Abstract: The type of a pressure sensor is automatically identified even when the input/output lines of the pressure sensor are three lines, i.e., power source lines (two of + and −) and a voltage output line for outputting a voltage corresponding to an applied pressure. The current value Ip, which flows through the power source lines of the pressure sensor, is made to be a different value depending on each type of the pressure sensor. A voltage value Vr (Vr=Ip×Rr, where Rr is a resistance value of a resistor) is measured by using a differential amplifier, and the voltage value Vr is compared with a voltage range previously recorded in ROM. Accordingly, the type of the pressure sensor can be automatically identified by using a microcomputer.

Abstract: A compensating method for a positioner is provided, which makes it possible to avoid any temperature-compensating circuit and any linearity-compensating circuit for a position sensor, and reduce the production cost. The position sensor, which detects the displacement amount of a movable section of an objective control device operated on the basis of a control signal outputted from the positioner, provides an output which is subjected to the temperature compensation calculation by using a linear expression including a slope and an intercept determined on the basis of a temperature measured by a temperature sensor to obtain a temperature-compensated output data.

Abstract: A positioner and method for generating an output signal for setting a controlled object to a control condition corresponding to an input signal, including a memory unit for storing a conversion relation for converting the input signal to a command signal; a signal conversion unit for converting the input signal to the command signal based on the conversion relation; a control unit for generating the output signal for controlling the controlled object corresponding to the command signal; and a setting unit for adjusting the command signal to obtain a desired control condition for each of a plurality of selected input signals, thereby generating a modified conversion relation between the input signal and the command signal. The modified conversion relation generated by the setting unit is stored in the memory unit as the conversion relation.

Abstract: When a steplike reference signal is supplied while a switch is open, an offset signal for compensating for the dead time of a pneumatic device is generated by an offset generator and supplied as a manipulated variable for the pneumatic device. When a feedback increases in level and a speed higher than a reference speed is detected by a speed detector, the switch is closed by a switching signal, switching from a PD control mode to a PID control mode. The pneumatic device thus controlled has a reduced response time and can made a quick response.

Abstract: When a reference signal is changed stepwise, a switch is open, and a pneumatic device with a dead time starts being actuated in a PD control mode. After elapse of the dead time, when a controlled variable changes and a position detector produces an output signal, a speed signal which is a differential of a feedback signal changes from a value "0". When a speed detector detects when the speed signal is equal to or greater than a predetermined value, a switching signal is applied to close the switch. After the switch is closed, the pneumatic device is actuated in a PID mode. An overshoot or an oscillation in a controlled variable due to the integration of the dead time in an I control mode can be suppressed.