The present invention provides for an improved network bus terminator (4), and related bus networks and bus network segments/trunks (1), and comprising a bus network terminator (4) including bus network termination functionality and a diagnostic analyzer (20) and wherein the degree of diagnostic functionality provided within the terminator (4) can then, as with the terminator itself, be provided as an inherent feature of the segment/trunk (1), and thus also the bus network, and can comprise limited, simple but suitably effective diagnostic functionality, and which can be inherently suited to bus analysis during a commissioning, and/or initial deployment, phase and be provided in a cost-effective manner.