700-PKT B 使用说明现货供应

详情描述：

整体式PLC的每一个I／O点的平均价格比模块式的便宜，且体积相对较小，所以一般用于系统工艺过程较为固定的小型控制系统中；而模块式PLC的功能扩展灵活方便，I／O点数量、输入点数与输出点数的比例、I／O模块的种类等方面，选择余地较大。维修时只要更换模块，判断故障的范围也很方便。因此，模块式PLC一般适用于较复杂系统和环境差（维修量大）的场合。根据PLC的安装方式，系统分为集中式、远程I／O式和多台PLC联网的分布式。集中式不需要设置驱动远程I／O硬件，系统反应快、成本低。大型系统经常采用远程I／O式，因为它们的装置分布范围很广，远程I／O可以分散安装在I／O装置附近，I／O连线比集中式的短，但需要增设驱动器和远程I／O电源。多台联网的分布式适用于多台设备分别独立控制，又要相互联系的场合，可以选用小型PLC，但必须要附加通信模块。 一般小型（低档）PLC具有逻辑运算、定时、计数等功能，对于只需要开关量控制的设备都可满足。对于以开关量控制为主，带少量模拟量控制的系统，可选用能带A／D和D／A单元。具有加减算术运算。数据传送功能的增强型低档PLC。对于控制较复杂，要求实现PID运算、闭环控制、通信联网等功能，可视控制规模大小及复杂程度，选用中档或PLC。但是中PLC价格较贵，一般大型机主要用于大规模过程控制和集散控制系统等场合。PLC的扫描工作方式引起的延迟可达2－3个扫描周期。对于大多数应用场合来说，PLC的响应速度都可以满足要求，不是主要问题。然而对于某些个别场合，则要求考虑PLC的响应速度。为了减少PLC的I／O响应的延迟时间，可以选用扫描速度高的PLC，或选用具有高速I／O处理功能指令的PLC，或选用具有快速响应模块和中断输入模块的PLC等。
The average price of each I / o point of the integrated PLC is cheaper than that of the modular PLC, and the volume is relatively small, so it is generally used in the small control system with relatively fixed system process; The function expansion of modular PLC is flexible and convenient. There is a large choice in the number of I / O points, the ratio of input points to output points, the types of I / O modules and so on. As long as the module is replaced during maintenance, it is also convenient to judge the fault range. Therefore, modular PLC is generally suitable for complex systems and poor environment (large amount of maintenance). According to the installation mode of PLC, the system is divided into centralized, remote I / O and distributed with multiple PLC networking. The centralized system does not need to set up remote I / O hardware, so the system has fast response and low cost. Large systems often adopt remote I / O type, because their devices are widely distributed. Remote I / O can be installed around I / O devices in a decentralized manner. The I / O connection is shorter than that of centralized ones, but it is necessary to add drivers and remote I / O power supply. The distributed of multiple networked devices is applicable to the occasions where multiple devices are controlled independently and connected with each other. Small PLC can be selected, but communication module must be added. Generally, small (low-grade) PLC has the functions of logic operation, timing, counting and so on, which can be satisfied for the equipment that only needs switching value control. For the system dominated by switching value control and with a small amount of analog control, a / D and D / a units can be selected. With addition and subtraction arithmetic operation. Enhanced low-grade PLC with data transmission function. For complex control, it is required to realize PID operation, closed-loop control, communication networking and other functions. Depending on the control scale and complexity, medium-grade or PLC shall be selected. However, the price of PLC is relatively expensive, and the general mainframe is mainly used in large-scale process control and distributed control system. The delay caused by the scanning mode of PLC can reach 2-3 scanning cycles. For most applications, the response speed of PLC can meet the requirements, which is not the main problem. However, for some individual occasions, it is required to consider the response speed of PLC. In order to reduce the delay time of I / O response of PLC, PLC with high scanning speed, PLC with high-speed I / O processing function command, PLC with fast response module and interrupt input module can be selected.