PLC未来发展趋势外文翻译-精品
文献翻译—可编程控制器技术讨论与未来发展
附录A：外文文献及译文PLC technique discussion and future developmentT.J.byersFrom:Electronic Test Equipment-principles and Applications. Princeton University. America Along with the development of the ages, the technique that is nowadays is also gradually perfect, the competition plays more more strong; the operation that list depends the artificial has already can't satisfied with the current manufacturing industry foreground, also can't guarantee the request of the higher quantity and high new the image of the technique business enterprise.The people see in produce practice, automate brought the tremendous convenience and the product quantities for people up of assurance, also eased the personnel's labor strength, reduce the establishment on the personnel. The target control of the hard realization in many complicated production lines, whole and excellent turn, the best decision etc., well-trained operation work, technical personnel or expert, governor but can judge and operate easily, can acquire the satisfied result. The research target of the artificial intelligence makes use of the calculator exactly to carry out, imitate these intelligences behavior, moderating the work through person's brain and calculators, with the mode that person's machine combine, for resolve the very complicated problem to look for the best pathWe come in sight of the control that links after the electric appliances in various situation, that is already the that time generation past, now of after use in the mold a perhaps simple equipments of grass-roots control that the electric appliances can do for the low level only;And the PLC emergence also became the epoch-making topic, adding the vivid software control through a very and stable hardware, making the automation head for the new high tide.The PLC biggest characteristics lie in: The electrical engineering teacher already no longer electric hardware up too many calculationses of cost, as long as order the importation that the button switch or the importation of the sensors order to link the PLC up can solve problem, pass to output to order the conjunction contact machine or control the start equipments of the big power after the electric appliances, but the exportation equipments direct conjunction of the small power can.PLC internal containment have the CPU of the CPU, and take to have an I/ O for expand of exterior to connect a people's address and saving machine three big pieces to constitute, CPU core is from an or many is tired to add the machine to constitute, mathematics that they have the logic operation ability, and can read the procedure save the contents of the machine to drive the homologous saving machine and I/ Os to connect after pass the calculation; The I/ O add inner part is tired the input and output system of the machine and exterior link, and deposit the related data into the procedure saving machine or data saving machine; The saving machine can deposit the data that the I/ O input in the saving machine, and in work adjusting to become tired to add the machine and I/ Os to connect, saving machine separately savingmachine RAM of the procedure saving machine ROM and datas, the ROM can can do deposit of the data permanence in the saving machine, but RAM only for the CPU computes the temporary calculation usage of hour of buffer space.The PLC anti- interference is very and excellent, our root need not concern its service life and the work situation bad, these all problems have already no longer become the topic that we fail, but stay to our is a concern to come to internal resources of make use of the PLC to strengthen the control ability of the equipments for us, make our equipments more gentle.PLC language is not we imagine of edit collected materials the language or language of Cs to carry on weaving the distance, but the trapezoid diagram that the adoption is original after the electric appliances to control, make the electrical engineering teacher while weaving to write the procedure very easy comprehended the PLC language, and a lot of non- electricity professional also very quickly know and go deep into to the PLC.Is PLC one of the advantage above and only, this is also one part that the people comprehend more and easily, in a lot of equipmentses, the people have already no longer hoped to see too many control buttons, they damage not only and easily and produce the artificial error easiest, small is not a main error perhaps you can still accept; But lead even is a fatal error greatly is what we can't is tolerant of. New technique always for bringing more safe and convenient operation for us, make we a lot of problems for face on sweep but light, do you understand the HMI? Says the HMI here you basically not clear what it is, also have no interest understanding, change one inside text explains it into the touch to hold or man-machine interface you knew, it combines with the PLC to our larger space.HMI the control not only only is reduced the control press button, increase the vivid of the control, more main of it is can sequence of, and at can the change data input to output the feedback with data, control in the temperature curve of imitate but also can keep the manifestation of view to come out. And can write the function help procedure through a plait to provide the help of various what lies in one's power, the one who make operate reduces the otiose error. Currently the HMI factory is also more and more, the function is also more and more strong, the price is also more and more low, the noodles of the usage are wide more and more. The HMI foreground can say that think ° to be good very.At a lot of situations, the list is is a smooth movement that can't guarantee the equipments by the control of the single machine, but pass the information exchanges of the equipments and equipments to attain the result that we want. For example fore pack and the examination of the empress work preface, we will arrive wrapping information feedback to examine the place, and examine the information of the place to also want the feedback to packing. Pass the information share thus to make both the chain connect, becoming a total body, the match of your that thus make is more close, at each other attain to reflect the result that mutually flick.The PLC correspondence has already come more more body now its value, at the PLC and correspondence between PLCs, can pass the communication of the information and the share of the datas to guarantee that of the equipments moderatesmutually, the result that arrive already to repair with each other. Data conversion the adoption RS232 between PLC connect to come to the transmission data, but the RS232 pick up a people and can guarantee 10 meters only of deliver the distance, if in the distance of 1000 meters we can pass the RS485 to carry on the correspondence, the longer distance can pass the MODEL only to carry on deliver.The PLC data transmission is just to be called a form to it in a piece of and continuous address that the data of the inner part delivers the other party, we, the PLC of the other party passes to read data in the watch to carry on the operation. If the data that data in the watch is a to establish generally, that is just the general data transmission, for example today of oil price rise, I want to deliver the price of the oil price to lose the oil ally on board, that is the share of the data; But take data in the watch for an instruction procedure that controls the PLC, that had the difficulty very much, for example you have to control one pedestal robot to press the action work that you imagine, you will draw up for it the form that a procedure combine with the data sends out to pass by.The form that information transport contain single work, the half a work and the difference of a workses .The meaning of the single work also is to say both, a can send out only, but a can receive only, for example a spy he can receive the designation of the superior only, but can't give the superior reply; A work of half is also 2 and can can send out similar to accept the data, but can't send out and accept at the same time, for example when you make a phone call is to can't answer the phone, the other party also; But whole pair works is both can send out and accept the data, and can send out and accept at the same time. Be like the Internet is a typical example.The process that information transport also has synchronous and different step cent: The data line and the clock lines are synchronous when synchronous meaning lie in sending out the data, is also the data signal and the clock signals to be carry on by the CPU to send out at the same time, this needs to all want the specialized clock signal each other to carry on the transmission and connect to send, and is constrained, the characteristics of this kind of method lies in its speed very quick, but correspond work time of take up the CPU and also want to be long oppositely, at the same time the technique difficulty also very big. Its request lies in can'ting have an error margins in a datas deliver, otherwise the whole piece according to compare the occurrence mistake, this on the hardware is a bigger difficulty. Applied more and more extensive in some appropriative equipmentses, be like the appropriative medical treatment equipments, the numerical signal equipments...etc., in compare the one data deliver, its result is very good.And the different step is an application the most extensive, this receive benefit in it of technique difficulty is opposite and want to be small, at the same time not need to prepare the specialized clock signal, its characteristics to lie in, its data is partition, the long-lost send out and accept, be the CPU is too busy of time can grind to a stop sex to work, also reduced the difficulty on the hardware, the data throw to lose at the same time opposite want to be little, we can pass the examination of the data to observe whether the data that we send out has the mistake or not, be like strange accidentally the method, tired addition and eight efficacies method etc., can use to helps whetherthe data that we examine to send out have or not the mistake occurrence, pass the feedback to carry on the discriminator.A line of transmission of the information contain a string of and combine the cent of: The usual PLC is 8 machines, certainly also having 16 machines. We can be an at the time of sending out the data a send out to the other party, also can be 88 send out the data to the other party, an and 8 differentiationses are also the as that we say to send out the data and combine sends out the data. A speed is more and slowly, but as long as 2 or three lines can solve problem, and can use the telephone line to carry on the long range control. But combine the oscular transmission speed is very quick of, it is a string of oscular of 25600%, occupy the advantage in the short distance, the in view of the fact TTL electricity is even, being limited by the scope of one meter generally, it combine unwell used for the data transmission of the long pull, thus the cost is too expensive.Under a lot of circumstances we are total to like to adopt the string to combine the conversion chip to carry on deliver, under this kind of circumstance not need us to carry on to depositted the machine to establish too and complicatedly, but carry on the data exchanges through the data transmission instruction directly, but is not a very viable way in the correspondence, because the PLC of the other party must has been wait for your data exportation at the time of sending out the data, it can't do other works.When you are reading the book, you hear someone knock on door, you stop to start up of affair, open the door and combine to continue with the one who knock on door a dialogue, the telephone of this time rang, you signal hint to connect a telephone, after connecting the telephone through, return overdo come together knock on door to have a conversation, after dialogue complete, you continue again to see your book, this kind of circumstance we are called the interruption to it, it has the authority, also having sex of have the initiative, the PLC had such function .Its characteristics lie in us and may meet the urgently abrupt affairs in the operation process of the equipments, we want to stop to start immediately up of work, the whereabouts manages the more important affair, this kind of circumstance is we usually meet of, PLC while carry out urgent mission, total will keep the current appearance first, for example the address of the procedure, CPU of tired add the machine data etc., be like to to stick down which the book that we see is when we open the door the page or simply make a mark, because we treat and would still need to continue immediately after book of see the behind. The CPU always does the affair that should do according to our will, but your mistake of give it an affair, it also would be same to do, this we must notice.The interruption is not only a, sometimes existing jointly with the hour several inside break, break off to have the preferred Class, they will carry out the interruption of the higher Class according to person's request. This kind of breaks off the medium interruption to also became to break off the set. The Class that certainly break off is relevant according to various resources of CPU with internal PLC, also following a heap of capacity size of also relevant fasten.The contents that break off has a lot of kinds, for example the exterior break off, correspondence in of send out and accept the interruption and settle and the clock thatcount break off, still have the WDT to reset the interruption etc., they enriched the CPU to respond to the category while handle various business. Speak thus perhaps you can't comprehend the internal structure and operation orders of the interruption completely also, we do a very small example to explain.Each equipments always will not forget a button, it also is at we meet the urgent circumstance use of, that is nasty to stop the button. When we meet the Human body trouble and surprised circumstances we as long as press it, the machine stops all operations immediately, and wait for processing the over surprised empress recover the operation again.Nasty stop the internal I/ O of the internal CPU of the button conjunction PLC to connect up, be to press button an exterior to trigger signal for CPU, the CPU carries on to the I/ O to examine again, being to confirm to have the exterior to trigger the signal, CPU protection the spot breaks off procedure counts the machine turn the homologous exterior I/ O automatically in the procedure to go to also, be exterior interruption procedure processing complete, the procedure counts the machine to return the main procedure to continue to work.Have 1:00 can what to explain is we generally would nasty stop the button of exterior break off to rise to the tallest Class, thus guarantee the safety.When we are work a work piece, giving the PLC a signal, counting PLC inner part the machine add 1 to compute us for a day of workload, a count the machine and can solve problem in brief, certainly they also can keep the data under the condition of dropping the electricity, urging the data not to throw to lose, this is also what we hope earnestly.The PLC still has the function that the high class counts the machine, being us while accept some datas of high speed, the high speed that here say is the data of the in all aspects tiny second class, for example the bar code scanner is scanning the data continuously, calculating high-speed signal of the data processor DSP etc., we will adopt the high class to count the machine to help we carry on count. It at the PLC carries out the procedure once discover that the high class counts the machine to should of interruption, will let go of the work on the hand immediately. The trapezoid diagram procedure that passes by to weave the distance again explains the high class for us to carry out procedure to count machine would automatic performance to should of work, thus rise the Class that the high class counts the machine to high one Class.You heard too many this phrases perhaps:" crash", the meaning that is mostly is a workload of CPU to lead greatly, the internal resources shortage etc. the circumstance can't result in procedure circulate. The PLC also has the similar circumstance, there is a watchdog WDT in the inner part of PLC, we can establish time that a procedure of WDT circulate, being to appear the procedure to jump to turn the mistake in the procedure movement process or the procedure is busy, movement time of the procedure exceeds WDT constitution time, the CPU turn but the WDT reset the appearance. The procedure restarts the movement, but will not carry on the breakage to the interruption.The PLC development has already entered for network ages of correspondence from the mode of the one, and together other works control the net plank and I/ O cardplanks to carry on the share easily. A state software can pass all se hardwares link, more animation picture of keep the view to carries on the control, and cans pass the Internet to carry on the control in the foreign land, the blast-off that is like the absolute being boat No.5 is to adopt this kind of way to make airship go up the sky.The development of the higher layer needs our continuous effort to obtain.The PLC emergence has already affected a few persons fully, we also obtained more knowledge and precepts from the top one experience of the generation, coming to the continuous development PLC technique, push it toward higher wave tide.中文翻译可编程控制器技术讨论与未来发展T.J.byers电子测试Equipment-principles和应用.普林斯顿大学.美国随着时代的发展,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应用于电梯的发展趋势 外文资料翻译
