Discrete interface devices

Airlines and airframers are looking increasingly beyond initial costs to life-cycle-costs, support and re-design costs. A potential path to benefits in these areas being explored today is integrated modular avionics (IMA). In order to support increased commonality and modularity within avionics, the burden of fault-isolation, fault-tolerance and redundancy is placed upon those subcomponents which will become the building-blocks of those systems. To further exploit architectural commonality it will be particularly important to standardize those functions and signals that interface as I/O between modules. One of the interface signal types which has been problematic in federated architectures and will continue to be problematic in modular architectures is the "discrete"; 28V-based switch and relay signals that provide binary status over a wide range of applications. Historically, the interface has been custom-tailored, using resistors, capacitors, diodes, and transistors, for each unique platform and black-box; redesigned for each new requirement. Customer requirements have been aggregated to develop a standard product that adds function, reliability, fault-tolerance as well as ease of interface to digital avionic systems.<>