What is a PLC control system and what is a PLC control system?

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1. Programmable logic controller, which adopts a class of programmable memory for its internal storage program, executes user-oriented instructions such as logic operation, sequence control, timing, counting and arithmetic operations, and controls various types of machinery or production processes through digital or analog input and output.

2. The programmable logic controller is essentially a computer dedicated to industrial control, and its hardware structure is basically the same as that of a microcomputer.

3. The basic composition is as follows:

A: Power supply.

B: Processing Unit (CPU.

c: Memory.

d: Input and output interface circuits.

e: Functional module.

f: Communication module.

PLC control system is a generation of new industrial control devices formed by introducing microelectronic technology, computer technology, automatic control technology and communication technology on the basis of the traditional sequence controller, which is used to replace the sequence control functions such as relay, execution logic, timing and counting, and establish a flexible remote control system. It has the characteristics of strong versatility, easy to use, wide adaptability, high reliability, strong anti-interference ability, and simple programming.

PLC control system, programmablelogiccontroller, is a programmable logic controller, designed for industrial production of a kind of digital operation of electronic devices, it uses a kind of programmable memory, for its internal storage program, the execution of logic operations, timing, counting and arithmetic operations and other user-oriented instructions, and through digital or analog input and output control of various types of machinery or production process. It is the core part of industrial control.

Since the introduction of programmablelogic controller (PLC) in the United States in the sixties of the twentieth century to replace the traditional relay control device, PLC has developed rapidly and has been widely used around the world. The functionality of the PLC is also constantly improving.

With the continuous development of computer technology, signal processing technology, control technology and network technology and the continuous improvement of user needs, PLC has added analog processing and motion control functions on the basis of switching processing. Today's PLC is no longer limited to logic control, but also plays a very important role in motion control, process hunger control and other fields.

PLC is equivalent to the brain of the machine, and the program we program is equivalent to the knowledge and rules that people hold. A machine is the equivalent of a human body, which is used to perform various actions of a PLC. Electricity, gas, liquid, etc. are equivalent to human muscles and nerves, and the limbs do PLC to issue instructions, and the energy is transmitted to the machine through electricity, gas, liquid, etc., and the machine executes.

The sensor feeds back the external situation to the PLC, which is equivalent to the human eye, nose, etc., and then feeds the external things back to the brain.

Take a person or animal as an example, PLC is the brain, the combination of PLC and machine is equivalent to the combination of human brain and body, but the program in the brain of human staring is much more complex than PLC, but the sensitivity and accuracy of the human brain is not as good as PLC.

Programmable controller, known as programmable controller in English, is referred to as PC. However, because PCs are easily confused with personal computers, PLC is still used as an abbreviation for programmable controllers. It is an electronic system device with microprocessor as the core of digital operation operation, designed for industrial field applications, it uses programmable memory, in which it is stored to perform logical operations, sequence control, timing counting and arithmetic operations and other operation instructions, and through digital or analog input and output interfaces, control various types of machinery or production processes.

PLC is the product of the combination of microcomputer technology and traditional relay contact control technology, which overcomes the shortcomings of complex wiring, low reliability, high power consumption, versatility and poor flexibility of mechanical contacts in the relay contact control system, makes full use of the advantages of microprocessors, and takes care of the skills and habits of on-site electrical operation and maintenance personnel, especially the programming of PLC, which does not require special computer programming language knowledge, but adopts a set of simple instructions based on the relay ladder diagram. Make the user's programming vivid, intuitive, convenient and easy to learn; It is also easy to debug and troubleshoot. After purchasing the required PLC, the user only needs to do a small amount of wiring and simple user programming according to the prompts of the manual, and the PLC can be flexibly and conveniently applied to production practice.

A: Power supply. The power supply of the PLC plays a very important role in the whole system. It can't work properly without a good and reliable power supply system, so PLC manufacturers also attach great importance to the design and manufacture of power supplies.

Generally, the AC voltage fluctuates in the range of +10% (+15%), and the PLC can be connected directly to the AC grid without other measures.

B: Processing Unit (CPU.

**The processing unit (CPU) is the control center of the PLC. It receives and stores the user program and data typed from the programmer in accordance with the functions assigned by the PLC system program; Check the status of the power supply, memory compartment, IO, and alert timers, and diagnose syntax errors in user programs. When the PLC is put into operation, first it receives the status and data of each input device in the field in the form of scanning, and stores them in the IO image area respectively, then reads the user program from the user program memory one by one, and sends the result of the logic or arithmetic operation according to the provisions of the instruction into the IO image area or the data register after the command is interpreted.

After all the user programs have been executed, the output status of each output area or the data in the output register will be transmitted to the corresponding output device, and so on until the operation is stopped.

In order to further improve the reliability of PLCs, a redundant system with dual CPUs or a voting system with three CPUs is used for large PLCs. This way, even if one CPU fails, the entire system will still function normally.

c: Memory.

The memory that holds the system software is called system program memory.

The memory that holds the application software is called the user program memory.

d: Input and output interface circuits.

1. The field input interface circuit consists of the optocoupler circuit and the input interface circuit of the microcomputer, which is the input channel of the interface interface between the PLC and the field control.

2. The field output interface circuit is integrated by the output data register, the strobe circuit and the interrupt request circuit, and the PLC outputs the corresponding control signal to the execution component in the field through the field output interface circuit.

e: Functional module.

Such as counting, positioning and other functional modules.

f: Communication module.

Hope...