中国地质大学长城学院本科毕业论文外文资料翻译系别：信息工程系专业：电气工程及其自动化姓名：学号： 043093122013年 3 月 18 日外文资料翻译译文PLC应用于电梯的发展趋势（PLC）是以计算机技术为核心的通用自动控制装置，在各行各业中得到了广泛的应用。
在电梯行业中，PLC的作用得到了充分的体现。
本文介绍了PLC控制的五层电梯模型的构成、主要功能、PLC的I/O接口分配、PLC的编程方法及对电梯系统的程序设计等。
通过对电梯控制系统的程序设计，实现了电梯的开关门控制以及在电梯运行方式下电梯的呼叫显示、上下行、起动、延时关门、平层、停靠开门、信号排队、顺向截梯和报警等控制功能。
通过对软件程序的编译、硬件的连接以及电梯模型与PLC控制系统的联调，使得控制系统在电梯模型运行过程中直观的体现出来，实现了对电梯功能的控制。
21世纪将会发展多用途、全功能的塔式建筑，超高速电梯继续成为研究方向。
曳引式超高速电梯的研究继续在采用超大容量电动机、高性能的微处理器、减振技术、新式滚轮导靴和安全钳、永磁同步电动机、轿厢气压缓解和噪声抑制系统等方面推进。
采用直线电机驱动的电梯也有较大研究空间。
未来超高速电梯舒适感会有明显提高。
电梯是标志现代物质文明的垂直运输工具、是机—电一体化的复杂运输设备。
它涉及电子技术、机械工程、电力电子技术、微机技术、电力拖动系统和土建工程等多个科学领域。
目前电梯的生产情况和使用数量已成为一个国家现代化程度的标志之一。
本次设计主要将可编程序控制器（PLC）和计算机应用到电梯的控制系统中去，以五层电梯为例来完成单台电梯PLC控制系统的总体设计方案、组成及模块化程序设计。
通过三菱FX2N与计算机通信来实现对电梯系统运行的控制。
首先确定电梯类型为客货两用梯，电梯载重量为1000千克，梯速为1.5米/秒，曳引电动机的转速为1000转/秒；再根据串联阻抗前后电动机的机械特性，选择合适的电梯速度控制曲线，实现电梯的交流调速；其次是电梯运行控制部分设计，包括轿厢门控制电路、平层控制电路、显示电路、集选控制电路、电梯消防运行回路；输入口计算点为58，输出口计算点数为35，选用三菱FX2-80MRPLC型的PLC，并进行了外围接线设计；最后进行软件编程。
2023年PLC技术发展呈现7大新动向报告模板
PLC技术在能源管理方面也有广泛的应用。例如，在风能和太阳能等可再生能源的发电和输配电中，PLC可以实现对电网的实时监控和控制，提高能源效率，降低能源浪费。
3. 能源领域：PLC技术在能源领域的应用，如风能、太阳能、水力发电等，可以提高设备的运行效率和稳定性，实现能源的智能化管理。
6. 环保领域：PLC技术可以用于自动化控制环保设备，例如废水处理系统、空气净化设备、垃圾焚烧设备等。
7. 交通领域：PLC技术可以用于自动化控制交通设备，例如交通信号灯、车辆监控系统、轨道交通控制系统等。
8. 能源领域：PLC技术可以用于自动化控制能源设备，例如风力发电设备、太阳能发电设备、火力发电设备等。
PLC技术在智能家居和医疗设备中的应用随着物联网技术的发展，PLC技术在智能家居领域的应用也越来越广泛。通过PLC控制器，可以实现家庭设备的统一管理和控制，提高家庭生活的便利性。
PLC技术在医疗设备中也有广泛应用。例如，PLC控制器可以用于医疗设备的自动化控制，提高医疗设备的精度和效率。
PLC技术在无人驾驶汽车和环境监测中的应用PLC技术在无人驾驶汽车中的应用也日益增多。通过PLC控制器，可以实现车辆的精确控制和协同操作，提高道路安全性和效率。
2. 物联网（IoT）集成PLC技术正在与物联网技术深度融合。通过将PLC设备连接到物联网网络中，可以实现设备之间的数据共享和远程监控，从而提高生产效率和降低运营成本。
3. 边缘计算的应用随着数据量的迅速增长，PLC技术正在引入边缘计算功能，以实时处理和分析数据，从而提高系统的响应速度和准确性。
机电一体化专业外文翻译--PLC工业PC与DCS的特点与趋势
外文原文：The characteristics and trends of PLC, DCS and industrial PC At present, widely used in industrial automation systems of the three large industrial PC, DCS and PLC. Here, for their economic and technological standards and development trends described.First, the characteristics and Application of PLC1. PLC ApplicationEarly PLC (Programmable Logic Controller, PLC), mainly to replace relay logic control to achieve. With computer technology, communications technology and the rapid development of automatic control technology, the PLC will be the traditional relay control technology and the emerging computer technology and communications technology integration, with high reliability, strong function and flexible, Programming simple, easy to use and a series of advantages, as well as good performance of the industrial environment and control targets of performance in industrial production in a wide range of applications.1969, the United States Digital Equipment Corporation (DEC) developed the world's first programmable controller. Early separation from the programmable controller components and small and medium-sized integrated circuit component, the main function previously performed by the relay is completed sequence control, such as timing. The early 1970s, small size, strong function and cheaper microprocessors used PLC, makes the PLC function has been enhanced significantly. In terms of hardware, in addition to maintaining its original switch modules, has also increased the simulation module, remote I / O modules and special function modules all. In terms of software, easy to use PLC Electric staff in the ladder diagram programming language, in addition to maintaining the original logic functions, has also increased the arithmetic operations, data processing and transmission, communications and self-diagnostic capabilities. In the 1980's, the late, as ultra-large-scale integrated circuit technology is developing rapidly, microprocessor market a sharp price drop, the PLC makes the microprocessors used by the general improvement in grades. Furthermore, in order to further improve the processing speed of PLC, themanufacturer has developed a dedicated logic chip, greatly improving the PLC hardware and software functions.2. Characteristics PLCIn the developed industrial countries, PLC has been widely used in all industrial sectors. According to "The United States market information" World PLC and software market report, in 1995 the global software PLC and its economies of scale of about 5 billion US dollars [5]. As electronic technology and the development of computer technology, the PLC functions are greatly enhanced, with the following characteristics:(1) high reliability. PLC benefited from the high-reliability hardware and software on a series of anti-jamming measures and the cycle of its special scanning methods of work.(2) with rich I / O interface module. PLC for different industrial field signal and the corresponding I / O modules and industrial devices or equipment at the scene of a direct connection. In addition to improving performance, it also has a variety of man-machine dialogue interface modules to the industrial composition of local area networks, it also multiple communications network interface module.(3) modular structure. To meet the needs of various industrial control, in addition to a small PLC unit, the vast majority of PLC are modular structure. PLC various components, including the CPU, power supply, I / O, etc. is modular in design from the rack and cables will connect each module, the system's size and function in accordance with the needs of users of its own portfolio.(4) easy to learn programming. Most of the PLC programming relay control circuit similar to the ladder diagram form, the user, do not have computer expertise, it is easy to general engineering and technical personnel understand and master.(5) Installation is simple and easy maintenance. PLC does not require specialized equipment room in a variety of industrial environments can be directly run. Various modules are run and fault indication devices, user-friendly understanding of the operation and find fault. The modular structure, so any failure of a module, users can replace the module, allowing the system to rapidly resume operation.Second, the characteristics and Application of industrial PC1.Industrial PC industrial control applicationsIndustrial PC hardware and software support of a broad, diverse varieties can take full advantage of excellent graphical user interface capabilities, the industrial users an enormously attractive. Early PC but not suitable for industrial process control automation applications, such as increasing modified by strengthening the protection of the case, such as cooling damping taken measures to meet the industrial environment is the application of some of the requirements of the characteristics of its early development. In recent years, with the further integration of chips increase, the increase in functionality, system board technology, packaging components and surface mount technology improvements, and standard industrial bus, a standard operating system and graphical user interface software development, the Industrial PC development and application to enter its peak period, the complete machine reliability improved hardware, system software has continually improved, greatly enriched applications, in-depth industrial automation and control industries in various fields. According to incomplete statistics, in the industrial automation industrial PC usage in the total industrial control computer 65%, and an annual growth rate of 21 per cent continued to expand. PC manufacturing industry by buying rate of the PC market as a whole accounted for about 10 percent. In the industrial automation process control systems used in industrial management industry accounted for 44.1%, applied to the console operator of 36.4%, applied to the management of the quality of 18.8%, applied to monitor and control, engineers console, Data Acquisition System respectively of the total 18.2%, 12.6% and 11.1%.Industrial PC A notable feature is independent of configuration, but also with the DCS, PLC, CNC and other computer connected network. At present, almost all DCS, PLC manufacturers use industrial PC control system preparation procedures, more and more companies use industrial control system operator interface PC as a workstation. Formed by the industrial PC computer control system in the field of industrial automation process control play a very important role, has been outstanding for factory and workshop level process control, data acquisition, batch processing, quality control, automation and machine optimization and experts control, and other tasks.2. Main features of the PC industry(1) an industry-standard applicationIn order to enable different computer manufacturers can be linked to one another, as well as take full advantage of the market varied PC components and the functions provided by the module, industrial PC with standard interface, which not only required by the IEEE, DIN and ISO standards, to adopt AT (ISA), EISA and STD, VME, Multibus Ⅱ, and other bus standards. Industrial PC now has been widely adopted PCI, PCMCIA bus standard, the two industry-standard bus for improved performance and speed of a PC great role.(2) to take the necessary protection measuresApplications must be based on the control of environmental conditions on the PC industry adopt various protective measures, adapted from a project management departments to the scene operational control applications. Industrial PC must be able tolerance of the harsh conditions at the production environment, we must have good heat dissipation, ventilation, waterproof, dustproof, anti-jamming and anti-corrosion and anti-shock, anti-vibration and a series of protective features.(3) industrial operating systemMS-DOS because of lack of memory, unable to support multi-task, the lack of real-time features networking capacity and poor, has been basically not used. Along with the main computer chip, the rapid development of higher speed and better performance of industrial PC endless. In addition, almost all software development companies have shifted the focus will be open to the OS / 2, Windows and Unix, and other operating systems. Especially suitable for industrial process control automation real-time multi-tasking operating system application of Windows NT/2000 PC industry has generally become the mainstream operating system.(4) and automation equipment and communications systemsIndustrial PC should be able to with a variety of automated equipment and systems for effective communication, such as PLC, DCS, data acquisition systems, as well as on a management computer communication. With the continuous development of new technologies, due to open systems and system integration technology for thedevelopment needs of the PC industry these communications will be increasingly important role in the show.Standard communications network to the development of the industrial PC applications more open, and will enable its small computer pose a greater threat. MAP agreement to Ethernet-based communication networks to allow various computer systems communicate with each other directly. Different levels of automation in the mutual communication network systems, require separate handling of the communication channel. Industrial PC required monitoring level from the lower level data acquisition system and transmitted to a computer on.(5) the safe operation ofIn addition to the PC industry adopt various protective measures, the need for the operation of state industrial PC monitor, monitor the operation of computer systems and software, scheduled inspection procedures specified in the implementation of the cycle. Computer should be able to monitor the power supply, and failure or excessive deviation warning signal was issued.2.Industrial PC the status quo and development trendIndustrial PC now have a wide range of performance and functionality, low-grade industrial PC with a CRT terminal operators, high-grade industrial workstation with a PC. Thus, high-grade and low-grade industrial PC workstation performance and the price of overlap, the difference is disappearing, industrial PC and workstations increasingly blurred the boundaries between.Industrial PC workstation is the industrial automation process control system applications excellent choice, standard communication networks and the use of graphical operating system makes industrial PC and other equipment to effectively communicate. With 32-bit and 64-bit computer chips and the emergence of use, will be further enhanced industrial PC workstation functionality and performance, but also to a higher future direction.Industrial PC software is in the process of industrial automation control system of a key application. Hardware performance and the improvement of the drop in prices, as well as standardization and greater efficiency, better graphics and the use of the operating system to promote industrial PC software is an important factor indevelopment. At present, the rapid development of industrial PC software on the market has thousands of independent software development company can supply in the industrial PC running on industrial process control configuration software package to meet the rapid growth of the industrial user needs. Industrial PC application of industrial process control software packages are running on the configuration of OS / 2, Windows, and UNIX operating system standard. Industrial process control applications have emerged in large quantities, software development companies can provide a large number of industrial PC on the run for the PLC, DCS, such as industrial automation and control system configuration tools and graphical user interface software. Many PLC, DCS manufacturers development of the software configuration tool for automatic control system has become an important component. They used to replace dedicated industrial PC workstations, for the creation of real-time database, the control loop, graphic footage showed police records, real-time and historical trend data recording and