| 摘要 |
PURPOSE:To prevent a malfunction due to noise at the time of the hot-line insertion/removal of a circuit board by providing a noise eliminating circuit on the bus input end of the circuit board. CONSTITUTION:Except at the time of hot-line insertion/removal of circuit boards 11 to 13, the signal on a busy signal line 2 is not asserted, and in a noise eliminating circuit 5, the signal from a bus signal line 1 is by-passed to an input buffer 3 through a selector 8 as it is. At the time of hot-line insertion/removal, the signal from the bus signal line 1 is delayed in many stages by a delay stage 6 in the noise eliminating circuit 5 since the signal from the busy signal line 2 is asserted, and the signal obtained by majority decision in a majority logic 7 is outputted through the selector 8 and supplied to the input buffer 3. The noise on the signal of the bus signal line 1 is eliminated by this noise eliminating circuit 5. Consequently, the signal inputted to the input buffer 3 is not affected by the noise even if the noise is generated on the bus signal line 1. |
