1. Do not execute the program: The input check is identified by the input LED indicator or the input monitor composed of a writer. When the input LED is not lit, it can be preliminarily determined that the external input system is faulty, and then check with the multimeter.
If the output voltage is abnormal, it can be determined that the input unit is faulty. When the LED is on but the internal monitor is not displayed, it is considered to be a fault of the input unit, CPU unit, or expansion unit.
The program performs a check through a monitor check on the writer. When the contact status of the ladder diagram does not match the result, it is a program error (e.g., double use of internal relays, etc.), or a malfunction in the calculation part.
Output checks can be identified using the output LED indicator. If the calculation result is correct but the output LED indicates an error, it can be considered as a fault of the CPU unit or 1/0 interface unit. When the output LED is bright but there is no output, it can be determined that the output unit is faulty, or the external load system is faulty.
2. Some programs are not executed: the check method is the same as the previous item, but if the input time of the counter, step controller, etc. is too short, there will be no response failure, then the input time should be checked whether the input time is large enough, and the verification can be carried out according to the relationship between the input time < the * response time of the input unit + the operation scanning time multiplied by 2.
3. If the power supply is powered off for a short time, the program content will also disappear: in order to make the microprocessor start correctly, the PLC is equipped with an initial reset point circuit and a saving program circuit when the power supply is disconnected. When such a circuit fails, the program cannot be saved. Check the on/off of the available power supply.
4. The PROM cannot be operated: first check whether the PROM is inserted well, and then determine whether the chip needs to be replaced.
5. After the power supply is re-invested or reset, the action stops: this fault can be considered as caused by noise interference or poor internal contact of the PLC. The cause of noise is generally caused by the reduction of the capacitance of the small capacitor in the circuit board or the poor performance of the components, and the cause of the poor contact can be checked by gently tapping the PLC body. Also check the plugged in status of the cables and connectors.
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Megmeet PLC – the three programming languages of PLC
1. The ladder diagram language is the most commonly used programming language in PLC programming. The CPU reads physical input into a memory table, often referred to as an "input table". The form is evaluated for use in the procedure. Different platforms, using different types of registers; In each scan cycle, follow from left to right, ...
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Megmeet inverter - the selection principle and precautions of the inverter
1. Select the inverter according to the load characteristics
A: Fans and pumps are the most common loads: the requirements for the inverter are the simplest, as long as the inverter capacity is equal to the capacity of the motor (air compressors, deep water pumps, sediment pumps, and fast-changing music fountains need to increase their capacity).
...
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Megmeet PLC - the basic composition of PLC
a. Power supply
The power supply of the PLC plays a very important role in the whole system. It can't work properly without a good and reliable power supply system, so PLC manufacturers also attach great importance to the design and manufacture of power supplies. General AC voltage fluctuations are +10% (+15%) ...
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Solutions to common faults of Megmeet inverter (2)
Fault three
Fault phenomenon: There is a rebound phenomenon when the rotation starts
Solution: 1. Set the start frequency P08.02 and start frequency time P08.03 appropriately (such as P08.02=P08.03=0.5)
2. Appropriately reduce the stator resistance (P03.07) and no-load current value (P03.11 ...
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Various welding methods for Megmeet welding machines
1) Hand arc welding (STICK)
Shielded Arc Welding (abbreviated SMAW) in English,
The principle is: the arc occurs between the coating electrode and the base metal, and the welding method of arc thermal ablation electrode and base metal is used. The outer layer of the electrode is covered with solder, which is dissipated in case of heat.
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Megmeet PLC – the maintenance steps of the PLC control cabinet
1. Data backup
When carrying out maintenance, we must cut off the power, data backup between power outages is an important link, for the data that needs to be archived for a long time, you can back up the historical trend data to the mobile hard disk, and then turn off the Windows-based operating system (Note...
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Megmeet PLC - What is the difference between PLC and MCU?
1. PLC is a relatively mature control system composed of single-chip microcomputer, which is the product of a mature and stable single-chip microcomputer application system that has been debugged. It is highly versatile.
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Megmeet inverter - the role and application of the inverter control cabinet introduction
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According to the needs of working conditions, AC transmission can be installed in the frequency conversion cabinet.
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Megmeet servo drive - common faults and treatment methods of servo drives
1. The motor runs differently in both directions
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2. The motor speed is abnormal
Cause of failure ...
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Megmeet inverter - maintenance precautions and items for high-voltage inverters
Precautions for maintenance of high-voltage inverters
1. Carefully monitor and record the display parameters on the man-machine interface of the inverter, and reflect the abnormality immediately
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Megmeet PLC - how the PLC communicates with the host computer
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Common faults and solutions of Megmeet inverter
Fault one
Fault phenomenon: the leakage protection switch trips, the inverter is energized or the equipment leakage protection switch is operated during operation
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Megmeet inverter - inverter braking mode and advantages and disadvantages introduction
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Megmeet inverter - introduction to the classification of inverters
1. Classified according to the input voltage level
According to the input voltage level, the inverter can be divided into low-voltage inverter and high-voltage inverter, and the low-voltage inverter is common in China with single-phase 220 V inverter, three-phase 220 V inverter, and i-phase 380 V inverter. High-voltage inverters are commonly used in 6 kV, 10 kV transformers.
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Megmeet drives – routine and regular maintenance of drives
1. Maintenance items and scope:
Daily maintenance and maintenance of inverter
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Megmeet inverter - common faults and treatment methods of high-voltage inverters
1. Control through this abnormal failure
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Megmeet drives – what are the basic requirements for regular replacement of drive components?
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The cause and treatment method of the fault code Eroc1 of Megmeet inverter
1. Overcurrent fault of inverter
Fault Code: OCF.
(1) Fault name: inverter overcurrent fault
(2) The cause of the failure: the motor nameplate data input is incorrect: the load dragged by the motor is too heavy: the machinery is stuck; Motor stalled.
(3) ...
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