Today, I'd like to share with you some experiences and suggestions for learning PLC programming!
- Learning PLC programming requires strong perseverance and ample patience.
Everyone has their strengths. Some view programming as a lengthy and tedious task, while others see it as an intriguing intellectual game. When seeing symbols neatly arranged according to one's own logic, and the PLC operating methodically as per my instructions, one's personal interest is greatly satisfied.
- Learning PLC programming necessitates the courage to practice and experiment.
Only by continuously executing these instructions on the PLC and observing the results can one truly understand the functions of PLC instructions.
Many beginners approach PLC with confusion, often stemming from fear of damaging the equipment. However, these fears are unfounded. While thoroughly reading the manual is crucial, relying solely on books will not make one an engineer. Furthermore, manuals cannot cover every aspect. When encountering unfamiliar instructions, I prefer to create a small program and run it on the PLC. By modifying conditions one by one and observing the results (MicroWin provides excellent monitoring tools), I can then reinterpret the manual's descriptions, gaining a more intuitive understanding of the instructions' functions and usage methods. There's no need to worry about the program causing issues or affecting the PLC's normal operation. Only by running the PLC can one discover if there are any problems with the program.
Discovering and solving problems is a testament to one's growing competence. Setting aside hardware operations, I have yet to encounter a situation where software issues damaged a PLC solely from a software perspective. Here, there's no need to fear the consequences of miswired relay circuits. Therefore, bold experimentation is the inevitable path in PLC programming. Of course, bold experimentation does not equate to reckless operation; it must adhere to necessary norms. Additionally, it's crucial to note that before confirming the program's reliability, never connect loads to avoid unnecessary losses. LED displays can indicate digital outputs, while analog processing can be addressed through hardware or software simulation methods.
- Learning PLC programming necessitates rigorous logical thinking.
Programming itself is a process of logical thinking. In high-level languages, conditional statements such as "if-then-else" and "select" are frequently used, embodying the causal relationship in logic. PLC programs are composed of these causal relationships: evaluating whether conditions are met and subsequently executing corresponding instructions. Initially, PLCs were designed to replace relay logic circuits, thus inheriting the descriptive approach of using contacts as trigger conditions from relay circuits.
In PLCs, virtual contacts replace the metal contacts of relays, but the logical relationships expressed by relay circuits are fully preserved. Even with the introduction of numerical processing that relay circuits struggle to handle, PLCs fundamentally still execute individual causal relationships. Therefore, meticulously organizing the logical relationships among various events of the object is a crucial preparatory step before programming. When I receive a task, my first action is to compile a logical relationship diagram, discuss it with the user repeatedly, and obtain their approval before proceeding with the actual programming process.
- Essential Knowledge Indispensable for Learning PLC
The program of a PLC directly interacts with the specific process of the target object, making an understanding of the object's specific process paramount. During my interactions with users, I utilize my knowledge of Unit Operations to analyze their process, assist them in organizing the various logical relationships within process control, and even include the configuration of various instruments and hardware.
- Cultivating Good Programming Habits for Learning PLC
Each individual has their unique programming habits and characteristics, and it is not feasible to enforce uniformity. However, there are some good habits that should be followed by the majority. Firstly, clarify logical and timing relationships, and create a program flowchart. Secondly, allocate the main program, subroutines, and interrupt routines appropriately. Thirdly, allocate registers wisely and create a register symbol table.
Lastly, PLCs offer a vast array of instructions and modules, making them significantly more convenient than microcontrollers. However, as a beginner, it is advisable to start with simple instructions to achieve your objectives, even if it may seem rudimentary. This approach serves as a solid foundation for entry and will aid in understanding more complex instructions. Once you have gained some experience, you should consider mastering the application of complex instructions and optimizing your programs.