Explanation of basic knowledge of PLC control cabinet

PLC-Based Control Cabinet is a complete set of electrical control equipment, mainly used to realize automatic control of motors, switches and other actuators. As a key component of the industrial automation system, Automation Panel Cabinet has multiple protection functions such as overload, short circuit and phase loss. It has a compact structure, stable operation, and comprehensive functions. According to the actual control scale, Electrical System Cabinets can be flexibly combined to achieve independent control of a single cabinet, or to form a distributed control system (DSC) through industrial Ethernet or fieldbus networks, thereby adapting to industrial automation application scenarios of different scales, and are widely used in electric power, metallurgy, chemical industry, papermaking, environmental protection, water treatment and other industries.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Air switch: As the main power control component in the cabinet. PLC: Select according to engineering needs. Small projects can use integrated compact Dustproof PLC cabinets (Compact PLC Cabinet); large projects can use modular or redundant PLC systems to ensure high reliability. 24V DC power supply: Most PLCs come with a 24V DC power supply, but if there is a large load or an isolated power supply is required, an additional switching power supply is required. Relay: When the PLC output is 24V DC and the control loop requires a 220V AC node, a relay is required for level conversion and isolation. Terminal blocks: configured according to the number of signals, are the basic components of wiring in the cabinet. In addition, switches, additional circuit breakers and other equipment can be added according to on-site needs for instrument power supply or communication with the host computer.

 

Power supply: A reliable power supply system is the basis for the normal operation of the PLC. When the AC voltage fluctuation is within the range of +10%~+15%, it can be directly connected to the power grid. Central processing unit (CPU): The control center of PLC, responsible for receiving and storing user programs, diagnosing system status, and performing logical and arithmetic operations. In large systems, dual-CPU redundancy or three-CPU voting mechanisms can be used to improve reliability. Memory: The storage system software is called system program memory, and the storage application software is called user program memory. Input and output interface circuit: Interfaces with on-site input signals through optical coupling circuits and outputs control signals to the execution components. Function modules: special modules such as high-speed counting, positioning control, etc. Communication module: supports data exchange with the host computer, other controllers or field devices.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The PLC running process is divided into three stages: input sampling, user program execution, and output refresh. These three stages constitute a scan cycle. Input sampling stage: read all input statuses in sequence and store them in the I/O image area. After this phase, even if the external input changes, the image area data will not change. User program execution stage: Scan the user program (such as a ladder diagram) from top to bottom and from left to right, perform logical operations, and refresh the status of the corresponding coil or output in the RAM or I/O image area. Output refresh stage: The CPU refreshes all output latch circuits according to the status of the I/O image area, drives external devices, and achieves actual output.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Standard PLC Cabinet can complete equipment-level automation and process-level automation control, and has the characteristics of strong network communication capabilities, good system scalability, and superior anti-interference performance. Typical applications include constant pressure water supply, air compressor control, fan and pump management, central air conditioning systems, port machinery, machine tools, boilers, paper machinery and food processing equipment, etc. The Modular PLC Cabinet can also flexibly configure I/O modules according to process changes to improve system adaptability.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

We focus on the R&D and manufacturing of PLC control cabinet, providing products in a variety of materials and specifications, from metal electrical cabinets, stainless steel electrical cabinets to GRP electrical cabinets. We are committed to providing customers with reliable and professional electrical cabinet solutions.