GESVDU-1D-8946 Isolator Board

Description

GESVDU-1D-8946 Isolator Board

GESVDU-1D-8946 Isolator Board

The fieldbus control system, which became practical in the 1990s, is rapidly developing and is currently the latest control system in the world. The fieldbus control system is currently a hot topic in automation technology and is receiving increasing attention from domestic and foreign automation equipment manufacturers and users. The emergence of fieldbus control systems will bring another revolution to the field of automation, with its depth and breadth surpassing any other time in history, thus ushering in a new era of automation.

In some industries, FCS has evolved from PLC; In other industries, FCS has evolved from DCS, so there are countless connections and essential differences between FCS, PLC, and DCS. This article attempts to analyze the characteristics and differences of PLC, DCS, and FCS control systems, pointing out their origins and development directions.

2. Basic characteristics of PLC, DCS, and FCS control systems
At present, there are three major control systems in continuous process production automatic control (PA) or commonly referred to as industrial process control, namely PLC, DCS, and FCS. Their basic characteristics are as follows:

2.1 PLC
(1) The development from on-off control to sequential control and transportation processing is from bottom to top. (2) Multiple functions such as continuous PID control, PID in the interrupt station. (3) A single PC can be used as the master station, and multiple PLCs of the same type can be used as slaves. (4) It is also possible to have one PLC as the master station and multiple PLCs of the same type as the slave stations, forming a PLC network. The convenience of using a PC as the main station is that when users program, they do not need to know the communication protocol, as long as they write it in the format specified in the manual. (5) The PLC grid can serve as both an independent DCS/TDCS and a subsystem of DCS/TDCS. (6) Large systems are the same as DCS/TDCS, such as TDC3000, CENTUMCS, WDPFI, and MOD300. (7) PLC networks such as Siemens’ SINEC-L1, SINEC-H1, S4, S5, S6, S7, etc., GE’s GENET, Mitsubishi’s MELSEC-NET, MELSEC-NET/MINI. (8) Mainly used for sequential control in industrial processes, the new PLC also has closed-loop control function. (9) Manufacturers: GOULD (USA), AB (USA), GE (USA), OMRON (Japan), MITSUBISHI (Japan), Siemens (Germany), etc.

2.2 DCS or TDCS
(1) DCS and TDCS are monitoring technologies that integrate 4C (Communication, Computer, Control, CRT) technology. (2) A tree like topology system from top to bottom, where communication is the key. (3) In the interrupt station, PID connects the computer with on-site instruments and control devices. (4) It is a tree topology and parallel continuous link structure, with a large number of cables running parallel from relay stations to on-site instruments and meters. (5) Analog signal, A/D-D/A, mixed with microprocessor. (6) One instrument is connected to the I/O line by line and connected to the local area network LAN by the control station. (7) DCS is a three-level structure consisting of control (engineer station), operation (operator station), and on-site instruments (on-site measurement and control station). (8) The disadvantage is that the cost is high, and the products of each company cannot be interchanged or interoperated. Most DCS systems are different from each other. (9) Used for large-scale continuous process control, such as petrochemicals. (10) Manufacturers: Bailey (USA), Westinghouse (USA), HITACH (Japan), LEEDS&NORTHRMP (USA), SIEMENS (Germany), Foxboro (USA), ABB (Switzerland), Hartmann&Braun (Germany), Yokogawa (Japan), Honeywell (USA), Taylor (USA), etc.

2.3 FCS
(1) The basic tasks are: essential (intrinsic) safety, hazardous areas, volatile processes, and difficult to deal with extraordinary environments.

(2) Fully digital, intelligent, and multifunctional replacement of analog single function instruments, meters, and control devices.

(3) Use two wires to connect dispersed on-site instruments, control devices, PID, and control centers, replacing each instrument with two wires.

(4) PID is equal to instruments, meters, and control devices on the bus.

(5) Multi variable, multi node, serial, and digital communication systems replace single variable, single point, parallel, and analog systems.

(6) It is interconnected, bidirectional, and open instead of unidirectional and closed.

(7) Replace centralized control stations with decentralized virtual control stations.

(8) Operated by the on-site computer, it can also be connected to the upper computer and connected to the upper computer on the same bus.

(9) Local area network, which can then be connected to the internet.

(10) Change traditional signal standards, communication standards, and system standards into the enterprise management network.

(11) Manufacturers: Honeywell, Smar, Fisher Rosemount, AB/Rockwell, Elsag Bailey, Foxboro, Yamatake, Yokogawa, Siemens Europe, GEC Alsthom, Schneider, Process Data, ABB, etc.

(12) Typical examples of Class 3 FCS include: 1) continuous process automation control, such as petrochemical industry, where “intrinsic safety explosion-proof” technology is absolutely important. Typical products include FF, World FIP, and Profibus PA; 2) Discrete process action automatic control, such as automotive manufacturing robots and automobiles, typical products are Profibus DP and CANbus; 3) Multi point control such as building automation, typical products are LON Work and Profibus FMS.

From the description of the basic points mentioned above, have we noticed that none of the three systems used for process control were developed specifically for power plants, or in their early stages of development, they were not the preferred control objects for systems based on power plants. And in the instructions for using these systems, power plants are never considered the preferred scope of application, and some do not mention power plants at all in the scope of application. It is strange now that these three control systems, especially DCS and PLC, have been widely used in power plants and have achieved very good results.

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