We all know that electrical engineering is a complex field. Today, we'll take PLC programming as an example to discuss how to improve your skills. PLC control is used in actual engineering projects, so the level of system design directly affects the entire control system and the reliability of equipment operation! Do you agree?
So how can we design a stable, reliable, safe, easy-to-debug, and easy-to-maintain control system based on different control requirements? This is also a question we need to consider when designing PLC control systems.
Let's first understand the principles that should be followed in system design.
The engineering design of a PLC control system can generally be divided into five basic steps: system planning, hardware design, software design, system debugging, and technical document preparation.
The following are the basic design principles:
1. First, all operations of the equipment, production machinery, and production processes must be completed;
2. The design aims to meet the equipment's requirements for product processing quality and production efficiency;
3. Ensure the system operates safely, stably, and reliably;
4. Simplify the control system structure as much as possible to reduce production costs;
5. Maximize automation levels to reduce labor costs;
6. Improved operational performance and facilitated future maintenance.
Of the design principles mentioned above, I believe the most important are meeting system control requirements, ensuring system safety and reliability, and simplifying the system structure. Below, I will explain why each of these principles are important.
I. Meet system control requirements
The design of a PLC control system must ensure that it can realize all the actions of the object and meet all the technical requirements of the object.
Therefore, before designing a system, designers must go deep into the production site or conduct research on the mechanical, pneumatic, and hydraulic components and working principles of the controlled object to fully understand the actions that the equipment or machinery needs to perform and the functions it should have, as well as the performance and parameters of various actuators, etc. Then, designers need to plan the control system and determine the overall system scheme.
II. Ensure system security and reliability
In the specific technical design phase after the overall system scheme is determined, designers must first consider the system's safety and reliability to ensure that the control system can work safely, stably, and reliably for a long time.
In terms of system safety, it includes ensuring the personal safety of operators and the safety of equipment. Therefore, the system design must comply with various relevant safety standards and fully consider various safety protection measures, such as safety circuits and safety protection.
For components involving personal safety, strict action "interlocking" and similar measures must be implemented in the design of the electrical control system. For example, the forward and reverse contactors of motors should be "interlocked" in operation. These interlocks cannot only be implemented in the PLC user program, but must also be guaranteed in the high-voltage control circuit to prevent accidents that endanger equipment safety.
III. Simplify System Structure
Under the premise of meeting the various control requirements of the controlled object, ensuring system safety and reliability, and not affecting the system's control level and function, our system design should be as simple and practical as possible.
Simplifying the system architecture is not only necessary to reduce manufacturing costs, but also an important measure to improve system reliability.
So what does this simplified system include? The simplified system includes several aspects such as simplified operation, simplified routing, and simplified procedures.
1. For example, we can provide a user-friendly interface to make operation and use as convenient as possible, or minimize unnecessary control buttons and other operating elements.
2. Alternatively, the system control circuit design should be as simple as possible, minimizing unnecessary control components and wiring. Simple and practical control circuits not only reduce manufacturing costs, but more importantly, they improve the safety and reliability of the system, making it easier for users to operate and maintain.
3. PLC user programs should also be simplified as much as possible. The instructions used should be as concise as possible. Avoid making the program more complicated or making it more difficult for others to understand.
4. When using ladder diagram programming, minimize the number of unnecessary auxiliary relays and contacts. Excessive auxiliary relays and contacts not only affect program execution speed and prolong loop scan time, but also create unnecessary trouble for program checking and reading.
