An Introduction to PLC 英语介绍

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PLC的英文作文

PLC的英文作文英文：PLC (Programmable Logic Controller) is a type of industrial control system used to automate various processes. It is widely used in manufacturing, packaging, and assembly industries. As a PLC engineer, I have been working with PLCs for many years and have gained a wealthof experience in programming and troubleshooting.One of the advantages of using a PLC is its flexibility. It can be programmed to perform a wide range of tasks and can be easily reprogrammed if changes are needed. For example, in a manufacturing plant, a PLC can be programmedto control the speed of a conveyor belt, the temperature of an oven, and the pressure of a hydraulic system. If the production process changes, the PLC can be reprogrammed to accommodate the new requirements.Another advantage of using a PLC is its reliability.PLCs are designed to operate in harsh industrial environments and can withstand extreme temperatures, humidity, and vibrations. They are also equipped withbuilt-in diagnostic tools that can detect and diagnose faults, making it easier to troubleshoot and repair problems.However, there are also some challenges when working with PLCs. One of the challenges is the complexity of programming. PLC programming requires a high level of technical knowledge and expertise. It also requires a deep understanding of the specific application and the process being controlled. Therefore, it is important to have a well-trained and experienced engineer to ensure that the PLC is programmed correctly.Another challenge is the need for regular maintenance. PLCs are electronic devices that can be affected by wear and tear, as well as environmental factors. Regular maintenance is essential to ensure that the PLC is functioning correctly and to avoid downtime. This includes checking for loose connections, cleaning the system, andreplacing worn-out components.In summary, PLCs are an essential part of modern industrial automation. They provide flexibility and reliability, but also require technical expertise andregular maintenance to ensure optimal performance.中文：PLC（可编程逻辑控制器）是一种用于自动化各种过程的工业控制系统。

PLC工程师的英语自我介绍

PLC工程师的英语自我介绍Hello!My name is****School of engineering cost management profession al students.It is an honor to participate in this interview,four years of university s tudy and life,I have strict demands on themselves,hard-working,hard-working,pragmatic and systematic study of engineering cost based curriculum knowledg e,and achieved excellent results.I have always been diligent,conscientious,and actively adapt to the environment,and make unremitting efforts for their own sel f value.The college has served as student union Vice Minister of the Propaganda De partment of the organization,has the strong organization ability,activity plannin g ability,communication ability,and have good language skills and team spirit,w ork together with the Department Director at the University,jointly organizing an d planning a number of large and medium-sized Youth League activities,and ach ieved very well,get the praise of teachers and administrators.Honesty is my personal principle,I believe that my ability is good enough for most of the position,I love the business of your company,sincerely look forward to your leadership,the building blocks for this glorious cause;and continuous lea rning,progress in practice.I am***College of engineering construction project cost manageme nt syst em of professional students.During college,I with outstanding achievements,th e school has won a comprehensive,nationalmotivational scholarships,and has b een rated as"excellent students"honorary title,in order to meet the needs of pr ofessional knowledge.In the cost of the specialty,I studied engineering costcontrol>and<<<>,engineering economics,municipal engineering measurement and valuation","co nstruction project measurement and valuation>,<installation><Engineering Measurement and valuation,contract management and bidding>,<>buildinghitecture.The school often do professional curriculum design,and carries on the scene a week to observe the internship site,with senior engineer Huang workers learni ng and practice,grasp the application of theodolite on the site,the test block of concrete,steel banding and familiar with reinforcement diagram,the solution sh ould handle construction visa etc..Theoretical knowledge and practice in school t ogether,more full grasp of professional skills.The study,I participated in many so cial practice activities,to exercise their own hard work,strict in demands of wind.Modern society is in need of compound talents of combining theory and pra ctice.I will through continuous learning to improve themselves,to prove himself i n practice.Strive to realize their value of life,to contribute to the development of your :Mr.X sex:Male Marital status:unmarried MiaoNationality:Residence:Hunan-Jishou age:25Location:Guangdong-Dongguan height:163cm Hope:Guangdong That position:Electrical/electronics components-Electrical Engineer Position:Electrical Education experience 20xx-09~20xx-07 of Shaanxi University of Science and Technology haojingc ollege electrical engineering machine automatio。

