1. The connection line is loose and the contact is poor
When the run indicator of the PLC turns red, the position of the plug changes to green with a manual move, indicating that the plug is loose, and it is best to replace the new connecting wire, and the plug is frequently plugged and unplugged, which will also lead to poor contact.
2. Strong electrical interference (external interference)
Close to the inverter and other strong electrical equipment or equipment, motors and other ungrounded protection and the shell is live, these factors may interfere with the work of the PLC, resulting in the PLC is protected to stop automatically, and the interference is weakened or eliminated and resumed. At the same time, the harsh environment: high temperature, electromagnetism, strong radiation, etc. will also affect the normal operation of the PLC.
3. Overload
Some PLCs come with a 24 volt DC power supply, if the connected load is too much, the PLC will be in the power protection state and restart.
Solution: Add a switching power supply, and use the switching power supply to supply power to these loads to reduce the burden of the PLC
Fourth, hardware problems
If none of the above problems are true, then it may be an internal hardware problem that needs to be taken apart and carefully checked.
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Hollysys DCS - the main factor of DCS signal interference
Resistive coupling interference
In the process of work, many factories ignore the problem of wire aging. When a variety of signal lines are transmitted together, other transmission signals will be affected due to the aging and leakage of the insulation material on the wire, and other transmission signals will be interfered with. ...
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Hollysys OCS industrial optical bus control system was successfully applied in Sinopec project
On November 13, 2022, Zhong'an United Coal Chemical Branch came with exciting news that the 20,000 tons/year butene-1 plant produced qualified butene-1 products at 22 o'clock on the same day, and the one-time start-up was successful. The control system of the device adopts the innovative technology product "OCS Industrial Optical Bus Control ...
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Hollysys DCS - Introduction to the hardware architecture of DCS distributed control system
DCS usually adopts a hierarchical and progressive structure, each level is composed of several subsystems, and each subsystem achieves a number of specific finite goals, forming a pyramid structure. Examining the hierarchical structure of DCS, DCS level and control management level are the two most basic links that make up DCS.
Process control...
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Hollysys successfully signed 16 sets of control system projects for 10 million tons of oil refining enterprises
Recently, Hangzhou Hollysys Automation Co., Ltd. (hereinafter referred to as Hollysys Company) successfully signed a contract with PetroChina Liaoyang Petrochemical Branch (hereinafter referred to as PetroChina Liaoyang Petrochemical) to construct and rectify 16 sets of control system projects during the planned overhaul in 2023 - 9 ...
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Troubleshooting steps of Hollysys DCS system
The steps of DCS system troubleshooting include:
(1) Check the fault caused by improper use.
Common types of operational faults include operator errors, terminal wiring faults, module installation faults, and power supply failures.
(2) Troubleshoot the improper operation of the DCS system ...
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The scientific and technological achievements of "SCADA system development and refined oil pipeline application based on independent chips and operating systems" have reached the international advanced level
On October 15, 2022, the scientific and technological achievement of "SCADA system development and refined oil pipeline application based on independent chips and operating systems" jointly completed by South China Branch of National Petroleum Pipeline Network Group Co., Ltd. and Hangzhou Hollysys Automation Co., Ltd. successfully passed the China Petroleum and Chemical Industry Co., Ltd.
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Hollyps PLC - the control method of PLC and frequency converter connection
1. Use the analog output module of the PLC to control the analog output module of the inverter The analog output module of the PLC outputs a 0-5V voltage signal or a 4-20mA current signal, which is used as the analog input signal of the inverter to control the output frequency of the inverter. This control method is simple to wiring, but it needs to be selected and changed.
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Hollysys plc - the difference between DCS and PLC
1. DCS is a "distributed control system", while PLC (programmable controller) is just a control "device", which is the difference between the two. The system can realize the function and coordination of any equipment, and the PLC equipment only realizes the function of this unit.
