| 摘要 |
PURPOSE:To relieve remarkably load of supervisory station and a communication line by supervising a bit data representing the state of a data link level and an application level of each station onto a token path field. CONSTITUTION:A control field C of a token frame consists of 8-bit and a modifier bit data modifying normal/abnormal state of an application processor (main processor) 11 of a station enters the 7-th bit (hatched lines in figure). A communication controller 15 generates a live list representing the normal/abnormal state of each station from a source address SA of the frame. The live list is generated for each station and all bytes of a station whose data link level is failed are logical 0. In the live list, a bit representing the state of the data link level and a bit representing the state of the application level, in total 2-bit, are used in each station.
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