process control, simulation, and other tasks. Now, for the process of surveillance and control, unit control, factory data collection, process optimization control, process control, simulation, statistical quality-control (SQC), the Statistical Process Control (SPC) and expert system for the control of industrial automation and control package has been tremendous developments. DAE applications such as IBM's software platform and the emergence of applications, the application provides a unified software development tool. Application Platform features from the PC-industry data exchange within the factory to the coordination of multiple systems, the standard data interface allows computer control equipment and exchange of data and information networks, for integrated information management and control system provides great convenience.Along with the standard graphical operating system continuously improve and develop, process control and industrial automation package greatly enriched, the industrial PC applications will increasingly strong.Three, the characteristics and Application of DCSDCS since its birth, after decades of continuous improvement, development and modernization has been very mature. Compared with the early, the scale of their systems, control functions, and other areas have been tremendous developments inchanges in the reliability, flexibility, adaptability, scalability, cost-effective integrated technical indicators have seen increased and improved. Has been widely used in petrochemical, pharmaceutical, energy, chemicals, paper, oil refining, metallurgy and food and beverage, and other industries, and has made very significant economic and social benefits. According to statistics, production facilities from analog instruments to DCS control the economic benefits can be achieved by the overall efficiency of 60%. DCS average payback period for 12, after the introduction of advanced control strategies can reduce the payback period of 0.5 to 1 year. DCS is today into various kinds of advanced control technology and equipment, and to the comprehensive integrated information management and automated process control systems, that is, CIMS direction.1. Development processFrom 1975, the DCS roughly experienced the 1975 ~ 1980, the first generation, from 1980 to 1985 the second generation, and after 1985 the third generation of three stages of development. Many manufacturers take DCS phased development strategy, adopted in the early systems continue to develop and improve, then launched with a variety of new features of the new system, the new system compatible with the original equipment homogeneous.Early DCS storage capacity small, relatively simple function. System modules include process control, process interface modules, CRT operator station, control computer and data Highway, Part 5. Its characteristics are using microprocessors to achieve decentralized control, CRT operator station and the process control unit separation operation carried out on display and remote control configuration. Honeywell company TDC-2000 is the first generation of the representation of DCS products.DCS mainly by second-generation local area networks, multi-function controllers, the computers, enhanced operator station, multifunction operator station, the connector between the network, system management module, and other components. Its characteristics are achieved more thoroughly decentralized control, decrease in the number of wiring, and anti-performance enhancement, improved level of standardization of hardware, high universality, function more comprehensive. Notonly strengthened control, and strengthening the system-wide information management, the introduction of local area networks and fiber optic communications technology. During this period the representation of the company products include Honeywell TDC-3000 and Westinghouse WDPF systems.DCS new generation is the most important feature of the process control, monitoring, management, scheduling organically integrate, through the use of open systems and standards such as MAP communication networks, such as Ethernet and Fieldbus solve different manufacturers equipment interconnection between issues. During the system is the development of a number of new features, using a 32 or 64-bit microprocessor, and a powerful workstations and enhanced the sequence control, volume control, the system can accommodate industrial PC and PLC; software greatly enriched by the standard graphical operating system platforms, and the user interface; introduction of the expert system, process control and other senior adaptive control function. Its products include Foxbor company representative I / A Series intelligent control system, ABB-Bailey INFI 90, ABB company Freelance 2000, RTP company RTP 2000/2200 HCS (Mixed Control System), and Yokogawa XL mXL, Honeywell Corporation TDC-3000 LCN / VCN-PM and Siemens PCS 7 systems.2. New characteristics and new development(1) Open to the DCS system to develop in the direction of CIMSAlong with the standard communication network and the development of fieldbus technology, a multi-level communications network DCS is the progressive realization of the full liberalization. The new system is the adoption of the ISO OSI model, the communication protocol to meet MAP / TOP or IEEE standards. In a backbone network, widely used MAP 3.0 agreement or ISO / OSI model; middle layer to use Mini MAP, IEEE 802.3, Ethernet or Proway; equipment is used at the lowest level fieldbus or bus to connect the transmitter. Open systems change the past DCS manufacturers self-contained closed situation, and make industrial users in the application of automation hardware and software have a greater choice.DCS is the new generation of multi-level multi-regional development. With multi-level communication networks as a tool for the entire factory or enterpriseinformation management and production control integration, the lowest level in the factory using digital equipment integrated into the scene DCS, in the solution of local senior management of various types of computer networks and interconnection, thus achieving optimal scheduling, decision-making, as well as the overall production process optimization. This production with the use of computer programs, product development, production processes and the material flow and information flow, integrated management system requirements for the development of CIMS. DCS use of open systems gradually to the direction of CIMS is integrated automation control system integrated a basic method.(2) workstations and graphical user interface features strengthen the operating stationWorkstations (including industrial PC workstations) and the use of graphical user interface, making recognizable DCS operator station. Many DCS manufacturers will be more DEC, SUN and companies such as Apollo Unix workstation tasks for the operator interface and control certain tasks, and corresponding use of the Motif, Penlook, X Window, OS / 2, Windows and other graphical user interface. Workstations cost-effective prices, high efficiency, and provides a user-friendly operator interface equipment. High-function workstations and high-resolution graphics equipment used, making operation to handle the greater amount of information, higher quality information processing, and use the mouse, touch screen, the cursor to the ball-type, as well as a number of other human-machine engineering.(3) a 32 or 64-bit processor hardware performance improved32 or 64-bit microcomputer development and use, is a milestone in the development of computer technology, the DCS hardware performance has a significant impact on the improvement. At present, most DCS has spent 32 or 64 computer to replace the original 16 aircraft, therefore, the corresponding process control stations and upgrade the operator stations. Series 86 using Intel processors Extended PC manufacturers now mainly uses the Pentium processor handling interface tasks while using M68 series producers are increasingly used in the 68020,68030 more processors. Most workstation processor performance to 5 ~ 50 M instructions / s. DCS process controllers use 32 or more processors, the performanceincrease than 2 times greater than before, the communication speed of the bus more than three times the network data transmission speed of 10,100,1000 Mb / s, the communications distance up to 20 km, I / O points up to 20,000 more, with the same scale system cheaper than the previous 30 to 40 percent.(4) Enhanced batch processing capacityEarly DCS mainly used for process control, DCS batch processing function has continually increased, and more and show its importance. DCS use menu operation and fill in the blank approach to system configuration and graphics features are suitable for batch processing applications. DCS vast majority of new products use the same controller can achieve continuous and batch process control. DCS logic operation in the software, such as Boolean functions more functions, enhanced Sequence Control System and volume control. If ABB-Bailey INFI 90 system uses a batch-processing language Batch 90 automatic processing of documents and internal Chaxi capacity, and function codes, ladder diagram mixed use, it can be directly read and write functional code and ladder diagram, allowing the interlock logic Disconnect in the order of control logic for implementation, simplifies the batch processing logic implementation.(5) software greatly enriched, an increase of senior controlIn the operating system, Windows NT and Unix open systems as a representative of a broad development prospects, its features include multi-user, multi-tasking, good character and can be transplanted networking capabilities. At present, real-time industrial automation in the Unix process control system of the openness of the structure play an important role, with the exception of DCS manufacturers for the development of their own operating systems, Unix and Windows NT are in a variety of DCS in the most widely used standard operating system.DCS configuration software modules used for the object-oriented language and the language of some system uses advanced programming language and graphics software. Configuration process normally use input and output, selection, calculation, logic, the police, limit the rate of order and control modules such as soft connections, a different control loop. Menu and fill in the blank-control operation makes configuration very easy.DCS control algorithm is continuously improve and develop. Apart from achieving PID, nonlinear, feedforward, Cascade, feedforward and feedback, but also the sequence control logic control and the ladder diagram, and the self-tuning PID parameters set, adaptive control. DCS manufacturers for the provision of various software modules, such as SPC / SQC (statistical-process control / statistical quality-control), CAD, artificial intelligence and expert systems, greatly enriched the DCS software library, an increase of high-level control system , the senior now on the market has reached thousands of control packages. Expert System, multivariable predictive control, fuzzy logic control and artificial neural network technology has been gradually practical and commercialization.DCS future software design and development will continue to focus on the following several aspects of the characteristics: modular program design, object-oriented programming; dedicated programming method used to achieve the X Window, voice recognition, etc., in order to industrial automation users provide more flexibility in the application of the operator interface.(6) intelligent sensors and other digital equipment to enter the scene of DCSAt present, the industrial process control automation company has introduced a large number of microprocessors, have both analog and digital signal output, and digital communication capabilities of intelligent field instrument. DCS manufacturers are using a variety of methods of the digital field devices integrated into its own system. Honeywell IACD such as two-way communication system for intelligent transmitter and TDC-3000 process controller connections and other components; ABB-Pele two-way communication system using 9600 baud FSK physical layer transmission, including its hardware input Fieldbus Fieldbus modules and terminal unit, software management procedures, including the transmitter and the transmitter function block; Moore company Mycro HART door connector can support 256 point-to-point connections or over 480 points connected intelligent transmitter; Foxbro companies addition to its own digital equipment integrated into the scene intelligent I / O system, also provides more than 60 other manufacturers, connecting doors connector.Fieldbus standard, from the bottom-up equipment to achieve the interconnection of different manufacturers, with the current technology development trend. At present, the development of fieldbus standard has been a high degree of international attention, is integrated industrial automation control system indispensable component. With the standardization of fieldbus communication technology development, the more intelligent DCS and control will shift downward, decentralized control equipment at the field level. They will DCS in the diagnosis and treatment provide a better platform, which enables more advanced DCS to open forms.(7) DCS further accommodate industrial PC and PLCIndustrial PC and PLC equipment as the DCS is now very common. DCS overwhelming majority of manufacturers has been providing industrial PC, PLC to DCS network connected to the hardware interface and application software.Industrial PC can make use of touch-screen and CRT window, a menu-driven approach may be to establish control strategy can also be used to achieve a plug on the motherboard and external communication. Through appropriate software and hardware interfaces, industrial PC with DCS in the process of connecting loop controller for loop control graphics. DCS industrial use as a PC operating station, programming terminals, surveillance, Taiwan, workstations, such as ABB-Pele, companies such as DCS Feixieer few years ago and the IBM PC compatible, DEC Professional, as well as 300 personal computers, etc. used for system configuration, monitoring, programming, and other tasks. Apart from some manufacturers developed a series of interface components and software, industrial PC as a DCS operator stations and other tasks, but also by third-party manufacturers such as OnSpec, and other process control packages.The relationship between the PLC and DCS is not only combine, and compete. Most are now combining DCS ladder logic programming technology, all PLC increases the simulation module to deal with the continuous production process. PLC through structural improvements, communications and networking capacity and control functions to increase and the introduction of similar DCS operator station, with monitoring computer operator interface. DCS also continuously enhance and batch processing capabilities, a small-scale, high-functional, modular direction. ThusDCS and PLC are gradually move closer, the two boundaries become increasingly blurred. They are functional and application of mutual penetration and integration. Thus, in many applications, it is difficult to distinguish between what is the PLC, which is the DCS. DCS are generally of the PLC interface can be connected to the PLC in the DCS. At present, a PLC-based DCS developed very quickly, discrete manufacturing and process industries tend to use hybrid control strategy PLC / DCS. Some of the same chassis system will be continuous control and PLC logic function together, not a separate PLC systems, such as the United States RTP 2000/2200 by the HCS that way, the system will be complete PLC and DCS features integrated together with the application of a control strategy Configuration Software NetSuite can complete all the control functions in the design and configuration.(8) Use of new technologies such as optical fiber communicationDCS in its development process and draw upon a variety of advanced technology. Optical fiber communications, high-density large-capacity disk surface mount technology, voice synthesis and recognition, multimedia, and other new technologies, as well as low-power CMOS RISC processor and other devices and has been in some of the new DCS has been fully applied. Optical fiber communications technology in the application of DCS more extensive. Because fiber is small in size, and large amounts of information, small signal attenuation and frequency bandwidth, anti-interference capability, transmission speed, the advantages of high reliability, high-speed access DCS used by the twisted pair and coaxial cable will gradually be replaced by fiber optic cable, making further enhance the effectiveness of communications systems. To further enhance system reliability, DCS communications bus network, as well as all levels of man-machine interface, controller interface at the scene and have been widely adopted redundant, fault-tolerant and fault isolation, and other protective measures.3. DCS to the future direction of CIMSDCS What is the future? A foreign process control experts to depict that image: DCS is disappearing, but the functions provided by the DCS will never disappear, they adapt to efficient, secure, real-time industrial process control automation needs of chassis control will continue to exist, but control room of the future will face。
