基于网络信息的自动化控制英文毕业论文.doc

基于网络信息的自动化控制英文毕业论文 Control Based on Network and Information A Automation Networking Application Areas Networking is used in all areas of automation. In factory automation, process automation and building automation networks perform diverse tasks. Likewise, there are distinct differences between tasks performed for applications in different industry sectors that all have unique characteristics and consequently varying requirements. The way devices are connected, configured, and exchange data also differ. There is no one-size-fits-all for industrial networks; rather, buses are optimized foter different characteristics. For example, factory automation and process automation are often used in harsh and hazardous environments where a production interruption is costly. These requirements contrast significantly with building automation, for example, where keeping costs low is a main driving force. Factory Automation Factories with assembly-line manufacturing, as in the automotive, bottling, and machinery industries, are predominantly controlled using discrete logic and sensors that sense whether or not, for example, a process machine has a box standing in front of it. The network types ideal for simple discrete I/O focus on low overhead and small data packets, but they are unsuitable for larger, messages like configuration download and the like. Examples of this network type are Seriplex, Interbus-S, and AS-I (AS-Interface), which are sometimes called sensor buses or bit level buses. Other more advanced protocols oriented toward discrete logic include DeviceNet, ControlNet, and PROFIBUS (DP and FMS application profiles). These buses are sometimes referred to as device buses or byte-level buses. Factory automation involves fast-moving machinery and therefore requires quicker response than slower processes. Traditionally, these tasks have been handled by PLCs. Process Automation Process plants in industry segments like refining, pulp paper, power, and chemicals are dom