A-B 1771-NC6 罗克韦尔 PLC模块

A-B 1771-NC6 罗克韦尔 PLC模块

1、主机

主机部分包括处理器(CPU)、程序存储器和用户程序及数据存储器。CPU是PLC的核心，它用以运行用户程序、监控输入/输出接口状态、作出逻辑判断和进行数据处理，即读取输入变量、完成用户指令规定的操作，将结果送到输出端，并响应外部设备(如电脑、打印机等)的请求以及进行内部判断等。

PLC的内部存储器有两类，一类是程序存储器，主要存放和监控程序及对用户程序作编译处理的程序，程序已由厂家固定，用户不能更改;另一类是用户程序及数据存储器，主要存放用户编制的应用程序及暂存数据和中间结果。

2、输入/输出(I/O)接口

I/O接口是PLC与输入/输出设备连接的部件。输入接口接受输入设备(如按钮、传感器、触点、行程开关等)的控制。输出接口是将主机经处理后的结果通过功放电路去驱动输出设备(如器、电磁阀、指示灯等)。

I/O接口一般采用光电耦合电路，以电磁，从而了可靠性。I/O点数即输入/输出端子数是PLC的一项主要技术指标，通常小型机有几十个点，中型机有几百个点，大型机将千点。

1. Host computer

The host part includes the processor (CPU), program memory and user program and data memory. The CPU is the core of the PLC, which is used to run the user program, monitor the input/output interface status, make logical judgments and data processing, that is, read the input variables, complete the operation specified by the user's instructions, send the results to the output, and respond to the requests of external devices (such as computers, printers, etc.) and make internal judgments.

The internal memory of PLC has two types, one is the program memory, mainly store and monitor the program and compile the program for the user program, the program has been fixed by the manufacturer, the user can not change; The other is the user program and data memory, which mainly stores the application program prepared by the user and stores the temporary data and intermediate results.

2, input/output (I/O) interface

The I/O interface is the part that connects the PLC to the input/output device. The input interface accepts control from input devices such as buttons, sensors, contacts, travel switches, etc. The output interface is the result of the host after processing through the power amplifier circuit to drive the output device (such as the device, solenoid valve, indicator light, etc.).

I/O interfaces generally use photoelectric coupled circuits to electromagnetic, thus ensuring reliability. I/O points, that is, the number of input/output terminals is a major technical indicator of PLC, usually minicomputers have dozens of points, medium-sized machines have hundreds of points, and mainframes will have thousands of points.