PLC开关量输出类型大致分为三种，继电器输出型、晶体管输出型和可控硅输出型。继电器输出交流直流都可以，晶体管常见有5VDC和24VDC输出，可控硅比较少见，只有特殊输出型号才有。 考虑选用的输出模块类型，通常继电器输出模块具有价格低、使用电压范围广、导通压降小n

PLC的工作原理为：当PLC控制器投入运行后，其工作过程一般分为三个阶段，即输入采样、用户程序执行和输出刷新三个阶段。完成上述三个阶段称作一个扫描周期。1、输入采样阶段在输入采样阶段，PLC控制器以扫描方式依次地读入所有输入状态和数据，并将它们存入I/O映象区中的相应得单元内。输入采样结束后，转入用户程序执行和输出刷新阶段。2、用户程序执行阶段在用户程序执行阶段，PLC控制器总是按由上而下的顺序依次地扫描用户程序(梯形图)。3、输出刷新阶段当扫描用户程序结束后，PLC控制器就进入输出刷新阶段。在此期间，CPU按照I/O映象区内对应的状态和数据刷新所有的输出锁存电路，再经输出电路驱动相应的外设。
模块电源是可以直接贴装在印刷电路板上的电源供应器，可为专用集成电路（ASIC）、数字信号处理器 (DSP)、微处理器、存储器、现场可编程门阵列 (FPGA) 及其他数字或模拟负载提供供电。一般来说，这类模块称为负载 (POL) 电源供应系统或使用点电源供应系统 (PUPS)。由于模块式结构的优点明显，因此模块电源广泛用于交换设备、接入设备、移动通讯、微波通讯以及光传输、路由器等通信领域和汽车电子、航空航天等。
●设计简单。只需一个电源模块，配上少量分立元件，即可获得电源。

●缩短开发周期。模块电源一般备有多种输入、输出选择。用户也可以重复迭加或交叉迭加，构成积木式组合电源，实现多路输入、输出，大大削减了样机开发时间。
●变更灵活。产品设计如需更改，只需转换或并联另一合适电源模块即可。
●技术要求低。模块电源一般配备标准化前端、高集成电源模块和其他元件，因此令电源设计更简单。
●模块电源外壳有集热沉、散热器和外壳三位一体的结构形式，实现了模块电源的传导冷却方式，使电源的温度值趋近于最小值。同时，又赋予了模块电源规范性的包装。
●质优可靠。模块电源一般均采用全自动化生产，并配以高科技生产技术，因此品质稳定、可靠。
●用途广泛：模块电源可广泛应用于航空航天、机车舰船、军工兵器、发电配电、邮电通信、冶金矿山、自动控制、家用电器、仪器仪表和科研实验等社会生产和生活的各个领域，尤其是在高可靠和高技术领域发挥着不可替代的重要作用。

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PLC switch output types can be roughly divided into three types: relay output type, transistor output type, and thyristor output type. Relay outputs can be both AC and DC. Transistors commonly have 5VDC and 24VDC outputs, while thyristors are relatively rare and only available in special output models. Consider the type of output module to choose, usually relay output modules have low price, wide voltage range, and small conduction voltage drop

The working principle of PLC is that after the PLC controller is put into operation, its working process is generally divided into three stages, namely input sampling, user program execution, and output refreshing. Completing the above three stages is called a scanning cycle. 1. In the input sampling stage, the PLC controller sequentially reads in all input states and data in a scanning manner, and stores them in the corresponding units in the I/O image area. After the input sampling is completed, it enters the user program execution and output refresh phase. 2. During the user program execution phase, the PLC controller always scans the user program (ladder diagram) in a top-down order. 3. After scanning the user program, the PLC controller enters the output refresh stage. During this period, the CPU refreshes all output latch circuits according to the corresponding state and data in the I/O image area, and then drives the corresponding peripherals through the output circuit.
Module power supply is a power supply that can be directly mounted on printed circuit boards, providing power for specialized integrated circuits (ASICs), digital signal processors (DSPs), microprocessors, memory, field programmable gate arrays (FPGAs), and other digital or analog loads. Generally speaking, these types of modules are referred to as load (POL) power supply systems or point of use power supply systems (PUPS). Due to the obvious advantages of modular structure, modular power supplies are widely used in communication fields such as switching devices, access devices, mobile communication, microwave communication, optical transmission, routers, and automotive electronics, aerospace, etc.
The design is simple. Only one power module with a small number of discrete components is needed to obtain the power supply.

Shorten the development cycle. Modular power supplies generally come with multiple input and output options. Users can also repeat or cross stack to form a modular combination power supply, achieving multiple inputs and outputs, greatly reducing prototype development time.
● Flexible changes. If the product design needs to be changed, simply convert or connect another suitable power module in parallel.
Low technical requirements. Modular power supplies are generally equipped with standardized front-end, highly integrated power modules, and other components, making power supply design simpler.
The module power supply housing has a three in one structure of heat sink, heat sink, and housing, which realizes the conduction cooling method of the module power supply, making the temperature value of the power supply close to the minimum value. At the same time, it also endows the module power supply with standardized packaging.
High quality and reliability. Modular power supplies are generally produced with full automation and high-tech production technology, resulting in stable and reliable quality.
Widely used: Modular power supplies can be widely used in various fields of social production and life, such as aerospace, locomotives and ships, military weapons, power generation and distribution, postal and telecommunications, metallurgy and mining, automatic control, household appliances, instruments and meters, and scientific research experiments, especially in highly reliable and high-tech fields, playing an irreplaceable important role.