Abstract: The present invention relates to a switch device having a sensor for effecting a detection process such as a confirming the operation of an ejector or the like, confirming the existence of an object fed by a suction pad, or confirming the attracted state of an object fed by the suction pad. The invention further relates to a control device-to-sensor wiring structure which is electrically connected to the switch device. The switch device can be reduced in size and weight by detachably positioning a setting section, having a controlling means and a displaying means, on a body of the switch device and removing the setting section as required. Further, the wiring structure makes it possible to simplify wiring and avoid the possibility of miswiring, by eliminating the need for a power line to be connected to each sensor.

Abstract: First and second thresholds are established which define a pressure difference relative to a maximum pressure level for a fluid under pressure, which maximum pressure level is detected by a pressure detecting device, and a third threshold is also established which is lower than the maximum pressure level and higher than the first and second thresholds. While a pressure detected by the pressure detecting device ranges between the first and second thresholds, an output signal is supplied to a drive member. When a pressure lower than the third threshold is detected by the pressure detecting device, an output signal indicative of a predicted failure is produced. The output signal indicative of a predicted failure is produced when a pressure lower than the third threshold is detected a plurality of times by the pressure detecting device.