Hollysys PLC - the basic structure of PLC controller is introduced

Examining the hierarchical structure of DCS, DCS level and control management level are the two most basic links that make up DCS. The process control stage specifically realizes the decentralized control functions such as signal input, conversion, operation and output. The controls at the process control level vary in different DCS, ...

CNC machine tool PLC (programmable logic controller) has the following common faults in the operation process, and the following corresponding solutions are taken for the faults in the work engineering to make the equipment operate normally. 1. The power grid fluctuates too much, and the PLC does not work It is manifested as no output of the PLC. Check first ...

(1) High reliability DCS is designed to be fault-tolerant, so that when a computer fails, it does not cause the system to lose other functions. In addition, because the tasks undertaken by the individual computers in the system are relatively simple, it is possible to adopt a specific structure and ...

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 ...

Merit: 1. High reliability: The DCS system has multiple redundancy, backup and recovery mechanisms, which can ensure the high reliability and stability of the system. 2. Sensitivity: The DCS system can be customized according to different industrial processes to meet different control requirements. 3. Efficiency: D...

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, ...

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...

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)

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 ...

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. PLC can control the frequency conversion through the program ...

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.

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...

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 ...

(1) There are three forms of programmable controller: relay output, thyristor output, and transistor output. (2) The wiring of the output terminal is divided into independent output and common output. When the output relay or thyristor of the PLC is activated, the two output terminals of the same number are turned on. In different groups, you can ...

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 ...

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.

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 ...

(1) Select the appropriate PLC model and I/O points, and select the special function module when there are special function requirements. (2) Familiar with the selected PLC programming instructions and compilation software. (3) Carry out soft component planning, including internal relays, holding relays, data registers, ...

1. Check before power-on If the cable insulation resistance meets the requirements (greater than 5M ohms), check the cable insulation resistance test record, and spot check the actual measurement if necessary. Check that all power cables, signal cables, and communication buses should be connected. Control stations, operator stations, engineer stations, etc.

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).