or print them. Data processing is generally used for large -scale control systems, such as unmanned flexible manufacturing systems; can also be used for process control systems, such as papermaking, metallurgy, and some large -scale control systems in the food industry.
4.6 communication and network
PLC communication contains communication between PLC and communication between PLC and other smart devices. With the development of computer control, the development of factory automated networks has developed rapidly. PLC manufacturers attach great importance to the communication functions of PLC and have launched their own network systems. The newly produced PLC has communication interfaces, and communication is very convenient.
5. PLC's domestic and foreign conditions
In in the process of industrial production, a large number of switching quantity is controlled. Data collection. Traditionally, these functions are achieved through pneumatic or electrical control systems. In 1968, the US GM (General Motors) Company proposed the request to replace the relay control device. Electrical control, this is the first generation of programmable program controllers. It is said that the first PLC.
is limited to the component conditions and computer development levels at the time. The composition of scale integrated circuits can complete simple logical control and time and counting functions. Micro -processor appeared in the early 1970s. People quickly introduced it to a programmable controller, which enabled PLC to add functions such as operations, data transmission and processing, and completed industrial control devices that really have computer characteristics. In order to facilitate the use of engineering and technical personnel who are familiar with relay and contactor systems, the programmable controller adopts a trapezoidal diagram similar to the relay circuit diagram as the main programming language, and the computer storage elements participating in computing and processing are named after the relay. At this time, the PLC is a combination of the concept of microcomputer technology and relay conventional control. After the personal computers (PC) developed, for the sake of convenience and the functional characteristics of the programmable controller, the programmable controller was named Logic (PLC).
The middle and late 1970s, programmable controllers entered the practical development stage, and computer technology has fully introduced the programmable controller to make its function leap. Higher computing speed, ultra -small volume, more reliable industrial anti -interference design, simulation operations, PID functions and high cost performance have established its position in modern industry. In the early 1980s, programming controllers had been widely used in advanced industrial countries. During this period, the development of programmable controllers is characterized by large -scale, high -speed, high -performance, and product series. Another characteristic of this stage is that the number of countries in the world's programmable controllers is increasing, and the output is increasing. This marks that the programmable controller has entered the mature stage.
In the 1980s to the mid -1990s, the fastest period of PLC was developing, and the annual growth rate has been maintained from 30 to 40%. During this period, the PLC was greatly improved in processing simulation capacity, digital computing power, human -machine interface capabilities, and network capabilities. PLC gradually entered the field of process control. In some applications, DCS was replaced in some applications. system.
The development of programming controllers at the end of the 20th century is more suitable for the needs of modern industry. In terms of control scale, large -scale and ultra -small machines were developed during this period; in terms of control capabilities, a variety of special functional units were born, and various controls such as pressure, temperature, speed, displacement, etc. Scenes; From the perspective of product supporting capabilities, the production of various human -machine interface and communication units is produced, making it easier to support the industrial control equipment of the programmable controller. At present, the application of programmable controllers in the fields of machinery manufacturing, petrochemical, metallurgical steel, automobiles, and light industry have made great development.
The introduction, application, development, and production of programmable controllers began with reform and opening up. Initially, a large number of programmable controllers were used in the introduction of equipment. Next, the application of PLC has been continuously expanded in the production equipment and products of various enterprises. At present, my country has already produced small and medium -sized programming controllers. The CF series produced by Shanghai Dongwu Electric Co., Ltd., DKK and D series produced by Hangzhou Machine Tool Electric Factory, S series produced by the Dalian Group Machine Tool Research Institute, YZ series produced by Suzhou Electronics Computer Factory already have a certain scale It was applied in industrial products. In addition, Chinese and foreign joint ventures such as Wuxi Huaguang Company and Shanghai Township Corporation are also well -known PLC manufacturers in my country. It can be expected that with the deepening of my country's modernization process, PLC will have a wider application world in my country.
6. PLC Future Outlook
21 century, PLC will have greater development. From a technical point of view, the new achievements of computer technology will be applied more in the design and manufacturing of the programmable controller. There will be a faster computing speed, larger storage capacity, and stronger intelligence. From the perspective of product scale, , Will further develop in ultra -small and oversized directions; from the perspective of product supporting, the variety of products will be richer and more complete. The perfect human -machine interface and complete communication equipment will better adapt to various industrial control controls The needs of the occasion; from the perspective of the market, the situation of the production of multi -variety products in each country will be broken with the intensification of international competition. A few brands will monopolize the international market, and the international programming language will appear. From the perspective of development, the programmable controller and other industrial control computing unit networks constitute a large -scale control system are the development direction of programming controller technology. The current computer distribution control system DCS (Control System) already has a large number of programmable controller applications. With the development of computer networks, programmable controllers, as an important part of automated control network and international universal network, will play an increasingly large role in many areas other than industry and industry.
1.2 PLC's composition
In structural division, PLC is divided into two types: fixed and combined (modular). The fixed PLC includes CPU board, I/O board, display panel, memory block, power supply, etc. These elements are combined into a non -demolished whole. Module PLC includes CPU modules, I/O modules, memory, power modules, bottom plates, or racks. These modules can be configured in accordance with certain rules.
