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1、中文2180字PLC-based controlsystem design vending machineWith highly modern peopleslives, allintelligent automated newmodelis gradually into our dailylives, and more and more vending machines morewidely used, it is to peopleslives broughtgreat convenient, and therefore its reliable and stable design, hi
2、ghlights the importance of vending machines are to becompleted no vending, optical, mechanical, electricalintegration of business automation equipment. Vending machines have not any space restrictions, convenient advantage of can24h daily sales. For vending machine design a controlsystemwith reliabl
3、e performance,wide voltage range and easy programming, easy to maintain. Vending machine for the automated business representatives arewidely used in public places. The traditionalvending machine controlsystem using SCM as the controlso that not onlywilldo a great jobwith the ratio of the input and
4、output interfaces and immunity system is relatively poor, it is also very cumbersome to maintain, and expensive. ProgrammableLogic Controller (PLC) is acombination ofcomputer technology, automatic controltechnology andcommunication technology and a newtype of industrialcontroldevices developed its h
5、igh reliability, simple programming, and easy maintenance have been in the field of industrialcontrolvending machineswidely used because of thecompletion of thecommunity as a retailand integrated services independent facilities require it to be reliable structure, high stability and efficiency. Deve
6、lopment of PLC andcomputer technology, semiconductor technology, controlis closely related to the development of technology, digitaltechnology, high-techcommunications network technology, the development of these high-tech promote the development of PLC, the PLC and the development of these high-tec
7、h a higher update request promote their development. From the perspective of the development trend of the vending machine, and its appearance is due to thelabor-intensive to technology-intensive industrialstructure of the product of socialchange. Mass production, mass consumption, and changes in con
8、sumption patterns and sales environment, requires the emergence of newdistribution channels;while relatively supermarket, department store shopping and other newdistribution channels,labor costs are rising; coupledwith thelimitations of the venue shopping convenience and the constraints, etc. These
9、factors. Vending machine industry haslong been the rapid development in the United States, Japan and other countries, has gainedwide popularity in many countries. According to industry estimates, Chinas vending machine ownership is not too much, relative to trend 1300000000populous country and the d
10、evelopment of retailformats in terms of development China vending machine industrywillbe more broad. CentralProcessing Unit (CPU) is the brain of a PLC controller. CPU itself is usually one of the microcontrollers. Aforetime thesewere8-bit microcontrollers such as8051, and nowthese are 16-and32-bit
11、microcontrollers. Unspoken rule is that youllfind 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 contro
12、llers, program execution, memory operation, overseeing input and setting up of an output. PLC controllers havecomplex routines for memory checkup in order to ensure that PLC memorywas not damaged (memory checkup is done for safety reasons).Generally speaking, CPU unit makes a great number of check-u
13、ps of the PLC controller itself so eventualerrorswould be discovered early. You can simplylook at any PLC controller and see that there are severalindicators in the form. oflightdiodes for error signalization. System memory (today mostly implemented in FLASH technology) is used by a PLC for a proces
14、s controlsystem. Aside form. this operating system it also contains a user program translated formaladder diagram to a binary form. FLASH memory contents can be changed only in casewhere user program is being changed. PLC controllerswere used earlier instead of PLASH memory and have had EPROM2memory
15、 instead of FLASH memorywhich had to be erasedwith UVlamp and programmed on programmers.With the use of FLASH technology this processwas greatly shortened. Reprogramming a program memory is done through a serialcable in a program for application development. User memory is divided into blocks having
16、 specialfunctions. Some parts of a memory are used for storing input and output status. The realstatus 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 valuewould be stored in this part of t
