A bus coupler is a device meant to help users switch between two or more computer buses on the fly. Unlike other bus switching methods, in which the computers must be shut off to avoid electrical problems, a bus coupler allows users to change buses without going through this process.The primary task of a bus coupler is to help users switch between different buses on a network. This task normally takes a relatively long time, because the power has to be turned off, the other bus has to be confirmed as safe, the computer has to start back up and the buses have to power up