A Candidate for Linear Token-Passing, High-Speed Data Bus Systems

Future avionics systems will have distributed architectures requiring computers and data transfer systems that can perform real-time calculations and are fault tolerant. Previously developed data bus standards such as MIL-STD-1553 are inadequate for these applications.

Existing standards will not meet the needs of the future. They are too slow; have functions that are single-point failures; do not take advantage of new technologies such as fiber optics; and have poor efficiency when applied to distributed architectures.

To meet the needs of data buses for distributed, real-time, fault-tolerant architectures of the future, a candidate High-Speed Data Bus (HSDB) protocol has been developed by the authors.

This paper describes the performance characteristics of the candidate HSDB protocol including the following:

• Token-passing protocol. Token-passing best meets the needs because it is inherently distributed.
• Fiber optics implementation. Fiber optics is the media of choice because of its gready improved data rate, weight, and EMI characteristics.
• Host interface. The host interface is examined with respect to its interaction with the HSDB terminal.
• Performance against the HART benchmarks. The candidate HSDB protocol performs very well when it is evaluated against the SAE AE-9B High-Speed Data Bus Applications Requirements Task (HART) group developed benchmarks.