PW481-50 YOKOGAWA 输入输出模块

PW481-50 YOKOGAWA 输入输出模块

PW481-50 YOKOGAWA 输入输出模块

简单可编程逻辑控制器的运算功能包括逻辑运算、计时和计数功能;普通可编程逻辑控制器的运算功能还包括数据移位、比较等运算功能;较复杂运算功能有代数运算、数据传送等;大型可编程逻辑控制器中还有模拟量的PID运算和其他高级运算功能。随着开放系统的出现，在可编程逻辑控制器中都已具有通信功能，有些产品具有与下位机的通信，有些产品具有与同位机或上位机的通信，有些产品还具有与工厂或企业网进行数据通信的功能。

设计选型时应从实际应用的要求出发，合理选用所需的运算功能。大多数应用场合，只需要逻辑运算和计时计数功能，有些应用需要数据传送和比较，当用于模拟量检测和控制时，才使用代数运算，数值转换和PID运算等。要显示数据时需要译码和编码等运算。

控制功能包括PID控制运算、前馈补偿控制运算、比值控制运算等，应根据控制要求确定。可编程逻辑控制器主要用于顺序逻辑控制，因此，大多数场合常采用单回路或多回路控制器解决模拟量的控制，有时也采用专用的智能输入输出单元完成所需的控制功能，提高可编程逻辑控制器的处理速度和节省存储器容量。例如采用PID控制单元、高速计数器、带速度补偿的模拟单元、ASC码转换单元等。

PW481-50 YOKOGAWA 输入输出模块

The operation function of simple programmable logic controller includes logic operation, timing and counting function; The arithmetic function of ordinary programmable logic controller also includes the arithmetic function of data shift and comparison. More complex operation functions include algebraic operation, data transfer, etc. The large programmable logic controller also has analog PID operation and other advanced operation functions. With the emergence of open systems, programmable logic controllers have communication functions, some products have communication with the next machine, some products have communication with the peer machine or host computer, and some products also have the function of data communication with the factory or enterprise network.

Design and selection should be based on the requirements of practical applications, reasonable selection of the required computing functions. Most applications only need logical operations and timing and counting functions, some applications need data transfer and comparison, when used for analog detection and control, only use algebraic operations, numerical conversion and PID operations. Operations such as decoding and encoding are required to display the data.

The control function includes PID control operation, feedforward compensation control operation, ratio control operation, etc., which should be determined according to the control requirements. Programmable logic controller is mainly used for sequential logic control, therefore, most occasions often use a single loop or multi-loop controller to solve the analog control, and sometimes also use a dedicated intelligent input and output unit to complete the required control functions, improve the processing speed of programmable logic controller and save memory capacity. For example, PID control unit, high-speed counter, analog unit with speed compensation, ASC code conversion unit, etc.