1. Logic control of switching quantity
This is the most basic and most extensive application field of PLC, which replaces the traditional relay circuit to achieve logic control and sequence control, which can be used for the control of a single device, as well as for multi-machine group control and automatic assembly line. Such as injection molding machines, printing machines, staple machines, combination machine tools, grinding machines, packaging production lines, electroplating lines, etc.
2. Analog control
In industrial processes, there are many continuously varying quantities, such as temperature, pressure, flow, level and velocity, which are analogue. In order for a programmable controller to process analog quantities, it is necessary to implement A/D conversion and D/A conversion between analog and digital. PLC manufacturers produce supporting A/D and D/A conversion modules, so that programmable controllers are used for analog control.
3. Motion control
PLC can be used for the control of circular or linear motion. In terms of control mechanism configuration, in the early days, it was directly used for switching I/O modules to connect position sensors and actuators, and now special motion control modules are generally used. For example, single- or multi-axis position control modules that can drive stepper motors or servo motors. Almost all the products of the world's major PLC manufacturers have motion control functions, which are widely used in various machinery, machine tools, robots, elevators and other occasions.
4. Process control
Process control refers to the closed-loop control of analog quantities such as temperature, pressure, and flow. As an industrial control computer, PLC can program a variety of control algorithm programs to complete closed-loop control. PID adjustment is the most widely used adjustment method in general closed-loop control systems. Large and medium-sized PLCs have PID modules, and many small PLCs also have this functional module. PID processing is generally to run a dedicated PID subroutine. Process control has a wide range of applications in metallurgy, chemical industry, heat treatment, boiler control and other occasions.
5. Data processing
Modern PLC has the functions of mathematical operation (including matrix operation, function operation, logic operation), data transmission, data conversion, sorting, table lookup, bit operation, etc., which can complete the collection, analysis and processing of data. This data can be compared with a reference value stored in memory, which can be used to control certain operations, or it can be transmitted to other smart devices using communication functions, or they can be printed and tabulated. Data processing is generally used in large-scale control systems, such as unmanned flexible manufacturing systems; It can also be used in process control systems, such as some large-scale control systems in the papermaking, metallurgy, and food industries.
6. Communication and networking
PLC communication includes communication between PLCs and communication between PLCs and other intelligent devices. With the development of computer control, the factory automation network has developed rapidly, and all PLC manufacturers attach great importance to the communication function of PLC and have launched their own network systems. The newly produced PLCs all have communication interfaces, which are very convenient for communication.
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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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Bureau Veritas signed a strategic cooperation agreement with Hollysys Group and issued a ball valve functional safety certificate to it
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and Lisi DCS - the difference between DCS control and PLC control
1. PLC programmable logic controller (programmable controller).
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Hollysys will make a blockbuster appearance at the first Shenzhen Nuclear Expo in 2022
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The theme of this year's Nuclear Expo is "Nuclear Gathering in the Bay Area, Activating the World".
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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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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 DCS - the main factor of DCS signal interference
Resistive coupling interference
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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
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Hollysys PLC – How to calculate the analog quantity in PLC
1、-10—10V。 When the voltage of -10V-10V is converted to F448-0BB8Hex (-3000-3000) at 6000 resolution; At 12000 resolution, it is converted to E890—1770Hex (-6000—6000).
2、0—10V。 At a voltage of 0-10V, at a resolution of 12000 ...
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Hollysys DCS output module - K-AO02 advantages introduced
1. The output accuracy is as high as 0.05%, which greatly improves the operation efficiency of the system.
2. The full-scale output of the channel signal is 0-22.7mA, and the output range is wide;
3. It can be adapted to the enhanced base to achieve channel resistance to 220VAC;
4. It has a perfect channel signal diagnosis function, which can be realized.
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Hollysys PLC - a component of the 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
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Hollysys DCS - DCS system operation problem analysis and preventive measures
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and Lisi PLC - the difference between PLC control system and relay control system
(1) From the point of view of control methods
The control logic of the electrical control system adopts hardware wiring, and the series connection or well connection of the electrical mechanical contact is combined into the control logic, and the connection is complex, large in size, and in large power consumption, and it is difficult to change or increase the function after the system is formed. Other than that...
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Hollysys PLC - three forms of PLC output circuit
1. Relay output circuit
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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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Hollysys went to Shaanxi Traffic Control Group for a discussion and exchange
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Hollysys PLC - PLC should be noted in operation (2)
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Hollysys DCS - Introduction to I/O in DCS control system
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Hollysys assisted the successful construction and operation of the largest natural gas deep processing base in Xinjiang
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Tarim Oilfield Natural Gas Ethane Recovery Project ...
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