METHOD FOR MULTI-READING A PLURALITY OF ID'S

摘要

A question device specifies a maximum read range (S0, e0) where ID to be read is present (step S1) and the question device transmits a read request command to a response device (2) (step S2). When a response is received, it is judged whether the response is from a plurality of response devices (2) or a single response device (2) (step S5). When a plurality of responses are identified, the power exponent e of the read range (S, e) is modified to e' = e - 1 (step S6). When a single response is identified, the ID of the response device (2) which has responded is read (step S8) and the start end S of the read range (S, e) is updated to S' = S + d (=2<e>) (step S9). When the previous response flag F is other than "a plurality of responses present", the power exponent e of the read range (S, e) is modified to e' = e + 1 (step S13).