目 录前言 ·····················································1第一章 绪论·············································21.1密码锁的进展 ·······································2第二章 密码锁的硬件设计 ······························42.1 S7—200PLC的系统组成 ······························42.2 控制要求 ···········································52.3 PLC的选型 ··········································52.4 I/O口分配表 ········································6 2.5 PLC外部接线图 ······································8第三章 密码锁的软件设计 ································93.1梯形图 ·············································93.2程序分析 ··········································163.3 程序设计的局限性和优点 ····························17小 结 ············································18致谢 ···············································19【参考文献】···········································19基于西门子 PLC 密码锁电气控制系统的讨论【摘要】 本设计是采纳西门子 PLC 来设计密码程序的，程序中应用到了近 20 个计数器。设计的密码锁外观图类似于银行取款机台上的键盘。给人感觉就和那种输入密码的过程一样。其实不然，本设计中采纳了计数器控制的特点，每个计数器的次数设定为几次那么所对应的按键就要按几次。本设计分为开锁环节和解锁环节，开锁环节设定六个按键有效，解锁环节设定了七个按键有效，这样一来设定的开锁密码位数就大于等于...
