Abstract: A method of and apparatus for controlling a triple-coil servo valve arranged having a tripled control system each of which is composed of components of a coil, a servo amplifier and a controller, the method of and the apparatus for controlling the triple servo valve including means for specifying the abnormality of each of the components, servo amplifier output separation means, means capable of desirably combining the components and means for compensating the servo amplifier. If two control systems of the tripled control system are faulty in such a manner that at least one coil, at least one servo amplifier or at least one controller is abnormal, the triple-coil servo is operated by combining the normal components or by compensating the servo amplifier so that the continuation of the operation of the plant is enabled.

Abstract: A process control system has a timer circuit which fixes operational periods by issuing an instruction for starting each of a plurality of time periods in such a manner that the computation of control blocks will occur during periods of fixed duration. A periodic operation selection circuit selects control blocks to be computed within each time period in response to an instruction from the timer circuit. Control blocks selected by the periodic operation selection circuit and an instruction for completion of the computation of control blocks for each time period are stacked in an operation instruction circuit, which issues an instruction for consecutively executing the operation of the control blocks and an instruction for effecting an idle operation after completion of the operation of control blocks for each time period.