Understand the five main points of PLC program planning!

1. Security runs through the whole process The most important thing about security is to pay attention to ideology; Then, it should be supplemented by technical means. Here, although the word "auxiliary" is used, it should not be underestimated. It is important to note the weight of the word "ensure"; This is to highlight the importance of "ideological focus". On the basis of in-depth and comprehensive understanding of the control objectives and process, considering the operation safety, we should try our best to deal with the accidental and unsafe elements in the operation or action process, and prepare a process compliant, safe, reliable, easy to operate and convenient to maintain control procedures. Of course, the improvement of the security system is also an aspect. 2. Advance preparation is a prerequisite The importance of early preparation is believed to be well known by many friends, including the understanding of the control requirements, the overall planning ideas, and even the grasp of relevant common sense and basic common sense. Please refer to the previous two summaries. Similarly, many friends will know that the first step is to prepare in advance, and the second is to grasp the PLC hardware wiring and software operation. In a broad sense, learning PLC is also a cumulative process, which can also be summed up in the "preparatory work". This is called preparing for a rainy day. Opportunities favor those who are prepared. 3. The program structure must be reasonably arranged The structure of a good program should be clear and reasonable, which can facilitate the reading and debugging of the program; When the amount of programs is large or the control is messy, pay attention to the use of planning methods and programming skills. "The program architecture is very important", which means that the use of subprograms not only reduces the program capacity, but also increases the readability, which facilitates the debugging and modification of the program. Usually, when practicing programming or preparing small programs, if you have time, you can do this kind of practice, for example, choose different plans and different ideas to compare, so as to broaden your ideas and gain experience. 4. Program debugging is an integral part It is necessary to debug the compiled program to discover faults and improve functions. Debugging is divided into simulation debugging (imitating the actual situation) and on-site debugging; Only the programs approved by on-site commissioning and operation are available. In addition, it is necessary to consider the debugging comprehensively, list as many situations as possible, including misoperation, poor components, and sudden power failure, and pay attention to the cooperation between PLC and peripheral circuits. PLC is an integral part of the control system, so it is necessary to consider it in the whole system. 5. In normal learning and heap Some common sense and experience need to rely on ordinary accumulation, which is the actual experience of many friends. PLC programming itself, especially the basic use of small PLC, is generally easy. For example, some people have used Mitsubishi FX2N, Siemens 200 and Panasonic FP0, and feel that it is easy to start with the basic instructions; For functional instructions, after consulting manuals and conducting brief experiments, they can also meet most of the programming needs. But for medium-sized PLC, more common sense is needed. Some experienced people emphasized the necessity of starting, "Learn by doing, learn by doing, and achieve great results through repetition"; "I feel that I still need to practice and learn quickly. If I don't do it, I will forget it". Also use the existing conditions to learn. In fact, many experiences can be gained in maintenance, such as other people's good methods and shortcomings, including the function of the program and circuit planning, which can be used in future planning.