Introduction of PLC

1. A programmable logic controller (PLC), comprising a processor unit for sequential control of a process and for data communication with at least one external system, which PLC is arranged to execute tasks cyclically during sequential control, in each cycle a given period of time being available to each task, said tasks comprising a user task for executing an application program and a communication task for taking over control parameters for the application program which have been acquired during data communication with the at least one external system, the ratio of the durations of the periods available to the execution of the communication task and the application program being adjustable during the execution of the application program.2. A programmable logic controller as claimed in Claim 1, in which the duration of the period available to the communication task can be adjusted via the application program.3. A programmable logic controller as claimed in Claim 1 or 2, in which the period available to the communication task is adjustable within predetermined limits.4. A programmable logic controller as claimed in Claim 1, 2 or 3, in which the processor (CPU) comprisesa first processor (SCP) for sequential control and a second processor (DCP) for data communication with the at least one external system, and a communication unit (MBX) for communication between the first and the second processor.5. A programmable logic controller as claimed in Claim 1, 2, 3 or 4, in which the external system whose control parameters acquired during the communication task originate from a user console and/or a programming system and/or another programmable logic controller and/or a central computer.Description:The invention relates to a programmable logic controller (PLC), comprising a processor unit for sequential control of a process and for data communication with at least one external system, which PLC is arranged to execute tasks cyclically during sequential control.Generally speaking, a PLC is a (micro)processor or a system of (micro)processors for the execution of a specific task, for example the monitoring and control of a process. Such a process may be the control of a machine as well as of a complex of collaborating installations. For correct operation it is necessary to execute a number of tasks while responding to signals originating from the process or system to be controlled and to control parameters from, for example a user console. The various tasks to be executed in a PLC are carried out in a fixed order; during a cycle (to be referred to hereinafter as the PLC cycle) a given amount of time is made available to each of said tasks.The tasks in a typical PLC cycle are: general overhead, required for correct operation of the programmable logic controller; writing of data, for example signals from the system controlled; execution of the user task, i.e. the processing of the signals entered so as to form control signals for the system; output of the control signals; external communication, for example with an operator console and/or a central computer. The length of the period assigned to each task is fixed, so that the total cycle time is fixed and hence also the total response time (TRT) of the programmable logic controller. The totalresponse time is the time elapsing between the instant at which the value of one of the input signals changes and the instant at which this change influences the outgoing control signals.Moreover, the PLC should communicate with an external system, for example a user console, in which case it is necessary not only to write control parameters of the external system but also to check these parameters for mutual consistency and consistency as regards the instantaneous state of the process or system to be controlled. After completion of this check and adaptation of the parameters, if necessary, during the execution of the communication task the new values must be transferred to the part of the processor which can be accessed by the user program.In a conventional system as described above, the TRT may be subject to fluctuations because the number of operations to be carried out during the user or communication task may vary, for example in dependence on the values or the changes of the input signals and/or control parameters to be taken over. For example, it may occur that the communication time of several PLC cycles is required so as to take over a completely new set of control parameters. Consequently, much time is spent on the execution of the application program without the new parameters being (fully) taken into account. During this period a number of PLC cycles elapse without useful control being performed, leading to a serious increase of the response time of the system.If, in order to avoid this situation, the communication time is fixed as the maximum time required to take over the parameters, it will often occur that this time is not completely necessary, so that many PLC cycles have an idle period in which no task whatsoever is performed. This also slows down the operation of the PLC.It is inter alia an object of the invention to provide a programmable logic controller in which the duration of the PLC cycle amounts to at the most a time desired by the user, in which idle time in a cycle can be simply avoided and the execution of cycles which are useless with respect to control can be reduced.To achieve this, a PLC in accordance with the invention has the property that in each cycle a given period of time is available to each task, said tasks comprising a user task for executing an application program and a communication task for taking over control parameters for the application program which have been acquired during data communication with the at least one external system, the ratio of the durations of the periods available to the execution of the communication task and the application program being adjustable during the execution of the application program. In situations where it is expected that the user task will require a large amount of time or where interruptions of the user task must be minimized, for example during a time-critical phase of the operation of a machine, the time for the communication task is adjusted to a low value.In cases where a change of the control parameters can be executed without seriously disturbing the process, the time for the user task may be comparatively shorter and that for the communication task comparatively longer. In a non-critical phase of the process or machine control, this aspect is not detrimental to the system being controlled, so that the increase of the total response time is not objectionable. In comparison with a system in which switching over to a system task must wait until even a prolonged user task has been completely executed, a PLC in accordance with the invention offers theadvantage that the cycle time variation is predetermined and is long only in specific circumstances as desired by the user.In a preferred embodiment of the PLC in accordance with the invention the duration of the period available to the communication task can be adjusted via the application program. This is advantageous because in the application program it is known whether the controlled system or process is in atime-critical phase or not and when a large amount of new data is to be expected. This aspect is taken into account in the allocation of the communication time.In an embodiment of the invention the period available to the communication task is adjustable within predetermined limits. If the communication time has a minimum value unequal to zero and is also bound to a maximum, the communication task as well as the user task is activated in each cycle. It is thus ensured that, via the communication task, the user program can always be influenced from the external system.In a further embodiment of the invention the processor (CPU) comprises a first processor (SCP) for sequential control and a second processor (DCP) for data communication with the at least one external system, and a communication unit (MBX) for communication between the first and the second