INTERFACE DEVICE, ON/OFF DATA INTERFACE UNIT, LOG DATA INTERFACE UNIT, AND PROGRAMMABLE LOGIC CONTROLLER SYSTEM

摘要

[Problem] To collect production information for process equipment inexpensively and by means of a simple operation, without posing a processing burden to the system side in terms of a production information collection computer system. [Solution] Provided is a first interface unit 31, comprising: a first input terminal whereto is inputted either an AC signal or a DC signal as on/off data; a smoothing circuit connected in series to the first input terminal for smoothing when the AC signal is inputted; a voltage regulator circuit for regulating a signal voltage outputted from the smoothing circuit according to the signal voltage inputted into the first input terminal, such that the signal voltage is constant; and a switching element for switching in accordance with the signal whose voltage was regulated. Also provided is a second interface unit 32, comprising: a second input terminal whereto is inputted either a current signal or a voltage signal as log data; a current/voltage conversion circuit connected in series to the second input terminal for converting, when the current signal has been inputted, to the voltage signal in accordance with the current signal; and an analog-digital conversion unit for converting to digital data in accordance with the voltage of said signal.