1. Used for power switch control

The ability of PLC to control the switch is relatively strong. The entry and exit levels controlled can be as little as a dozen points or dozens of points, and as many as hundreds, thousands, or even more than 100,000 points. Because it can connect to the network, the level is basically not restricted, no matter how many Points can be mastered, and the logical problems to be mastered can be various: compositional, sequential, real-time, timing, non-counting, must-counting, fixed order, arbitrary All of these things can be done at work.

The hardware configuration structure of PLC is variable, and the software system is programmable, which is more flexible when used for control. Multiple sets or multiple programs can be written and activated as needed. It is very suitable for the needs of multi-working conditions and multi-state switching on the industrial production site.

There are many cases of using PLC for switch control, such as metallurgy, machinery, light industry, chemical industry, textiles, etc., almost all industrial industries need to use it. At present, the primary purpose of PLC is that other controllers cannot be compared, that is, it can be used for switching control conveniently and reliably.

2. Used for analog input control

Analog input, such as current, voltage, temperature, pressure, etc., its size is constantly changing. Industrial production, especially continuous processing, always needs to control these electrostatic force constants.

As an industrial control electronic system, if PLC cannot control these quantities, it is a big problem, so each PLC manufacturer will carry out a lot of development in these areas. At present, not only large and medium-sized machines can carry out analog input control, that is to say, small machines can also carry out such control. PLC carries out analog input control, and it must be equipped with A/D and D/A modules for mutual conversion between analog input and digital input. It's all I/O modules, but unique I/O modules.

The A/D module is to convert the analog input of the external circuit into a large digital quantity, and then send it to the PLC; the D/A module is to convert the large digital quantity of the PLC into an analog input, and then give it to the external circuit. As a unique I/O module, it still has I/O power circuit anti-interference, internal and external power circuit protection, and I/O automotive relay (or internal automotive relay, which is a part of the running memory in PLC work) Area, readable and writable) exchange information content these characteristics.

The A in the A/D here is mostly current, or voltage, and also temperature. A in D/A is mostly seen in working voltage or current. The voltage and current ranges are mostly 0-5V, 0-10V, 4-20mA, and some can handle positive and negative numbers. For D here, 8-bit numbers are mostly seen in small computers, and 12-bit numbers are mostly seen in medium and large computers. A/D and D/A have single channel and multi-channel. Multi-channel accounts for more I/O automotive relays. With A/D and D/A modules, the remaining solutions are all digital, which is not too difficult for a PLC with information resource management capabilities. Medium and large PLCs have stronger processing capabilities. Not only can they add, subtract, multiply, and divide large numbers, they can also perform square root and interpolation, and they can also perform floating-point calculations. Some also have PID commands, which can control errors. Carry out proportion, differentiation, integral and calculation to form corresponding output, which is basically calculated by the computer.

In this way, it is completely possible to achieve analog input control with PLC.

PLC performs analog input control, and there are modules composed of A/D and D/A, and can be controlled by PID or fuzzy control algorithm, which can achieve high control quality. The advantage of using PLC for analog input control is that while performing analog input control, the switching value can also be controlled. This advantage is not available in other controllers, or the maintenance of control is not as convenient as PLC. Of course, if the system software is purely for analog input, using a PLC will not be as good as using a controller in terms of features and prices.

3. Used for fitness control

The specific static force constant, in addition to the switch value and analog input, also has motion control. For example, the offset of CNC lathe components is still expressed in large numbers. For motion control, the effective method is NC, that is, numerical control technology. This is a computer-based control technology that came out in the United States in the 1950s. Now it is very popular and very sound.

At present, the proportion of CNC machine tools for metal drilling in advanced countries has exceeded 40% to 80%, and some are even higher. PLC is based on the technology of electronic computers and is becoming more and more perfect. PLC can accept counting single pulse, the frequency can reach several k to tens of kHZ, it can receive this single pulse in various ways, and it can also receive multi-channel. Some PLCs also have a single pulse output function, and the single pulse frequency can reach tens of kilowatts. With these two functions, plus PLC has data processing methods and computing capabilities, if you configure a corresponding controller (such as a rotary encoder) Or single-pulse servo motor equipment, it can completely achieve a lot of control according to the basic principle of NC.

High and medium PLCs are also developed with NC modules, or motion modules, which can maintain point control. The Fitness Motion module also maintains profile tool radius compensation for control over curved motion. Therefore, if the PLC is equipped with such a module, it can completely use the NC method to carry out the control of large numbers. The newly developed motion module even launched the computer language of NC technology, which provides convenience for realizing digital control with PLC as soon as possible.

4. For data collection

With the development of PLC technology, its data storage area is getting bigger and bigger. For example, the data storage area (DM area) of the PLC of Deweisen Enterprise can exceed 9999 words. Such a huge data storage area can store a lot of data information. Data collection can use electronic counters to record the total number of pulses collected, and copy them to the DM area for regular execution. The A/D module can also be used for data collection. After the analog input is converted into a large digital value, it is copied to the DM area for regular execution. The PLC can also be equipped with a small printer to print out the data in the DM area on time.

The PLC can also communicate with the computer, and the computer reads the data in the DM area, and the computer processes the data. At this time, the PLC becomes the data acquisition terminal of the electronic computer.

Power engineering customers have used PLC to record the customer's electricity consumption status in real time, so as to maintain the charging standard method of different electricity consumption time and different billing methods, and encourage customers to use more electricity during the low tide period of electricity consumption, exceeding the effective The purpose of electricity consumption and saving electricity.

5. Used as a data signal monitor

There are a lot of PLC self-checking signals, and there are also a lot of internal components, and most users do not make full use of its functions. In fact, it can be used to monitor the PLC's own work, or to monitor the control object. For a complicated control system, especially an automatic control system, a monitor and even further self-diagnosis are very necessary. It can reduce system failures, and if there is a failure, it can be searched and the total value can be increased without any problem. The operation time is reduced, the repair time of common faults is reduced, and the reliability of the system software is improved.

6. Used to connect to the network and communicate

PLC has strong network connection and communication capabilities, and new network connection structures are released continuously.

The PLC can be connected with the personal computer for communication, and the computer can be used to participate in programming and control the management of the PLC, making the PLC more convenient to use.

In order to make full use of the functions of the computer, one computer can be implemented to control and manage several PLCs, up to 32 at most. It is also possible for one PLC to communicate with two or more computers to exchange information, so as to maintain more monitoring of the PLC control system. PLC and PLC can also communicate, one-to-one PLC communication, multiple PLC communication, as many as dozens or hundreds.