毕业设计--人力资源管理.doc

三层楼电梯 PLC 控制统设计摘要 电梯作为高层建筑物的重要交通工具与人们的工作和生活日益紧密联系。 PLC 作为新一代工业控制器， 以其高可靠性和技术先进性， 在电梯控制中得到广泛应用，从而使电梯由传统的继电器控制方式发展为计算机控制的一个重要方 向，成为当前电梯控制和技术改造的热点之一。为此，自行设计并制作了 3 层 集选电梯。 此电梯所采用的类型为 OMRON 公司 C 系列的超小型 C20P 可编程序控 制器。 PLC 程序设计采用模块化编程思想， 即根据各功能实现的条件及原则设计 各个功能模块。设计的程序完成电梯自动运行功能如：内选外召唤信号的登记、消号、到层开门、上下自动运行等。合理分配轿厢内指令的执行和厅外召唤的 应答。关于 PLC 控制系统的基本结构及电梯控统的安装与调试重点介绍如下。 关键词 PLC 电梯 逻辑控制 程序设计 Central Processing Unit (CPU) is the brain of a PLC controller. CPU itself is usually one of the microcontrollers. Aforetime these were 8-bit microcontrollers such as 8051, and now these are 16-and 32-bit microcontrollers. Unspoken rule is that you’ll find mostly Hitachi and Fujicu microcontrollers in PLC controllers by Japanese makers, Siemens in European controllers, and Motorola microcontrollers in American ones. CPU also takes care of communication, interconnectedness among other parts of PLC controllers, program execution, memory operation, overseeing input and setting up of an output. PLC controllers have complex routines for memory checkup in order to ensure that PLC memory was not damaged (memory checkup is done for safety reasons).Generally speaking, CPU unit makes a great number of check-ups of the PLC controller itself so eventual errors would be discovered early. You can simply look at any PLC controller and see that there are several indicators in the form. of light diodes for error signalization. System memory (today mostly implemented in FLASH technology) is used by a PLC for a process control system. Aside form. this operating system it also contains a user program translated forma ladder diagram to a binary form. FLASH memory contents can be changed only in case where user program is being changed. PLC controllers were used earlier instead of PLASH memory and have had EPROM memory instead of FLASH memory which had to be erased with UV lamp and programmed on programmers. With the use of FLASH technology this process was greatly shortened. Reprogramming a program memory is done