UDD406A 数字输入模块 抗干扰能力强

UDD406A 数字输入模块 抗干扰能力强

UDD406A从PLC的硬件结构形式上，PLC可以分为整体固定I/O型，基本单元加扩展型，模块式，集成式，分布式5种基本结构形式。
PLC的组成  ：
UDD406A
中央处理单元(CPU)是PLC的控制中枢，是PLC的核心起神经中枢的作用，每套PLC至少有一个CPU。它按照PLC系统程序赋予的功能接收并存储从编程器键入的用户程序和数据；检查电源、存储器、I/O以及警戒定时器的状态，并能诊断用户程序中的语法错误。当PLC投入运行时，首先它以扫描的方式接收现场各输入装置的状态和数据，并分别存入I/O映象区，然后从用户程序存储器中逐条读取用户程序，经过命令解释后按指令的规定执行逻辑或算数运算的结果送入I/O映象区或数据寄存器内。等所有的用户程序执行完毕之后，zui后将I/O映象区的各输出状态或输出寄存器内的数据传送到相应的输出装置，如此循环运行，直到停止运行。
为了进一步提高PLC的可靠性，对大型PLC还采用双CPU构成冗余系统，或采用三CPU的表决式系统。这样，即使某个CPU出现故障，整个系统仍能正常运行。
CPU速度和内存容量是PLC的重要参数，它们决定着PLC的工作速度，I/O数量及软件容量等，因此限制着控制规模。
UDD406A
系统程序存储器是存放系统软件的存储器；用户程序存储器是存放PLC用户程序应用;数据存储器用来存储PLC程序执行时的中间状态与信息，它相当于PC的内存。
UDD406A
PLC与电气回路的接口，是通过输入输出部分（I/O）完成的。I/O模块集成了PLC的I/O电路，其输入暂存器反映输入信号状态，输出点反映输出锁存器状态。输入模块将电信号变换成数字信号进入PLC系统，输出模块相反。I/O分为开关量输入（DI），开关量输出（DO），模拟量输入（AI），模拟量输出（AO）等模块。

UDD406A 数字输入模块 抗干扰能力强

UDD406A From the PLC hardware structure form, PLC can be divided into the whole fixed I/O type, basic unit plus expansion type, modular, integrated, distributed 5 basic structure forms.
Composition of PLC:
UDD406A
The central processing unit (CPU) is the control center of the PLC, the core of the PLC plays the role of the nerve center, and each PLC has at least one CPU. It receives and stores the user programs and data entered from the programmer according to the function given by the PLC system program; Check the status of power supply, memory, I/O, and alarm timers, and diagnose syntax errors in user programs. When the PLC is put into operation, it first receives the status and data of each input device in the field by scanning, and stores them into the I/O image area, and then reads the user program one by one from the user program memory, and sends the results of logic or arithmetic operations into the I/O image area or data register after command interpretation according to the instructions. After all the user programs are executed, the data in each output state or output register in the I/O image area is finally transmitted to the corresponding output device, and so the cycle runs until it stops running.
In order to further improve the reliability of the PLC, the large PLC is also used to form a redundant system with two cpus, or a three-CPU voting system. In this way, even if one CPU fails, the whole system can still run normally.
CPU speed and memory capacity are important parameters of PLC, which determine the working speed of PLC, the amount of I/O and the software capacity, and therefore limit the control scale.
UDD406A
System program memory is the memory that stores system software. The user program memory is to store the PLC user program application; The data memory is used to store the intermediate state and information when the PLC program is executed, which is equivalent to the memory of the PC.
UDD406A
The interface between the PLC and the electrical circuit is completed through the input and output part (I/O). I/O module integrates PLC I/O circuit, the input register reflects the input signal state, the output point reflects the output latch state. The input module converts the electrical signal into a digital signal into the PLC system, and the output module is the opposite. I/O is divided into switching input (DI), switching output (DO), analog input (AI), analog output (AO) and other modules.

UDD406A 数字输入模块 抗干扰能力强