Abstract: A semiconductor device comprises an analog switch and digital circuitry, both of which are formed on a single integrated circuit chip and share a node coupled to external circuitry. A first power source, provided in the device, is coupled to an input terminal of the analog switch whose output is operatively coupled to the node, and a second power source is also provided so as to supply electric power to the digital circuitry whose input or output is operatively coupled to the node. A back gate voltage controller, coupled to a back gate of the analog switch, is provided in order to control a voltage applied to the back gate in response to an operation mode control signal for determining whether the analog switch or the digital circuitry is to be enabled.

Abstract: Between two units which are separately arranged, a power source signal is supplied from one of the two units to the other unit via electromagnetic induction coupling by using induction coils, and data signals are mutually transmitted and received between both of the units. A change in coupling distance between the induction coils provided for the two units is detected from a signal level of a reception signal from the unit which receives the power supply. When the reception signal level decreases, the signal level of the power supply signal is increased.

Abstract: A plurality of terminal units are connected to the central unit by one optical fiber line in a loop form, thereby forming a communication link. The central unit converts the data including the terminal address and control bit into the serial optical signal and outputs this optical signal. The terminal unit receives and interpretes the optical signal from the central unit and ON/OFF controls the solenoid valve. After completion of the control, the terminal unit rewrites the control bit in the reception data to the data bit indicative of the operating state of the valve and transmits the data bit to the next terminal unit. The central unit receives the signal from the final terminal unit and interprets the bit data which was rewritten from the control bit by the terminal unit, thereby displaying the operating state of the valve.

Abstract: A circuit for change-over of electric signal set points applied as control inputs to a fluid control valve for controlling the pressure or flow rate of a fluid. A priority circuit including a priority encoder or priority chain is provided in an input section for set point select and change-over instruction signals from an external sequential controller. When two or more of the instruction signals are applied simultaneously, only the highest priority instruction is received to select the desired set point and the other instructions are ignored.

Abstract: A digital valve control apparatus for regulating opening of a digital valve by a pulse motor, comprising means for setting desired position and displacement speed of the pulse motor and means for selecting the set position and the set speed in response to instruction signals. While pulses having period corresponding to the set speed are produced by a frequency divider, the present position of the pulse motor is compared with the set position by a comparator. The pulses are fed to a counter which counts up or down to supply the output for driving the pulse motor until the comparator produces the coincident output.