There are many types of PLC motor control cabinets, so there are very big differences in the realization of functions, storage, control scale, appearance and so on. Therefore, there is no strict and unified standard for the classification of PLC, but it is roughly divided into total points according to I/O, which constitute the structure and function. This is also a brief description of the classification by constituent structure. According to the structure, it can be divided into two kinds of integral type and control module type.

What is the classification of machine control cabinets according to their constituent structures 1. Integrated PLC

Integrated PLC is a PLC that installs microprocessors, operating memory, I / O sockets, switching power supplies and other hardware configurations in the main chassis. The integrated PLC can also be composed of a basic unit (called a server) with a certain number of I / O points and different functions to expand the module structure. This kind of PLC has the characteristics of compact structure, small size, high quality and low price, but the protection is not as good as the latter. PLC with this kind of structure is more common in small and medium-sized PLC.

Modular Design PLC

Modular design The PLC divides each part of the PLC into several independent control modules. For example, the CPU and the running memory form the main controller, the switching power supply forms the power supply chip, a number of input points form the input (I) control module, and a number of export points form the output (O) control module. This control module dedicates certain functions to a certain program module. Users can select the required control module and its architecture or assembly slide to form a modular design PLC. This kind of PLC has the characteristics of configuration software, convenient assembly, easy to expand and maintain. It is mainly used in small and medium-sized and large PLC. Because its output and input control module can also be selected according to actual needs, so the composition is flexible and diverse, and the maintenance is convenient. Therefore, there are also some microcomputers with modular design and construction. Recently, there is also a PLC configuration that combines the advantages of the integral and modular design type into a so-called stacked PLC motor control cabinet. The CPU, running memory, switching power supply, I / O and other modules remain independent. Control modules, but they are connected according to cables and can be stacked in stages, which not only saves the flexible configuration of the modules, but also shows the advantages of overall compact size.

What are the special requirements for the PLC system control cabinet used (1) Temperature: The medium temperature is related to the operating temperature of the component, usually between 5°C and 40°C.

(2) air relative humidity: PLC system control cabinet installation environment should be as dry as possible. The allowable range of air humidity in nature is 95%, and there is no condensation phenomenon.

(3) Natural environment standard air pressure: The standard air pressure of the living environment installed in the cabinet is 1080-795 HPA (equivalent to altitude -1000-2000m)

(4) unique pollutants: when the box is polluted by unique environment, it must meet the following specifications: SO2:<0.5 ppm; Hydrogen chloride:<0.1 ppm; Right:<60%, no condensation.

Under the influence of ambient air: In the following areas of use, may lead to poor contact RF connector and parts erosion, so must use air filtration and other measures.

(1) In areas with high levels of smoke, acid and fans and their kitchen fumes, organic solutions and other places, the internal structure of the environment temperature can not see the rise of large and medium-sized closed control cabinets.

(2) Air filtration (air filtration) is required in the control cabinet, especially in areas with corrosive gases. The internal structure of the cabinet should be slightly pressurized to prevent the outside corrosive gas from entering.

(3) In areas where there is no combustible gas, the control cabinet may become an open flame. Explosion-proof electrical equipment can be assembled or cannot be used.

When applying the PLC system control cabinet, we must pay attention to whether the surrounding environment meets the requirements of ambient humidity or ambient temperature. If not, it will greatly endanger the normal start of the machine. Therefore, we should be fully prepared before operation.