1.3 The composition of CPU
CPU is the core of the PLC, the role of the neuron center, each set of PLC has at least one CPU. Collect the status or data sent by the on -site input device by scanning, and store it in the specified registers. At the same time, the working status and syntax errors in the process of diagnosis of the power supply and the internal circuit of the PLC. After entering and running, read the instructions one by one from the user program memory, and then generate a corresponding control signal according to the task specified in the instructions after analysis to command the control circuit.
CPU is mainly composed of computing, controller, register, and data, control and status bus that realizes them. The CPU unit also includes peripheral chips, bus interfaces and related circuits. Memory is mainly used for storage programs and data, which is an indispensable unit of PLC.
Itdasiers, there is no need to analyze the internal circuit of the CPU in detail, but there should be enough understanding of the working mechanism of each part. The CPU controller controls the CPU work, and it reads instructions, interpretation instructions and execution instructions. But the rhythm of the work is controlled by the shock signal. The operator is used to perform digital or logical operations and work under the controller command. The register participates in the operation and stores the intermediate result of the operation. It is also working under the controller command.
CPU speed and memory capacity are important parameters of PLC. They determine the operating speed of PLC, the number of IO, and the software capacity, so it is limited to the control scale.
1.4 I/O module
PLC and electrical circuit interfaces are completed by input and output parts (I/O). The I/O module integrates the I/O circuit of the PLC. The input of the input memory reflects the input signal state, and the output point reflects the output lock memory status. The input module transforms the electrical signal into a digital signal into the PLC system, and the output module is opposite. I/O is divided into switch quantity input (DI), switching output (DO), analog input (AI), analog output (AO) and other modules.
The commonly used I/O classification is as follows:
The switch amount: divided according to voltage levels, there are 220VAC, 110VAC, 24VDC, divided according to isolation, there is relay isolation and transistor isolation. rn模拟量：按信号类型分，有电流型（4-20mA,0-20mA）、电压型（0-10V,0-5V,-10-10V）等，按精度分，有12bit, 14bit, 16bit, etc.
In addition to the above -mentioned universal IO, there are special IO modules, such as thermal resistance, thermocouple, pulse and other modules.
In the number of module specifications and quantity according to the number of I/O points. I/O modules can be more or less, but the maximum capabilities of the CPU can be managed by the CPU, that is, the maximum bottom plate or rack slot limit limit is limited Essence
1.5 Power module
PLC power supply is used to provide working power supply for integrated circuits of PLC modules. At the same time, some also provide 24V working power supply to the input circuit. The power input type is: AC power supply (220VAC or 110VAC), DC power supply (commonly used 24VDC).
1.6 bottom panel or rack
. Most module PLC uses the bottom plate or rack. Its function is: on the electrical, realize the connection between each module, so that the CPU can access all the modules on the bottom plate, mechanical machinery, machinery On the top, the connection between each module makes each module form a whole.
1.7 PLC system of other devices
1.7.1
programmatic equipment: programmer is an indispensable device for PLC development, monitoring operation, inspection and maintenance The working conditions of the system controlled by PLC and PLC are determined, but it does not directly participate in the operation of the on -site control operation. The editor PLC generally has a handheld programmer. At present, computers (running programming software) serve as programmers. That is the upper machine of our system.
1.7.2 Human -machine interface: The easiest human -machine interface is indicator lights and buttons. The current application of the LCD screen (or touch screen) type operator terminal application is becoming more and more extensive. As a human -machine interface, it is very popular.
1.8 PLC's communication network
This can quickly and effectively collect, transmit production and management data by relying on advanced industrial network technology. Therefore, the importance of the network in the integration of the network is becoming more and more significant, and some people even put forward the view that "the network is the controller".
PLC has the function of communication networking. It enables the PLC and PLC
, between PLC and upper computers and other smart devices. Most PLCs have the RS-232 interface, and there are some interfaces that support their respective communication protocols. PLC's communication now uses data communication, Profibus
or industrial Ethernet network through multi -point interface (MPI).
2 PLC control system design basic principles
2.1 Maximum control requirements of the controlled object.
2.2 On the premise of meeting the control requirements, strive to make the control system simple, economical, use and maintenance.
2.3 Guarantee control system is safe and reliable.
2.4 Considering the development of production and the improvement of the process should be appropriately leaving the balance when selecting the PLC capacity.
3 PLC software system and commonly used programming languages ​​
3.1 PLC software system consists of two parts: system program and user program. The system program includes monitoring programs, compilation programs, diagnostic procedures, etc., which are mainly used to manage the entire machine, translate the program language into machine language, and diagnose machine failure. System software is provided by PLC manufacturers and solidified in EPROM, and cannot be directly accessible and intervened. The user program is an application (that is, logical control) that users use PLC's programming language according to the requirements of on -site control to achieve various controls. STEP7 is a standard software package for SIMATIC programming logic controller configuration and programming, that is, user programs, we use Step7 for online surveillance of hardware configuration and logical program compilation, and logical program execution results.