processor. Using two, task-specific processors in the PLC, the data communication with external systems and the control of the controlled system are executed in parallel. This means an acceleration of the sequential control of the controlled system.These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.In the drawings: Fig. 1 shows a block diagram of a PLC with components of a system to be controlled which are coupled thereto; Figs. 2a and 2b show the various types of tasks in a PLC cycle; Fig. 3 shows a flow chart of an application program for a PLC in accordance with the invention.The block diagram of Fig. 1 shows a programmable logic controller PLC which is coupled, for example via a serial bus SBS, to a number of sensors S1, S2, ... whereby signals of a system to be controlled (not shown) are measured and entered into the programmable logic controller PLC. The programmable logic controller PLC is also coupled to actuators A1, A2, ..., for example via the same serial bus SBS, in order to apply control signals for the system to be controlled thereto. Besides a single bus SBS, separate buses for input signals and control signals are also feasible. Apart from coupling to the serial bus SBS, with which the programmable logic controller is coupled to the controlled system, the controller is also coupled to one or more external systems.Shown are, by way of example, a user console or man-machine interface MMI for entering instructions and displaying the state of the controlled system and the logic controller, a programming and debugging system PDS for programming and testing the controller, an external computer system HST, and a connection to other logic controllers via a network NTW.The programmable logic controller PLC comprises a central processor unit CPU with one or more storage modules and an interface module IFC to the serial bus or buses SBS. The storage modulescontain inter alia a system program and an application program. The processor unit CPU can be subdivided into a section SCP which performs the sequential control of the controlled system, via sensors and actuators, and a section DCP which handles the data communication with the external systems NTW, HST, MMI and PDS. The latter section not only reads the parameters presented by the various external systems, but also checks these parameters for mutual consistency and solves conflicts, if any.Figs. 2a and 2b diagrammatically illustrate the execution of the tasks during a PLC cycle. Fig. 2a shows the execution of the tasks in case one processor is available which executes process control as well as data communication with external systems. Fig. 2b shows the execution of the tasks for process control if a separate processor is available for data communication. The sections DC1 and DC2 in Fig. 2a indicate when the processor exchanges data with external systems for the entering and execution of parameters, respectively. To this end, a driver DRV is activated from time to time. Furthermore, the parameters are checked and written into the appropriate storage locations in the logic controller. When the controller executes the blocks INP, USR, OUT, COM and FMW, the sequential control tasks are performed.During the block INP, analog and digital signals from the sensors are read; the block USR indicates that this information is processed in conformity with the instructions in the application program. Upon execution of the block OUT, calculated control signals are applied to the actuators. During the block COM, data is exchanged between the sequential control task and the data communication task. During this task data blocks are exchanged between the section dedicated to control and the section dedicated to data communication, for example by writing and reading in a memory accessible to both tasks. This exchange cannot take place continuously, because the sets of control parameters whereto the application program reacts would then be inconsistent. Finally, in the block FMW a so-called firmware program governs the internal processing of the controller.The firmware program ensures that commands entered via the parameters are executed in program blocks during the data communication task in as far as permitted by the allocated time. This is realized, for example via a look-up table stating for each command or program block how much time is required for the execution thereof. If not all commands can be executed within a PLC cycle, the other commands are postponed until the next cycle. Thus, the execution of the various commands is not interrupted when the allocated time is exceeded.Fig. 2b shows the same for a system comprising two processors. In the left-hand part of the Figure the tasks INP, USR, OUT, COM and FMW of the sequential control processor are given. The right-hand part of the Figure shows that the data communication task with excursions to drivers DRV.In a situation involving one processor, the change induced in the time allocation of the communication task by the application program will relate mainly to the communication with external units such as the operator console or central computer. This is the part of the PLC cycle which is denoted by the reference DCP in Fig. 2a. When two processors are involved, notably the communication task COM/MBX, controlling the communication between the two processors, will be affected.Both in the case of one and in the case of two processors the exchange of data between the data communication task and the sequential control task takes place via a memory MBX which can beaddressed from both tasks. As is shown in the Figs. 2a and 2b, the writing and reading from the memory MBX in the sequence control task takes place during a part of the cycle executed during this task. During a cycle, a given amount of time is allocated to each task in the sequence control.Fig. 3 shows a flow chart of an application program for a programmable logic controller in accordance with the invention. The application program shown controls two phases of the operation of a machine or process. The first phase, indicated in section 30, is a time-critical phase, for example the filling and subsequent opening of the mould of an injection moulding machine. The second phase, denoted by the reference 40, is far less time-critical and in the case of an injection moulding machine it concerns, for example the removal of the workpiece and the closing of the mould. A further control task in whichtime-critical as well as less time-critical phases occur is the control of a numerically controlled milling machine or lathe.The phase during which a workpiece is actually being worked is substantially more time-critical than the displacement of tool or workpiece in free space or the exchange of a tool.The program is started by a command, for example from a user console, thus fetching the necessary control parameters which indicate how the action is to be performed. Subsequently, the program starts first in the time-critical phase. In accordance with the invention first (in block 32) the period available to data communication will be adjusted to a very small value, for example 2 ms.Subsequently, the time-critical phase is executed, during which successively: in block 41 the instantaneous state of the machine or the process is determined on the basis of the parameters entered during the input task of a PLC cycle; in block 42 the necessary corrections are calculated; in block 43 the necessary control signals are entered in the memory locations wherefrom they are applied to the actuators during the execution task of the PLC cycle; and finally in block 44 it is checked whether this first phase may be terminated. If not, this cycle within the user task is repeated; otherwise, the operation proceeds to the second phase. This phase consists of the same tasks, indicated by the blocks 51, 52, 53 and 54, respectively.However, this second phase 50 is preceded by a block 33 informing the firmware program that the data communication phase of a PLC cycle must be long, for example 10 or 20 ms. During this long phase large blocks of control parameters can be made available to the user task in one or only a few PLC cycles.。

