FM131A HollySys Base Module, Shanghai Sijian Intelligent Technology Co., Ltd. is engaged in technical development, technical consultation, technical transfer in the fields of intelligent technology, information technology, and automation technology, as well as the sales of electrical equipment, automation equipment, electronic products, communication products, and electromechanical products. Industrial automation products: PLC, DCS, sensors, frequency converters, encoders, relays, servo drives, soft starters, touch screens. Brands involved in the products include: Eurotherm, Schneider, Siemens, ABB, SICK, P+F, E+H, Yokogawa, Yamakawa, Mitsubishi, Emerson, Honeywell, FANUC, GE, Eaton Electrical, CT
Basic Steps in Designing a Programmable Logic Controller Control System
Main Content of FM131A HollySys Base Module System Design
(1) Formulate the technical conditions for the control system design. Technical conditions are generally determined in the form of a design task book, which serves as the basis for the entire design;
(2) Select the electrical drive form and actuators such as motors and solenoid valves;
(3) Determine the model of the PLC;
(4) Prepare the PLC input/output allocation table or draw the input/output terminal wiring diagram;
(5) Write the software specification according to the system design requirements, and then use the corresponding programming language (commonly ladder diagram) for program design;
(6) Understand and follow user cognitive psychology, pay attention to the design of the human-machine interface, and enhance the friendly relationship between humans and machines;
(7) Design the operating console, electrical cabinet, and non-standard electrical components;
(8) Write the design manual and user manual;
Depending on the specific task, the above content can be appropriately adjusted. (2) Selection of Storage Capacity
The user storage capacity can only be roughly estimated. In systems that only control switching values, it can be estimated by multiplying the total number of input points by 10 words/point plus the total number of output points multiplied by 5 words/point; counters/timers are estimated at (3 to 5) words/each; when there is arithmetic processing, estimate at (5 to 10) words/quantity; in systems with analog input/output, it can be estimated that each input (or output) channel of analog signal requires about (80 to 100) words of storage capacity; when there is communication processing, roughly estimate at more than 200 words per interface. Generally, a margin of 50 to 100% of the estimated capacity is reserved. For inexperienced designers, a larger margin should be left when selecting capacity.
(3) Selection of I/O Response Time
The I/O response time of a PLC includes input circuit delay, output circuit delay, and time delay caused by the scanning working mode (generally 2 to 3 scanning cycles). For switching control systems, the PLC and I/O response time can generally meet the requirements of practical engineering, and the I/O response issue may not need to be considered. However, for analog control systems, especially closed-loop systems, this issue must be considered.