3.2 PLC's programming language
3.2.1 Standard language graphic diagram language is also our most commonly used language. It has the following characteristics
3.2.1.1 It is a graphic language, it Along the uses of relay contacts, coils, series and other terms in the traditional control diagram, and some graphic symbols. The left and right vertical lines are called left and right bus.
3.2.1.2 The contacts (contacts) in the trapezoidal diagram can only be opened and normally closed. The contact can be the switch of the PLC input point connection or the state of the PLC internal relay or internal register, counter, etc.
3.2.1.3 The contacts in the trapezoidal diagram can be arbitrarily stringed and connected, but the coils can only be connected in parallel.
3.2.1.4 Internal relay, counter, register, etc. cannot directly control the external load, and can only be used for the internal use of the CPU.
3.2.1.5 PLC is a scanning incident in a circulating event. The results of the scanning cycle in the same scanning cycle are left in the output state. Essence
3.2.2 statement language, similar to the assembly language.
3.2.3 Logic function diagram language, follows the semiconductor logic box diagram to express. Generally, an operational frame represents a function input and output on the right.
4 Step7 program use
4.1 Create a project structure. The project is like a folder. All data exists in the layered structure. You can use it at any time. After creating a project, all other tasks are performed under this project.
4.2 Configuration of a station, a station stands is to specify the programmable controller you want to use, such as S7300, S7400, etc.
4.3 Configuration hardware, the configuration hardware is to specify the templates to be used in the configuration table in the configuration table and what kind of address to access these templates in the user program. generate. The characteristics of the template can also be assigned with parameters.
4.4 Configuration network and communication connection. The basis of the communication is the pre -configuration network, that is, to create a subnet that meets your control scheme, setting up network characteristics, setting network connection characteristics, and any network of networks that are connected to the network. Need connections. The network address is also automatically generated by the program. If the experience is not changed, you must not modify it.
4.5 Define the symbols, which can define local or shared symbols in the symbol table, and replace the absolute address with these more descriptive symbol names in your user program. The naming of the symbol is generally written in the letter without more than 8 bytes. It is best not to use a long Chinese character to describe it, otherwise it will have a great impact on the execution of the program.
4.6 Create a program, and create a programming language connected to the template or not related to the template with a trapezoid diagram. Creation procedures are one of the important tasks of our control project. Generally, line -shaped programming (based on a block, OB1), distributed programming (writing function block FB, OB1 tissue calls), and structured programming (write universal block). We most often use structured programming and distributed programming, and rarely use line programming.
4.7 download program to a programmable controller. After completing all configuration, parameter assignment and programming tasks, you can download the entire user program to the programmable controller. When downloading the program, the programming controller must be in the allowable download work mode (Stop or Run-P),
run-p mode represents that this program will download a block at a time. There may be conflicts, so the CPU is generally switched to the STOP mode before downloading.
5 Wincc program uses
5.1 Introduction, Wincc is an industrial technology neutral system that solves visualization and control tasks in production and process automation. It has a powerful function of controlling automation process. It is based on the operation and surveillance system of personal computer. It is easy to combine standards and user procedures to establish accurate production requirements for human -machine interfaces. Wincc has two versions of the RC version (with a configuration and development environment) and the RT version (only the operating environment). We generally use the RC version.
5.2 Wincc Simple use step
5.2.1 Variable management, first determine the communication method installation of the driver, and then define the internal variables and external variables. The external variable is the maximum authorized 64K authorized by the Wincc software authorized by you to buy. Bytes, internal variables are not limited.
5.2.2 The graphics editor is generated. The graphic editor is a vector -oriented diagram for the creation of the screen. You can also use many graphic objects containing objects and style libraries to create complex process screens. You can add dynamics to a single graphic object through action programming.
5.2.3 Alarm record settings, the alarm records provide display and operation options to obtain and archive the results. You can choose message blocks, message levels, message types, message display and reports at will. In order to display messages during operation, alarm control controls containing object libraries containing the object library in the graphic editor.
5.2.4 Variable records, variable records are used to collect data from the operation and prepare to display and archive them.
5.2.5 The statement configuration, the statement configuration is achieved through the report editor. It is a reporting system for the integrated report of the time -oriented data timer or event control document for messages, operation, archiving content, and current or archived data. You can freely choose the form of user reports.
5.2.6 The application of global scripts. The global script is the general name of the C language function and action. According to different types of scripts, it is used to deal with the object configuration and process it through the internal C language compiler. Global script movement acts in the operation of process execution. A trigger can start the execution of these actions.
5.2.7 User manager settings, the user manager is used to allocate and control the user's access permissions and run the system editor. Every time a user is established, the access right of the Wincc function is set up and distributed independently to this user. At least 999 different authorization can be distributed.
5.2.8 Cross meter indexes, cross sees are referenced to find and display all usage places for objects, such as variables, screens and functions. Using the "link" function can change the variable name without causing the configuration inconsistency

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