摘要：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。近年来,我国的自动售货机行业突飞猛进:在汽车总站、商厦、医院、小区、学校等地区都能找到自动售货机的踪迹。本篇论文主要讲述了基于PLC的自动售货机的控制系统的设计。

　　　本论文设计的是基于西门子S7-200 系列PLC构成的自动售货机监控系统，本文阐述了自动售货机的来源与发展，以及它在国内外发展的现状，对自动售货机的方案进行了论证，介绍了PLC的基本组成、特点以及工作原理，对基于西门子S7-200 系列PLC构成的自动售货机系统整体设计过程进行较为细致的论述。    文中详尽地介绍了自动售货机的各硬件组成，并完成了PLC外部接线图。在PLC梯形图的编写时，文中采用的是西门子PLC梯形图专用编译软件STEP7来进行编写。介绍了自动售货机的基本原理以及工作流程，然后以一次交易过程为例，把交易过程分为几个程序块，然后分别对程序块进行编程。具体说明了可编程序控制器在自动售货机中的作用。程序涉及到了自动售货机工作的绝大部分过程。利用PLC控制的自动售货机提高了系统的稳定性，保证自动售货机能够长期稳定运行。

关键词：售货机、PLC、I/O点的分配、商业设备

Abstract：The vending machine is to be completed unattended vending, set light, machines, electricity integration of commercial automation equipment. In recent years, China's vending machine industry make a spurt of progress: the car terminal, commercial buildings, hospitals, schools, residential areas can be found in the vending machine. This article is mainly about PLC based vending machine control system design.

　　This thesis is based on the design of Siemens S7-200 series PLC vending machine monitoring system, this paper expounds the origin and development of the automatic vending machine, and it is in the domestic and foreign development status, the vending machine's plan to have proof, introduced the PLC basic composition, characteristics and working principle, based on Siemens S7-200series PLC vending machine system overall design process are more detailed exposition.

　　The paper introduces the hardware composition of the vending machine, and completed PLC external wiring diagram. In the PLC ladder programming, this paper adopts Siemens PLC ladder diagram is a special compiler software STEP7to carry on the compilation. Introduced vending machine's basic principle as well as the work flow, then take a transaction process as an example, the transaction process is divided into several blocks, and then the block of programming. Detailed description of programmable controller in vending machine function. The procedure involved the vending machine work most course. Use of PLC control of the vending machine can improve the stability of the system, ensures the automatic vending machine capable of long-term stable operation.

Key words: vending machine, PLC, I/O point distribution, Commercial equipment