The Study Of The Fieldbus (Profibus) Protocol And The Realization Of The Terminal Instrument

In the process of the industrial production, owing to the increasing expansion of the production scale, the growing complexity of the production craft and the majority of the craft reference number to measure and control, the automation of the production process must be realized by adopting the progressive industrial process control system and the intelligent instrument. The cardinal requirements of the contemporary control system are to rapidly and efficiently collect and transmit the field production data and the managerial data, to promptly and precisely achieve the variety of information from the field facilities. Therefore, the high-intelligent, high-speeding-processing control facilities, like the field control computer and PLC etc, and the variety of the intelligent equipment, or the intelligent transducer should be interconnected.With the swift growth of information technology and the profound revolution of the industrial automation system frame, the scope of the information exchange also rapidly covers every level from the total-branched-network collective automation system and enterprise information system based on the former. The Fieldbus technology, which calls an extensive attention to itself in the automation world and will become the developing trend in that world, is the right revolutionary technology adjusting to the necessary.The Fieldbus is the kind of serial, digital and multy-points data bus among the field facilities, intrument and the auto-control equipment system in the control room equipped in the production process field. The Fieldbus is located at the base layer of the production control and network frame and is directly connected with the factory field facilities; For one thing, the field measurement control facilities would be interconnected to remain a communication network so that the information between the different net-band and the different field communication facilities could be shared. For another, the variety of the running information on the spot would be transmitted to the control room far from the spot and then connected with the control terminals and the high-level control-managed network to realize information share, so that the relation between the field control facilities of the production process and the higher-controlled administrative level could mutually be understood. The Fieldbus in the automation system like manufacturing, flow industry, metallurgy, electricity, transportation and building etc, remain an extensive application future.Through the study toward the Fieldbus' development in the subject, the Profibus is considered as the main study goal. At the present, the Profibus is one of the internationally applicable Fieldbus standards. Famous for its unique technology characteristic, severely accredited rule, open criterion, the supports of the majority of factory merchant and the continuously developing application profile, the Profibus has been the most important Fieldbus' standards.The study toward the Profibus aims to develop the intelligent intrument based on the Profibus. After study mainly toward the Profibus' protocol and the running principle in the subject, the profound understanding of the Profibus -PA profile could be achieved from which we could pick out the reference number related to the intelligent instrument and supply technology support for the software and hadwre development of the intelligent instrument.