Abstract: The invention relates to methods and apparatus for isolating faults in link-connected systems utilizing fault reports generated from within the system itself. The reports are transmitted to a central location, preferably during a predetermined time period, and are used to create a single error message identifying the probable nature and location of the fault. A preferred embodiment of the invention does not require either the construction or maintenance of systemwide configuration tables, commonly used performing fault location and analysis. Instead, each unit of a pair of link coupled units, initially or on reconnection, interrogates a link adapter at the other end of the link for an identifier that identifies both the remote unit and the remote link adapter. This "nearest neighbor" information is stored locally at each unit, and is transmitted to the central location when an error is detected.

Abstract: A self-anchoring poke-thru wiring device for the extension of communication and/or electrical wiring through a passage in a floor designed to prevent the spread of fire from one side of the floor to the other and facilitate ready installation and removal of the device from above the floor opening. The device includes a pair of upper conduit portions aligned with a pair of lower conduit portions and a plurality of fire resistant expandable disks retained between an upper and a lower plate intermediate the pairs of conduit portions, the disks and plates including aligned apertures with the conduit portions providing separate wireway channels. The upper conduit portions lead into an outlet box via a floor plate. A pair of generally V-shaped resilient retaining members are removably secured to opposite sides of the upper plate.