A system for monitoring/logging events across disparate network busses using a global master clock for timestamping, particularly for aircraft

Modern aircraft utilise numerous line replacement units (LRU) 520,530,540 for control, monitoring, avionics and such like. The LRUs are interconnected using communication busses 500,510 which may utilise a number of heterogeneous protocols. For example Mil-Std-1553 and ARINC-429. The invention proposes a network probe 434 for monitoring/logging traffic on these disparate busses. The probe records events on each bus and tags them using a universal master clock 560. The tagged events can then be forwarded to other systems 580 for further processing or display to users. The system may correlate events on different busses to investigate communication latencies.