PROCEDE DE TRANSMISSION DE DONNEES

A method and system for transmitting data between a central control unit and a plurality of terminals arranged in a loop configuration in which each terminal includes a shift register and a two-position switch, the former short circuiting the terminal and the latter interposing the shift register in the loop. When the central unit wants to know which terminals have data to transmit to it, it sends a B character on the loop, which is intercepted by the registers of all the terminals. The terminals which have data to transmit place their switch in its second position and load their register with their identification number. The central unit then sends a sequence of A characters which are intercepted by the terminals which have their switch in the second position and which shift the identification numbers from register to register and so forth to the central unit, thus enabling the central unit to determine which terminals have data to transmit.