自动化专业英语——Introductions to PLC

n.词首大写字母 6. internal adj.内在的，国内的
潜在的，可能的
n. 潜能，潜力，电压
8. pulse n.脉搏，脉冲
9. register n. 登记，注册，寄存器
vt. 登记，把...挂号
vi. 登记，注册
10. retentive adj. 保持的
vt. 转换，转变 18. temporary adj.暂时的 19. timer n.计时员，记时员 20. transistor n.[电子]晶体管
2020年7月1日8时59分
专业英语
3
21. triac <美> [电子]三端双向可控硅开关元件 22. via prep. 经，通过，经由
2020年7月1日8时59分
专业英语
5
PLC(可编程控制器)是为替代实现机器顺序控制所必须的继电器电路而发明的装置。
句中that引导的定语从句用来修饰主语a device，短语for machine control用来说明sequential relay circuits的作用。
2020年7月1日8时59分
2020年7月1日8时59分
专业英语
12
4. 常用的it结构的固定译法
It turned out that the good Lord had not led him astray.
后来证明，敬爱的上帝并没有使他迷途。
2020年7月1日8时59分
专业英语
13
Lesson 19 Introductions to PLC
New words and phrases :
1. circuit n.电路，一圈，周游 2. data storage n.数据保存，资料保存 3. dedicated adj.专注的，献身的 4. execute vt.执行，处死，制成使 5. initial adj. 最初的，词首的

PLC技术中英文翻译可编程控制器技术(英语原文中文翻译)

l 中文翻译可编程控制器技术随着时代的发展当今的技术也日趋完善、竞争愈演愈烈单靠人工的操作已不能满足于目前的制造业前景也无法保证更高质量的要求和高新技术企业的形象.人们在生产实践中看到自动化给人们带来了极大的便利和产品质量上的保证同时也减轻了人员的劳动强度减少了人员上的编制.在许多复杂的生产过程中难以实现的目标控制、整体优化、最佳决策等熟练的操作工、技术人员或专家、管理者却能够容易判断和操作可以获得满意的效果.人工智能的研究目标正是利用计算机来实现、模拟这些智能行为通过人脑与计算机协调工作以人机结合的模式为解决十分复杂的问题寻找最佳的途径我们在各种场合看到了继电器连接的控制，那已经是时代的过去，如今的继电器只能作为低端的基层控制模块或者简单的设备中使用到；而 PLC的出现也成为了划时代的主题，通过极其稳定的硬件穿插灵活的软件控制，使得自动化走向了新的高潮。

PLC的最大特点在于：电气工程师已不再电气的硬件上花费太多的心计，只要将按钮开关或感应器的输入点连接到 PLC的输入点上就能解决问题，通过输出点连接接触器或继电器来控制大功率的启动设备，而小功率的输出设备直接连接就可以。

PLC 的内部包含了具有中央处理器的CPU，并带有外部 I/O 口扩展的 I/O 接口地址和存储器三大块组成，CPU的核心是由一个或者多个累加器组成，它们具有逻辑的数学运算能力，并能读取程序存储器的内容通过计算后去驱动相应的存储器和 I/O 接口；I/O口将内部累加器和外部的输入和输出系统连接起来，并将相关的数据存入程序存储器或者数据存储器中；存储器可以将 I/O口输入的数据存入存储器中，并在工作时调转到累加器和 I/O接口上，存储器分程序存储器 lROM 和数据存储器 RAMROM可以将数据永久的存入存储器中，而 RAM 只能作为 CPU计算时临时计算使用的缓冲空间。

PLC的抗干扰是极其优秀的，我们根本不用去关心它的使用寿命和工作场合的恶劣，这些所有的问题已不再成为我们失败的主题，而留给我们的是关心如何来利用 PLC 的内部资源为我们加强设备的控制能力，使我们的设备更加的柔性。

