1. The switching signal of PLC controls the inverter
The output point and COM point of the PLC (MR type or MT type) are directly connected to the STF (forward start), RH (high speed), RM (medium speed), RL (low speed), and SG input ports of the inverter. The PLC can control the start, stop and reset of the inverter through the program; It can also control different combinations of high-speed, medium-speed and low-speed terminals of the inverter to achieve multi-stage speed operation. However, because it is controlled by switching quantities, the speed regulation curve is not a continuous smooth curve, and fine speed adjustment cannot be realized.
2. The analog signal of PLC controls the frequency converter
Hardware: FX1N, FX2N PLC host, equipped with 1 simple FX1N-1DA-BD extended analog output board; or analog input-output hybrid module FX0N-3A; or FX2N-2DA with two outputs; or FX2N-4DA module with four outputs, etc. Advantages: PLC programming is simple and convenient, the speed control curve is smooth and continuous, and the work is stable.
3. The PLC uses RS-485 communication method to control the inverter
This is the most commonly used method, and the PLC is programmed using RS serial communication commands. Advantages: simple hardware, lowest cost, can control 32 inverters. Disadvantages: Programming workload is large.
4. The PLC uses RS-485 Modbus-RTU communication method to control the inverter
Mitsubishi drives can be built with various types of communication options, such as the FR-A5NC option for CC-Link fieldbuses; FR-A5AP(A) option for Profibus DP fieldbus; FR-A5ND option for DeviceNet fieldbus and more. Mitsubishi FX series PLC has a corresponding communication interface module to connect with it.
Advantages: fast speed, long distance, high efficiency, stable operation, simple programming, and a large number of inverters that can be connected. Disadvantages: high cost.
5. The PLC adopts fieldbus mode to control the inverter
Mitsubishi drives can be built with various types of communication options, such as the FR-A5NC option for CC-Link fieldbuses; FR-A5AP(A) option for Profibus DP fieldbus; FR-A5ND option for DeviceNet fieldbus and more. Mitsubishi FX series PLC has a corresponding communication interface module to connect with it.
Advantages: fast speed, long distance, high efficiency, stable operation, simple programming, and a large number of inverters that can be connected. Disadvantages: high cost.
6. Expand memory
Advantages: low cost, easy to learn and use, reliable performance Disadvantages: It can only be used in systems with no more than 8 inverters.
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Hollysys DCS – the steps for DCS to properly power off and power on
DCS is properly blacked out
When the DCS needs to be powered off for maintenance due to overhaul or other reasons, we often directly power off the DCS, but sometimes this non-standard operation will bring serious consequences, such as configuration loss, PID parameter loss, etc. So there is a need for blackouts and re-on...
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Hollysys won the 2022 China Intelligent Transportation Association Science and Technology Award"
On October 18, 2022, the China Intelligent Transportation Association released the list of winners of the "2022 China Intelligent Transportation Association Science and Technology Award", which includes the Science and Technology Progress Award, the Technology Invention Award, and the Outstanding Innovative Talent Award. Among them, Beijing Hollysys System Engineering Co., Ltd. ...
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Hollysys PLC - PLC should be noted in operation (three, four, five)
3. Main anti-interference measures
(1) Reasonable treatment of power supply to suppress the interference introduced by the power grid
For grid disturbances introduced by the power supply, an isolation transformer with a shielded ratio of 1:1 can be installed to reduce the interference between the equipment and the ground.
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Hollysys PLC - What are the selection methods of PLC?
1. Budget for input and output (I/O) points
When budgeting I/O points, the appropriate margin should be considered, usually based on the calculated number of input and output points, and then add 10%-20% of the expandable, and after the margin, it will be used as the budget data of input and output points. When ordering in practice, it is also necessary to rely on the manufacturer's ...
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What should be paid attention to when cooperating with Lysys PLC-PLC and inverter?
1. Input of switch command signal
The input signal of the inverter includes a switch-type command signal that controls the operating status such as operation/stop, forward/reverse, section speed, and joging. Frequency converters usually make use of relay contacts or components with relay contact switching characteristics (such as crystals).
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Hollysys PLC - what are the commonly used networking methods of PLC?
