How to learn PLC? How to learn PLC? I have never learned before, where should I start? -Solutions - Huaqiang Electronic Network

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How to learn plc? How to learn PLC? I have never learned before, where should I start?
There are a lot of friends who haven't studied well at school or who have taken the last bus at work. I don't know where to start when I learn PLC. Here, I will summarize my own suggestions.
Disclaimer: The following opinions are purely personal opinions. If you have no effect on you and waste your time, don't look for me and ask your heart to go!
Students who study automation at school are all starting from the freshman year and then start learning PLC in their sophomore or junior year. This kind of course arrangement makes sense because of the wide range of knowledge about PLCs. To illustrate: I have studied electrical engineering, analog electronics, digital electronics, computer applications and other related courses in colleges and junior colleges. This provides a pre-requisite for learning PLC.
But many friends have already joined the work, what should I do? Panic, I will introduce some necessary knowledge points here, as long as you master, and then learn PLC, many related problems will be solved.
First, the number system and the code system are decimal, binary, hexadecimal, and octal.
The code system is ASCII code, BCD code, etc., as long as you have a little understanding, you don't have to go into it.
Decimal: From small to big, I don't know what definition, anyway, it is 0123456879, every tenth into one.
Binary: The basic working signal in a digital circuit is a binary digital signal, the two basic numbers 0 and 1.
8 and hexadecimal do not have to go deeper, unless you use network communication to edit the check code (this verification program can be found online).
So, here, the more detailed is the conversion between decimal and binary.
This is very important, you can't figure out the binary, you don't know the question "Why the timer is 32767" and so on.
Second, the data type is based on the Siemens S7-200 series (different programming software, the length of the data type has subtle changes)
Data types are divided into: Bit, Byte, Word, Double Word, Int, Double Word, Real (Float, floating point, with decimal point) Must be expressed in decimal form, such as 2.1, 1.0).
We need to know 8 bits = 1 byte, 2 bytes = 1 word (integer), 2 words (integer) = 1 double word (double integer) = 1 real number, these three formulas represent the length ratio between each data, some In the sense of real numbers and double words, double integers can be equal, because double words and double integers can not represent decimals, so they are not equal in a certain sense, but the data length is 32 bits.
There are other data types such as strings, which are not commonly used by beginners, so they don't introduce too much. After you have a certain PLC foundation, you will save time and get twice the result with half the effort.
Third, logical algebraic logic algebra, also known as Boolean algebra, is a mathematical tool for studying logic circuits, which provides a theoretical basis for analyzing and designing logic circuits. What is studied in logical algebra is the relationship between logical functions and logical variables.
Logical variables, like algebra in mathematics in our middle school, can be represented by letters A, B, and C.
Logical algebra is a mathematics used to describe logical relationships and reflect the laws of logical variables.
For example:
1+1=2 is the ordinary algebra of our middle school era
a+b=c is the logical algebra we are going to talk about now. As for the specific values ​​of a, b, and c, it is not necessarily.
Logical Algebra Operations Ordinary algebra operations have addition, subtraction, multiplication and division. In logic algebra, they have their own operation.
They are "and", "or" and "not". Other operations have evolved from these three simple operations.
1, and: When all conditions are 1, the result is 1.
2, or: As long as there is a condition of 1, the result is 1.
3. Non: The conditions and results are always the opposite.
The logical operation is actually very simple. The "condition" in the above definition is not 0 or 1. Usually we call 1 as true and 0 as false. Not true or false, not 0 is 1.
For example and operation Y=A·B, it can also be written as Y=AB
0·0=0 0·1=0 1·0=0 1·1=1
The definition I gave above, is it all 1 when the condition is 1, the result is 1?
OR operation Y=A+B
0+0=0 0+1=1 1+0=1 1+1=1
The definition I gave above is that as long as there is a condition of 1, the result is 1?