PLC的介绍（英文）

PLC introducedThe graduation project topic is the application of PLC in the servo servo system, the PLC application and understanding of the graduate design, following the basic knowledge of PLC to make a brief introduction.The PLC can be programmed controller is the new industrial control devices based on computer technology. The PLC in the PLC draft standards issued by the International Electrotechnical Commission in 1987 made the following definition: "the PLC is a specially designed for applications in industrial environments digital computing operation of electronic devices which can be programmed memory, with to implementation of the logical, sequential operation, timing, counting and arithmetic operations, such as operating instructions in its internal storage and can be digital or analog inputs and outputs to control various types of machinery or production processes. PLC and its related peripherals should be easy and industrial control systems to form a whole, easy to extend the principle of functional design. "A.PLC features(a)High reliability, strong anti-jamming capabilityHigh reliability is the key to performance of the electrical control equipment.PLC is due to the introduction of modern LSI technology, strict production process, the internal circuit to take the advanced anti-jamming technology, with high reliability. For example, the Mitsubishi F series PLC MTBF up to 300,000 hours. Redundant CPU PLC, the average time between failures is longer. From a machine outside the circuit of the PLC, the PLC constitutes a control system, and compared to the same scale relay contactor system, electrical wiring and switch contacts have been reduced to hundreds or even thousands, the fault will be greatly reduced. In addition, PLC with a self-detection of hardware failure, failure to timely alert. In the application software, application can also be incorporated into the peripheral devices and fault diagnostic procedures, also received the fault self-diagnostic protection circuit outside the PLC system and equipment. In this way, the entire system with high reliability is also not surprising.Complete, fully functional, and applicability(b)Complete, fully functional, the applicabilityPLC development today, has formed a large, medium and small scale series products. Can be used for industrial control applications of all sizes. In addition to the logical processing functions, the modern PLC mostly data computing power can be used for a variety of digital control. In recent years the emergence of a large number of functional units of the PLC, PLC penetrated into the position control, temperature control, CNC and other industrial control. With PLC communication capability enhancement and development of human-computer interface technology, the use of PLC composed of a varietyof control systems have become very easy.(c)Easy to use, well received by engineers and technicians welcomePLC as a general-purpose industrial control computer, industrial control equipment for industrial and mining enterprises. It easy to interface, programming language is easy to be accepted for engineering and technical personnel. The ladder language graphic symbol and expression and relay circuit is very close, only a small number of switch PLC logic control instructions can easily relay circuit. Not familiar with the electronic circuit, people do not understand computer theory and assembly language using a computer to engage in industrial control to open the door.(d)System design, construction workload is small, easy to maintain, easy to transformPLC storage logic instead of wiring logic, greatly reduce the external wiring of control equipment, control system design and construction of the cycle is much shorter, while maintaining also become easily. More important is that the same device after the change the change the production process become possible. It is suitable for the occasion of many varieties, small batch production.(e)Small size, light weight, low energy consumptionUltra-Small PLC, for example, the newly produced species at the bottom of size less than 100mm, weighs less than 150g, only a few watts of power. Due to small size it is easy to load the internal machinery is the ideal control device for mechanical and electrical integration.B.The composition of the PLCPLC is divided into fixed and modular (modular) two points from the structure. Fixed PLC CPU board, I / O board, display panel, memory blocks, power, and these elements are combined into a non-removable as a whole. Modular PLC CPU module, I / O modules, memory, power supply modules, backplane or rack, these modules can be combined according to certain rules configuration.(a)The composition of the CPUCPU is the core of the PLC, since the role of the nerve center, at least one CPU in each PLC, the PLC system program, the functions entrusted to the reception and storage of user programs and data collected from field input devices sent a scanned stateor data, and deposit shall be required to register, at the same time, the diagnostic power and the working status of the PLC internal circuitry and programming process in syntax errors. Into operation from the user program memory, one by one read command, the corresponding control signal analysis and then according to the mandate of instruction, to command the control circuit.CPU is the main contact between the computing device, controller, register, and to implement them, control and status bus, a CPU unit also includes a peripheral chips, bus interface, and related circuit. Memory is mainly used for storing programs and data is an integral unit in PLC.User opinion, unnecessarily detailed analysis of the internal circuitry of the CPU, but on the part of the working mechanism should have sufficient understanding. The CPU controller controls the CPU to read instructions, which explain the instructions and execute instructions. However, the pace of work is controlled by the oscillation signal. The arithmetic unit is used for digital or logic operation under the command of the controller. Register to participate in operations, and store intermediate results of operations, it is under the command of the controller.CPU speed and memory capacity are important parameters in the PLC, they determine the pace of work of the PLC, IO number and software capacity, thus limiting the size of the control.