| 摘要 |
<p>PURPOSE:To prevent data from misoutput and a system from stop and to improve reliability by delaying a reset signal for a fixed period at the start of maintenance of a hot-line. CONSTITUTION:A digital input unit 5 is constituted of a maintenance connector 11, an interruption generating circuit 12, an input data connector 13, a digital input circuit 14, and a data bus driver 17 and a delay circuit 20 is also added to the unit 5. The unit 5 is connected to a system bus through an interruption signal line 15 and a data bus 16 and the hot-line maintenance and inspection of the unit 5 are executed by fitting a sub-connector 10 from the external. The added delay circuit 20 generates a reset signal RS with the delay of a fixed period from the input of a maintenance signal MA. The delay circuit 20 is constituted of a monostable FF21, time constant setting circuits 20, 23 and a power ON reset circuit 24. Consequently, the reset signal RS is activated with the delay of the fixed period at the start of maintenance of the hot-line, so that the loading/unloading of the hot-line to/form the unit 5 can be attained.</p> |
