Visual inspection First of all, the overall appearance of the PLC system can be checked and the risk factors in the system can be checked in a timely manner. For example, some parts that have entered the wear out period should be replaced at regular intervals; corresponding measures must be taken for the factors that have been found to be causing safety to the system. Therefore, only after you have become familiar with and understand the various modules of the entire system can you truly grasp the areas where the system faults may be distributed. Macroscopic diagnosis The macroscopic diagnosis method refers to the diagnosis based on the existing work experience to check whether it is a fault caused by improper operation, that is, according to the surface phenomenon of the system fault to determine the cause and area of ​​the fault, and timely check the power supply is turned on, the line Whether it is correct and whether the on-site operation is normative. Microscopic detection The microscopic detection method is mainly aimed at the software design failures that may occur in the system. Once this happens, it is necessary to check the system's hardware design and software design. For example, for CPU fault detection. CPU failure is mainly reflected in the corresponding LED light is not on or the CPU unit is down. When this happens, the following three main reasons are considered: First, the power supply cannot work due to noise interference; second, the electrical components on the CPU internal bus have failed; and third, the CPU control program is lost. Therefore, for the fault of the CPU software, it is necessary to determine the specific cause of the fault according to the actual situation in each region. If it is due to noise interference caused by the failure, then you need to restart the CPU to start the system if there is a problem within the program, then you have to reload or modify the system program. Dynamic detection In the entire control system work, since the components of each part and the controller itself are in operation, these controllers and components may malfunction at any time and place. Therefore, in order to timely detect the cause of the failure, there are The need for a comprehensive and dynamic testing of the system. The dynamic detection of the system can be realized through the design software, and the entire process of fault occurrence can be detected in real time through software monitoring. The specific work is mainly completed in the following three steps: First, the input test. This part mainly realizes the detection and conversion functions of the feedback signals of the external switching systems; the second is the system state transition. This part mainly realizes the signal detection and historical status of each area in the system. The third is the output detection. This section mainly determines the status of each control signal based on the current state of the system. After the PLC control system executes these three steps in turn within one monitoring cycle, it can achieve full control of the system. 1. High quality imported Compressor energy saving and low noise.Compressor brand Embraco and Danfoss is available for customers to choose. Showcase Refrigerator,Freezer Showcase,Display Refrigerator Showcase,Supermarket Showcase Refrigerators ShanDong XiMaiD Commercial electrical appliance Co. LTD , https://www.sdximaide.com
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