The Real-time Performance Of Switched Industrial Ethernet And Time Triggered CAN System

Real-time performance is one of the most important technologies in industrial networks. Currently, organizations and factories in 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.On the base of the network calculus model of crossbar Ethernet switch and the messages transmit model of the industrial networks, the arrival curve of industrial data and the service curve of switch are got. From the two curves the transmit delay bound and relative required memory bound were educed. These results can instruct the design and implementation of the industrial Ethernet.To resolve the problems of transmit reliability and scheduling delay of the output buffer, a policy of delay guaranteed window bandwidth allocation was presented, which is based on the window flow principle. The credit closed loop was induced into switch to guarantee the reliable switch. What's more, the number of credits to guarantee the maximum transmit delay was got based on the network calculus model of industrial switch. So, the sufficient bandwidth can be allocated to provide delay guaranteed transmit service for the hard real-time data in the industrial Ethernet.To resolve the problem of competition between real-time and non real-time data, an improved industrial Ethernet switch was presented based on the double-channel switch model of SIMENS. This model establishes real-time and non real-time logical channel in the switch to realize the differentiated service. To improve the real-time ability of real-time channel and the fairness of the non real-time channel the MR-WRR and I-DWRR were presented. What's more, an industrial Ethernet switch composed of PC, multi-port NIC ZX346Q and Linux was designed to validate the model and scheduling policies presented.To improve the real-time performance of the fieldbus, a mixed time-triggered CAN named MTT-CAN was presented, in which the time axes was divided into synchronous phase and asynchronous phase to make full use of the merits of time-triggered and event-triggered mechanisms. We applied the deterministic and stochastic Petri net theory to model the MTT-CAN and relative simulation wasrealized. The simulation results proves that MTT-CAN improve the real-time performance and bandwidth utilization rate, what's more, the non real-time messages can be transmitted by selecting the bandwidth rate in the asynchronous phase properly.