【机械类文献翻译】PLC技术讨论和未来发展
英文原文PLC technique discussion and future developmentAlong with the development of the ages, the technique that is nowadays is also gradually perfect, the competition plays more more strong; the operation that list depends the artificial has already can't satisfied with the current manufacturing industry foreground, also can't guarantee the request of the higher quantity and high new the image of the technique business enterprise.The people see in produce practice, automate brought the tremendous convenience and the product quantities for people up of assurance, also eased the personnel's labor strength, reduce the establishment on the personnel. The target control of the hard realization in many complicated production lines, whole and excellent turn, the best decision etc., well-trained operation work, technical personnel or expert, governor but can judge and operate easily, can acquire the satisfied result. The research target of the artificial intelligence makes use of the calculator exactly to carry out, imitate these intelligences behavior, moderating the work through person's brain and calculators, with the mode that person's machine combine, for resolve the very complicated problem to look for the best pathWe come in sight of the control that links after the electric appliances in various situation, that is already the that time generation past, now of after use in the mold a perhaps simple equipments of grass-roots control that the electric appliances can do for the low level only;And the PLC emergence also became the epoch-making topic, adding the vivid software control through a very and stable hardware, making the automation head for the new high tide.The PLC biggest characteristics lie in: The electrical engineering teacher already no longer electric hardware up too many calculations of cost, as long as order the importation that the button switch or the importation of the sensors order to link the PLC up can solve problem, pass to output to order the conjunction contact machine or control the start equipments of the big power after the electric appliances, but the exportation equipments direct conjunction of the small power can.PLC internal containment have the CPU of the CPU, and take to have an I/ O for expand of exterior to connect a people's address and saving machine three big pieces to constitute, CPU core is from an or many is tired to add the machine to constitute, mathematics that they have the logic operation ability, and can read the procedure save the contents of the machine to drive the homologous saving machine and I/ Os to connect after pass the calculation; The I/ O add inner part is tired the input and output system of the machine and exterior link, and deposit the related data into the procedure saving machine or data saving machine; The saving machine can deposit the data that the I/ O input in the saving machine, and in work adjusting to become tired to add the machine and I/ Os to connect, saving machine separately saving machine RAM of the procedure saving machine ROM and datas, the ROM can can do deposit of the data permanence in the saving machine, but RAM only for the CPU computes the temporary calculation usage of hour of buffer space.The PLC anti- interference is very and excellent, our root need not concern its service life and the work situation bad, these all problems have already no longer become the topic that we fail, but stay to our is a concern to come to internal resources of make use of the PLC to strengthen the control ability of theequipments for us, make our equipments more gentle.PLC language is not we imagine of edit collected materials the language or language of Cs to carry on weaving the distance, but the trapezoid diagram that the adoption is original after the electric appliances to control, make the electrical engineering teacher while weaving to write the procedure very easy comprehended the PLC language, and a lot of non- electricity professional also very quickly know and go deep into to the PLC.Is PLC one of the advantage above and only, this is also one part that the people comprehend more and easily, in a lot of equipments, the people have already no longer hoped to see too many control buttons, they damage not only and easily and produce the artificial error easiest, small is not a main error perhaps you can still accept; But lead even is a fatal error greatly is what we can't is tolerant of. New technique always for bringing more safe and convenient operation for us, make we a lot of problems for face on sweep but light, do you understand the HMI? Says the HMI here you basically not clear what it is, also have no interest understanding, change one inside text explains it into the touch to hold or man-machine interface you knew, it combines with the PLC to our larger space.HMI the control not only only is reduced the control press button, increase the vivid of the control, more main of it is can sequence of, and at can the change data input to output the feedback with data, control in the temperature curve of imitate but also can keep the manifestation of view to come out. And can write the function help procedure through a plait to provide the help of various what lies in one's power, the one who make operate reduces the otiose error. Currently the HMI factory is also more and more, the function is also more and more strong, the price is also more and more low, the noodles of the usage are wide more and more. The HMI foreground can say that think ° to be good very.At a lot of situations, the list is is a smooth movement that can't guarantee the equipments by the control of the single machine, but pass the information exchanges of the equipments and equipments to attain the result that we want. For example fore pack and the examination of the empress work preface, we will arrive wrapping information feedback to examine the place, and examine the information of the place to also want the feedback to packing. Pass the information share thus to make both the chain connect, becoming a total body, the match of your that thus make is more close, at each other attain to reflect the result that mutually flick.The PLC correspondence has already come more more body now its value, at the PLC and correspondence between PLC, can pass the communication of the information and the share of the datas to guarantee that of the equipments moderates mutually, the result that arrive already to repair with each other. Data conversion the adoption RS232 between PLC connect to come to the transmission data, but the RS232 pick up a people and can guarantee 10 meters only of deliver the distance, if in the distance of 1000 meters we can pass the RS485 to carry on the correspondence, the longer distance can pass the MODEL only to carry on deliver.The PLC data transmission is just to be called a form to it in a piece of and continuous address that the data of the inner part delivers the other party, we, the PLC of the other party passes to read data in the watch to carry on the operation. If the data that data in the watch is a to establish generally, that is just the general data transmission, for example today of oil price rise, I want to deliver the price of the oil price to lose the oil allyon board, that is the share of the data; But take data in the watch for an instruction procedure that controls the PLC, that had the difficulty very much, for example you have to control one pedestal robot to press the action work that you imagine, you will draw up for it the form that a procedure combine with the data sends out to pass by.The form that information transport contain single work, the half a work and the difference of a works .The meaning of the single work also is to say both, a can send out only, but a can receive only, for example a spy he can receive the designation of the superior only, but can't give the superior reply; A work of half is also 2 and can can send out similar to accept the data, but can't send out and accept at the same time, for example when you make a phone call is to can't answer the phone, the other party also; But whole pair works is both can send out and accept the data, and can send out and accept at the same time. Be like the Internet is a typical example.The process that information transport also has synchronous and different step cent: The data line and the clock lines are synchronous when synchronous meaning lie in sending out the data, is also the data signal and the clock signals to be carry on by the CPU to send out at the same time, this needs to all want the specialized clock signal each other to carry on the transmission and connect to send, and is constrained, the characteristics of this kind of method lies in its speed very quick, but correspond work time of take up the CPU and also want to be long oppositely, at the same time the technique difficulty also very big. Its request lies in can't have an error margins in a data deliver, otherwise the whole piece according to compare the occurrence mistake, this on the hardware is a bigger difficulty. Applied more and more extensive in some appropriative equipments, be like the appropriative medical treatment equipments, the numerical signal equipments...etc., in compare the one data deliver, its result is very good.And the different step is an application the most extensive, this receive benefit in it of technique difficulty is opposite and want to be small, at the same time not need to prepare the specialized clock signal, its characteristics to lie in, its data is partition, the long-lost send out and accept, be the CPU is too busy of time can grind to a stop sex to work, also reduced the difficulty on the hardware, the data throw to lose at the same time opposite want to be little, we can pass the examination of the data to observe whether the data that we send out has the mistake or not, be like strange accidentally the method, tired addition and eight efficacies method etc., can use to helps whether the data that we examine to send out have or not the mistake occurrence, pass the feedback to carry on the discriminator.A line of transmission of the information contain a string of and combine the cent of: The usual PLC is 8 machines, certainly also having 16 machines. We can be an at the time of sending out the data a send out to the other party, also can be 88 send out the data to the other party, an and 8 differentiations are also the as that we say to send out the data and combine sends out the data. A speed is more and slowly, but as long as 2 or three lines can solve problem, and can use the telephone line to carry on the long range control. But combine the oscular transmission speed is very quick of, it is a string of oscular of 25600%, occupy the advantage in the short distance, the in view of the fact TTL electricity is even, being limited by the scope of one meter generally, it combine unwell used for the data transmission of the long pull, thus the cost is too expensive.Under a lot of circumstances we are total to like to adopt the string to combine the conversion chip to carryon deliver, under this kind of circumstance not need us to carry on to deposited the machine to establish too and complicatedly, but carry on the data exchanges through the data transmission instruction directly, but is not a very viable way in the correspondence, because the PLC of the other party must has been wait for your data exportation at the time of sending out the data, it can't do other works.When you are reading the book, you hear someone knock on door, you stop to start up of affair, open the door and combine to continue with the one who knock on door a dialogue, the telephone of this time rang, you signal hint to connect a telephone, after connecting the telephone through, return overdo come together knock on door to have a conversation, after dialogue complete, you continue again to see your book, this kind of circumstance we are called the interruption to it, it has the authority, also having sex of have the initiative, the PLC had such function .Its characteristics lie in us and may meet the urgently abrupt affairs in the operation process of the equipments, we want to stop to start immediately up of work, the whereabouts manages the more important affair, this kind of circumstance is we usually meet of, PLC while carry out urgent mission, total will keep the current appearance first, for example the address of the procedure, CPU of tired add the machine data etc., be like to to stick down which the book that we see is when we open the door the page or simply make a mark, because we treat and would still need to continue immediately after book of see the behind. The CPU always does the affair that should do according to our will, but your mistake of give it an affair, it also would be same to do, this we must notice.The interruption is not only a, sometimes existing jointly with the hour several inside break, break off to have the preferred Class, they will carry out the interruption of the higher Class according to person's request. This kind of breaks off the medium interruption to also became to break off the set. The Class that certainly break off is relevant according to various resources of CPU with internal PLC, also following a heap of capacity size of also relevant fasten.The contents that break off has a lot of kinds, for example the exterior break off, correspondence in of send out and accept the interruption and settle and the clock that count break off, still have the WDT to reset the interruption etc., they enriched the CPU to respond to the category while handle various business. Speak thus perhaps you can't comprehend the internal structure and operation orders of the interruption completely also, we do a very small example to explain.Each equipments always will not forget a button, it also is at we meet the urgent circumstance use of, that is nasty to stop the button. When we meet the Human body trouble and surprised circumstances we as long as press it, the machine stops all operations immediately, and wait for processing the over surprised empress recover the operation again.Nasty stop