The real-time information scheduling method of industrial control network based on queuing theory

The scheduling method of real-time information is one of the important factors which affect the real-time property of industrial control network. According to the generated characteristics of information in industrial real-time system, an arrival process which generated time spacing between adjacent information shall not be less than a constant has been presented. For the polling system, each node generates real-time information and non-real-time information, the concept of virtual node has been introduced. To apply the multiple vacations queuing theory, each virtual node has been as an M/G/1 queue system with multiple vacations, the real-time information scheduling method based on queuing theory has been presented (abbreviation: RSQT), and computational formula of real-time information waiting time has been deduced. Using MATLAB simulation experiments verify the influence of the information arrival rate to information transmission delay time, and giving theoretical reference for parameter optimization of RSQT method. Simulation results show that the information waiting time increases with the increase of information arrival rate. When information arrival rate increases to 9.5, the waiting time has increased by 8.53% than when information arrival rate is 5.0. When the system load is greater than 70%, the waiting time is increasing at a rate of about 73%.