Fault detection apparatus, fault detection method, and fault detection program

A fault detection apparatus comprising:

• a memory comprising a comparison-result storing unit;
• and
• a processor which executes a comparison unit and a judgment unit;
• wherein the comparison unit compares polarities of a plurality of redundant input signals, each of which indicates a detection of input to a device from a respective input source,
• wherein the comparison-result storing unit stores therein a comparison result of the comparison unit for each predetermined sampling cycle,
• wherein the judgment unit judges whether the plurality of redundant input signals are normal using a plurality of comparison results for a predetermined number of samplings in a time-series order from a latest comparison result among a plurality of comparison results stored in the comparison-result storing unit,
• wherein the judgment unit counts number of comparison results showing that at least one of the polarities of the plurality of redundant input signals is different among the comparison results for the number of samplings for each sampling cycle, and makes a judgment as abnormal when the count value is equal to or larger than a predetermined judgment threshold value and normal otherwise, and
• wherein the comparison unit compares the polarities of the redundant input signals to each other.

A fault detection apparatus comprising:

• a memory comprising a first comparison-result storing unit and a second comparison result storing unit;
• and
• a processor which executes a comparison unit and a judgment unit;
• wherein the comparison unit compares polarities of a plurality of redundant input signals, each of which indicates a detection of input to a device from a respective input source,
• wherein the first comparison-result storing unit stores therein n comparison results of the comparison unit for each predetermined sampling cycle from a latest comparison result in a time-series order, where n is a positive integer;
• wherein the second comparison-result storing unit stores therein, when n comparison results are stored in the first comparison-result storing unit, a count value showing that all the polarities of the plurality of redundant input signals match with each other in the time-series order,
• wherein the judgment unit adds, for each sampling cycle, a count value of the comparison results showing that all the polarities of the redundant input signals match with each other among the count values stored in the second comparison-result storing unit to a count value from a latest count value to a count value of a predetermined number of samplings among the n comparison results stored in the first comparison-result storing unit to obtain a total count value of the comparison results showing that all the plurality of the redundant input signals match with each other among the comparison results of the number of samplings, and makes a judgment as normal when the total count value is equal to or larger than a predetermined judgment threshold value and abnormal when the total count value is smaller than the predetermined judgment threshold value, and
• wherein the comparison unit compares the polarities of the redundant input signals to each other.

A fault detection apparatus comprising:

• a memory comprising a first comparison-result storing unit and a second comparison result storing unit;
• and
• a processor which executes a comparison unit and a judgment unit;
• wherein the comparison unit that compares polarities of a plurality of redundant input signals, whether the polarities of the redundant input signals match with each other, where each of the plurality of redundant input signals indicates a detection of input to a device from a respective input source,
• wherein the first comparison-result storing unit stores therein n comparison results of the comparison unit for each predetermined sampling cycle from a latest comparison result in a time-series order, where n is a positive integer,
• wherein the second comparison-result storing unit stores therein, when n comparison results are stored in the first comparison-result storing unit, a count value showing that at least one of the polarities of the plurality of redundant input signals is different in the time-series order, and
• wherein the judgment unit adds, for each sampling cycle, a count value of the comparison results showing that at least one of the polarities of the redundant input signals is different among the count values stored in the second comparison-result storing unit to a count value from a latest count value to a count value of a predetermined number of samplings among the n comparison results stored in the first comparison-result storing unit to obtain a total count value of the comparison results showing that at least one of the plurality of the redundant input signals is different among the comparison results of the number of samplings, and makes a judgment as abnormal when the total count value is equal to or larger than a predetermined judgment threshold value and normal when the total count value is smaller than the predetermined judgment threshold value.

A fault detection apparatus comprising:

• a memory comprising a comparison-result storing unit;
• and
• a processor which executes a comparison um and a judgment unit;
• wherein the comparison unit compares polarities of a plurality of redundant input signals, each of which indicates a detection of input to a device from a respective input source,
• wherein the comparison-result storing unit stores therein a comparison result from the comparison unit for each predetermined sampling cycle,
• wherein the judgment unit judges whether the plurality of redundant input signals are normal using a plurality of comparison results for a predetermined number of samplings in a time-series order from a latest comparison result among a plurality of comparison results stored in the comparison-result storing unit,
• wherein the judgment unit counts number of comparison results showing that all the polarities of the plurality of redundant input signals match with each other among the comparison results for the number of samplings for each sampling cycle, and makes a judgment as normal when the count value is equal to or larger than a predetermined judgment threshold value and abnormal otherwise, and
• wherein the judging unit judges whether an input detection unit operates as normal or abnormal, wherein the input detection unit is provided in the device which is an input/output station that controls at least one external device connected thereto.