the internal I/ O of the internal CPU of the button conjunction PLC to connect up, be to press button an exterior to trigger signal for CPU, the CPU carries on to the I/ O to examine again, being to confirm to have the exterior to trigger the signal, CPU protection the spot breaks off procedure counts the machine turn the homologous exterior I/ O automatically in the procedure to go to also, be exterior interruption procedure processing complete, the procedure counts the machine to return the main procedure to continue to work.Have 1:00 can what to explain is we generally would nasty stop the button of exterior break off to rise to the tallest Class, thus guarantee the safety.When we are work a work piece, giving the PLC a signal, counting PLC inner part the machine add 1 tocompute us for a day of workload, a count the machine and can solve problem in brief, certainly they also can keep the data under the condition of dropping the electricity, urging the data not to throw to lose, this is also what we hope earnestly.The PLC still has the function that the high class counts the machine, being us while accept some datas of high speed, the high speed that here say is the data of the in all aspects tiny second class, for example the bar code scanner is scanning the data continuously, calculating high-speed signal of the data processor DSP etc., we will adopt the high class to count the machine to help we carry on count. It at the PLC carries out the procedure once discover that the high class counts the machine to should of interruption, will let go of the work on the hand immediately. The trapezoid diagram procedure that passes by to weave the distance again explains the high class for us to carry out procedure to count machine would automatic performance to should of work, thus rise the Class that the high class counts the machine to high one Class.Y ou heard too many this phrases perhaps:" crash", the meaning that is mostly is a workload of CPU to lead greatly, the internal resources shortage etc. the circumstance can't result in procedure circulate. The PLC also has the similar circumstance, there is a watchdog WDT in the inner part of PLC, we can establish time that a procedure of WDT circulate, being to appear the procedure to jump to turn the mistake in the procedure movement process or the procedure is busy, movement time of the procedure exceeds WDT constitution time, the CPU turn but the WDT reset the appearance. The procedure restarts the movement, but will not carry on the breakage to the interruption.The PLC development has already entered for network ages of correspondence from the mode of the one, and together other works control the net plank and I/ O card planks to carry on the share easily. A state software can pass all se hardwares link, more animation picture of keep the view to carries on the control, and cans pass the Internet to carry on the control in the foreign land, the blast-off that is like the absolute being boat No.5 is to adopt this kind of way to make airship go up the sky.The development of the higher layer needs our continuous effort to obtain.The PLC emergence has already affected a few persons fully, we also obtained more knowledge and precepts from the top one experience of the generation, coming to the continuous development PLC technique, push it toward higher wave tide.中文译文PLC技术讨论和未来发展随着时代的发展,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。
plc外文翻译---谈plc的应用与发展-plc设计
附录On the application and development of PLC1.PLC definitionProgrammable logic controller, or PLC (Programmable logic Controller), refers to computer technology as the basis for the new industrial control devices. In 1987 the International Electrotechnical Commission (International Electrical Committee) standards promulgated by the PLC in the draft of the PLC made the following definition: "PLC is a specialist in industrial environments for the application of digital design and operation of electronic computing devices. It can be used in the preparation process memory, used in the implementation of its internal storage logical, sequential computing, timing, counting and arithmetic operations such as Operation The directive, and through digital or analog input and output, control various types of machinery or production process. PLC and its related peripheral equipment should be in accordance with the industrial control system easy to form a whole, easy to expand its functions to the principle and design. "2.PLC characteristicshigh reliability, strong anti-interference capabilityHigh reliability of electrical control equipment is the key to performance. PLC due to the introduction of modern large-scale integrated circuit technology, rigorous production process, the internal circuitry to take an advanced anti-jamming technology, high reliability. For example, Mitsubishi has produced an average of the F-Series PLC trouble-free time as much as 300,000 hours. Some use the redundant CPU PLC, the average working hours of trouble-free longer. PLC from the machine outside the circuit, the use of a PLC control system, and equal access for the scale of the relay systems, electrical wiring and switch contact has been reduced to hundreds or even percent, fault also greatly reduced.In addition, PLC with self-detection hardware failure, a failure to timely warning information. In the application software, applications can also peripheral devices into the fault diagnosis procedures, in addition to the system PLC and equipment outside the circuit fault diagnosis also be protected. In this way, the whole system is extremely high reliability is also not strange.equipped, with perfect functions, the applicabilityPLC to develop today, has formed a large, medium and small size of the serialization of various products. Can be used for various industrial control the scale of occasions. Apart from the logic processing functions, most of the modern PLC has a complete data computing power and can be used for a variety of digital control of the area. In recent years PLC emergence of a large number of functional units so that the PLC to infiltrate into a position of control, temperature control, CNC, and other industrial control. PLC communication capabilities coupled with the strengthening of human-computer interface technology and the development and use of various PLC control system very easily.easy to learn and use, welcomed by the engineering and technical personnel PLC as the general industrial computer, industrial and mining enterprises are facing the industrial equipment. It easy interface, easy programming language for engineering and technical staff. Ladder language and graphic symbols and expressions of the relay circuit very close, only a small number of switches of the PLC logic control orders can easily achieve the functions of the relay circuit. Is not familiar with the electronic circuits, computers do not understand the principles and compilation of language people use computers to carry out industrial control opened the door.system design, construction workload of small, maintenance-friendly, easy to transformPLC logic with memory instead of wiring logic, greatly reducing the wiring outside the control equipment, control systems design and construction of the much shorter cycle, while maintaining it has become easier. What is more important is to make the same equipment have been changes in procedures to change the production process possible. This is very suitable for many species, the small batch production of occasions. applicationsswitch to the logic of controlThis is the most basic PLC, the most extensive areas of application, which replaced the traditional relay circuits, and logic control, sequence control, can be usedsingle-control device, can also be used for more automation and control aircraft assembly line.analog controlIn the course of industrial production, many of the continuous changes, such as temperature, pressure, flow, level and speed are all analog. In order to deal with programmable analog controller, the need to achieve analog (Analog) and digital (Digital) between the A / D converter and D / A converter. PLC manufacturers are supporting the production of A / D and D / A converter module so that the programmable logic controller for analog control.Motion ControlPLC can be used circular motion or linear motion control. From the control of institutions targeted, the switching capacity for early direct I / O modules position sensor and executive bodies, now generally used for the movement control module. Such as stepper motor drive servo motor or the location of single or multi-axis control module. PLC the world's major manufacturers of products almost all movement control, widely used in all kinds of machinery, machine tools, robots, elevators, and other occasions.Process ControlRefers to the process control temperature, pressure, flow simulation of theclosed-loop control. As industrial computer, PLC to the preparation of a variety of control algorithms procedures, complete closed-loop control. PID regulator is generally closed-loop control system used in more conditioning methods. PID modules are large and medium-sized PLC, the PLC also has many small feature of this module. PID is running for the processing of PID subroutine. Process control in the metallurgical, chemical, heat treatment, boiler control, and other occasions have a very wide range of applications.Data ProcessingModern PLC with math (including matrix computing, computing functions, logic operation), data transmission, data conversion, sorting, look-up table, in operation, and other functions, to complete the data collection, analysis and treatment. These data can be stored in the memory of the reference value, the completion of a control operation, can also use the communication sent to other intelligent devices, or print them tabulation. Data processing for large-scale control systems such as unmanned control of flexible manufacturing systems; can also be used for process control systems, such as paper making, metallurgy, food industry in some large-scale control system.4. PLC of the situation at home and abroadThe world's first recognized the PLC is the 1969 . Digital Equipment Corporation (DEC) developed. Limited to conditions at the time of the components and computer development, early PLC mainly by discrete components and small and medium-scale integrated circuit components, can complete a simple logic control and timing, counting function. In the early 1970s a microprocessor. People will soon introduce its programmable logic controller, PLC an increase of computing, data transmission and processing functions, complete with a real computer features of industrial control devices. In order to facilitate familiar with the relay, contact the system engineering and technical staff, and the PLC adopt a similar ladder relay circuit as the main programming language, and will participate in the operation of the computer storage and processing components are named to the relay . At this time of the PLC for computer technologyand relay the concept of combining conventional control of the product.China's introduction of the PLC, applications, development, production is accompanied by reform and opening up began. The first is the introduction oflarge-scale use of the equipment in the PLC. Next in the production of business equipment and products continue to expand the application of the PLC. At present, China has its own can produce small and medium-sized PLC. East Electric Co., Ltd. Shanghai housing production CF Series, Hangzhou Machine Tool Factory production of electrical and DKK D series, Dalian Machine Tool Institute combination of the S-Series production, the Suzhou plant production of computers and other products YZ series has a certain scale And access to industrial products in the application. In addition, Wuxi Huaguang Company, Shanghai Rural Island companies such as Sino-foreign joint ventures in China is relatively well-known manufacturer of the PLC. It can be expected, with the deepening of China's modernization process, PLC in China will have a wider application of heaven and earth.5. PLC Future21 Century, PLC will have a greater development. From a technical perspective, the new achievements in computer technology will be applied to more programmable controllers on the design and manufacture, there will be faster and faster, greater storage capacity, more intelligent species emerged from the products on the scale , Will be further to the ultra-small and super-large direction, from the matching of products, the products of the species will be more rich and more complete specifications, the perfect man-machine interface, improved communications equipment will be better adapted to various industrial control Occasions demand from the market, the production of their respective countries and more varieties of products with international competition will intensify and break, there will be a few brand monopoly of the international market situation, there will be international common programming language from the network The development of the situation, the PLC and other industrial control of a large computer network control system is PLC technology development direction. The current computer distributed control system DCS (Distributed Control System) has been a lot of programmable logic controller applications. Along with the development of computer networks, automatic control programmable logic controller as a common network and international network an important part in industry and industrial fields outside of the increasing role.谈PLC的应用与发展1.可编程控制器的定义可编程控制器，简称PLC（Programmable logic Controller）,是指以计算机技术为基础的新型工业控制装置。
(完整版)PLC英文文献+翻译
