Today, I would like to share some experiences and advice from an expert regarding learning PLC programming!
1. Learning PLC programming requires strong willpower and sufficient patience
Everyone has their strengths. Some people view programming as a tedious and lengthy task; others see it as an interesting intellectual game. When I see symbols arranged neatly according to my thoughts, and the PLC operates in an orderly manner according to my requirements, my personal interest is greatly satisfied.
2. Learning PLC programming requires the confidence to practice boldly
Only by continuously running these instructions on the PLC and observing the results can one understand the function of PLC instructions.
Many beginners feel confused about PLCs, often due to fear of damaging the equipment. However, this fear is unfounded. Carefully reading the manual is very important, but merely reading will not make one an engineer. Moreover, the content in the manual is not exhaustive. When I encounter unfamiliar instructions, I like to write a small program to run on the PLC. Then, I modify the conditions one by one and observe the results (MicroWin provides excellent monitoring tools for users), which allows me to understand the descriptions in the manual more intuitively. There is no need to worry that the programs I write will cause issues that affect the normal operation of the PLC. The only way to discover if there are problems with the program is to run it on the PLC.
Identifying and solving problems is a way to improve one’s abilities. Setting aside hardware operations, I have not encountered any cases where software issues damaged the PLC. There is no need to worry about the consequences of incorrectly connecting relay circuits. Therefore, bold practice is an essential path in PLC programming. Of course, bold practice does not mean reckless operation; it must follow necessary standards. One more thing to note is that before the program has been reliably verified, do not connect loads to avoid unnecessary losses. Digital outputs can be displayed with LEDs; analog processing can be addressed using some hardware or software simulation methods.
3. Learning PLC programming requires meticulous logical thinking
Programming itself is a logical thinking process. In high-level languages, the most commonly used conditional statements are if-then-else and select, which represent causal relationships in logic. PLC programs are composed of these causal relationships: determining whether conditions are met and then deciding to execute corresponding instructions. The original PLC was designed to replace relay logic circuits, thus inheriting the description method of using contacts as trigger conditions.
In PLCs, virtual contacts replace the metal contacts of relays, while the logical relationships expressed by relay circuits are still preserved. Even when introducing numerical processing that relays cannot handle, PLCs fundamentally execute a series of causal relationships. Therefore, clarifying the logical relationships between various events is a crucial preparatory step before programming. After receiving a task, the first thing I do is organize a logic relationship diagram, discuss it repeatedly with the user, and obtain their approval before truly entering the programming process.
4. Relevant knowledge is indispensable for learning PLC
The PLC program directly affects the specific process of the object, so understanding the specific process is very important. In my communication with users, I analyze their processes using my knowledge of Unit Operations, assisting them in organizing the various logical relationships in process control, including the configuration of various instruments and hardware.
5. Good programming habits are essential for learning PLC
Everyone has different habits and characteristics in programming, and uniformity cannot be forced. However, some good habits should be followed by most people. First, clarify logical and timing relationships and create program flowcharts; second, allocate main programs, subprograms, and interrupt programs reasonably; third, allocate registers appropriately and create a register symbol table.
Finally, PLCs provide a wealth of instructions and modules, making them much more convenient than microcontrollers. However, beginners should try to use simple instructions to achieve their goals. Although it may seem a bit rudimentary, it is a good way to get started and will help you understand more complex instructions. Once you have gained some experience, you should consider mastering the application of complex instructions and optimizing your programs.