| 摘要 |
<p>PURPOSE:To attain the hot line attachment/detachment operation of the faulty/ its substituting card units even when a degeneration trouble, etc., of a bus driver or a bus receiver are generated by providing a normally-on type bus signal switch into a bus connector. CONSTITUTION:The photo-MOS relays RL1 - RLn serving as the normally-on type bus signal switches are put into the bus signal pins P1 - Pn of a bus connector 12 respectively. When a card unit 11 is separated from a system bus, the power equivalent to +5V is supplied to a photo-MOS relay driving signal DV. Thus a photo-MOS relay driver D0 is turned on and all relays RL1 - RLn are set in the high impedance states. Then the unit 11 is taken out of a mother board 14. Thus the faulty/its substituting card units can be attached/detached in a hot line state even with the degeneration troubles of the bus drivers D1 - Dn or the bus receivers R1 - Rn.</p> |