自动化专业本科毕业设计英文翻译学院(部)：专业班级：学生姓名：指导教师：年月日Programmable Logic ControllerONE：PLC overviewProgrammable 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 interface. TWO：History of PLCProgrammable Logic Controllers (PLC), a computing device invented by Richard E. Morley in 1968, have been widely used in industry including manufacturing systems, transportation systems, chemical process facilities, and many others. At that time, the PLC replaced the hardwired logic with soft-wired logic or so-called relay ladder logic (RLL), a programming language visually resembling the hardwired logic, and reduced thereby the configuration time from 6 months down to 6 days [Moody and Morley, 1999].Although PC based control has started to come into place, PLC based control will remain the technique to which the majority of industrial applications will adhere due to its higher performance, lower price, and superior reliability in harsh environments. Moreover, according to a study on the PLC market of Frost and Sullivan [1995], an increase of the annual sales volume to 15 million PLC per year with the hardware value of more than 8 billion US dollars has been predicted, though the prices of computing hardware is steadily dropping. The inventor of the PLC, Richard E Morley, fairly considers the PLC market as a 5-billion industry at the present time.Though PLCs are widely used in industrial practice, the programming of PLC based control systems is still very much relying on trial-and-error. Alike software engineering, PLC software design is facing the software dilemma or crisis in a similar way. Morley himself emphasized this aspect most forcefully by indicatingIf houses were built like software projects, a single woodpecker could d estroy civilization.”Particularly, practical problems in PLC programming are to eliminate software bugs and to reduce the maintenance costs of old ladderlogic programs. Though the hardware costs of PLC are dropping continuously, reducing the scan time of the ladder logic is still an issue in industry so that low-cost PLC can be used.In general, the productivity in generating PLC is far behind compared to other domains, for instance, VLSI design, where efficient computer aided design tools are in practice. Existent software engineering methodologies are not necessarily applicable to the PLC based software design because PLC-programming requires a simultaneous consideration of hardware and software. The software design becomes, thereby, more and more the major cost driver. In many industrial design projects, more than of the manpower allocated for the control system design and installation is scheduled for testing and debugging PLC programs.In addition, current PLC based control systems are not properly designed to support the growing demand for flexibility and reconfigurability of manufacturing systems. A further problem, impelling the need for a systematic design methodology, is the increasing software complexity in large-scale projects.The objective of this thesis is to develop a systematic software design methodology for PLC operated automation systems. The design methodology involves high-level description based on state transition models that treat automation control systems as discrete event systems, a stepwise design process, and set of design rules providing guidance and measurements to achieve a successful design. The tangible outcome of this research is to find a way to reduce the uncertainty in managing the control software development process, that is, reducing programming and debugging time and their variation, increasing flexibility of the automation systems, and enabling software reusability through modularity. The goal is to overcome shortcomings of current programming strategies that are based on the experience of the individual software developer. Three：now of PLCFrom the structure is divided into fixed PLC and Module PLC, the two kinds of PLC including CPU board, I/O board, display panel, memory block, power, these elements into a do not remove overall. Module type PLC including CPU module, I/O modules, memory, thepower modules, bottom or a frame, these modules can be according to certain rules combination configuration.In the user view, a detailed analysis of the CPU's internal unnecessary, but working mechanism of every part of the circuit. The CPU control works, by it reads CPU instruction, interprets the instruction and executes instructions. But the pace of work by shock signal control.Unit work under the controller command used in a digital or logic operations.In computing and storage register of computation result, it is also among the controller command and work. CPU speed and memory capacity is the important parameters fot PLC . its determines the PLC speed of work, IO PLC number and software capacity, so limits to control size.Central Processing Unit (CPU) is the brain of a PLC controller. CPU itself is usually one of the microcontrollers. Aforetime these were 8-bit microcontrollers such as 8051, and now these are 16-and 32-bit microcontrollers. Unspoken rule is that you’ll find mostly Hitachi and Fujicu microcontrollers in PLC controllers by Japanese makers, Siemens in European controllers, and Motorola microcontrollers in American ones. CPU also takes care of communication, interconnectedness among other parts of PLC controllers, program execution, memory operation, overseeing input and setting up of an output.System memory (today mostly implemented in FLASH technology) is used by a PLC for a process control system. Aside form. this operating system it also contains a user program translated foram ladder diagram to a binary form. FLASH memory contents can be changed only in case where user program is being changed. PLC controllers were used earlier instead of PLASH memory and have had EPROM memory instead of FLASH memory which had to be erased with UV lamp and programmed on programmers. With the use of FLASH technology this process was greatly shortened. Reprogramming a program memory is done through a serial cable in a program for application development.User memory is divided into blocks having special functions. Some parts of a memory are used for storing input and output status. The real status of an input is stored either as “1”or as “0”in a specific memory bit/each input or output has one corresponding bit in memory. Other parts of memory are used to store variable contents for variables used in used program. For example, time value, or counter value would be stored in this part of the memory.PLC controller can be reprogrammed through a computer (usual way), but also through manual programmers (consoles). This practically means that each PLC controller can programmed through a computer if you have the software needed for programming. Today’s transmission computers are ideal for reprogramming a PLC controller in factory itself. This is of great importance to industry. Once the system is corrected, it is also important to read the right program into a PLC again. It is also good to check from time to time whether program in a PLC has not changed. This helps to avoid hazardous situations in factory rooms (some automakers have established communication networks which regularly check programs in PLC controllers to ensure execution only of good programs).Almost every program for programming a PLC controller possesses various useful options such as: forced switching on and off of the system input/outputs (I/O lines), program follow up in real time as well as documenting a diagram. This documenting is necessary to understand and define failures and malfunctions. Programmer can add remarks, names of input or output devices, and comments that can be useful when finding errors, or with system maintenance. Adding comments and remarks enables any technician (and not just a person who developed the system) to understand a ladder diagram right away. Comments and remarks can even quote precisely part numbers if replacements would be needed. This would speed up a repair of any problems that come up due to bad parts. The old way was such that a person who developed a system had protection on the program, so nobody aside from this person could understand how it was done. Correctly documented ladder diagram allows any technician to understand thoroughly how system functions.Electrical supply is used in bringing electrical energy to central processing unit. Most PLC controllers work either at 24 VDC or 220V AC. On some PLC controllers you’ll find electrical supply as a separatemodule. Those are usually bigger PLC controllers, while small and medium series already contain the supply module. User has to determine how much current to take from I/O module to ensure that electrical supply provides appropriate amount of current. Different types of modules use different amounts of electrical current.This electrical supply is usually not used to start external input or output. User has to provide separate supplies in starting PLC controller inputs because then you can ensure so called “pure” supply for the PLC controller. With pure supply we mean supply where industrial environment can not affect it damagingly. Some of the smaller PLC controllers supply their inputs with voltage from a small supply source already incorporated into a PLC.Four：PLC design criteriaA systematic approach to designing PLC software can overcome deficiencies in the traditional way of programming manufacturing control systems, and can have wide ramifications in several industrial applications. Automation control systems are modeled by formal languages or, equivalently, by state machines. Formal representations provide a high-level description of the behavior of the system to be controlled. State machines can be analytically evaluated as to whether or not they meet the desired goals. Secondly, a state machine description provides a structured representation to convey the logical requirements and constraints such as detailed safety rules. Thirdly, well-defined control systems design outcomes are conducive to automatic code generation- An ability to produce control software executable on commercial distinct logic controllers can reduce programming lead-time and labor cost. In particular, the thesis is relevant with respect to the following aspects.In modern manufacturing, systems are characterized by product and process innovation, become customer-driven and thus have to respond quickly to changing system requirements. A major challenge is therefore to provide enabling technologies that can economically reconfigure automation control systems in response to changing needs and new opportunities. Design and operational knowledge can be reused inreal-time, therefore, giving a significant competitive edge in industrial practice.Studies have shown that programming methodologies in automation systems have not been able to match rapid increase in use of computing resources. For instance, the programming of PLC still relies on a conventional programming style with ladder logic diagrams. As a result, the delays and resources in programming are a major stumbling stone for the progress of manufacturing industry. Testing and debugging may consume over 50% of the manpower allocated for the PLC program design. Standards [IEC 60848, 1999; IEC-61131-3, 1993; IEC 61499, 1998; ISO 15745-1, 1999] have been formed to fix and disseminate state-of-the-art design methods, but they normally cannot participate in advancing the knowledge of efficient program and system design.A systematic approach will increase the level of design automation through reusing existing software components, and will provide methods to make large-scale system design manageable. Likewise, it will improve software quality and reliability and will be relevant to systems high security standards, especially those having hazardous impact on the environment such as airport control, and public railroads.The software industry is regarded as a performance destructor and complexity generator. Steadily shrinking hardware prices spoils the need for software performance in terms of code optimization and efficiency. The result is that massive and less efficient software code on one hand outpaces the gains in hardware performance on the other hand. Secondly, software proliferates into complexity of unmanageable dimensions; software redesign and maintenance-essential in modern automation systems-becomes nearly impossible. Particularly, PLC programs have evolved from a couple lines of code 25 years ago to thousands of lines of code with a similar number of 1/O points. Increased safety, for instance new policies on fire protection, and the flexibility of modern automation systems add complexity to the program design process. Consequently, the life-cycle cost of software is a permanently growing fraction of the total cost. 80-90% of these costs are going into software maintenance, debugging, adaptation and expansion to meet changing needs.Today, 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.From 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.可编程控制器一、PLC概述可编程控制器是60年代末在美国首先出现的，当时叫可编程逻辑控制器PLC（Programmable Logic Controller），目的是用来取代继电器。
PLC发展和未来中英文对照外文翻译文献
中英文资料对照外文翻译中英文对照外文翻译The development and future of PLCPart 1 PLC overviewProgrammable 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 productionprocesses. 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.Part 2 History of PLCProgrammable Logic Controllers (PLC), a computing device invented by Richard E. Morley in 1968, have been widely used in industry including manufacturing systems, transportation systems, chemical process facilities, and many others. At that time, the PLC replaced the hardwired logic with soft-wired logic or so-called relay ladder logic (RLL), a programming language visually resembling the hardwired logic, and reduced thereby the configuration time from 6 months down to 6 days [Moody and Morley, 1999].Although PC based control has started to come into place, PLC based control will remain the technique to which the majority of industrial applications will adhere due to its higher performance, lower price, and superior reliability in harsh environments. Moreover, according to a study on the PLC market of Frost and Sullivan [1995], an increase of the annual sales volume to 15 million PLCs per year with the hardware value of more than 8 billion US dollars has been predicted, though the prices of computing hardware is steadily dropping. The inventor of the PLC, Richard E Morley, fairly considers the PLC market as a 5-billion industry at the present time.Though PLCs are widely used in industrial practice, the programming of PLC based control systems is still very much relying on trial-and-error. Alike software engineering, PLC software design is facing the software dilemma or crisis in a similar way. Morley himself emphasized this aspect most forcefully by indicating`If houses were built like software projects, a single woodpecker could destroy civilization.”Particularly, practical problems in PLC programming are to eliminate software bugs and to reduce the maintenance costs of old ladder logic programs. Though the hardware costs of PLCs are dropping continuously, reducing the scan time of the ladder logic is still an issue in industry so that low-cost PLCs can be used.In general, the productivity in generating PLC is far behind compared to other domains, for instance, VLSI design, where efficient computer aided design tools are inpractice. Existent software engineering methodologies are not necessarily applicable to the PLC based software design because PLC-programming requires a simultaneous consideration of hardware and software. The software design becomes, thereby, more and more the major cost driver. In many industrial design projects, more than of the manpower allocated for the control system design and installation is scheduled for testing and debugging PLC programs.In addition, current PLC based control systems are not properly designed to support the growing demand for flexibility and reconfigurability of manufacturing systems. A further problem, impelling the need for a systematic design methodology, is the increasing software complexity in large-scale projects.The objective of this thesis is to develop a systematic software design methodology for PLC operated automation systems. The design methodology involves high-level description based on state transition models that treat automation control systems as discrete event systems, a stepwise design process, and set of design rules providing guidance and measurements to achieve a successful design. The tangible outcome of this research is to find a way to reduce the uncertainty in managing the control software development process, that is, reducing programming and debugging time and their variation, increasing flexibility of the automation systems, and enabling software reusability through modularity. The goal is to overcome shortcomings of current programming strategies that are based on the experience of the individual software developer.Part 3 Now of PLCFrom the structure is divided into fixed PLC and Module PLC, the two kinds of PLC including CPU board, I/O board, display panel, memory block, power, these elements into a do not remove overall. Module type PLC including CPU module, I/O modules, memory, the power modules, bottom or a frame, these modules can be according to certain rules combination configuration.In the user view, a detailed analysis of the CPU's internal unnecessary, but working mechanism of every part of the circuit. The CPU control works, by it reads CPU instruction, interprets the instruction and executes instructions. But the pace of work by shock signal control.Unit work under the controller command used in a digital or logic operation.In computing and storage register of computation result, it is also among the controller command and work. CPU speed and memory capacity is the important parameters