2. In terms of networking, the DCS network is ...
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Hollysys PLC - Classification and application of PLC
1. Switch logic control
Switching logic control is the basis of PLC. It is the first use case and the most extensive of all. Replace the previous relay circuit control and realize logic sequence control; It can be used for the control of stand-alone equipment, and can also be used for group control and ...
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Hollysys PLC - Introduction to the 4 basic concepts of PLC signals
Analog signal: refers to a continuous current signal or voltage signal, and analog signal can be divided into standard signal and non-standard signal.
Switching signal: It can be divided into active signal and passive signal, which is basically an on-off signal, and can be measured on and off with a multimeter ohm.
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Hollysys PLC - Introduction to the composition of PLC control cabinet
1. Open empty
A master air switch that is the power control for the entire cabinet.
2. Power supply
A 24VDC switching power supply.
3、PLC
This should be chosen according to the needs of the project. If the scale of the project is small, the integrated PLC can be used directly; If the item ...
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Hollysys DCS - What is DCS distributed control system?
DCS is the English abbreviation of distributed control system (Distributed Control System), distributed control system is referred to as DCS, which can also be literally translated as "distributed control system" or "distributed computer control system". The decentralized control system is based on the microprocessor, and the control function is decentralized.
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What are the functions of Hollysys PLC - PLC data acquisition gateway?
1. Rich networking and interface functions, easy to deploy
It supports 5G/4G/3G/WIFI/Ethernet, WAN/optical fiber and other network access modes, network port/serial port/IO port/CAN port and other equipment access, and supports LoRa wireless transmission, disconnection reconnection and multi-network mutual backup function.
2. Abundant ...
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Bureau Veritas signed a strategic cooperation agreement with Hollysys Group and issued a ball valve functional safety certificate to it
Recently, the signing ceremony of the strategic cooperation between Bureau Veritas and Hollysys and the functional safety certification ceremony of Hollysys valves were held in the Hangzhou base of Hollysys. Mr. Ye Jiong, General Manager of Bureau Veritas Technology Center, Mr. Zhong Aimin, Director of Product Certification Center, Mr. Yang Yang, Sales Director of Eastern Region, and Mr. Yang Yang, Director of Functional Safety ...
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Hollysys DCS - DCS fault maintenance measures
Whether it is a new unit or an upgraded DCS, the equipment of the system and controller should focus on the reliability and load factor (including redundancy) objectives. The load rate planning of the communication bus must be controlled within a reasonable range, and the load rate of the controller should be balanced as much as possible.
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Hollysys DCS - the selection, design and debugging of DCS system
1. The configuration of the system and controller should focus on reliability and load rate (including redundancy). The communication load rate must be controlled within a reasonable range, and the load rate of the controller must be balanced as much as possible to avoid the occurrence of "high load" problems.
2. The distribution of system control logic should not be too much.
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Hollysys assisted Qingdao Petrochemical DCS upgrade
In December 2020, the equipment of Sinopec Qingdao Petrochemical Co., Ltd. (hereinafter referred to as Qingdao Petrochemical) 5 million tons/year oil refining integration project, which was upgraded and transformed by Hollysys, was successfully operated, marking the successful completion of the DCS equipment upgrading task. This upgrade is a major development for Sinopec Industrial Holdings.
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Hollysys DCS - How to deal with DCS system failure?
1. View the data on the monitoring screen
When the following situations occur, it means that there is a problem with the control system, and the microcomputer maintenance personnel should be notified immediately for maintenance, and the operator should go to the site to deal with it.
(1) Frequently changing data does not change for a long time, and several or all data do not ...
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Hollysys PLC - maintenance steps of 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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Hollysys PLC - Introduction to the classification of PLC according to the structure and form
According to the structural form of PLC, PLC can be divided into two categories: integral type and modular type.
(1) Integral PLC
The integral PLC is a centralized power, CPU, I/O interface and other components in a chassis, which has the characteristics of compact structure, small size and low price. Small PLC ...
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