| 摘要 |
<p>PURPOSE:To make easy the ON-line maintenance, by holding the initializing state until the initializing switch is OFF at the process input and output unit to prevent the misinput to CPU and misoutput to the plant. CONSTITUTION:When the switch SW1 is ON, FF2 is reset through the gate G2 and gate G1 is stopped. Further, the disconnection of the process input and output unit PIO and the data bus line is made without giving effect to others. Further, after the end of repairment with disconnection, the unit 1 is connected to the data bus line while the switch SW1 is ON and the SW1 is OFF. Thus, the unit PIO holds the initializing state until the switch SW1 is OFF to prevent the misoutput to the plant and the misinput to CPU. Thus, the ON-line maintenance can be made easy.</p> |
