In situ probe with improved diagnostics and compensation

1. A process combustion transmitter comprising;

a process probe extendible into a flow of process combustion exhaust, the process probe having a measurement cell and a diffuser, the measurement cell and the diffuser defining a chamber within the process probe;

electronic circuitry coupled to the measurement cell and configured to provide an indication relative to a combustion process based on an output signal of the measurement cell;

a pressure sensor operably coupled to the electronic circuitry and fluidically coupled to the chamber; and

wherein the electronic circuitry is configured to provide an adjusted calibration based on pressure measured within the chamber during a calibration, and wherein the electronic circuitry is configured to provide an indication of diffuser plugging based on pressure measured during the calibration.

2. The process combustion transmitter of claim 1 , wherein the indication is a local annunciation.

3. The process combustion transmitter of claim 1 , wherein the indication is communicated in accordance with a process communication protocol.

4. The process combustion transmitter of claim 1 , wherein the electronic circuitry is configured to resume process measurements after calibration using the adjusted calibration.

5. The process combustion transmitter of claim 4 , wherein the electronic circuitry is configured to wait a selected amount of time after calibration before resuming process measurements.

6. The process combustion transmitter of claim 5 , wherein the amount of time is selected based on the pressure measured during calibration.

7. The process combustion transmitter of claim 1 , wherein the electronic circuitry includes a controller coupled to measurement circuitry and wherein the measurement circuitry is operably coupled to the pressure sensor.

8. The process combustion transmitter of claim 7 , and wherein the electronic circuitry further comprises a communication module coupled to the controller and configured to communicate in accordance with a process communication protocol.

9. A method of calibrating a process combustion transmitter, the method comprising:

providing a flow of calibration gas into a chamber defined, at least partially, by a measurement cell and a diffuser;

measuring a pressure of calibration gas in the chamber while the calibration gas is flowing;

measuring the measurement cell response to the calibration gas;

providing an adjusted calibration based on the measurement cell response and the measured pressure;

providing an indication of diffuser plugging based on the measured pressure.

10. The method of claim 9 , wherein the measurement cell includes an oxygen sensor.

11. The method of claim 10 , wherein the measurement cell is a zirconia oxide-based oxygen sensor.

12. The method of claim 9 , and further comprising waiting a selected amount of time after the calibration to begin providing process measurements using the adjusted calibration.

13. The method of claim 12 , wherein the selected amount of time is based on the pressure measured during calibration.

14. A method of calibrating a process combustion transmitter, the method comprising:

providing a flow of calibration gas into a chamber defined, at least partially, by a measurement cell and a diffuser;

measuring a pressure of calibration gas in the chamber while the calibration gas is flowing;

measuring the measurement cell response to the calibration gas;

providing an adjusted calibration based on the measurement cell response and the measured pressure; and

measuring a pressure within the chamber during normal operation and providing a compensated process variable output.

15. The method of claim 14 , and further comprising waiting a selected amount of time after the calibration to begin providing process measurements using the adjusted calibration.

16. The method of claim 15 , wherein the selected amount of time is based on the pressure measured during calibration.