在PLC控制系统中的系统思维

目前，随着微电子技术的发展，PLC控制系统的应用已经远远突破了早期的逻辑控制，从硬件到软件、从单机到系统、从逻辑控制到过程控制，功能异常强大，产品非常丰富，以西门子、罗克维尔、施耐德等几个知名品牌来说，产品系列非常齐全。几乎每个系列又都覆盖大、中、小各种规模的应用场合，给使用者全面、快速地掌握PLC的应用增加了很大难度。为阐述方便，本文从西门子S7系列PLC着手，希望从系统思维的角度来全面分析PLC控制系统在各种应用场合中产品选型与解决方案。

The system thinking in the PLC control system

Now,with the develo pment of micro-electronics,the application of PLC control system has breached th e early logical control out and away.From hardware to software,from stand-alone to system,from logical control to process control,the functions are very strong, the product are very rich.Such as Siemens,Rockwell and Schneider,the product ser ies are very complete,and the each series products almost cover with large,middl e and small scale applications.This increases very diffi-culty for the custom t o mastery PLC control technology entirely and rapidly.IN order to expatiate for its convenience,this ar-ticle will do my best to entirely analyse the PLC selec ting type and resolving projects from the angle of system thinking,ac-cording t o the Siemens s7series products.