Abstract: A data communication control system includes first and second control units each having a microcomputer, the second control unit carrying out a first interrupt processing which starts in accordance with a first timing signal having a first period, and a second interrupt processing which starts in accordance with a second timing signal having a second period, the second interrupt processing being for the second control unit to receive data transferred from the first control unit. The second timing signal is generated in the first control unit in such a manner that adjacent ones of the second timing signal have values of the second period different from each other. Therefore, even if the first interrupt processing and the second interrupt processing conincide with each other the coincidence is not continued whereby transfer of data can be reliably carried out.

Abstract: A scale pulse signal is produced whenever a revolution sensor detects a unit revolution angle formed an angle between cogs of poles. A time interval between the scale pulse signal is affected by an error in the formed angle. The time interval between the scale pulse signals can be corrected by using a correction coefficient detrmined by an actual value of the unit revolution angle detected by the revolution sensor and by a design value of the unit revolution angle, so that the time interval corresponds to the design value of the unit revolution angle.

Abstract: In a fuel injection system having a distribution-type fuel injection pump, fuel is supplied successively to cylinders of an engine from a pressurizing chamber of the pump. The pressurizing chamber communicates with a low-pressure chamber through a relief passageway opened and closed by an electromagnetic valve. During a stroke in which volume of the pressurizing chamber is reduced by each forward stroke of a plunger, opening and closing of the valve are controlled, to control starting timing and/or termination timing of fuel injection to the cylinders. A delay occurs in the starting timing and/or the termination timing with respect to drive pulses supplied to the valve, due to an operation delay of the valve. A plurality of memory sections are provided for storing therein delay times for the respective cylinders.

Abstract: A set rotation angle width related to a rotary machine, of which the rotation speed varies cyclically, is converted to a time width required for the rotary machine to rotate by the set rotation angle width from a given rotation angle position. The converted time width is corrected by a correcting coefficient so that the time width is not affected by the rotation variation of the rotary machine. The correcting coefficient is decided based on the rotation angle position and the rotation speed variation of the rotary machine related to the set rotation angle width from the rotation angle position, and by the correcting coefficient, correction is done so that an actual rotation angle width corresponding to the converted time width becomes the set rotation angle width.

Abstract: In a fuel injection system for an engine, a first controller calculates circuit rotational angle of a crankshaft on the basis of reference pulses and scale pulses from a detector for detecting rotation of the crankshaft. The first controller outputs a drive pulse representative of a closing command moving an electromagnetic valve to a closed position, at a timing with reference to the current rotational angle, to control a period, within which the valve is in the closed position, during forward stroke of a plunger. A second controller intermittently outputs drive pulses representative of the closing command, at an initial stage of engine start-up, independently of the crankshaft rotational angle. A time duration of each drive pulse from the second controller is shorter than a time duration required for the plunger forward stroke, and a period within which each drive pulse is not outputted from the second controller is also shorter than the time duration required for the plunger forward stroke.

Abstract: A solenoid driving circuit for supplying an exciting current whose level suddenly increases at the beginning of the flow of the current has a voltage inducing circuit for providing a pulse-like current component which suddenly increases at the beginning of the flow of the exciting current, a unidirectional element for supplying the pulse-like current component to the solenoid, a voltage limiting element for limiting the level of the pulse-like current component and applying a d.c. power to the solenoid, and a circuit for providing a stand-by current and the holding current to the solenoid, whereby the solenoid is effectively supplied with sufficient energy for driving it at high speed and the power required for maintaining the operation of the solenoid is reduced.