中文 2180字 PLC-based control system design vending machine With highly modern peoples lives, all intelligent automated new model is gradually into our daily lives, and more and more vending machines morewidely used, it is to peoples lives brought great convenient, and therefore its reliable and stable design, highlights the importance of vending machines are to be completed no vending, optical, mechanical, electrical integration of business automation equipment. Vending machines have not any space restrictions, convenient advantage of can 24h daily sales. For vending machine design a control system with reliable performance, wide voltage range and easy programming, easy to maintain. Vending machine for the automated business representatives are widely used in public places. The traditional vending machine control system using SCM as the control so that not only will do a great job with the ratio of the input and output interfaces and immunity system is relatively poor, it is also very cumbersome to maintain, and expensive. Programmable Logic Controller (PLC) is a combination of computer technology, automatic control technology and communication technology and a new type of industrial control devices developed its high reliability, simple programming, and easy maintenance have been in the field of industrial control vending machines widely used because of the completion of the community as a retail and integrated services independent facilities require it to be reliable structure, high stability and efficiency. Development of PLC and computer technology, semiconductor technology, control is closely related to the development of technology, digital technology, high-techcommunications network technology, the development of these high-tech promote the development of PLC, the PLC and the development of these high-tech a higher update request promote their development. From the perspective of the development trend of the vending machine, and its appearance is due to the labor-intensive to technology-intensive industrial structure of the product of social change. Mass production, mass consumption, and changes in consumption patterns and sales environment, requires the emergence of new distribution channels; while relatively supermarket, department store shopping and other newdistribution channels, labor costs are rising; coupled with the limitations of the venue shopping convenience and the constraints, etc. These factors. Vending machine industry has long been the rapid development in the United States, Japan and other countries, has gained wide popularity in many countries. According to industry estimates, Chinas vending machine ownership is not too much, relative to trend 1300000000 populous country and the development of retail formats in terms of development China vending machine industry will be more broad. 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 youll 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 ofcommunication, interconnectedness among other parts of PLC controllers, program execution, memory operation, overseeing input and setting up of an output. PLC controllers have complex routines for memory checkup in order to ensure that PLC memory was not damaged (memory checkup is done for safety reasons).Generally speaking, CPU unit makes a great number of check-ups of the PLC controller itself so eventual errors would be discovered early. You can simply look at any PLC controller and see that there are several indicators in the form. of light diodes for error signalization. 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 casewhere user program is being changed. PLC controllers were used earlier instead of PLASH memory and have had EPROM 2memory 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. Todays 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 asdocumenting 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. Thiswould speed up a repair of any problems that come up due to bad parts. The old way was such that a person who 3 developed a system had protection on the program, so nobody aside from this person could understand how it was done. Correctlydocumented 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 VAC. On some PLC controllers youll 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 supplywhere 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. 基于 PLC自動售貨機控制系統(tǒng)設計 隨著人們生活的高度現(xiàn)代化，全智能自動化的全新模式正在逐步走入我們的 日常生活，而自動售貨機越來越多越來越廣泛的應用，更是給人們的生活帶來了 極大的便利，因此，其可靠穩(wěn)定的設計，更加凸顯重要性，自動售貨機是可完成 無人自動售貨，集光、機、電一體化的商業(yè)自動化設備。自動售貨機具有不受任 何場地限制，方便快捷，可以每天 24h 售貨的優(yōu)點。針對自動售貨機設計一套控制系統(tǒng)，具有性能可靠、電壓使用范 圍寬及編程方便，維護方便。自動售貨機為自動化商業(yè)機械的代表被廣泛用于公共場所。 傳統(tǒng)的自動售貨機控制系統(tǒng)采用單片機作為控制核心這樣不僅會在輸入輸 出接口上做大量的工作與配比而且系統(tǒng)的抗干擾性也比較差，維護起來也非常麻煩，且費用高昂。 可編程序控制器 ( PLC)是綜合了計算機技術、自動控制技術和通訊技術而發(fā)展 起來的一種新型的工業(yè)控制裝置它具有可靠性高、編程簡單、維護方便等優(yōu)點已在工業(yè)控制領域得到廣泛地應用因為自動售貨機作為社會上完成商品零售和綜合服務的獨立設施要求它的結構必須可靠、穩(wěn)定和執(zhí)行效率高。 PLC 的發(fā)展與計算機技術、半導體技術、控制技術、數(shù)字技術、通信網(wǎng)絡技術等高新技術的發(fā)展 息息相關，這些高新技術的發(fā)展推動了 PLC 的發(fā)展，而 PLC 的發(fā)展又對這些高新技術提出了更高更新的要求，促進了他們的發(fā)展。 從自動售貨機的發(fā)展趨勢來看，它的出現(xiàn)是由于勞動密集型的產業(yè)構造向技術密集型社會轉變的產物。大量生產、大量消費以及消費模式和銷售環(huán)境的變化，要求出現(xiàn)新的流通渠道 ;而相對的超市、百貨購物中心等新的流通渠道的產生，人工費用也不斷上升 ;再加上場地的局限性以及購物的便利性等這些因素的制約。自動售貨機行業(yè)長期以來 在美國、日本等國家得到迅猛發(fā)展，目前已在多個國家得到廣泛普及。據(jù)業(yè)內人士估計，但中國的自動售貨機擁有量還不太多，相對于 13 億的人口大國和零售業(yè)態(tài)發(fā)展的趨勢而言，中國自動售貨機行業(yè)的發(fā)展 5 空間將更加廣闊。 從結構上分， PLC 分為固定式和組合式 (模塊式 )兩種。固定式 PLC包括 CPU 板、 I/O 板、顯示面板、內存塊、電源等，這些元素組合成一個不可拆卸的整體。模塊式 PLC 包括 CPU 模塊、 I/O 模塊、內存、電源模塊、底板或機架，這些模塊 可以按照一定規(guī)則組合配置。在使用者看來，不必要詳細分析 CPU 的內部電路，但對各部分的工作機制還是應有足夠的理解。 CPU 的控制器控制 CPU 工作，由它讀取指令、解釋指令及執(zhí) 行指令。但工作節(jié)奏由震蕩信號控制。運算器用于進行數(shù)字或邏輯運算，在控制 器指揮下工作。寄存器參與運算，并存儲運算的中間結果，它也是在控制器指揮下工作。 CPU 速度和內存容量是 PLC 的重要參數(shù)，它們決定著 PLC 的工作速度， IO 數(shù)量及軟件容量等，因此限制著控制規(guī)模。 PLC 使用系統(tǒng)存儲器 (現(xiàn)在大部分采用閃存技術了 )用于過程控制系統(tǒng)。除了 這個操作系統(tǒng)之外，它還包括一個由梯形圖 翻譯成而進制形式的用戶程序。快擦 型存儲器 (FLASH memory)的內容只有在改變用戶程序的時候可以被改變。 PLC 控制器比快擦型存儲器使用得更早， EPROM 存儲器比快擦型存儲器也更早，快擦 型存儲器必須用紫外線 (UV， Ultra-Violet Ray)燈擦除，并在編程器上進行編程。由于快擦型存儲器技術的應用，使得這個過程大大縮短了。在應用