Abstract: A field device which outputs a measured value and includes a self-diagnosis function which, when at least one specified error is detected, signals this error, marks the output measured value as temporarily invalid, and initiates the output of a substitute value that is used to trigger a safety-oriented response, where to prevent interventions when temporary errors occur, but without losing safety-relevant information, the field device includes a first and second timers having different expiration times that are started when the error is detected and are reset at the end of the detected error, where the first timer initiates the output of the substitute value when the first expiration time expires, where the second timer signals the error when the second expiration time expires, and where the signal is resettable if, at the same time, the output measured value is marked as valid via the second binary status signal.

Abstract: A field device which outputs a measured value and includes a self-diagnosis function which, when at least one specified error is detected, signals this error, marks the output measured value as temporarily invalid, and initiates the output of a substitute value that is used to trigger a safety-oriented response, where to prevent interventions when temporary errors occur, but without losing safety-relevant information, the field device includes a first and second timers having different expiration times that are started when the error is detected and are reset at the end of the detected error, where the first timer initiates the output of the substitute value when the first expiration time expires, where the second timer signals the error when the second expiration time expires, and where the signal is resettable if, at the same time, the output measured value is marked as valid via the second binary status signal.

Abstract: A method for measuring the concentration of a gas component in a measuring gas. An absorption line of the gas component is varied as a function of the wavelength of the light of a wavelength-tunable light source within a periodically sequential scanning interval. The absorption line of the gas component is modulated with a frequency (f0). Modulated light is guided through the measuring gas onto a detector. A measurement signal generated by the detector is demodulated upon determining a harmonic (nf0) of the frequency (f0). A measurement result is produced by fitting a setpoint curve to the profile of the demodulated measurement signal. Both demodulated measurement signal and setpoint cure are filtered with the aid of the same filter function. The filter function is operative to suppress noise signal components of the demodulated measurement signal that disturb both signal components of the demodulated measurement signal and the setpoint curve.

Abstract: A method for measuring the concentration of a gas component in a measuring gas. An absorption line of the gas component is varied as a function of the wavelength of the light of a wavelength-tunable light source within a periodically sequential scanning interval. The absorption line of the gas component is modulated with a frequency (f0) Modulated light is guided through the measuring gas onto a detector. A measurement signal generated by the detector is demodulated upon determining a harmonic (nf0) of the frequency (f0). A measurement result is produced by fitting a setpoint curve to the profile of the demodulated measurement signal. Both demodulated measurement signal and setpoint cure are filtered with the aid of the same filter function. The filter function is operative to suppress noise signal components of the demodulated measurement signal that disturb both signal components of the demodulated measurement signal and the setpoint curve.