Testing the subscriber interface to the ARINC 629 current mode bus

The use of the ARINC 629 Bus on the Boeing 777 airplane introduces new capabilities and new testing challenges. Complete testing of an LRU interface to the 629 Bus requires a sophisticated test approach to validate the redundancy and error checking incorporated in the Terminal Controller, SIM and Current-Mode-Coupler bus interface components. This paper describes basic 629 Bus operation and the redundancy and error checking incorporated in the 629 Bus interface components. The implications this carries for thorough testing lead to a discussion of the test resources required to perform this testing. A coupler module test resource is described that supports 629 stub waveform monitoring, attenuating and stress testing