Abstract: A poll command is sent by a central station to a plurality of remote stations connected along a data highway system. Upon receipt of the poll command, a remote station which desires to transmit data to the central station, responds with a reply pulse in a specific time position following the poll command. The position of the reply pulse is measured relative to the end of the poll command from the central station. Upon transmission of the poll command by the central station, a counter is started at the central station to count clock pulses arranged to occur at the end of each possible reply pulse position. Upon receipt of a reply pulse from a remote station, the count in the counter, which represents the binary address of the replying station, is stored in a memory and a memory address counter is incremented to control the storing of successive binary addresses in consecutive memory locations.