The Real-time Analysis Of Ethernet With Light Load

People need a high speed and low cost network in process control area. In the past several years, the standard of Ethernet had been improved much especially on determination, speed and information priority. Because of the rapid development of the exchanging technology the impediment of adopting Ethernet in control area is eliminated greatly. Recently, many organizations and companies are working on the implementation of seamless connection of Ethernet and f ieldbus . This developing trend makes Ethernet extend into lower layer.In this paper, m/M/1 model in queuing theory is applied to Ethernet modeling with light load. Through defining collision probability, collision probability coefficient, minimum feasible probability, tiny probability and maximum feasible collision times, the method for calculating maximum delay of network is clarified with the concept of maximum feasible collision times. It is illustrated that maximum delay of Ethernet becomes bigger with its load increase.The paper also discusses that the range of random number in Binary Exponential Back-off Algorithm influences maximum delay of Ethernet, and proper value of maximum random number can make Ethernet with light load have better real-time property and satisfy process control.