1 Universal serial port module
Based on the serial port communication module to realize the network connection, the network structure is shown in Figure 1, the form of computer link is adopted, the corresponding settings are carried out in the configuration software of the host computer, and the communication can be carried out with multiple PLCs without programming, and the FXlS of Mitsubishi ...
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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 PLC - Precautions in the operation of PLC (1)
First, the working environment
(1) Temperature
The PLC requires that the ambient temperature is 0-55oC, and it cannot be placed under the components with large heat generation during installation, and the surrounding ventilation and heat dissipation space should be large enough.
(2) Humidity
In order to ensure the insulation performance of PLC, the relative humidity of the air ...
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Hollysys PLC - the use of PLC serial port communication
Serial communication is done using 3 wires: (1) ground, (2) sending, and (3) receiving. Since serial communication is asynchronous, ports are capable of sending data on one wire and receiving data on the other. Other threads are used for handshakes, but are not required.
Serial communication is the heaviest ...
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Steps on how Hollysys DCS works on a computer
1. Confirm that the new computer has relevant interfaces and can be used normally, and Hollysys DCS software can run on the computer operating system
2. Device and Lisi DCS software, dongle, and related drivers (mainly redundant network cards, data hard disks, etc.)
3. Set up ...
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and Nesbitt DCS - the difference between SCADA and DCS and PLC
To put it simply, DCS is mainly used for process automation, PLC is mainly used for factory automation (production lines), and SCADA is mainly for wide-area needs, such as oil fields and pipelines that stretch for thousands of miles. If from the point of view of computers and networks, they are unified, and the reason for the difference is mainly in ...
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Hollysys DCS - DCS daily maintenance and fault analysis and troubleshooting methods
01. Power supply
The DCS power supply system is mostly a "dual backup hot redundant power supply", and the prevention and control of power failures is mainly reflected in the inspection and daily maintenance.
Generally speaking, as long as the unit is normal ...
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Hollysys DCS - a common fault of DCS
1. Field instrument equipment failure:
Field instrumentation equipment includes various transmitters, various switches, actuators, loads and components of various temperatures that are directly connected with the production process. If the field instrument fails, it directly affects the control function of the DCS system and the operator's ...
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Hollysys debuted at the 13th Berlin International Rail Transit Exhibition
On September 20, 2022, Berlin time, the 13th Germany Berlin International Rail Transit Exhibition (InnoTrans 2022) opened at the Berlin International Exhibition Center in Germany. Following the 2018 exhibition, Hollysys once again appeared at the Berlin International Railway Exhibition (hereinafter referred to as the Berlin Exhibition) ...
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Hollysys debuted at the XCon2022 Security Focus Information Security Technology Summit
On September 19, 2022, the XCon2022 Security Focus Information Security Technology Summit was successfully held in Beijing. More than 10 technical experts, heads of security departments, and front-line security experts from well-known domestic network security enterprises shared in-depth topics at the meeting.
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What are the three layers of the network structure of Hollysys DCS - DCS?
The bottom layer, the field control layer, that is, the field instrument and signal transmission, is mainly the collection of signals and the transmission of control signals. From field devices to control CPUs.
The middle layer, the system management layer, that is, the internal network layer of the DCS system, including the control station, the operation station, the historical server...
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Hollysys PLC - the working principle of PLC controller
1. Scanning technology
When the PLC is put into operation, its working process is generally divided into three stages, namely input sampling, user program execution and output refresh. The completion of these three phases is called a scan cycle. During the entire operation, the CPU of the PLC scans at a certain speed ...
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Hollysys automation solutions
Hollysys Automation provides automation solutions for many fields.
Intelligent TCM solutions
In order to make the drug achieve the harmony and unity of the doctor's peace of mind, the pharmacist's formula, and the patient's peace of mind, higher requirements are put forward for the pharmacy environment and hospital management. But...
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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 DCS - What are the specific contents of the major and minor repair projects of the DCS system?
(1) Overhaul projects
DCS system overhaul is carried out in the random group of main equipment overhaul, and the overhaul project includes the following:
1) Conduct a comprehensive inspection of the control equipment and make a record.
2) Copy the configuration of all modules, and verify the marks and addresses of the modules.
3) Qing ...
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