Abstract: An I/O circuit for use with an industrial controller provides a photovoltaic optical isolator communicating between a controller and a field-side of the I/O circuit, the photovoltaic optical isolator eliminating the need for high wattage power dropping circuits for powering the field-side of the I/O circuit from high-voltage field signals. The field effect transistor type transistors permit use of the low-power photovoltaic optical isolator while allowing flexible connections to various field circuit types.

Abstract: An I/O circuit for use with an industrial controller provides an input circuit with low power dissipation through the use of a series connected substantially nonresistance impedance. An AC waveform input activates a light emitting diode (LED) bridge to provide an optical signal which illuminates a photosensitive solid-state switch thereby providing optical isolation between the industrial controller and the controlled process or machine. By using a series connected substantially nonresistance impedance, reduced current demand by the input circuit may be realized, which allows reduced power dissipation. As a result, the same circuit allows receiving input signals over a greater range, such as 120 volts AC and 240 volts AC, and allows significantly smaller components with closer spacing for a more compact design.

Abstract: An I/O circuit for use with an industrial controller provides a zero-crossing detector circuit with low power dissipation through the use of a zero-crossing circuit that activates a light emitting diode of a photo coupler only for a very brief period of time at the zero-crossing (as opposed to at all times other than the zero-crossing). The circuit is coupled with a power supply circuit that uses a reactive element for voltage dropping as opposed to a resistive voltage drop element further reducing power consumption possible with the low power consumption of the photo coupler.

Abstract: An I/O circuit for use with an industrial controller provides an input circuit with low power dissipation through the use of a series connected substantially nonresistance impedance. An AC waveform input activates a light emitting diode (LED) bridge to provide an optical signal which illuminates a photosensitive solid-state switch thereby providing optical isolation between the industrial controller and the controlled process or machine. By using a series connected substantially nonresistance impedance, reduced current demand by the input circuit may be realized, which allows reduced power dissipation. As a result, the same circuit allows receiving input signals over a greater range, such as 120 volts AC and 240 volts AC, and allows significantly smaller components with closer spacing for a more compact design.

Abstract: An I/O circuit for use with an industrial controller provides a photovoltaic optical isolator communicating between a controller and a field-side of the I/O circuit, the photovoltaic optical isolator eliminating the need for high wattage power dropping circuits for powering the field-side of the I/O circuit from high-voltage field signals. The field effect transistor type transistors permit use of the low-power photovoltaic optical isolator while allowing flexible connections to various field circuit types.

Abstract: An I/O circuit for use with an industrial controller provides a zero-crossing detector circuit with low power dissipation through the use of a zero-crossing circuit that activates a light emitting diode of a photo coupler only for a very brief period of time at the zero-crossing (as opposed to at all times other than the zero-crossing). The circuit is coupled with a power supply circuit that uses a reactive element for voltage dropping as opposed to a resistive voltage drop element further reducing power consumption possible with the low power consumption of the photo coupler.

Abstract: An improved inrush current limiting circuit provides continuous control of current delivered to a filter capacitor based on the charge state of the filter capacitor.