The Strategies Of Access And Co-existence Of Multi-fieldbuses Based On The PROFIBUS Fieldbus

With the development of electronic technology, computer technology and network technology, the industrial production process control system is the scene toward the intelligent, digital and network-oriented direction. The traditional distributed control system(DCS) to the hierarchical control computer has gradually given way to the fieldbus network control system based on intelligent terminals and networks. The fieldbus network control system is the closed system which connects a variety of devices together through a suitable fieldbus, and the devices connected to the bus can be sensors,control, communications equipment and computers with a variety of features of intelligent and communications, which can directly exchange information through the bus. Therefore, the bus is the core to form a complete control network, this system has the ability to exchange information between devices, to self-adjust the devices, and to connect directly with the internet. The fieldbus network can be viewed as a direct terminal information system,which is a network control system based on information, to achieve flexible control, decentralized control, information sharing, optimize production processes, quantitative management of enterprises and improvement of production efficiency. Therefore, the field bus technology is the intersection of three major technologies:the process control technology, automation technology and computer network technology.Because of the advantages and features of fieldbus technology in industrial control systems,many well-known international cooperations since1980’s have launched several industrial fieldbuses and field communications protocols, such as:PROFIBUS, CAN, FF, IonWorkes, DeviceNet, WorldFIP, etc., but as a result of the technical standards used by different companies are not the same,that is to say, there is no single standard, which severely limit the development of information technology in the area of industrial control processes.The PROFIBUS fieldbus system is a European fieldbus standard launched by Siemens and other cooperations, which has great advantages and is the most widely used international and domestic industrial fieldbus systems. From the domestic point of view, on one hand, PROFIBUS fieldbus technology is more widely used:fieldbus technology has been used in the foreign wholesale introduction of fieldbus technology, production equipment and technologies (such as automotive, pharmaceutical and other production lines), such as Siemens, ABB’s PLC and DCS control systems,which has also been used in the field inspection equipment such as temperature, frequency, loop controller, etc. to the intelligent, network-oriented;On the other hand, the existing international variety of industrial fieldbus, most of the domestic scenes do not have the equipment and instruments connected PROFIBUS functions.In the context of co-existence and co-bulilding of a variety of industrial fieldbuses,and in the condition of most domestic field equipment and instruments not having the function of communication with PROFIBUS fieldbus, the study of access and co-existence of multi-fieldbuses based on the PROFIBUS fieldbus will have considerable significance. Through research, we have come a result that the coexistence of multi-fieldbuses based on PROFIBUS fieldbus control system is possible through rational planning, connection and communication devices and equipment not having the PROFIBUS functions to access PROFIBUS fieldbus system is also operable.