GE VME-7807RC-410001350-93007807-410001 K 数字输入模块

GE VME-7807RC-410001350-93007807-410001 K 数字输入模块

1.中央处理器中央处理器(CPU)由控制器、运算器和寄存器组成并集成在一个芯片内。CPU通过数据总线总线、地址总线、控制总线和电源总线与存储器、输入输出接口、编程器和电源相连接。

小型PLC的CPU采用8位或16位微处理器或单片机，如8031、M68000等，这类芯片价格很低;中型PLC的CPU采用16位或32位微处理器或单片机，如8086、96系列单片机等，这类芯片主要特点是集成度高、运算速度快且可靠性高;而大型PLC则需采用高速位片式微处理器。CPU按照PLC内系统程序赋予的功能指挥PLC控制系统完成各项工作任务。

⒉.存储器PLC内的存储器主要用于存放系统程序、用户程序和数据等。1)系统程序存储器PLC系统程序决定了PLC的基本功能，该部分程序由PLC制造厂家编写并固化在系统程序存储器中，主要有系统管理程序、用户指令解释程序和功能程序与系统程序调用等部分。

系统管理程序主要控制PLC的运行，使PLC按正确的次序工作;用户指令解释程序将PLC的用户指令转换为机器语言指令，传输到CPU内执行;功能程序与系统程序调用则负责调用不同的功能子程序及其管理程序。系统程序属于需长期保存的重要数据，所以其存储器采用ROM或EPROM。

ROM是只读存储器，该存储器只能读出内容，不能写入内容，ROM具有非易失性，即电源断开后仍能保存已存储的内容。EPEROM为可电擦除只读存储器，须用紫外线照射芯片上的透镜窗口才能擦除已写入内容，可电擦除可编程只读存储器还有E2PROM、FLASH等。

1. Central Processing Unit (CPU) The central processing unit (CPU) consists of a controller, an arithmetic device and registers and is integrated in a chip. The CPU is connected to the memory, input/output interface, programmer, and power supply through the data bus, address bus, control bus, and power supply bus.

The CPU of small PLC uses 8-bit or 16-bit microprocessor or single-chip microcomputer, such as 8031, M68000, etc., and the price of such chips is very low; The CPU of medium-sized PLC adopts 16-bit or 32-bit microprocessor or single-chip microcomputer, such as 8086, 96 series single-chip microcomputer, etc., the main features of this kind of chip are high integration, fast computing speed and high reliability; Large PLCS require high-speed bit-chip microprocessors. The CPU commands the PLC control system to complete various tasks according to the function given by the system program in the PLC.

The memory in the PLC is mainly used to store system programs, user programs and data. 1) System program memory PLC system program determines the basic function of PLC, the part of the program written by the PLC manufacturer and solidified in the system program memory, mainly system management program, user instruction interpretation program and function program and system program call and other parts.

The system management program mainly controls the operation of PLC, so that PLC works in the correct order; The user instruction interpreter converts the PLC user instruction into machine language instruction and transmits it to the CPU for execution. Function program and system program call are responsible for calling different function subroutines and their managers. The system program belongs to the important data that needs to be stored for a long time, so its memory uses ROM or EPROM.

ROM is read-only memory, the memory can only read the content, can not write the content, ROM has non-volatile, that is, after the power is disconnected can still save the stored content. EPEROM is electrically erasable read-only memory, which must be irradiated with ultraviolet light on the lens window on the chip to erase the written content, and electrically erasable programmable read-only memory as well as E2PROM, FLASH, etc.