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2 IEC 61131-3的积木式部件这一章解释IEC 61131-3标准的主要语言元素的含义和用法,这些通过几个实际应用的例子图解说明,每个例子建立在前者的基础上。向读者介绍术语和IEC 61131-3标准的构思,详细和综合地说明基本的观点和概念而不讨论标准本身[IEC 61131-3-94]的形式语言定义。本章第1节,通过包含最重要语言元素和提供IEC 61131-3编程方法综合的例子紧凑地介绍标准的概念范畴。本章将详细地解释术语“POU”(Program Or-ganisation Unit,程序组织单元),因为它是全面理
2 Building blocks of IEC 61131-3 This chapter explains the meaning and usage of the main language elements of the IEC 61131-3 standard, illustrated by several practical examples, each based on the former. Introduce the reader to the concepts of terminology and the IEC 61131-3 standard, detailing and synthesizing the basic ideas and concepts without discussing the formal language definitions of the standard itself [IEC 61131-3-94]. The first section of this chapter provides a compact introduction to the standard conceptual categories through examples that include the most important language elements and provide IEC 61131-3 programming method synthesis. This chapter explains in detail the term “POU” (Program Or-ganisation Unit) as it is comprehensive