Method and apparatus for monitoring AC input signals
First Claim
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1. A method for monitoring a plurality of AC input signals to a control system, comprising the steps of:
- generating an AC interrupt signal, based on an AC system signal which is substantially phase-synchronous with the AC input signals, for an interrupt time period corresponding to a time period when the AC system signal exceeds a predetermined threshold voltage;
checking the AC interrupt signal to verify that the AC system signal exceeds the predetermined threshold voltage;
setting a timer for a pseudo-random time value upon verification of the AC interrupt signal; and
sampling the AC input signals when the timer has reached the pseudo-random time value to determine the presence or absence of the AC input signals.
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Abstract
The present invention is a method and apparatus for monitoring a plurality of AC input signals to a control system. An AC interrupt signal is generated, based on an AC system signal which is substantially phase-synchronous with the AC input signals, for an interrupt time period corresponding to a time period when the AC system signal exceeds a predetermined threshold voltage. The AC interrupt signal is verified and a timer is set for a pseudo-random time value. The AC input signals are sampled when the timer has reached the pseudo-random time value to determine the presence or absence of valid AC input signals.
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Citations
15 Claims
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1. A method for monitoring a plurality of AC input signals to a control system, comprising the steps of:
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generating an AC interrupt signal, based on an AC system signal which is substantially phase-synchronous with the AC input signals, for an interrupt time period corresponding to a time period when the AC system signal exceeds a predetermined threshold voltage; checking the AC interrupt signal to verify that the AC system signal exceeds the predetermined threshold voltage; setting a timer for a pseudo-random time value upon verification of the AC interrupt signal; and sampling the AC input signals when the timer has reached the pseudo-random time value to determine the presence or absence of the AC input signals. - View Dependent Claims (2, 3)
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4. A method for detecting the presence or absence of a plurality of AC input signals to a control system, comprising the steps of:
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generating an AC interrupt signal, based on an AC system signal substantially phase-synchronous with the AC input signals, indicating the presence of a periodic half cycle of the AC system signal; setting a timer for a pseudo-random time value in response to the AC interrupt signal; and sampling the plurality of AC input signals when the timer has reached the pseudo-random time value to determine the presence or absence of periodic half cycles of the AC input signals. - View Dependent Claims (5, 6, 7, 8)
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9. For use in a burner control system, a detection apparatus for detecting the presence or absence of a plurality of AC input signals, the apparatus comprising:
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AC system signal detection means for producing an AC interrupt signal for a half cycle time interval corresponding to a period when an AC system signal exceeds a predetermined threshold where the AC system signal is substantially phase-synchronous with the AC input signals; timer setting means, coupled to the AC system signal detection means, for setting a timer for a pseudo-random time value in response to the AC interrupt signal; and input sampling means for sampling the AC input signals when the timer has reached the pseudo-random time value to determine the presence or absence of the AC input signals. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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Specification