Abstract: A diagnostic device for use in a process control system receives a sensor signal related to a process variable of a process sensed by a process variable sensor. A signal preprocessor provides a sensor power signal output as a function of a frequency distribution of power in the sensor signal. A process condition is determined based upon the sensor power signal.

Abstract: Diagnostic circuitry of a process device is used to detect degradation of a resistive element of the process device while the process device remains online, without the use of an additional power source. In addition, once degradation of the resistive element is detected, the diagnostic circuitry can be compensated for automatically. The diagnostic circuitry includes a testing circuit and a processing system. The testing circuit is coupled to the resistive element and is configured to apply a test signal to the resistive element. The test signal heats the resistive element and causes the resistive element to generate a response signal. The processing system compares a change in the response signal to a corresponding reference to detect degradation of the resistive element.

Abstract: A diagnostic device for use in a process control system receives a sensor signal related to a process variable of a process sensed by a process variable sensor. A signal preprocessor provides a sensor power signal output as a function of a frequency distribution of power in the sensor signal. A process condition is determined based upon the sensor power signal.

Abstract: Process device diagnostic is provided for diagnosing the condition of a process by receiving a process variable sensor signal. The process variable sensor senses vibration noise signals carried in a process fluid of the process. The vibration noise signals are generated by the process, such as by operation of process control elements. The diagnostics isolates the process noise signals in the process variable sensor signal and evaluates the isolated signal to diagnoses the process and the process devices.

Abstract: Diagnostic circuitry of a process device is used to detect degradation of a resistive element of the process device while the process device remains online and without an additional power source. The diagnostic circuitry includes a testing circuit and a processing system. The testing circuit is coupled to the resistive element and is configured to apply a test signal to the resistive element. The test signal heats the resistive element and causes the resistive element to generate a response signal. The processing system compares a time constant of the response signal to a corresponding reference to detect degradation of the resistive element.

Abstract: A process device couples to a process control loop. The process device receives a process signal. A memory in the process device contains a nominal parameter value. Computing circuitry provides an event output based upon the stored nominal value and the process signal. Output circuitry provides an output in response to the event output.

Abstract: A device in a process control system includes an electrical element which has a resistance. Self-heating circuitry coupled to the element provides a self-heating current to determine the self-heating index (SHI) of the element. Diagnostic information about the electrical element is provided based upon the self-heating index.

Abstract: A process device couples to a process control loop. The process device receives a process signal. A memory in the process device contains a nominal parameter value. Computing circuitry provides an event output based upon the stored nominal value and the process signal. Output circuitry provides an output in response to the event output.