Method of and apparatus for automated sensor diagnosis through quantitative measurement of one of sensor-to-earth conductance or loop resistance
First Claim
1. Apparatus for automated sensor validation diagnosis during and before operation of a plurality of sensors connected in a loop with voltage measurement apparatus and multiplexed by switching along loop lines to provide successive voltage measurements from the successive sensors to validate a process being monitored at different regions by the sensors, said apparatus having, in combination with voltage measurement apparatus connected to the plurality of process sensors in a loop by a switching multiplexer, an internal voltage source and a sensing impedance connected to earth and to the voltage measurement apparatus, respectively, that provide multiplexed measurements of sensor-to-earth conductance for successive sensors before and during their parameter sensing of the process, thereby providing the determination that the measured conductance still has those values required of properly operating sensors, thus checking the viability of such sensors to validate the process monitored by the sensors.
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Abstract
A method of and apparatus for automated sensor validation diagnosis during and before operation of pluralities of sensors connected by multiplex sequence in a loop with analog-to-digital converter voltage measurement apparatus responsive to the sensor signals for the primary task of validating a process under monitor by the sensors, wherein provision is made for periodically or selectively quantitatively measuring either (or both) sensor-to-earth conductance or loop resistance of the sensors to insure sensor viability.
56 Citations
20 Claims
- 1. Apparatus for automated sensor validation diagnosis during and before operation of a plurality of sensors connected in a loop with voltage measurement apparatus and multiplexed by switching along loop lines to provide successive voltage measurements from the successive sensors to validate a process being monitored at different regions by the sensors, said apparatus having, in combination with voltage measurement apparatus connected to the plurality of process sensors in a loop by a switching multiplexer, an internal voltage source and a sensing impedance connected to earth and to the voltage measurement apparatus, respectively, that provide multiplexed measurements of sensor-to-earth conductance for successive sensors before and during their parameter sensing of the process, thereby providing the determination that the measured conductance still has those values required of properly operating sensors, thus checking the viability of such sensors to validate the process monitored by the sensors.
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5. Apparatus for automated sensor validation diagnosis during and before operation of a plurality of sensors connected in a loop with voltage measurement apparatus and multiplexed by switching along loop lines to provide successive voltage measurements from the successive sensors to validate a process being monitored at different regions by the sensors, said apparatus providing for quantitatively measuring in multiplexing order one of the sensor-to-earth conductance and loop impedance of the sensors, and said apparatus, having, in combination with voltage measurement apparatus connected to the plurality of process sensors in a loop by a switching multiplexer, for sensor-to-earth conductance measurements, an internal voltage source and a sensing impedance to earth and to the voltage measurement apparatus, respectively, that provide multiplexed measurements of sensor-to-earth conductance for successive sensors;
- and in which, for loop impedance measurement, the apparatus is provided with an internal temperature-stable current source and a circuit for switching the source across the loop lines.
- View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
Specification