for PLC , its determines the PLC speed of work, IO PLC number and software capacity, so limits to control size.Central Processing Unit (CPU) is the brain of a PLC controller. CPU itself is usually one of the microcontrollers. Aforetime these were 8-bit microcontrollers such as 8051, and now these are 16-and 32-bit microcontrollers. Unspoken rule is that you’ll find mostly Hitachi and Fujicu microcontrollers in PLC controllers by Japanese makers, Siemens in European controllers, and Motorola microcontrollers in American ones. CPU also takes care of communication, interconnectedness among other parts of PLC controllers, program execution, memory operation, overseeing input and setting up of an output.System memory (today mostly implemented in FLASH technology) is used by a PLC for a process control system. Aside form. this operating system it also contains a user program translated forma ladder diagram to a binary form. FLASH memory contents can be changed only in case where user program is being changed. PLC controllers were used earlier instead of PLASH memory and have had EPROM memory instead of FLASH memory which had to be erased with UV lamp and programmed on programmers. With the use of FLASH technology this process was greatly shortened. Reprogramming a program memory is done through a serial cable in a program for application development.User memory is divided into blocks having special functions. Some parts of a memory are used for storing input and output status. The real status of an input is stored either as “1”or as “0”in a specific memory bit/ each input or output has one corresponding bit in memory. Other parts of memory are used to store variable contents for variables used in used program. For example, time value, or counter value would be stored in this part of the memory.PLC controller can be reprogrammed through a computer (usual way), but also through manual programmers (consoles). This practically means that each PLC controller can programmed through a computer if you have the software needed for programming. Today’s transmission computers are ideal for reprogramming a PLC controller in factory itself. This is of great importance to industry. Once the system is corrected, it is also important to read the right program into a PLC again. It is also good to check from time totime whether program in a PLC has not changed. This helps to avoid hazardous situations in factory rooms (some automakers have established communication networks which regularly check programs in PLC controllers to ensure execution only of good programs).Almost every program for programming a PLC controller possesses various useful options such as: forced switching on and off of the system input/outputs (I/O lines), program follow up in real time as well as documenting a diagram. This documenting is necessary to understand and define failures and malfunctions. Programmer can add remarks, names of input or output devices, and comments that can be useful when finding errors, or with system maintenance. Adding comments and remarks enables any technician (and not just a person who developed the system) to understand a ladder diagram right away. Comments and remarks can even quote precisely part numbers if replacements would be needed. This would speed up a repair of any problems that come up due to bad parts. The old way was such that a person who developed a system had protection on the program, so nobody aside from this person could understand how it was done. Correctly documented ladder diagram allows any technician to understand thoroughly how system functions.Electrical supply is used in bringing electrical energy to central processing unit. Most PLC controllers work either at 24 VDC or 220 V AC. On some PLC controllers you’ll find electrical supply as a separate module. Those are usually bigger PLC controllers, while small and medium series already contain the supply module. User has to determine how much current to take from I/O module to ensure that electrical supply provides appropriate amount of current. Different types of modules use different amounts of electrical current.This electrical supply is usually not used to start external input or output. User has to provide separate supplies in starting PLC controller inputs because then you can ensure so called “pure” supply for the PLC controller. With pure supply we mean supply where industrial environment can not affect it damagingly. Some of the smaller PLC controllers supply their inputs with voltage from a small supply source already incorporated into a PLC.Part 4 PLC design criteriaA systematic approach to designing PLC software can overcome deficiencies in thetraditional way of programming manufacturing control systems, and can have wide ramifications in several industrial applications. Automation control systems are modeled by formal languages or, equivalently, by state machines. Formal representations provide a high-level description of the behavior of the system to be controlled. State machines can be analytically evaluated as to whether or not they meet the desired goals. Secondly, a state machine description provides a structured representation to convey the logical requirements and constraints such as detailed safety rules. Thirdly, well-defined control systems design outcomes are conducive to automatic code generation- An ability to produce control software executable on commercial distinct logic controllers can reduce programming lead-time and labor cost. In particular, the thesis is relevant with respect to the following aspects.In modern manufacturing, systems are characterized by product and process innovation, become customer-driven and thus have to respond quickly to changing system requirements. A major challenge is therefore to provide enabling technologies that can economically reconfigure automation control systems in response to changing needs and new opportunities. Design and operational knowledge can be reused in real-time, therefore, giving a significant competitive edge in industrial practice.Studies have shown that programming methodologies in automation systems have not been able to match rapid increase in use of computing resources. For instance, the programming of PLCs still relies on a conventional programming style with ladder logic diagrams. As a result, the delays and resources in programming are a major stumbling stone for the progress of manufacturing industry. Testing and debugging may consume over 50% of the manpower allocated for the PLC program design. Standards [IEC 60848, 1999; IEC-61131-3, 1993; IEC 61499, 1998; ISO 15745-1, 1999] have been formed to fix and disseminate state-of-the-art design methods, but they normally cannot participate in advancing the knowledge of efficient program and system design.A systematic approach will increase the level of design automation through reusing existing software components, and will provide methods to make large-scale system design manageable. Likewise, it will improve software quality and reliability and will be relevant to systems high security standards, especially those having hazardous impact on the environment such as airport control, and public railroads.The software industry is regarded as a performance destructor and complexity generator. Steadily shrinking hardware prices spoils the need for software performance interms of code optimization and efficiency. The result is that massive and less efficient software code on one hand outpaces the gains in hardware performance on the other hand. Secondly, software proliferates into complexity of unmanageable dimensions; software redesign and maintenance-essential in modern automation systems-becomes nearly impossible. Particularly, PLC programs have evolved from a couple lines of code 25 years ago to thousands of lines of code with a similar number of 1/O points. Increased safety, for instance new policies on fire protection, and the flexibility of modern automation systems add complexity to the program design process. Consequently, the life-cycle cost of software is a permanently growing fraction of the total cost. 80-90% of these costs are going into software maintenance, debugging, adaptation and expansion to meet changing needs.Today, 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.From 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.Part 5 AK 1703 ACPFollowing the principle of our product development, AK 1703 ACP has highfunctionality and flexibility, through the implementation of innovative and reliable technologies, on the stable basis of a reliable product platform.For this, the system concept ACP (Automation, Control and Protection) creates the technological preconditions. Balanced functionality permits the flexible combination of automation, telecontrol and communication tasks. Complemented with the scalable performance and various redundancy configurations, an optimal adaptation to the respective requirements of the process is achieved.AK 1703 ACP is thus perfectly suitable for automation with integrated telecontrol technology as:• Telecontrol substation or central device• Automation unit with autonom ous functional groups• Data node, station control device, front-end or gateway• With local or remote peripherals• For rear panel installation or 19 inch assembly• Branch-neutral product, therefore versatile fields of application and high product stability• Versatile communication• Easy engineering• Plug & play for spare parts• Open system architecture• Scalable redundancy• The intelligent terminal - TM 1703The Base Unit AK 1703 ACP with Peripheral Elements has one basic system element CP-2010/CPC25 (Master control element) and CP-2012/PCCE25 (Processing and communication element) ,one bus line with max. 16 peripheral elements can be connected.CP-2010/CPC25 Features and FunctionsSystem Functions:• Central element,coordinating all system servicesCentral hub function for all connected basic system elements• Time managementCentral clock of the automation unitSetting and keeping the own clock`s time with a resolution of 10msSynchronization via serid communication via LAN or local• RedundancyV oting and change-over for redundant processing and communication elements of the own automation unitSupports voting and change-over by an external SCA-RS redundancy switchSupports applicational voting and change-over by an external system,e.g.a control system• SAT TOLLBOX|| connectionStoring firmware and parameters on a Flash CardCommunication:• Communication via installable protocol elements to any superior or subordinate automation unit• Automatic data flow routing• Priority based data transmission (priority control)• Own circular buffer and process image for each connected station(data keeping)• Redundant communication routesCommunication with redundant remote stations• Special application specific functions for dial-up trafficTest if stations are reachableProcess Peripherals:• T ransmission of spontaneous information objects from and to peripheral elements, via the serial Ax 1703 peripheral busFunctions for Automation:• Open-/closed-loop control function for the execution of freely definable user programs which are created with CAEX plus according to IEC 61131-3,ing function diagram technology512KB for user programApprox 50.000 variables and signals,2.000 of them retainedCycle of 10ms or a multiple thereofOnline testLoadable without service interruption• Redundant open-/closed-loop control functionsSynchronization via redundancy linkTransmission of periodic process information between the open-/closed-loop control function and the peripheral elements,via the serial Ax 1703 peripheral bus.PLC的发展和未来一、PLC概述可编程控制器是60年代末在美国首先出现的，当时叫可编程逻辑控制器PLC （Programmable Logic Controller），目的是用来取代继电器。
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学校代码：11517学号：201050712108HENAN INSTITUTE OF ENGINEERING文献翻译题目基于P LC的自动售货机控制系统设计学生姓名专业班级电气工程及其自动化0921班学号 20095071系（部）电气信息工程系指导教师(职称)完成时间 2011年 3 月 2日摘自《可编程控制器在过程自动化中的应用》Ahti Mikkor,Lembit RoosimolderDepartment of Product Development,Institute of Machinery,Tallinn technical University,Ehitajate tee 5,19086Tallinn.摘要：目前，控制问题解决了各种各样的技术操作部分：电子，液压，气动和机械。
函数- nality，可靠性和控制系统的价格是阻止开发的理由。
本文集中于可编程逻辑控制器（PLC），以五年在这方面的发展经验为基础。
成功的解决方案是问题重点。
具体的硬件，控制器编程的问题、数据/信号的交换和人机界面进行审议。
实际的建议，需要根据具体的方法来开发可编程控制器。
对于可能出现的错误和警告，提出可以帮助避免方法。
关键词：可编程控制器、自动化、自动化系统、过程自动化1引言现代的机器包括电子和机械两部分。
平衡两方面因素，初步规划和方案选择对最终结果起着至关重要的作用。
在控制方法的选择，继电器，专用设备，可编程逻辑控制器（PLC）和电子制造技术的发展。
这篇文章是基于PLC集中- S的经验，拥有超过5年的PLC - S 的实际工作经验中收集的。
双方强弱，积极和消极的做法进行了讨论。
建议使用可编程控制器帮助解决。
在规划基于PLC系统中最重要的决定是选择处理器类型。
误区是意味着修改额外费用或扩展完全新设备的需要。
最常见的错误是高估小型处理器编程的可能性。
有选择PLC的几种方法。
不幸的是，他们大多集中在电气方面的PLC - S 和允许的最大计数信号。
他们不涉及分析，以确定用户程序或通信可能的特殊需要。
基于几个现有的方法，实践经验和未来趋势的选择为开PLC的开发提供新的方法。
阿赫蒂瓦尔Mikkor已获得通过采取在超过15个大范围的自动化项目的一部分，以他的经验，这些项目包括电力消耗在AS昆达北欧水泥工厂监控系统的开发，更新测试流量计钻机，建设城镇Rakvere和普亚，污水处理厂在城里Jogeva 和发展动力涡轮安全系统，污水处理厂在塔尔图监测网络系统的集中供热。
2可编程控制器在投票站的使用2.1正面论据主要优势是灵活性提供可编程控制器（杰克，2003年）该系统的行为可以很容易地通过计划，没有任何其他的改动。
例如特殊装置使控制算法很难实现任何改变。
灵活性使得PLC的- S经常更换适合应用在机器人的例子。
在PLC - S的投入和产出之间的关系是由用户程序决定。
通过使用先进的编程技术比任何硬连接解决方案容易得多，以实现复杂的控制算法。
它使PLC在复杂的任务很有竞争力。
例如，在控制化学过程，特别模块，让大量不同的信号被连接到PLC系统。
PLC - S的使用，应考虑应用，需要一些“特殊”的输入或输出信号。
典型的例子是利用定位高速输入参考的数据。
通常个人电脑的可视化软件是由可编程序控制器PLC- S控制，也有一些特殊设备的PC软件包。
宽的PLC - S 的通信选择范围使得它能够收集到一个中央控制点。
搜集现场的所有设备的信息。
窄的PLC - S的通讯线路允许使用从本地过程控制系统的其他部分中收集信息。
现代通讯技术实现远程诊断和配置（杰克，2003年）。
这两方面显着降低了系统的总体维护成本。
2.2没有配备足够的内存来存储数据虽然未来的趋势在PLC内存大小，（录像机）专用设备的增长仍然是更适合于独立的数据记录应用。
对于网络解决方案，有可能使用可视化软件包一起与PLC - s到存档于任何数据库格式收集必要的数据。
如果记录的数据量小或者有控制功能也包括在内，采用PLC - S是合理的。
关于它的可视化软件，知道他们在标准版本的大多数不支持脱机录音通讯故障后，使我们无法获得向后从PLC的数据。
对PLC的现代通讯选项包括，例如以太网标准协议。
人们很容易用数据自动化系统的通信运营商中获得。
时间已经证明，最好的做法是保持这两方面分离的，如果有一个经常上网的通信需求。
几乎没有时间可追溯网络超载问题，也可能在自动化系统的通信。
所有的PLC - S的需要进行编程，所有的编程作品包括在控制算法和意外错误的风险。
特种设备是行之有效的，并且通常解决这类问题的。
如果有的话，它是经济的使用特殊设备。
安全应用需要最高的可靠性程度，应该包含最简单的设备和电路。
有一个规则，每一个链的新环节可能降低整体的可靠性。
在小型系统应用中，经常节省成本使用中继电路，而不是使用PLC的- S的。
3．今后的趋势过程自动化系统的进展是针对所谓的完全自动化，所有的人所要做的就是进入该产品的参数和其他一切工作由机器（松香，2000年）协调。
虽然目标遥遥领先，表明在这个方向的趋势运动。
首先，系统变得越来越规范。
从大型制造商组织到家庭的产品。
其目的是减少对来自同一公司不同的设备配置和维护工作所需的知识量。
同样重要的是这种方式构建的应用程序很容易扩展。
其次，沟通的重要性正在上升（休斯，2000）。
有很多原因，更多的要领有：更好的系统是不同部分的合作。
降低成本的布线。
减布线结果增加了故障率，也增加了那些发生的严重程度。
传感器与驱动器可以在从传统方法相比，如果使用的处理器覆盖更长的距离。
提高了系统的可扩展性。
在增加新设备时以最低的成本。
在某些情况下，最好是让许多小型的独立模块和网络架构。
该解决方案使系统继续工作，尽管一些地区已经失败。
方便的通信网络故障诊断为远程管理提供了可能性。
中央操作站，可形成相对容易。
可将设备连接形式（OPC基金会，2003）不同的生产厂家。
第三个重要趋势是散布所谓的软件控制器或软PLC - S的（西门子股份公司，2003年）的使用。
这些都是电脑软件为基础的解决方案，通过通信网络与现场设备。
有没有需要的处理器模块，使用的PC资源。
有些软PLC - S仍然为PC 处理器卡（图1）。
可靠的通信网络是必不可少的。
软PLC - S是非常适合于个人电脑的数据存储数据采集应用的。
图1。
西门子的SIMATIC WinAC插槽式PLC 412第四，组合装置（图2）同时包含操作员面板和中等规模的处理器模块得到普及（西门子股份公司，2002）。
这个解决方案的可能性很低，一些组件的重用使整个包便宜。
西门子SIMATIC组合设备的C7 – 613第五，处理器软件接管从PC软件性质。
收集的数据可以很容易地从生产到Office应用程序转移（西门子股份公司，2000）。
4 可编程控制器的控制方法可编程控制器的控制方法的选择是形成一个应用程序所需的特定属性列表中选择可编程控制器方法的开发。
有九个准则，其结果如表1所示。
通过比较做出选择与控制器的技术数据结果表。
以下是每一个参与标准的简短描述。
溶液的性质决定的是旧系统或全新的发展扩大。
在第一种情况下的系统和硬件的要求是有限的架构已经存在解决方案。
使用来自同一公司的硬件，使维修更方便，避免了整合的问题，将产品形式出现时，使用不同的生产厂家。
例如，许多硬件制造商结合自己的具体通信接口，直接将处理器模块和通用协议组合。
每一个需要特殊模块的（西门子股份公司，2003），它也可以减少备件库存金额，在系统全部采用同一类型的硬件。
最大的电力输入，允许输出的数量用标准来确定处理器。
如果复杂的控制算法和非标准功能是必需的，它不是最重要的参数了。
一般来说是金钱储蓄用于输入输出信号之一是更大的处理器模块，它来自于几个较小的邻近的位置。
在这种情况下，不会对通信网络的需要，也将会更容易编程。
特殊信号和模块通常为中型和大型控制器只提供家庭使用。
许多微控制器甚至没有可能性，加上模拟输出（西门子股份公司，2003）。
在某些情况下是使用特殊的模块的唯一途径，其他的（定位）这只是一个机会，为了省钱。
传感器和执行器的布局可有很大差异，有时远离传感器执行器（中长管抽吸液体）数公里。
在这种情况下，特殊的通讯网络（现场总线，如- inteface）可能是唯一的解决办法。
如果不是，它至少可以节省成本，减少布线工程。
并非所有可编程控制器通信协议的接口，处理器的性能在复杂的应用中有非常重要的作用。
最常见的问题是内存不足的时，有时也有数据存储器。
内存要求可估计的输入和输出信号的数量。
但在实践中100个数字输入输出点系统通常有3倍以上10个数字输入输出点的系统较小的程序。
只有这样，才能准确地估计项目的规模。
计划特色包括特殊程序功能的需要。
不同的应用领域有一些通常使用的功能，例如，在楼宇自动化温度控制中，编程要简单得多，如果这些功能已经进入系统软件中内置的处理器。
在过程自动化2个数字输出（上下）闭环PID调节是很常用的。
这可能是一个惊喜，但它不符合大多数微控制器（西门子股份公司，2003），对于一般的程序员它太复杂，开创了自己的调节器的标准功能包括在内。
基本上有2个解决方案：以避免这方面的建设和使用适用的控制器。
成果表现：交流在当今的自动化系统应用越来越广泛。
在某些情况下，作为条形码阅读器或电子权值非标准化装置必须到系统中。
然后，它的协议有至关重要的编程（自由港编程）功能。
标准化协议的具体模块需求：工作条件，通常可以克服使用特殊柜，但也有，改善了电磁干扰，湿度和振动性特定的系列可编程控制器。
在非常脏的环境中所有的冷却风扇都必须配备过滤器。
