• Seven steps to complete Siemens PLC debugging, electrical novices can learn even after reading it!
    Seven steps to complete Siemens PLC debugging, electrical novices can learn even after reading it! Aug 22, 2023
    Seven steps to complete Siemens PLC debugging, electrical novices can learn even after reading it! Many beginners in electrical engineering may not know how to start debugging after completing the design of electrical control cabinets and PLC programs, or some may encounter issues such as PLC burning due to improper debugging methods. So, how should the designed electrical system be debugged? You can follow the following seven steps. 1. Check the circuit according to the drawing (without power supply) The drawings of a general PLC system include two parts: inside cabinet drawings and outside cabinet drawings; Cabinet drawings refer to the wiring diagrams inside the cabinet; The drawings outside the cabinet are the wiring diagrams for all electrical cabinets. What needs to be checked in this section is; 1. Is the drawing design reasonable, including the capacity of various components, etc. 2. Check whether the components are connected strictly according to the drawing. The most important thing to note during this process is to check the power supply: 1. Ensure that the circuit is not short circuited. 2. Ensure that strong and weak currents are not mixed together; Because the PLC power supply is 24V, once 220V is connected to the PLC due to wiring errors, it is easy to burn the PLC or expansion module. 2. Check the external circuit of the PLC, commonly known as "dotting" After confirming the power supply, power on and test the input and output points, commonly known as "dotting". Testing the IO points requires testing one by one, including operation buttons, emergency stop buttons, operation indicator lights, cylinders and their limit switches, etc. The specific method is to have one person operate the buttons on the site side and the other person monitor the input and output signals on the PLC; For large systems, a test table should be established, that is, marked after testing. If any wiring errors are found during the construction process, they need to be dealt with immediately. In this step, it should be noted that it is necessary to back up the program and clear the program in the PLC or disable the program to avoid device actions caused by testing. 3. Check the mechanical structure and test the motor load This step requires checking whether the mechanical structure is tight, and whether the motor load is properly protected to avoid accidents caused by accidents. After the inspection is completed, it is necessary to manually test the operation of the equipment. For example, for forward and reverse rotation motors, it is necessary to test the integrity of the circuit and conduct live testing. For frequency converters, corresponding parameters should be set and motor optimization, static identification or dynamic identification should be carried out. It should be noted here that for some special loads, such as vertically moving loads, they need to be carried out by professional personnel to avoid testing accidents caused by improper control. 4. Debugging manual mode/semi-automatic mode and related logical relationships After testing both the IO point and load side, the next step is to debug in manual mode. The manual mode here can also be called semi-automatic mode, which does not directly press the solenoid valve or contactor by hand, but refers to driving the device through buttons or HMI buttons, which corresponds to the automatic state. Manual mode testing can decompose the automatic mode according to human preferences, making it easier to test the program. The most important aspect of this process is to test the safety functions, that is, to test whether the emergency stop, safety grating, and other safety functions have played a corresponding role while the equipment is running. 5. Debugging automatic mode according to production process After completing semi-automatic debugging, the automatic work can be further debugged. This link is the most important and requires testing various interlocks according to the production process, including logical interlocks, safety interlocks, etc., and testing several more work cycles to ensure that the system can work continuously and correctly. 6. Testing of special processes In addition to logic control, there are many expanded functions in the PLC system, such as PID control. After these logic debugging are basically completed, you can start debugging analog and pulse control. The most important thing is to select appropriate control parameters. Generally speaking, this process is relatively long. Be patient and make multiple choices of parameters before selecting the best one. Some PLCs have PID parameters that can be obtained through self tuning. But this self tuning process also takes a considerable amount of time to complete. 7. Complete all the steps above The entire debugging is basically completed. Next comes the step of pre production, which is a pre production work inspection. During this stage, special tests can be carried out in conjunction with production, such as whether the production rhythm is met, whether the safety function can still function under load, etc. Generally, the work can be completed after a certain period of continuous production.   Novice should pay special attention to the power supply. I remember that when I debugged the first project many years ago, the construction company connected the 220V contact and 24V contact of the pull cord switch of the large belt incorrectly (the pull cord switch of the belt is a safety device, with two sets of contacts, one is 220V to disconnect the control loop, the other is 24V to enter the PLC), which caused the burning of a digital input template. Later, it became a long memory. When debugging again, we must distinguish 220 and 24, I never had any problems again. ■Speed of Reply to Inquiries  Attn: Mr. Liao Mobile: +86 15259245292 Email:   WeChat/WhatsApp: +86 15259245292 Address: Room 1601, Building 6, Haicang Seattle, No. 330 Zhonglin Road, Haicang District, Xiamen City, Fujian Province

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