Development of 1553 mux bus simulation analysis algorithm

Abstract

MIL-STD-1553 is a protocol for a communication network, the life-line of aircrafts, space vehicles and unmanned aerial vehicles (UAVs) etc., on which the command and control computer and all the embedded Avionics subsystems of the platform are interconnected. The 1553 system integrator has to ensure that the defined limits of the 1553 standard for maximum bus loading and delay ratios are met for all the messages (in thousands) travelling on the data bus. The ICD (interface control document) of the individual subsystems are set/modified for maximum delay time (MDT)/refresh rate (RR) or message size (word count) of the messages on the basis of an analysis to make the communication network free from overload. This analysis defines the MDT/RR and word count of all the messages of the overall communication system resulting in an optimal communication system design. In this paper we have developed a novel algorithm/tool i.e. Mux Bus Simulation analysis tool (MUSAT) that analyzes the data bus loading and its delay ratio by simulating the real time communication operation of the application layer of the mission management computer (MMC) of the 1553 network. A novel data bus static optimization algorithm (DBSOA) is developed which schedules all the data words of the messages of any given Avionics system ICD into a number of minor frames of a major frame of data such that all the minor frames are nearly uniformly loaded. The developed tool (MUSAT) is based on the improved version of the DBSOA called ISBC (improved static bus control) algorithm that loads the messages of all the sub systems from the scheduled block list of the DBSOA asynchronously and dynamically depending upon their refresh rates. Complete data bus loading and delay ratio of all the messages are found for a specified overall time length comprising of 100s of major frames. With this type of message scheduling and loading, the performance of the 1553 communication network improves considerably i.e. the bus loading and delay ratio are optimal for the selected refresh rates /MDTs of the messages of the complete ICD. The 1553 communication network designed on the basis of this analysis fulfills all the requirements of MIL-STD-1553, and is free from communication overload. Furthermore, the ISBC algorithm makes possible the minimum number of iterations during the 1553 network avionics hardware integration cycle that result in the optimization of the communication system design.