This paper is based on the design of Siemens S7-200 PLC constitute the vending machine control system, this paper expounds source of the vending machine, and its development at home and abroad, the scheme design of vending machines are discussed, introduces the basic composition, characteristics of PLC and working principle, based on Siemens S7-200 PLC constitute the vending machine system, overall whole design process is discussed particularly.
The paper introduced in detail the vending machine, various hardware and completed PLC external hookup. In the writing of PLC ladder diagram, the Siemens PLC is special compiled software STEP7 ladder diagram to write. Introduces the basic principle of vending machines and work flow, and then to a transaction process, for example, the process is divided into several blocks, then respectively for program for programming block. Specify the programmable controller in vending machines. Program involve the vending machine working process and use the communication function among three PLC for two digital display.PLC control system, improve the vending machine, guarantee the stability of the vending machine to long-term and stable operation.
