Concept and composition of fieldbus control system
1. The concept of fieldbus control system (FCS)
Fieldbus control is a computer local area network for the automation control of industrial equipment. Fieldbus control relies on a microprocessor chip with detection, control, and communication capabilities. Digital instruments (equipment) achieve complete decentralized control in the field, and use these field scattered measurement and control equipment as a network node, and use these points as a bus The forms are connected to form a fieldbus control system. It belongs to the lowest network system, and is a network integrated fully distributed control system. It disperses all the functions of the original distributed DCS system field control machine at each network node. Therefore, the originally closed, dedicated system can be turned into an open, standard system. It can enable the products of different manufacturers to be interconnected, which is an update of the DCS system, which simplifies the system structure to a large extent, reduces the cost, better meets the practical requirements, and improves the reliability of system operation. Fieldbus control systems of different communication protocols are generally connected to the fieldbus network segment through the PC interface board of the bus slot in the industrial PC.
Microcyber corporation successfully developed the first domestic and third internationally certified FF H1 fieldbus protocol stack; the first domestic industrial Ethernet protocol (HSE); participated in the formulation of the first domestic Ethernet-based Factory Automation Protocol (EPA) international standard and the first industrial wireless communication WIA-PA international standard.
2. The composition of fieldbus control system
Fieldbus control system consists of three parts: measurement system, control system, and management system. The hardware and software of the communication part are its most distinctive parts.
1.） Fieldbus control system:
Software is an important part of the system. The software of the control system includes configuration software, maintenance software, simulation software, equipment software and monitoring software.
The first choice is to develop configuration software and control and operate the man-machine interface software MMI. Through the configuration software, the connection between the function blocks is completed, the function block parameters are selected, and the network configuration is performed. In the process of network operation, the system collects data, performs data processing and calculation in real time. Optimized control and logic control alarm, monitoring, display, report, etc.
2,） Fieldbus measurement system:
It is characterized by multi-variable and high-performance measurement, so that the measuring instrument has more functions such as calculation ability. Due to the use of digital signals, it has high resolution, high accuracy, strong anti-interference and anti-distortion capabilities, and also has the status of instrument equipment. Information, the processing process can be adjusted.
3,） equipment management system:
It can provide diagnostic information, management information, equipment operating status information (including smart meters) of the equipment itself and the process, and equipment manufacturing information provided by the manufacturer.
4.） Bus system computer service mode:
The client/server model is currently the more popular network computer service model. The server represents the data source (provider), and the application client represents the data consumer. It obtains data from the data source and performs further processing. The guest room machine runs on a PC or workstation. The server runs on a minicomputer or a mainframe, and it uses the intelligence, resources, and data of both parties to complete tasks.
5.） Database:
It can store a large amount of relevant data and applications in an organized and dynamic manner, realize full sharing and cross-access of data, and has a high degree of independence. During the operation of industrial equipment, the parameters continuously change, the data volume is large, and the real-time operation and control requirements are very high. Therefore, a distributed and real-time database system that can be accessed and operated mutually is formed. The mature ones on the market are Orad, sybas, Informix, SQL Server in relational databases; Infoplus, PI, ONSPEC in real-time databases, etc. .
6.） The hardware and software of the network system:
Network system hardware includes: system management host, server, gateway, protocol converter, hub, user computer, etc. and underlying intelligent instruments. Network system software includes network operating software such as NetWarc, LAN Mangger, Vines, and server operating software such as Lenix, os/2, Window NT. Application software database, communication protocol, network management protocol, etc.
