Engineer story sharing(6)

In the 1990s, I didn't go to college. I didn't know that the admission notices of ordinary radio and television universities were true and false. The school conditions were too bad. It was better to read a technical school. At that time, it was the same for amateurs to read a diploma.






The maintenance electrician who studied at the technical school can only test at the intermediate level at most. The PLC is not in the examination outline, so I didn’t study it, but the book still has a bit of content. At that time, the understanding of PLC was to replace the complicated relay control with ladder program. The circuit, the programming method that was understood at the time, replaced the contacts of the relay with the contacts of the ladder diagram.


Until the 6-year-old after working, the original technical school was disbanded, but the teacher responsible for organizing the identification was the teacher of the original technical school. I knew them very well. None of them knew the PLC, so I still had no chance to identify it. Touch to the PLC.






Two years later, the company organized a skill competition, and a professional college near the external committee organized it. At the time of the preliminaries (sub-company level), I knew that I had to test the PLC, but I didn't know what PLC. The result was only a fourth place. I only knew that it was Mitsubishi during the exam. The content of the test was two conveyor belts to transfer fruit boxes, count, Timed start and stop, the logic is very simple, but I can't enter a counter, I don't know if I need to add a K to indicate the number of times, and there is no help document.


I made some preparations in the finals. I didn't have any problems like the last difficulty test. The result was an electroplating production line. It was similar to the crane grabbing the electroplating materials and proceeding up and down in order. According to the thinking of the relay design, I got fainted, but I finally got a few points to perform a few steps. With the solid relay design and wiring advantages, I was lucky to get the first place. At the time, the company had more than 10 technicians who were trained and certified by external teachers.






Since then, I have participated in city-level and provincial-level skill competitions many times. Every time I have access to new content, I feel that I have learned a lot. Later I learned step and servo, multi-degree-of-freedom robots, touch screens, photoelectric switches, and various simulations. Training equipment, tested a senior technician, the competition directly obtained the second-level professional qualification certificate of the programmable control system designer, probably because Mitsubishi PLC is widely used, cheap, and easy to get started, so many vocational colleges choose Mitsubishi PLC as the teaching Training equipment.


2


How do I teach PLC myself?


First of all, to explain, I am just a newbie who has graduated for more than a year. Today is just to exchange and learn.






In November of 2013, I just finished the first semester of the seniors for only 8 weeks, and then started looking for an internship unit. I accidentally found a small company that specializes in machining equipment in my hometown.


Just entering the company is to follow the electrician's wiring and repair. Then the engineers in the company began to ask me to read some books, about PLC, servo, etc., because I learned a little about PLC in school, so I can see the instructions of the PLC can be understood, the servo is completely paralyzed.






Then after three months of this, the electrical engineer handed me the programming and debugging work of a very simple device. This equipment consists of only four cylinders and four motors, and the action flow is only five steps. But at the time, I didn't have any programming experience. I controlled a motor to rotate and stop. This kind of action can be completed. After one move, start the next motor, so it won't.


Then I took the example program that the electrical engineer gave me. There is a text screen on the device, and I copied a few programs. The single-step text screen starts and stops the motor. This has confidence, and later the automatic program was written.






After writing this program, another similar device was debugged. After the two sets of programs were written, the cyclic scans, self-locking interlocks, and the basic seven or eight instructions that were originally seen in the book have been further understood.


Later, I was exposed to servo control and Modbus communication.


Later, I contacted multiple brands of PLCs, then analog, Profibus, and configuration software.


Up to now, it has accumulated some experience. The end of the book is shallow, and the key to PLC learning is practice and constant sentiment. The following is my three steps to learn PLC, and share with you.


The first step: familiar with some basic knowledge of PLC, for example, the working principle of circular scanning, input and output image area, data storage knowledge.


Step 2: Skillfully use several basic instructions. My first second program used normally open contacts, normally closed contacts, coils, set, reset, delay timers and MOV instructions, just seven instructions, and later written programs, 90 Above %, these are the seven instructions. I strongly recommend that beginners first understand the seven instructions, write and play, master the other instructions, and the seven most important.






Step 3: You can try to play the "Advanced" command, such as communication, such as motion control, PID, and so on. There may be a strong sense of frustration at the beginning. After all, the basic instructions are easier to understand and accept, while the advanced instructions are boring and difficult to understand. This time is a real watershed with and without PLC. Everyone will have basic instructions. How can their ability stand out? So bite your teeth and pay a little more, and you will leave a lot of people behind you.


These are some of my experiences. I welcome everyone to share and discuss.


In those days, there was no condition for learning PLC, so create conditions for yourself. Although the conditions are tough, but looking back at the self-study day, I can't help but thank the one who did not give up self-study.
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