MAINS SIGNALLING SYSTEMS

摘要

A remote electricity metering system is known in which a central station (LC) communicates with meters (U1-U13) over the mains (10-14), with messages to remote meters being relayed by intermediate meters and the route of a message being determined by the central station. The present central station includes routing means which comprise, for each meter: a single route table (45-1) which contains a plurality of possible routes (46-1, etc) to the meter; route selector means (47) for selecting among those routes; and means (48, 49), operative if none of the routes in the table enable the meter to be reached, for generating a fresh route and inserting it in the table by displacing a single route from the table. A figure of merit may be stored (at 51) for each route, dependent on the quality of that route or simply on its length. Counters count (48) the number of successive failures of a route and (49) the number of successive failures of successive routes. Routes may be selected in dependence on the time and/or conditions in the mains system.