外文翻译-基于PLC自动售货机控制系统设计

外文翻译-基于PLC自动售货机控制系统设计

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PLC-based control system design vending machine

With highly modern people's lives, all intelligent automated new model is gradually into our daily lives, and more and more vending machines more widely used, it is to people's 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-tech communications 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.

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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 new distribution 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, China's 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 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. 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 case where user program is being changed. PLC controllers were used earlier instead of PLASH memory and have had EPROM

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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

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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 VAC. 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.

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基于PLC自动售货机控制系统设计

随着人们生活的高度现代化，全智能自动化的全新模式正在逐步走入我们的日常生活，而自动售货机越来越多越来越广泛的应用，更是给人们的生活带来了极大的便利，因此，其可靠稳定的设计，更加凸显重要性，自动售货机是可完成无人自动售货，集光、机、电一体化的商业自动化设备。自动售货机具有不受任何场地，方便快捷，可以每天24h售货的优点。针对自动售货机设计一套控制系统，具有性能可靠、电压使用范围宽及编程方便，维护方便。自动售货机为自动化商业机械的代表被广泛用于公共场所。

传统的自动售货机控制系统采用单片机作为控制核心这样不仅会在输入输出接口上做大量的工作与配比而且系统的抗干扰性也比较差，维护起来也非常麻烦，且费用高昂。

可编程序控制器( PLC)是综合了计算机技术、自动控制技术和通讯技术而发展起来的一种新型的工业控制装置它具有可靠性高、编程简单、维护方便等优点已在工业控制领域得到广泛地应用因为自动售货机作为社会上完成商品零售和综合服务的设施要求它的结构必须可靠、稳定和执行效率高。PLC的发展与计算机技术、半导体技术、控制技术、数字技术、通信网络技术等高新技术的发展息息相关，这些高新技术的发展推动了PLC的发展，而PLC的发展又对这些高新技术提出了更高更新的要求，促进了他们的发展。

从自动售货机的发展趋势来看，它的出现是由于劳动密集型的产业构造向技术密集型社会转变的产物。大量生产、大量消费以及消费模式和销售环境的变化，要求出现新的流

通渠道;而相对的超市、百货购物中心等新的流通渠道的产生，人工费用也不断上升;再加上场地的局限性以及购物的便利性等这些因素的制约。自动售货机行业长期以来在美国、日本等国家得到迅猛发展，目前已在多个国家得到广泛普及。据业内人士估计，但中国的自动售货机拥有量还不太多，相对于13亿的人口大国和零售业态发展的趋势而言，中国自动售货机行业的发展

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空间将更加广阔。

从结构上分，PLC分为固定式和组合式(模块式)两种。固定式PLC包括CPU板、I/O板、显示面板、内存块、电源等，这些元素组合成一个不可拆卸的整体。模块式PLC包括CPU模块、I/O模块、内存、电源模块、底板或机架，这些模块可以按照一定规则组合配置。

在使用者看来，不必要详细分析CPU的内部电路，但对各部分的工作机制还是应有足够的理解。CPU的控制器控制CPU工作，由它读取指令、解释指令及执行指令。但工作节奏由震荡信号控制。运算器用于进行数字或逻辑运算，在控制器指挥下工作。寄存器参与运算，并存储运算的中间结果，它也是在控制器指挥下工作。CPU速度和内存容量是PLC的重要参数，它们决定着PLC的工作速度，IO数量及软件容量等，因此着控制规模。

PLC使用系统存储器(现在大部分采用闪存技术了)用于过程控制系统。除了这个操作

系统之外，它还包括一个由梯形图翻译成而进制形式的用户程序。快擦型存储器(FLASH memory)的内容只有在改变用户程序的时候可以被改变。PLC控制器比快擦型存储器使用得更早，EPROM存储器比快擦型存储器也更早，快擦型存储器必须用紫外线(UV，Ultra-Violet Ray)灯擦除，并在编程器上进行编程。由于快擦型存储器技术的应用，使得这个过程大大缩短了。在应用程序开发中，通过一个串行电缆可以对程序存储器进行重新编程。

用户存储器被分成具有特殊功能的块。一部分存储器用来存储输入和输出状态。一个输入的实际状态存储状态存储在专用存储器位上，为“1”或者“0”。每一个输入和输出在存储器中都有一个相应的位。另外一部分存储器用来存储用户程序中的变量的内容。例如，定时器值，或者记数器值存放在存储器的这个部分。

PLC控制器可以通过计算机(通常方式)重新编程，但是也可以通过人工编程器9控制台)编程。实际上，这意味着，如果你有编程所需要的软件，早期PLC控制器可以通过计算机进行编程。今天的传输计算机是工厂自己对PLC控制器进行重新编程的理想设备。这对于工业企业来说是非常重要的。一旦系统修改结束，将正确的程序重新读入PLC控制器也是非常重要的。定期检查PLC中的程序是否改变是非常好的事情。这有助于避免车间发生危险情况(一些汽车制造商已经建

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立了通信网络，可以定期检查PLC中的程序，以保证运行的程序都是正确的)。

几乎所有用于为PLC控制器编程的程序都拥有各种不同的选项，例如系统输入/输出(I/O线)的强制开关，程序实时跟踪以及图表验证。图表验证对于理解、定义失败和故障非常必要。程序员可以添加标记，书日和输出设备名称，以及对于查找错误或者对于系统维护很有用的注释。添加注释和标记可以使技术人员(不仅仅是开发人员)很快理解梯形图。注释和标记甚至还可以准确地引用零件号，如果需要更换零件的话。这将加快由于损坏零件而引起的任何问题的修理速度。响应的旧方法是这样的，开发系统的人必须保护这个程序，他旁边再没有人知道系统是怎样完成的。正确的、备有证明文件的梯形图使任何技术人员都能彻底理解系统的功能。

电源是为处理单元提供电源的。大部分PLC控制器的工作电压为24VDC或者220VAC。在有些PLC控制器上，你可以看见作为模块的电源。用户必须确定从I/O模块取出多大电流来保证电源提供适当的电流。不同的模块使用不同的电流量。

该电源一般不用于启动外部输入或输出。用户必须提供的电源来启动PLC控制器的输入和输出，因为这样可以保证PLC控制器的所谓“纯电源”。使用纯电源意味着工业环境中的电源不会严重影响它。有些较小的PLC控制器从与PLC控制器集成在一起的小电源为它们的输入提供电压源。

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