ASCENDING AND DESCENDING LINE SEPARATION TYPE TOKEN COMMUNICATION SYSTEM

摘要

PURPOSE:To simplify the control logic of a station by transmitting some signals at all times to a descending extension transmitting means and at the same time transmitting permission packet signals for transmission to an ascending extension transmitting means with centralized control. CONSTITUTION:The idle signals are continuously transmitted to a descending extension transmission line 8 from a monitor node 7 even in case no packet signal is transmitted to the line 8. Terminals 16-18 can have easy phase-locking with the reception signal. No preamble is needed for the packet signal of the descending line. This improves the using efficiency of a transmission line. Furthermore the transmission of the incoming packet is possible to the descending line for a period when the ascending line is busy with the packet signal since the extension transmission lines are separated into ascending and descending lines. Thus it is possible to attain simultaneously the double bi-directional communication of outside line for mutual communication between extensions. In addition, the controls for generation of transmission permitting packet signals of the ascending line are concentrated to the node 7. Thus the control logic can be simplified for terminals.