What are the characteristics of PLC? If anyone understands, help solve it

What are the characteristics of PLC?

1) The system is flexible and easy to expand, with switching control as its specialty; PID loop control for continuous processes is also possible; And it can form a complex control system with the upper computer, such as DDC and DCS, etc., to realize the comprehensive automation of the production process.

2) Easy to use, simple programming, using concise ladder diagram, logic diagram or statement table and other programming languages, without computer knowledge, so the system development cycle is short, on-site debugging is easy. In addition, the program can be modified to change the control scheme without disassembling the hardware.

3) It can adapt to all kinds of harsh operating environments, with strong anti-interference ability and strong reliability, which is much higher than other models.

1. Flexible use and strong versatility - the hardware of PLC is standardized, and PLC products have been serialized, and there are many varieties of functional modules, which can flexibly compose a variety of control systems of different sizes and different functions. In the control system composed of PLC, only the corresponding input and output signal lines need to be connected to the terminals of the PLC.

2. High reliability and strong anti-interference ability - the microcomputer has strong functions but poor anti-interference ability, electromagnetic interference in the industrial field, power fluctuations, mechanical vibration, temperature and humidity changes, all of which may lead to the failure of the general microcomputer to work normally; The traditional relay-contactor control system has strong anti-interference ability, but due to the existence of a large number of mechanical contacts (easy to wear and ablation), the life is short, and the system reliability is poor.

3. Simple interface and convenient maintenance - the interface of the PLC is designed according to the requirements of industrial control, with strong load capacity (the input and output can be directly connected to AC 220V, DC 24V and other strong electricity), and the interface circuit is generally modular, which is easy to repair and replace. Some PLCs can even plug and unplug the input and output modules with electricity, and the faulty modules can be directly replaced without offline power failure.

4. Small size, low power consumption, cost-effective - take small PLC (TSX21) as an example, it has 128 IO interfaces, which can be equivalent to the control function of the system composed of 400 800 relays, and its size is only 216 127 110mm3, heavy, and the no-load power consumption without interface is, and its cost is only equivalent to 10 20 of the relay system with the same function.

1.High reliability and strong anti-interference ability.

High reliability is a key performance of electrical control equipment. Due to the use of modern large-scale integrated circuit technology, PLC is manufactured with strict production process, and the internal circuit adopts advanced anti-interference technology, which has high reliability. For example, Mitsubishi's F-series PLCs have an average time between failures of up to 300,000 hours.

Some PLCs that use redundant CPUs have a longer mean time between failures. From the perspective of the external circuit of PLC, the use of PLC to form a control system, compared with the relay contactor system of the same scale, the electrical wiring and switch contacts have been reduced to hundreds or even thousands, and the fault is greatly reduced. In addition, the PLC is equipped with a hardware fault self-detection function, which can send out an alarm message in time when a fault occurs.

In the application software, the user can also program the fault self-diagnosis program of the peripheral devices, so that the circuits and equipment in the system other than the PLC can also obtain fault self-diagnosis protection. In this way, it is not surprising that the entire system is extremely reliable.

2.It is fully furnished, functionally perfect, and has strong applicability.

With the development of PLC to this day, it has formed a series of products of various scales of large, medium and small. It can be used in industrial control applications of all sizes. In addition to logic processing functions, most modern PLCs have perfect data computing capabilities and can be used in various digital control fields.

In recent years, a large number of functional units of PLC have emerged, so that PLC has penetrated into various industrial controls such as position control, temperature control, and CNC. Coupled with the enhancement of PLC communication capabilities and the development of human-machine interface technology, it has become very easy to use PLC to form various control systems.

3.It is easy to learn and use, and is well received by engineers and technicians.

PLC, as a general industrial control computer, is an industrial control equipment for industrial and mining enterprises. It interfaces easily and the programming language is easy for engineers to accept. The graphic symbols of the ladder diagram language are quite close to the expression and relay circuit diagram, and the function of the relay circuit can be easily realized with only a small number of switching logic control instructions of the PLC.

It opens the door for people who are not familiar with electronic circuits, computer principles and assembly language to use computers to engage in industrial control.

4.The design and construction of the system is small, easy to maintain, and easy to transform.

The PLC replaces the wiring logic with storage logic, which greatly reduces the wiring outside the control equipment, greatly shortens the cycle of control system design and construction, and makes maintenance easier. What's more, it makes it possible to change the production process with the same equipment through changing the program. This is ideal for high-mix, low-volume production.

5.Small size, light weight and low energy consumption.

Taking ultra-small PLC as an example, the newly produced varieties have a bottom size of less than 100mm, a weight of less than 150g, and a power consumption of only a few watts. Due to its small size, it is easy to fit into the machine, and it is an ideal control equipment for mechatronics.

What does PLC mean, power line communication.

Reliable (more reliable than the contact output of a relay).

Easy to operate (programmed automatic control, basically no need to think about operation).

Flexible (analog, digital and switching quantities can be output through program conversion) Yunnan Xibot Technology Technology Department.

PLC is a single-chip microcomputer that is formed, which is easy to operate, stable and easy to maintain and overhaul.

The disadvantage is that the secrecy is not as good as that of a microcontroller.

Flexible, stable, reliable and convenient.

Intuitive and convenient programming, stable and reliable operation.

A programmable logic controller is an electronic system of digital operations designed for use in industrial environments. It uses a programmable memory to store instructions for performing operations such as logic operations, sequence control, timing, counting, and arithmetic operations, and controls various types of mechanical equipment or production processes through digital or analog inputs and outputs.

Uses of PLC technology:

1. Open-loop control.

Open-loop control of switching quantities is the most basic control function of PLC. The instruction system of PLC has powerful logic operation ability, and it is easy to realize various logic control methods such as timing, counting, and sequential (stepping). Most PLCs are used to replace traditional relay contactor control systems.

2. Analog closed-loop.

For the analog closed-loop control system, in addition to the input and output of the switching quantity, there should also be the input and output points of the analog quantity, so that the sampling input and adjustment output can realize the continuous adjustment and control of temperature, flow, pressure, displacement, speed and other parameters. At present, PLCs not only have this function for large and medium-sized machines, but also some small machines also have this function.

3. Digital control.

When the control system has a rotary encoder and a pulse servo device (such as a stepper motor), the PLC can be used to realize the function of receiving and outputting high-speed pulses, realize digital control, and the more advanced PLC has also specially developed a digital control module, which can realize the curve interpolation function, and recently launched a new type of motion unit module, and can also provide a programming language for digital control technology, so that PLC realizes digital control more simply.

4. Data collection and monitoring.

Because the PLC is mainly used for on-site control, it is a very necessary function to collect on-site data, and on this basis, the PLC is connected with the upper computer or touch screen, which can not only observe the current value of these data, but also carry out statistical analysis in time.

Some PLCs have a data logging unit, which can be inserted into the unit with a memory card of a general personal computer to save the collected data. Another feature of PLC is that the self-test signal is more Using this feature, the PLC control system can realize white diagnostic monitoring, reduce the failure of the system, and improve the reliability of the system.

1. High reliability and strong anti-interference ability.

2. Strong versatility and wide adaptability.

3. Strong function and high cost performance.

4. The control program is variable, saving a lot of time.

5. The programming is simple and easy to master.

6. The workload of system design, installation and commissioning is small.

7. Easy maintenance.

8. Small size and heavy. , light weight, low energy consumption.

Let's see what others have to say.