Solid state gas detection sensor diagnostic

1. A metal oxide semiconductor-based toxic gas detector comprising:

a metal oxide semiconductor-based gas sensor, the gas sensor having an electrical characteristic that varies with a concentration of a toxic gas;

measurement circuitry coupled to the metal oxide semiconductor-based gas sensor, the measurement circuitry being configured to measure the electrical characteristic and provide a digital indication of the measured electrical characteristic; and

a controller coupled to the measurement circuitry and configured to provide a toxic gas output based on the digital indication, the controller being further configured to detect a fluctuation in measured digital indications of the measured electrical characteristic over a period of time, and, based on the detected fluctuation, provide a diagnostic indication relative to the metal oxide semiconductor-based sensor.

2. The metal oxide semiconductor-based toxic gas detector of claim 1 , and further comprising communication circuitry coupled to the controller and configured to communicate in accordance with a process industry standard communication protocol.

3. The metal oxide semiconductor-based toxic gas detector of claim 2 , wherein the communication circuitry is wireless communication circuitry.

4. The metal oxide semiconductor-based toxic gas detector of claim 1 , wherein the controller is coupled to memory that stores a plurality of digital indications and wherein the controller processes the plurality of digital indications in order to determine a level of fluctuations.

5. The metal oxide semiconductor-based toxic gas detector of claim 4 , wherein the processing includes determining a statistical quantity relative to the plurality of digital indications.

6. The metal oxide semiconductor-based toxic gas detector of claim 5 , wherein the statistical quantity is a fluctuation characteristic obtained digitally.

7. The metal oxide semiconductor-based toxic gas detector of claim 4 , wherein the level of fluctuations is compared to a pre-determined threshold in order to generate the diagnostic indication.

8. The metal oxide semiconductor-based toxic gas detector of claim 7 , wherein the threshold is related to a type of the metal oxide semiconductor-based toxic gas sensor.

9. The metal oxide semiconductor-based toxic gas detector of claim 7 , wherein the diagnostic indication is communicated over a process communication loop or segment.

10. The metal oxide semiconductor-based toxic gas detector of claim 7 , wherein the diagnostic indication is provided locally by the detector.

11. A method of operating a toxic gas detector having a metal oxide semiconductor-based toxic gas sensor, the method comprising;

obtaining a sequence of measurements of an electrical characteristic of the metal oxide semiconductor-based toxic gas sensor;

processing, using a controller of the toxic gas detector, the sequence of measurements of electrical characteristics to detect a fluctuation in the measurements:

providing a toxic gas detector output based on at least one of the electrical characteristic measurements; and

generating a diagnostic output based on the detected fluctuations, and wherein diagnostic indication comprises a detected stale sensor.

12. The method of claim 11 , wherein generating the diagnostic output based on the fluctuations includes calculating a statistical quantity of the sequence of measurements.

13. The method of claim 12 , wherein the statistical quantity is indicative of a fluctuation characteristic obtained digitally.

14. The method of claim 12 , wherein the statistical quantity is compared to a pre-determined threshold in order to determine whether to generate the diagnostic output.

15. The method of claim 11 , wherein the diagnostic output is communicated over a process communication loop or segment.

16. The method of claim 11 , wherein the diagnostic output is communicated wirelessly.

17. The method of claim 11 , wherein the diagnostic output is communicated locally by the toxic gas detector.