Research On OPC UA Service Scheduling Based On Time-Sensitive Networking

With the rise of Industry 4.0,the Industrial Internet is developing rapidly,of which the network is the foundation of the Industrial Internet.At present,the network in the factory has a "two-tier and three-tier"structure,and the Information Technology(IT)network and the Operation Technology(OT)network are independent of each other,making it difficult to realize data transmission in a unified network architecture,which greatly This greatly reduces data transmission efficiency and increases communication costs.The convergence of the two can effectively solve this problem.The combination of Open Platform Communication Unified Architecture(OPC UA)and Time-Sensitive Networking(TSN)constitutes a unified and open network communication architecture,which can realize the convergence of IT and OT.The combination of OPC UA and TSN constitutes a unified and open network communication architecture that enables the convergence of IT and OT.The research on OPC UA service scheduling based on time-sensitive networks is of great significance because it can combine the safe and reliable semantic interoperability of OPC UA with the real-time and deterministic network behavior of TSN to provide a unified and standardized solution for real-time industrial communication.OPC UA services are implemented based on communication between OPC UA applications.The current implementation of OPC UA application scenarios based on TSN is relatively simple and lacks the analysis of OPC UA service traffic.For realizing low-latency communication of OPC UA applications based on TSN network,the underlying TSN network cannot obtain the latency parameters of OPC UA service traffic,such as period,end-to-end delay and jitter,which makes it difficult to complete the network configuration of TSN.In addition,the network-level traffic scheduling provided by the TSN cannot fully guarantee the real-time OPC UA service at the terminal,and the application-level end-to-end delay is related to the underlying network scheduling and the task scheduling within the terminal system.Based on the above problem analysis,the main work of this paper is as follows:Firstly,we complete the research on the communication technology of OPC UA service based on TSN.This paper analyzes the OPC UA and TSN convergence network model,establishes the mapping mechanism of OPC UA Pub/Sub messages and TSN frames,and realizes the mapping of OPC UA service flows to TSN network flows.And the network configuration scheme of OPC UA terminal and TSN is designed according to IEEE 802.1Qcc protocol.Based on this,this paper builds the experimental architecture of OPC UA service communication based on TSN controller,and complete the workflow design and testing of each functional module in the architecture to realize the automatic interaction configuration from OPC UA terminal to TSN network.The final comparison of OPC UA Pub/Sub packet latency analysis with and without TSN scheduling support at the bottom layer proves that the application packets based on TSN network have better transmission performance,and the transmission latency is improved by 80%on average.Secondly,for the underlying TSN network scheduling calculation process,this paper proposes the joint scheduling algorithm of terminal service flow and TSN network flow,and makes optimization based on Satisfiability Modulo Theories(SMT)solution process.The system modeling transforms the joint scheduling problem of terminal service flow and network flow into a mathematical solution problem,and the scheduling solution domain is expanded from the network link domain to the sum of terminal link domain and network link domain,and the scheduling constraints are established and solved by the SMT solver.In this paper,we divide terminal service flows into communication service flows and noncommunication service flows according to their characteristics,prioritize the use of the SMT solver to solve the scheduling of terminal communication service flows and the underlying network flows,and then traverse each terminal to determine the scheduling of non-communication service flows on the remaining solution space of each terminal link using the real-time scheduling deadline priority algorithm.The overall solution performance is improved by reducing the solution size of the SMT solver.Finally,the effectiveness of this optimization algorithm is analyzed through simulation experiments.