The Real-time Performance Of Industrial Ethernet Based On RTLinux/Linux

Real-time performance is one of the most important technologies in industrial networks. Currently, organizations and factories in the native and abroad have presented some industrial Ethernet standards, which are based on Ethernet+TCP/IP. However, these standards don't provide excellent real-time resolution for the data link layer, so it is necessary to research.Based on Phase Loop and PID, a precise and simple clock synchronization algorithm is presented combining with the exactly computation. The traditional Ethernet experiment platform based on RTLinux is built to verify the algorithm, and the node's real-time network subsystem is built. The results of the experiment prove that the synchronization algorithm presented here eliminates the effect of the clock drift and higher precision and better dynamic characters are achieved. The algorithm is realized in a module, which can be extended for the further study of synchronization algorithm and distributed real-time system.On the basis of describing the message model and system model of switched industrial Ethernet, an industrial Ethernet switch composed of PC, multi-port NIC ZX346Q and Linux was designed to study and validate the model and scheduling policies.In the Linux traffic control environment, a double channel model which provides differentiated service for the real-time and non real-time data was implemented in the switch. After introducing a new MR-WRR queuing discipline with Linux kernel programming, a basic framework to realize general queuing discipline is provided. The results of the experiment on the switched industrial Ethernet show that the double-channel model is effective.