(b)I / O modulesThe interface of the PLC and the electrical circuit is completed by the input and output portion (I / O). I / O modules with integrated PLC's I / O circuit, the input registers reflect the state of the input signal, output point to reflect the state of the output latch. The input module electrical signals into a digital signal into a PLC system, the output module is the opposite. I / O module is divided into the digital input (DI), digital output (DO), analog input (AI), analog output (AO).The I / O are classified as follows:Switch: the voltage level points, 220VAC, 110VAC, 24VDC, points by way of isolation and separation of relays and transistor isolation.Analog: Signal type, current-(4-20mA, 0-20mA), voltage type (0-10V,0-5V,-10-10V), etc., precision points, 12bit, 14bit, 16bit.In addition to these general-purpose IO, there are special IO module, such as thermal resistance, thermocouple, pulse module.I / O points to determine the module specification and quantity, I / O modules can be more or less, but the maximum number of the ability of the CPU can manage the basic configuration, that is, by the largest number of floor or rack slot limit.(c)Power supply modulePLC power supply IC for the PLC module supplies power to operate. At the same time, some of the input circuit to provide 24V power supply. Power input type: AC power (220VAC or 110VAC), DC power supply (usually24VDC).C. Working principlePut into operation when the programmable logic controller, the course of their work is generally divided into three stages, that is, the input sample, the user program execution and output refresh three stages. Completion of the three stages is called a scan cycle. During the entire operation, the CPU of the programmable logic controller scan speed, repeat the above three stages. (a)Input sampling phaseThe input sampling stage, the programmable logic controller in order toscan read into the state of all input and data, and deposit them with the corresponding unit in the I / O image area. Transferred to the user program execution and output refresh period after the end of the input samp le. In both phases, even if the input state and data changes, the state and data of the corresponding unit in the I / O image area will not change. Therefore, if the input pulse signal, the signal of the pulse width must be greater than one scan cycle, in order to ensure that in any case, the input can be read into the.(b)User program execution stageIn the user program execution stage, programmable logic controllers are always followed by a top-down order to scan the user program (ladder). Scan each one ladder, and always scan by the contact of the ladder left of the control of line, and first left and right first and then the order of logical operations on the control circuit by the contact form , then the logical result of the operation, refresh the logic of the coil system RAM storage area corresponding state; or refresh the state of the output coil corresponding bits in the I / O image area; or determine whether to perform the ladder the provisions of the special function instruction.That is, during user program execution, only the input status and data points in the I / O image area does not change, the output point and soft devices in the I / O image area or system RAM storage areastatus and data are likely to change, but came in above the ladder program execution results will be ranked below those who used these coils or data ladder work; the contrary, the row below the ladder, thethe status of logic coils to be refreshed or the data can only be to the next scan cycle can be ranked on top of the program work.If you use the I / O instruction immediately you can directly access the I / O points in the process of program execution. That the use of I / O instruction, the input process image register values are not updated, the program directly from the I / O module value, the output process image register is immediately updated, this immediately enter some difference.(c)Output refresh periodWhen the scan the user program after the end of the programmable logic controller to enter the output refresh period. During this time, the CPU in accordance with the I / O image area corresponding to the state and data refresh all of the output latch circuit driven by the output circuit corresponding peripherals. At this time, is the real output of the programmable logic controller.D.PLC applicationsAt present, the PLC at home and abroad has been widely used in iron and steel, petroleum, chemicals, electricity, building materials, machinery manufacturing, automobile, textile, transportation, environmental protection and cultural entertainment industry, usage can be broadly divided into the following categories.(a)Switch logic controlThis is the PLC basic, wide range of applications, which replaces thetraditional relay circuit, logic control, sequential control, both for the control of a single device, can also be used for multi-group control and automated assembly line.Such as injection molding machines, printing presses, stapler machine, combined machine tools, grinding machines, packaging production lines, electroplating lines and so on.