| 摘要 |
PURPOSE:To detect recovery automatically and to shorten polling time, by separating a downed slave station from normal polling and sending common polling to make a restored slave station output a recovery response and insert the restored slave station into the normal polling again. CONSTITUTION:When the slave stations TS2, TS5 are downed, pollings N2, N5 are removed, and when the slave station TS2 has the priority, a common polling C2 is inserted into the last position of a normal polling string. The normal polling includes the processing to supervise time at the no response of the slave station and the common polling waits only the minimum time to check the recovery response from the downed terminal and then moves to the normal polling N1 immediately. When only the slave station TS5 is restored, the slave station TS5 sends a recovery response to the master station CS when the response time of the self-station is reached after passing the time of T5 from the reception of the common polling C2. Receiving said recovery response, the master station CS inserts the normal polling N5 for the slave station TS5 from the next polling group. After receiving the normal polling N5 after recovery, the slave station TS5 loses the right of response to the common polling. |
