| 摘要 |
PURPOSE:To prevent collision between signals by allowing a signal to arrive at a photocoupler after a lapse of time assigned previously to each station after vacancy of the photocoupler is detected, by providing each station with the function of detecting the vacancy of the photocoupler. CONSTITUTION:Reception parts S1R-S4R of respective stations are arranged equally at distance (l) from photocoupler C and can detect the no-signal state (vacant state) of the photocoupler at the same time. Once the said vacant state is detected, stations whose transmission parts S1T-S4T have transmission requests start the transmission and since respective transmission parts are arranged at intervals of length (l) from the photocoupler as shown in the figure, data arriving at photocoupler C from respective transmission parts S1T-S4T never overlap, so that the collision between data is prevented. |
