First of all, compared with the learning of other programming languages, the development of PLC will be more difficult. For example, if you want to learn the development of PHP and java, you can buy some video tutorials to learn and develop on your own computer. And generally only need to work in the office, or even at home. If your local computer project can run, it can basically run on the server. If it can't run, it is generally a problem of the software version and class library configured by the server and the permissions.
But for the development and learning of PLC, it will be more difficult, because when you are doing the Internet of Things system, the factors to be considered are not only simple code, but also stronger logical ability and practical experience. For example, if you need to complete a packaging assembly line and the goods need to be packaged or coated, you may need to do some other actions. At this time, you should not only consider the signal sent back by the machine, but also consider the time to make a judgment. There are also some induction lamp, which you need to test on the spot. PLC engineers need not only professional technical ability, but also some electrical knowledge. Testing on the spot doesn't really send a worker around you all day. You need to debug every electrical component you need yourself. Naturally, you also need some communication skills. If you have been a supervisor, you will understand that building a good relationship with the construction team is not only about your own identity, but also about integrating with them, because helping you with the test is actually just a help and will not give them more salary.
The above is what I realized in the real project. Although I'm not a PLC engineer, a senior PLC engineer with more than ten years' experience told me that if no one takes care of this line of PLC, even if I work for 7-8 years, I won't have my own ability. Therefore, my suggestion is that although we should specialize in our own research, the most important thing is to join a company, humbly ask the old-timers inside, and learn from other people's experience while acquiring technology.
Having said that, this is my first time to answer questions related to PLC, but because I admire PLC engineers very much, I still answered your questions. I hope you can succeed.