These topics are all good. But things related to the system can't be debugged without physical objects. Therefore, you can only choose what you can find in kind. PLC is easier to use. The assembly language of single chip microcomputer is basically the same as that of PLC. If we can handle one, the other will soon be.

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These topics can find some physical objects relatively. If you have a PLC at hand, of course it's easy. If there is no PLC, I think MCU is your choice. The cheapest PLC is only a few hundred dollars. Single chip microcomputer is cheap. Go to Taobao to buy a best seller. That product is generally used by more people. The seller also has some technical support. You can also join some QQ groups or something. See more websites for these studies. Don't watch everything, download everything. Find a few with ready-made things. Do more. If you have a computer once, it is better to watch it ten thousand times. Have confidence. Just make up your mind to learn!