| 摘要 |
PURPOSE:To prevent an increment of traffic for the trunk circuit and at the same time secure a normal communication even when a transmission delay occurs, by using the polling signal and the closure signal between the main terminal and the subordinate terminal of the polling system. CONSTITUTION:In a communication cycle during which the send-back of data complets from the subordinate terminals TD1-TDn selected by the polling signal P and after a start of transmission of signal P through the main terminal TM, the repeating device RM transmits the P indication signal that indicates a transmission of signal P to TD to the repeating device RD when the first P signal is received from TM, and then sends the closure signal E back to TM. After this, the signal E is transmitted to TM when a coincidence is obtained between the subsequent P signal and the preceding P signal and in case the data is not received and accumulated from the selected TD, and the data is sent to TM during accumulation. On the other hand, RD transmits the signal P repetitively when receiving the signal S from TD and then sends the data, if receives, to RM. |
