The Design And Implementation Of An Optical Real-time Ethernet MAC Protocol

Over the years, the field bus standards applied in industrial automation field are complicated with distinct characteristics and poor interoperability. With the development of Internet, the Ethernet technology has become a dominant network technology in information technology field, which has significant advantages such as low cost, high speed, uniform standards, better compatibility, etc. Thus, Ethernet is proposed to be extended to industrial automation field, in order to achieve the network integration from the management layer to the industrial field layer. However, industrial automation networks have the strict real-time and time-deterministic requirements, which are precisely the weakness of Ethernet. To solve this problem, Real-Time Ethernet (RTE) technology is introduced, with extensions or improvements based on Ethernet to meet the stringent real-time requirements.This paper innovated introduce the Ethernet Passive Optical Network (EPON) widely used in the optical access field into the industrial control field, and propose the REPON network which is based on multipoint passive optical network. Compared with the existing Real-time Ethernet standards, REPON network inherits the advantages of passive optical networks, and achieves a better real-time performance by its Real-time Medium Access Control (MAC) protocol. This paper makes the related exploration and research work for the REPON Real-time Medium Access Control protocol. The main contents are as follows:1) From the Ethernet perspective, comparing several kinds of current representative Real-time Ethernet technology, introduce the overall structure and design of the novel optical Real-time Ethernet protocol REPON with real-time user services support capabilities from the network structure and data link layer Real-time Medium Access Control method these two aspects.2) Implement the Real-time Medium Access Control protocol of central node and access node in FPGA (Field Programmable Gate Array) platform, detailed analysis of the working principle and implementation method of the main modules, and simulated the real-time MAC functions. The simulation result shows that the hardware controllers can meet the strict real-time requirements and achieve real-time access for user services.3) Take CAN (Controller Area Network) real-time service accessing as an example, build a reliable 100Mbps REPON-CAN experimental network on hardware platform to verify the feasibility and reliability of the REPON MAC protocol. The experimentation results show that this REPON MAC protocol can provide an excellent real-time performance, e.g. less than 200μs response time when connected with 16 users.