POLLING COMMUNICATION METHOD

摘要

PROBLEM TO BE SOLVED: To reduce a polling wait time by placing priority depending on kinds of each slave and data and causing contention through different delay times. SOLUTION: In the case of sending data from a slave 60 to a master 50, the master 50 sends a data packet C including information to inform start of contention to the slave 60. The slave 60 having data to be sent to the master 50 monitors its own reception port while awaiting a transmission opportunity for a prescribed delay time depending on the priority generated in itself at random. Then only a slave having no data to receive its own reception port generates at random its own preamble data D for the delay time generated in itself at random and sends the data to the master 50 and the master 50 sends the same preamble data E. The slave 60 compares the received preamble data E with the preamble data D sent by itself and sends a data packet F going to be sent when they are identical to each other.