| 摘要 |
PURPOSE:To secure the safety of a control system, by enabling the manual control as the last backup means in case the automatic control becomes impossible. CONSTITUTION:When a counter 23 or a D/A converter 24 of a digital controller 2 is faulty, a contact 25x of an analog memory 25 opens to make contacts 25c and 25b conduct. Then a control station 1 increases or decreases a memory part 25M of the memory 25 with an increase/decrease signal and by a manual PB, and the output signal controls a control valve 3 through contacts 25b and 25c. While, the part 25M is driven with a manual signal h2 if the counter 23 has a fault. In this case, the value of the part 25M is fed back to the counter 23 by a signal K. |
