Electromechanical Drive control Seventh Week study Note--PLC

I forgot to write my weekly study notes (⊙﹏⊙) at the weekend, so I sold a moe first.

PLC is a kind of control way to know, now began to formally study it makes me feel very excited. However, the teacher gave the exercise, so missed some of the course content, but study notes, after-school self-study and consult should also calculate.

First, the basic composition

1. Power supply Unit

The power supply of the programmable logic controller plays a very important role in the whole system. Because the central processing unit and so on are DC power, but also need to eliminate voltage fluctuations in the power supply components, temperature changes in the impact of the output voltage and so on, protection components. There is also a backup battery inside the power supply to prevent loss of RAM information when power is lost.

2. Central processing Unit (CPU)

The central processing unit (CPU) is the control center of the programmable logic controller. It receives and stores the user programs and data typed from the programmer according to the functions given by the Programmable Logic controller system program, checks the status of power, memory, I/O, and alert timers, and can diagnose grammatical errors in the user program. When the programmable logic controller is put into operation, first it receives the status and data of each input device in the field by scanning, and then stores the I/O image area Separately, then reads the user program from the user program memory, and then executes the result of the logic or arithmetic operation according to the instruction after the command is interpreted and fed into i/ o image area or data register. After all the user programs have been executed, the data from each output state or output register in the I/O image area is finally transferred to the corresponding output device, so that it runs until it stops running.

3. Memory

Store programs and data

4. Input/output interface circuit

Includes input and output circuitry

5. Programmer

PLC is an important peripheral equipment, the program can be compiled, debugging, monitoring, modification, editing. It feels like the keyboard plus the IDE.

Second, the principle of work

(Finally, incidentally, circular scanning works very often, such as HTML5 game production in order to detect user action, MCU in order to prevent memory overflow write watchdog, etc.)

Electromechanical Drive control Seventh Week study Note--PLC