Input sampling stage

In the input sampling stage, PLC scan mode sequentially reads all input states and data, and store them in the I / O image area corresponding the unit. After the end of the input plc analog input module sample, into the user program execution and output refresh period. In both stages, and even if the input data changes state, status, and data I / O of the image area of the corresponding cell is not changed. Therefore, if the input is a pulse signal, the width of the pulse signal

plc analog input output io module

must be greater than one scanning cycle, in order to ensure that in any case, the input can be read.

Output Wiring

Programmable controller with relay output, thyristor output, transistor output three kinds of forms. The output wiring into separate output and common output. When the PLC output relay or programmable logic controller plc thyristor action, the two outputs of the same number of turns. In different groups, and the voltage level can be different types of output voltage. However, the output in the same group only of the same type, the same level of power supply voltage. Since the output Plc high speed counting modules element of the PLC is encapsulated in a printed circuit board and connected to the terminal board, the load connected to the output element shorted If the burning of printed circuit board, therefore, the application of the fuse to protect the output element.

I / O modules

PLC interface with the electrical circuit, the input and output section by the (I / O) completion. I / O modules with integrated PLC's I / O circuit, the input signal status register reflects the input and output points to reflect the state of the output latch. The programmable logic controller input module signals into the electrical signals into digital PLC system, the opposite output module. I / O into the digital input (DI), digital output (DO), analog input (AI), analog output (AO) and other modules. Switch means that only the opening and closing (or 1 and 0) signals, analog two states refers to continuous change. Commonly used I / O classified as follows: Switch: Press voltage level points with 220VAC, 110VAC, 24VDC, by isolating way points, with relay isolation and transistor isolation. Analog: divided by signal type, there is a current type (4-20mA, 0-20mA), voltage type (0-10V, 0-5V, -10-10V), etc., according to the accuracy of points, there are 12bit, 14bit, 16bit, etc. . In addition to the general Plc analog input output module purpose IO, there are special IO modules, such as thermal resistance, thermocouple, pulse and other modules. Press the I / O module specifications and determine the number of points, I / O modules can be more or less, but its maximum number of CPU capacity can be managed by the basic configuration, namely by the largest floor or rack slot limit.　　

Plc high speed counting modules basics

Plc high speed counting modules: PLC English stands for Programmable Logic Controller, Chinese called the programmable logic controller programmable logic controller, is defined as: an electronic digital computing system operation, designed for use in industrial environments and design. It uses a programmable memory for storing its internal procedures, to perform logical, sequential control, timing, counting and arithmetic user-oriented operating instructions, and through digital or analog input / output control of all types of machinery or production processes. DCS Distributed Control System: DCS English name DISTRIBUTED CONTROL SYSTEM, Chinese called the Distributed Control System. DCS may be interpreted as the analog loop control more widely used in the industry, as the risk resulting from Plc analog input output module the decentralized control, and management of an automated high-tech products, and display the concentration. DCS generally consists of five parts: 1: Controller 2: I / O board 3: Operating Station 4: Communication Network 5: Graphics and pass away software.