5结论可编程控制器的主要好处是：灵活实现方便的沟通和复杂的控制算法替代方案时应考虑可靠性系统尽量简单可记录特殊设备适当的解决方案和硬件的选择对最终结果有很大的影响。
如果这一步失误，一些项目的总体预算方案可能要发生变化，一些硬件要更换。
根据他的实际经验，笔者已经形成了一个选择可编程控制器的方法。
它有9个标准的：-输出允许（数字，模拟，输入，输出）的解决方案（新的或现有）的电气输入：最大数量自然需要特殊的模块（高速数字输出）传感器与致动器布局（本地或周边）处理器（程序和数据存储器）特色方案（特殊功能）通讯需求（现场总线，ASCII）的性能工作条件（湿度，温度，振动，粉尘）没有什么方法保证总是指出最好的解决方案，但使用确定的方法能避免了失误。
参考文献[1] Hughes, T. A. Programmable Controllers, Third Edition. ISA – The Instrumentation, Systems, and Automation Society, 2000, 334 p.[2] Jack, H. Automating Manufacturing Systems with PLC-s, 828 p., Available:[3] /~jackh/books/plcs/pdf/plcbook4_2.pdf,Accessed:3.10.2003[4] LOGO! Manual. Siemens AG, 2003, 312 p.[5] OPC Foundation homepage: /, Accessed: 9.11.2003[6] Rosin, A. Programmable Controllers Simatic S7. Tallinn, TTU, 2000, 120 p. [Master Thesis] –in Estonian.[7] Berger, H. Automating with SIMATIC. Siemens AG, 2003, 214 p.[8] SIMATIC Programming with STEP 7 V 5.2: Manual. Siemens AG, 2002, 610 p.[9] SIMATIC S7-200 Programmable Controller System Manual. Siemens AG, 2003, 474 p.[10] SIMATIC HMI WinCC Configuration Manual. Volume 1, 2, 3. Siemens AG 2000, 468 p.4th International DAAAM Conference"INDUSTRIAL ENGINEERING – INNOVATION AS COMPETITIVE EDGE FOR SME"29 - 30th April 2004, Tallinn, EstoniaPROGRAMMABLE LOGIC CONTROLLERS INPROCESS AUTOMATIONAhti Mikkor, Lembit RoosimölderDepartment of Product Development, Institute of Machinery,Tallinn Technical University, Ehitajate tee 5, 19086 Tallinn, Estoniaahti.mikkor@Abstract: Nowadays, control problems are solved using operating components from a wide variety of technologies: electronics, hydraulics, pneumatics and mechanics. Functio-nality, reliability and price of the controlled system are deter-mined by the quality of the solution made. The paper concentrates on practical use of programmable logic controllers (PLC) that is based on the five years project development experience in this area. Successful solutions and problems are under focus.Specific hardware, controller programming problems, data/signals exchange and human machine interfaces are considered. As a result the method for selecting programmable controllers according to specific needs is developed. Practical suggestions, possible hazards and warnings are proposed that could help to avoid mistakes.Key words: programmable controllers, PLC, automation, automation systems, process automation.1. INTRODUCTIONModern machinery consists of both mechanical and electronic parts. Overall functionality is determined by “balance” between these components. Initial planning and solution selection plays critical role in final result.In control methods the selection has to be made between relay-based circuits, special devices, programmable logic controllers (PLC) and new development electronics. This article is concentrated on PLC-s and experience that has collected over 5-year practical work with PLC-s. Strong and weak sides, positive and negative practices are discussed. Suggestions weather to use programmable controllers or not have been formed to help decision making.The most important decision in planning PLC-based system is selecting processor type. Mistakes mean extra costs for modifications or even need for completely new devices. The most common error is overestimating programming possibilities of small-sized processors. There are several methods for selecting PLC. Unfortunately most of them focus on electrical side of PLC-s and maximum count of signals allowed. They don’t involve analysis to determine possible special needs for user program or communications.Based on several existing methods, practical experience and future trends a new method for selecting PLC was developed. Ahti Mikkor has gained his experience by taking part in more than 15 big-scale automation projects. These projects include development of power consumption monitoring system in AS Kunda Nordic Cement factory, renewing testing rig for flowmeters, building Ahtme powerplant turbine safety systems, water treatment plants in towns Rakvere and Põlva, waste water treatment plant in town Jõgeva and development of monitoring system forcentral heating network in Tartu.2. PROS AND CONS IN USING PROGRAMMABLE LOGIC CONTROLLERS2.1 Positive argumentsThe main advantage that programmable controllers provide is flexibility (Jack, 2003). Behaviour of the system can be easily changed via program without any other alterations. Special devices for example make any changes in control algorithm very hard to implement. Flexibility makes PLC-s well suitable for frequently changed applications, for example in robotics.In PLC-s the relations between inputs and outputs are determined by user program. By using advanced programming technologies it is much easier to implement complex control algorithms than in any hard-wired solutions. It makes PLC-s very competitive for complex tasks, for example in controlling chemical processes.Special modules allow vast amount of different signals to be connected to the PLC system. Use of PLC-s should be considered in applications that require some “special” input or output signals. Typical example would be positioning using reference data from high-speed input.Typically PC visualization software packages are made for PLC-s. Some special devices have also PC software packages. Wide range of communication options between PLC-s makes it possible to gather all information from field devices into one central control point.Communication lines between PLC-s allow using information collected from other parts of the system in local process control. Modern communication technologies enable remote diagnostics and configuration (Jack, 2003). These two significantly reduce overall maintenance costs of the system.2.2 Negative argumentsProgrammable controllers are not equipped with enough memory to store big amounts of data. Although future trends show growth in PLC memory sizes, special devices (recorders) are still better suited for standalone datalogging applications. For networked solutions there is possibility to use visualization software packages together with PLC-s to archive collected data in any database format necessary. If logged data amounts are small or there are also control functions included, it’s reasonable to still use PLC-s. About visualization software packages it’s good to know that in standard versions most of them do not support offline recording so that after communication breakdown it is not possible to acquire data backwards from PLC.Modern communication options for PLC-s include standard protocols for example Ethernet. It is tempting to use existing office networks also as data carrier for automation system communications. Time has shown that it is better practice to keep these two separated if there is a need for constant online communication. Hardly traceable temporal network overloads can cause problems also in automation system communications All PLC-s need be programmed. All programming works include risk for accidental errors in control algorithm. Special devices are well tested and generally free of this kind of problems. If available, it’s economically thoughtful to use special devices.Safety applications that require highest degree of reliability should contain simplest devices and circuits possible. There is a rule that every new link in chain decreases overall reliability.In small applications it’s often cost saving to use relay-based circuits instead of PLC-s.3. FUTURE TRENDSProgress in process automation systems is aiming at so called complete automation when allthe human has to do is to enter the parameters of the product wanted and everything else is carried out by machines (Rosin, 2000). Although the destination lies far ahead, trends indicate movement in that direction.Firstly, systems become more and more standardized. Big manufacturers organize their products into families. The aim is to reduce amount of knowledge needed for configuration and maintenance works of different devices from same company. It’s also important that this way built applications are easily expandable.Secondly, importance of communication is rising (Hughes, 2000). There are many reasons, some of more essentials are:• Better collaboration of different parts of the system.• Cutting costs on cabling. Less cabling results fall in fault probability, but also increases severity of ones that occur.• Sensors and actuators can be at longer distances from the pro cessor module than if using conventional methods.• Increased scalability of the systems. New devices can be added at minimal costs.• At some cases it is better to make architecture of many small independent modules and network them. This solution enables system to keep working although some parts have failed.•Communication networks ease fault diagnostics and provide remote management possibilities. Central operating stations can be formed relatively easy.• Possibility to connect devices form differ ent manufacturers (OPC Foundation, 2003).Third important tendency is spreading use of so called software controllers or Soft PLC-s (Siemens AG, 2003). These are PC software-based solutions that relate with field devices via communication networks. There is no need for processor module, resources of PC are used. Some Soft PLC-s are still formed as processor cards for PC (figure 1). Reliable communication networks are essential. Soft PLC-s are well suited for data acquisition applications because of data storage possibilities of PC-s.Figure 1. Siemens Simatic WinAC Slot PLC 412Fourthly, combo-devices (figure 2) that contain both operator panel and medium size processor module gain popularity (Siemens AG, 2002). In this solution possibility of disturbances is low and reuse of some components make whole package cheaper.Figure 2. Combo device Siemens Simatic C7-613Fifthly, processor software takes over properties from PC software. Data collected from production can be easily transferred into office applications (Siemens AG, 2000).4. METHOD FOR SELECTING PROGRAMMABLE CONTROLLERA method for forming an application specific list of required properties for selecting programmable controller was developed. There are nine criterions and the results are presented in Table 1. Selection is made by comparing results table with controller’s technical data. Following is short description of every criteria involved.Nature of solution determines weather it is expanding of old system or completely new development. In first case the architecture of system and hardware requirements are limited by already existing solution. Using hardware from same company makes servicing easier and avoids integration problems that would occur when using products form different manufacturers. For example many hardware producers integrate their own specific communication interfaces directly into processor module and for every universal protocol a special module is needed (Siemens AG, 2003). It is also possible to reduce spare part stock amounts when using same type hardware all over the system.Maximum number of electrical inputs-outputs allowed is classical criteria to determine processor class. If complex control algorithms and non-standard functions ar e needed, it’s not the most important parameter any more. Generally it is money saving to use one bigger processor module for input-output signals that originate from nearby locations than several smaller ones. In this case there will be no need for communication network and programming will be easier too. Special signals and modules are usually available for medium and large controller families only. Many microcontrollers do not even have possibility to add analogue output (Siemens AG, 2003). In some cases using special modules is the only way, in other ones (positioning) it is just an opportunity to save money.Layouts of sensors and actuators can be very different, sometimes the sensors are located several kilometres away from the actuator (pumping liquids in long pipes). In this case special communication network (Profibus, AS-inteface) might be the only solution. If not, it can at least save costs by reducing cabling works. Not all programmable controllers have interfaces for communication protocols.Properties of processor have important role in complex applications. Most common problem is lack of programming memory, sometimes also data memory. Memory requirements can be estimated by number of input and output signals. But in practice 100 digital input-output points system often has 3 times smaller program than 10 digital input-output points system. The only way to estimate program size exactly is using previous experience.Program specialities include special program functions needed. Different areas of applications have some typically used functions, for example temperature control in building automation. Programming is much simpler if these functions are already built into system software of processor. In process automation 2 digital output (up-down) closed loop PID regulation is quite often used. It might be a surprise but it’s not included in most of the microcontrollers (Siemens AG, 2003) and for average programmer it’s too complicated task to create his own regulator using standard functions. Basically there are 2 solutions: either to avoid this construction or to use applicable controller.Table 1. Table for method resultsCommunication is becoming more important in nowadays automation systems. In some cases non-standardised devices as barcode readers or electronic weights have to be included into the system. Then it’s vital to have functions for protocol programming (freeport programming). Standardised protocols demand existence of specific modules.Working conditions can usually be overcome by using special cabinets, but there are also specific series of programmable controllers that have improved resistance for electromagnetic disturbances, humidity and vibrations. In very dusty environments all cooling ventilators have to be equipped withfilters.5. CONCLUSIONSMain benefits of programmable controllers are:• flexibility• communication possibilities• realisation of complex control algorithms• reliabilityAlternative solutions should be considered if:• system is very simple• spe cial devices are available• data recording is necessaryInitial selection of appropriate solution and hardware has great influence on final result. Mistakes in this step significantly increase overall budget of project as some programs might have to be changed and some hardware replaced.Based on his practical experience the author has formed a method for selecting programmable controller. It has 9 criteria’s:• nature of solution (new or existing)• maximum number of electrical inputs-outputs allowed (digital, analogue, inputs, outputs) • need for special modules (high-speed digital outputs)• layout of sensors and actuators (local or periphery)• properties of processor (program and data memory)• program specialities (special functions)• commu nication needs (Profibus, ASCII)• working conditions (humidity, temperature, vibration, dust)Method is not guaranteed to always point out the best selection, but using it certainly avoids mistakes.6. REFERENCESHughes, T. A. Programmable Controllers, Third Edition. ISA – The Instrumentation, Systems, and Automation Society, 2000, 334 p.Jack, H. Automating Manufacturing Systems with PLC-s, 828 p., Available:/~jackh/books/plcs/pdf/plcbook4_2.pdf, Accessed:3.10.2003LOGO! Manual. Siemens AG, 2003, 312 p.OPC Foundation homepage: /, Accessed: 9.11.2003Rosin, A. Programmable Controllers Simatic S7. Tallinn, TTU, 2000, 120 p. [Master Thesis] – in Estonian.Berger, H. Automating with SIMATIC. Siemens AG, 2003, 214 p.SIMATIC Programming with STEP 7 V 5.2: Manual. Siemens AG, 2002, 610 p.SIMATIC S7-200 Programmable Controller System Manual. Siemens AG, 2003, 474 p.SIMATIC HMI WinCC Configuration Manual. Volume 1, 2, 3. Siemens AG 2000, 468 p.。