(b)Analog ControlIn the industrial production process, there are many continuous variables, such as temperature, pressure, flow, level and speed are analog. To make the programmable controller to handle analog, analog (Analog) and Digital (Digital) A / D conversion and D / A conversion. PLC manufacturers are supporting the production of A / D and D / A converter module, the programmable controller for analog control.(c)Motion ControlPLC can be used in a circular motion or linear motion control.From the configuration of the control mechanism, early used directly in the switch I / O modules to connect the position sensors and actuators, is now generally use a dedicated motion control module. Drive a single or multi-axis position of the stepper motor or servo motor control module. The world on all major PLC manufacturers products almost every motion control functions, widely used in a variety of machinery, machine tools, robots, elevators and other occasions. (d)Process controlProcess control refers to the closed-loop control of temperature, pressure, flow analog. As an industrial control computer, the PLC can prepare a variety of control algorithm, the complete closed-loop control. PID regulation is a general closed-loop control system using more regulation. And medium-sized PLC have PID modules, and many small PLC also has this feature module. PID processing is generally run a dedicated PID subroutine. Process control in metallurgy, chemical industry, heat treatment, boiler control and so on a very wide range of applications.(e)Data processingModern PLC math (including matrix operations, functions, operation, logic operation), data transfer, data conversion, sorting, look-up table, bit operation functions, you can complete the data collection, analysis and processing.These data can be compared with the reference value stored in memory to complete the control operation can also use the communication functions to other intelligent devices, or print them tabulation. The data processing is generally used for large-scale control systems, flexible manufacturing systems such as unmanned control; can be used for process control systems, such as papermaking, metallurgy, food industry, some large-scale control system.(f)Communications and networkingPLC communication with the communication between PLC and communication between the PLC and other intelligent devices.With the development of computer control, factory automation, network development,the PLC manufacturers have attached great importance to the PLC communication function, have launched their own network systems. The newly produced PLC communication interface, communication is very convenient. E. History of the development(a)OriginGeneral Motors in 1968 to replace the relay control device requirements;In 1969, Digital Equipment Corporation developed the first programmable logic controller PDP-14, successful trial in the U.S. GM's production line, using procedural means for the first time used in electrical control, which is the first generationprogrammable logic controllers, said Programmable, is recognized as the world's first PLC.In 1969, the United States developed the world's first PDP-14;In 1971, Japan developed the first DCS-8;In 1973, Germany developed the first PLC;In 1974, the Chinese developed the first PLC.(b)DevelopingThe microprocessor in the early 1970s. Will soon be introduced into the programmable logic controller, programmable logic controller to increase the computing, data transmission and processing and other functions, the real computer features of industrial control devices. Programmable logic controller is the product of combining conventional control concepts of computer technology and relay. Development of personal computers, in order to facilitate and reflect the features of the programmable controller, programmable logic controllers be called the Programmable Logic Controller (PLC).The late 1970s, the programmable logic controller into the practical stage of development, computer technology has the full introduction of the programmable controller, a leap to make it function. Higher operating speed, ultra-compact size, the more reliable industrial anti-jamming design, analog computing, the PID function and the high cost laid in modern industry.The early 1980s, the programmable logic controller has been widely used in the advanced industrial countries. Production of programmable controllers on the country in the world is increasing, production is rising. This indicates that the programmable controller has entered a mature stage.1980s to the mid-1990s, the fastest-growing period of the programmable logic controller, the annual growth rate has been maintained at 30 to 40 percent. During this period, the PLC in the processing capacity of analog, digital computing power, man-machine interface capabilities and network capabilities have been greatly improved, programmable logic controllers gradually into the field of process control in the field of process control is replaced in some applications dominance of the DCS system.The late 20th century, the development characteristics of the programmable logic controller is more responsive to the needs of modern industry. This period the development of mainframes and super-minicomputer,the birth of a variety of special function units, the production of a variety of man-machine interface unit, communication unit, so that the application of programmable logic controllers, industrial control equipment supporting easier.。

