一、引言可编程控制器(PLC)是以微处理器为核心,综合了微电子技术、自动化技术、网络通讯技术于一体的通用工业控制装置。近十年来,它已广泛应用于机械、冶金、能源、化工、交通、电力等领域中,成为现代工业控制的三大支柱(PLC、机器人和CAD/CAM)之一。 I. INTRODUCTION The programmable logic controller (PLC) is a general-purpose industrial control device that integrates microelectronic technology, automation technology and network communication technology with the microprocessor as the core. In the past ten years, it has been widely used in the fields of machinery, metallurgy, energy, chemical industry, transportation, electricity and so on and has become one of the three pillars of modern industrial control (PLC, robot and CAD / CAM).