目录引 言························································································4第一章 概述·················································································51.1 数控系统的简介····················································································51.1.1 数控系统发展简史及趋势······································································51.1.2 数控（NC）阶段·················································································51.2.3 计算机数控（CNC）阶段······································································51.2 PLC 简介····························································································61.2.1 PLC 定义···························································································61.2.2PLC 的结构与组成···············································································61.2.3PLC 的工作原理··················································································61.3 PLC 和 NC 的关系····································································...
