I read an electronic magazine in which there is a report on what are the detailed uses in programmable logic. After reading, I became interested in the detailed uses in programmable logic. Today I come to this forum to turn to you to discuss my understandings are appropriate.
Here are my personal understandings:
1, programmable controller referred to as PC, which has undergone a programmable matrix controller PMC, programmable sequence controller PSC, programmable logic controller PLC and programmable logic controller PC several different periods. For the sake of distinguishing with a personal computer (PC), the old name of the programmable logic controller is still used.
PLC is a digital computing electronic system, applied to the industrial environment and design. It uses programmable memory to store instructions for operations such as logical operations, sequential control, timing, counting, and arithmetic operations, and through digital, analog input and output. Control all types of machinery or production processes. PLC and its related equipment, are easy to integrate with the industrial controller system, easy to expand the function of the principle of design.
PLC is based on a microprocessing technology, the control processing rules stored in the memory, used to control the main switch or control parameters, including logic control, mechanical and electrical motion control or process control and other industrial control areas of the new Industrial control devices.
2.2 PLC features
PLC is a user-specific industrial control computer, with many obvious features.
- High reliability, strong anti-interference ability
In order to limit the occurrence of the fault or in the event of failure, can quickly detect the point of failure, and the fault is limited to the local, the PC manufacturers in the hardware and software to take a variety of measures to make the PC itself has a strong Self-diagnostic ability, can give timely error information, stop running waiting for repair, but also to the PC has a strong anti-interference ability.
2. Versatility, control procedures variable, easy to use
PLC variety of a variety of hardware devices, can be configured to meet the requirements of the control system, users do not have their own design and production of hardware devices. After the user has determined the hardware, it is not necessary to change the hard device of the PLC when the production process is changed or the production equipment is updated. Only the adaptation program can meet the requirements. Therefore, PLC in addition to stand-alone control, the factory automation has also been widely used.
3. Strong function, wide adaptability
Modern PLC not only logic operation, timing, counting, sequential control and other functions, but also has a digital and analog input and output, power-driven, communications, man-machine dialogue, self-test, record display and other functions. Can control a production machinery, a production line, but also control a production process.
4. Programming is simple and easy to master
At present, most PLCs still use relay control in the form of “ladder programming”. Both inherited the traditional control lines clear and intuitive, but also take into account the majority of factory electrical and technical personnel of the reading habits and programming level, it is very easy to accept and master. When the PLC executes the ladder program, it is translated into assembly language by interpreter and executed (PLC interpreter is added internally). The length of the ladder program is longer than the user program written directly in assembly language, but it is negligible for most electromechanical control devices to meet the control requirements.
5. Reduced the design and construction of the control system
As the PLC uses a software to replace the relay control system in a large number of intermediate relays, time relays, counters and other devices, control cabinet design and installation wiring greatly reduced the workload. At the same time, PLC user program can be simulated in the laboratory debugging, but also reduces the on-site debugging workload. And, because of the low failure rate of PLC and a strong monitoring function, modular and so on, so that maintenance is also very convenient.
6. Small size, light weight, low power consumption, easy maintenance
PLC is the microelectronics technology used in industrial equipment products, its compact, solid, small size, light weight, low power consumption. And because of the strong anti-interference ability of PLC, easy to load the internal equipment, is to achieve the ideal mechanical and electrical integration control equipment.
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2.3 PLC function and application*
Programmable controller at home and abroad widely used in steel, petrochemical, machinery manufacturing, automotive assembly, electricity, textile, electronic information industry and other industries. At present the typical PLC function has the following points.
Sequential control: This is the most widely used field of programmable controllers, replacing the traditional relay sequence control, such as injection molding machines, printing machines, staplers, cutters, combination machines, grinders, assembly lines, packaging lines Pipeline and elevator control.
Program control: In the industrial production process, there are many continuous changes in the amount, such as temperature, pressure, flow, liquid, speed, current and voltage, called analog. The programmable controller has A / D and D / A conversion modules, so that the programmable controller can be used for analog control for program control.
Data processing: General programmable controllers are equipped with four arithmetic instructions, you can easily on the production process to deal with the information. PLC can be used to form a monitoring system, data collection and processing, control the production process. Higher-level programmable controllers have position control modules for controlling stepper motors for position control of various machines.
Communication networking: Some control systems require multiple PLCs to be connected or used by a computer and multiple PLCs to form a distributed control system. The communication module of the programmable controller can meet these communication networking requirements.
Display Print: The programmable controller can also connect peripheral devices such as display terminals and printing for display and printing.
Ps: Excuse me if I was wrong in words or expressions as I am a green hand in the field of programmable logic. I need continual learnings.
What is your idea ? Do you agree with my ideas ? Any of your ideas would be highly appreciated.
May someone would like to help ?
thanks in advance