Patent ID: 8120367

Claim:
An analog input device to which an analog signal outputted from an external device is inputted, for collecting the analog signal, comprising: a scanning circuit which includes a first insulation transformer for insulating the inputted analog signal; a power supply section for charging a test voltage used for detecting a disconnection caused in the external device; a second insulation transformer in which the scanning circuit and the power supply section are connected with each other in parallel; and control means for outputting a pulse signal to be inputted to the second insulation transformer, wherein: the second insulation transformer receives a drive pulse for switching the scanning circuit from the control means and insulates the drive pulse to send the drive pulse to the scanning circuit, and also receives a power supply pulse for feeding power to the power supply section from the control means and insulates the power supply pulse to send the power supply pulse to the power supply section; and the control means performs a timing control so that the drive pulse and the power supply pulse are not outputted at the same time, and outputs the drive pulse and the power supply pulse therefrom.