PLC的英文介绍

PLC IntroductionProgrammable controller is the first in the late 1960s in the United States, then called Plc programmable logic controller (Programmable Logic Controller) is used to replace relays. For the implementation of the logical judgment, timing, sequence number, and other control functions. The concept is presented Plc General Motors Corporation. Plc and the basic design is the computer functional improvements, flexible, generic and other advantages and relay control system simple and easy to operate, such as the advantages of cheap prices combined controller hardware is standard and overall. According to the practical application of target software in order to control the content of the user procedures memory controller, the controller and connecting the accused convenient target.In the mid-1970s, the Plc has been widely used as a central processing unit microprocessor, import export module and the external circuits are used, large-scale integrated circuits even when the Plc is no longer the only logical (IC) judgment functions also have data processing, PID conditioning and data communications functions. International Electro technical Commission (IEC) standards promulgated programmable controller for programmable controller draft made the following definition : programmable controller is a digital electronic computers operating system, specifically for applications in the industrial design environment. It used programmable memory, used to implement logic in their internal storage operations, sequence control, timing, counting and arithmetic operations, such as operating instructions, and through digital and analog input and output, the control of various types of machinery or production processes. Programmable controller and related peripherals, and industrial control systems easily linked to form a whole, to expand its functional design. Programmable controller for the user, is a non-contact equipment, the procedures can be changed to change production processes. The programmable controller has become a powerful tool for factory automation, widely popular replication. Programmable controller is user-oriented industries dedicated control computer, with many distinctive features.First, high reliability, anti-interference capability;Second，programming visual, simple;Third, adaptability good;Fourth functional improvements, strong functional interface1.Design Theory DevelopmentToday, the primary focus of most design research is based on mechanical or electrical products. One of the by-products of this proposed research is to enhance our fundamental understanding of design theory and methodology by extending it to the field of engineering systems design.A system design theory for large-scale and complex system is not yet fully developed. Particularly, the question of how to simplify a complicated or complex design task has not been tackled in a scientific way. Furthermore, building a bridge between design theory and the latest epistemological outcomes of formal representations in computer sciences and operations research, such as discrete event system modeling, can advance future development in engineering design.2.Application in Logical Hardware DesignFrom a logical perspective, PLC software design is similar to the hardware design of integrated circuits. Modern VLSI designs are extremely complex with several million parts and a product development time of 3 years [Whitney, 1996]. The design process is normally separated into a component design and a system design stage. At component design stage, single functions are designed and verified. At system design stage, components are aggregated and the whole system behavior and functionality is tested through simulation. In general, a complete verification is impossible. Hence, a systematic approach as exemplified for the PLC program design may impact the logical hardware design.Programming languagesHigher level PLC programming languages have been around for some time, but lately their popularity has been mushrooming. As Raymond Lavelle, vice president and general manager, Siemens Energy and Automation. Inc, Programmable Controls Division, points out :”As programmable controls are being used for more and more sophisticated operations, languages other than ladder logic become more practical, efficient, and powerful. For example, it's very difficult to write a trigonometric function using ladder logic. ”Languages gaining acceptance include Boolean, control system flowcharting, and such function chart languages as Graphtec and its variations. And these’s incre asing interest in languages like C and BASIC.PLCs in process controlThus far, PLCs have not been used extensively for continuous process control. Will this continue? ”The feeling that I’ve gotten,” says Ken Jeannette, manager, product planning, Series One and Series Six products, at GE Frame North America, "is that PLCs will be used in the process industry but not necessarily for process control.”Several vendors-obviously betting that the opposite will happen-have introduced PLCs optimized for process applications. Rich Ryan ,manager, commercial marketing, Allen-Bradley Programmable Controls Div, cites PLCs’ increasing use in such industries as food, chemicals, and petroleum. Ryan feel there are two types of applications in which they’re appropriate.”One, "he says, "is where the size of the process control system that's being automated doesn’t justify DCS[distributed control systems].With the starting price tags of those products being relatively high, a programmable controller makes sense for small, low loop count applications. The seconds where you have to integrate the loop closely with the sequential logic. Batch controller sere prime examples, where the sequence and maintaining the process variable are intertwined so closely that the benefits of having a programmable controller to do the sequential logic outweighs some of the disadvantages of not having a distributed control system.”Bill Barkovtz, president of Triconex, predicts that "all future controllers that come out in the process control system business will embrace a lot more PLC technology and a lot more PLC functionality than they ever did before.”Communications and MAPCommunications are vital to an individual automation cell and to the automated factory as a whole. We've heard a lot about MAP in the last few years, and a lot of companies have jumped on the band wagon. Many, however were disappointed when a fully-defined and completed MAP specification didn’t appear immediately. Says Larry Kumara:”Right now , MAP is still a moving target for the manufacturers specification that is not final. Presently, for example, people are introducing products to meet the MAP 2.1standard.Yet 2.1-based products will be obsolete when the new standard for MAP,3.0is introduced.”Because of this, many PLC vendors are holding off on full MAP implementations. Omron, for example , has an ongoing MAP-compatibilityprogram, but Frank Newborn, vice president of Omron’s Industrial Division, reports that because of the lack of a firm definition, Omron's PLCs don't yet talk to MAP.Since it’s unlikely that an individual PLC would talk to broadband MAP anyway, makers are concentrating n proprietary networks. According to Sal Provanzano, users fear that if they do get on board and vendors withdraw from MAP, they ‘ll pulse width modulation control system be the ones left holding a communications structure that’s not supported.。

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An Introduction to
PLC
An Introduction to PLC
The PLC in the PLC draft standards issued by the International Electrotechnical Commission in 1987 made the following definition: "the PLC is a specially designed for applications in industrial environments digital computing operation of electronic devices which can be programmed memory
The working principle of PLC is
Put into operation when the programmable logic controller, the course of their work is generally
divided into three stages, that is, the input sample,
processes
The characteristics of PLC are：
High reliability, strong anti-jamming capability ； Complete, fully functional, the applicability；Easy
to use, well received by engineers and technicians
The composition of PLC
PLC is divided into fixed and modular (modular) two points from the structure. / O board, display panel, memory blocks, power, and these elements are combined into a non-removable as a whole. Modular PLC CPU module, I / O modules, memory, power supply modules, backplane or rack, these modules can be combined according to certain rules configuration.
The history of the development of PLC is
In 1969, the United States developed the world's first PDP-14;
In 1971, Japan developed the first DCS-8;
In 1973, Germany developed the first PLC;
arithmetic operations, such as operating
instructions in its internal storage and can be digital or analog inputs and outputs to control
various types of machinery or production
In 1974, the Chinese developed the first PLC.
In 1971, Japan developed the first DCS-8;
The role of PLC is to with
The role of PLC is to with to implementation of the logical, sequential operation, timing, counting and
the user program execution and output refresh three stages. Completion of the three stages is
called a scan cycle. During the entire operation,
the CPU of the programmable logic controller scan speed, repeat the above three stages.
welcome；System design, construction workload is small, easy to maintain, easy to transform
Small size, light weight, low energy consumption；
PLC is an ideal control device for mechatronics.
The impact of PLC
He simplifies the complex relay circuit into a program diagram, and his graphical programming language is very easy to handle, and the program is very easy to modify with a relay contactor, simplifying the workload of the electrical industry staff and directly improving the production efficiency of the industrial sector