Magnetic flowmeter output verification

• US 20080258736A1
• Filed: 04/19/2007
• Published: 10/23/2008
• Est. Priority Date: 04/19/2007
• Status: Active Grant

• Current Assignee: Micro Motion Incorporated (Emerson Electric Company)
• Original Assignee: Rosemount Incorporated (Emerson Electric Company)
• Inventors: Foss, Scot R., Schulz, Robert K., Totenhagen, William G., Hunter, Kirk A.
• Granted Patent: US 7,619,418 B2
• Time in Patent Office: Days
• US Class Current: 324/537
• CPC Class Codes: G01F 1/60 Circuits therefor
• CPC Class Codes: G01F 15/063 using electrical means
• CPC Class Codes: G01F 15/065 with transmission devices, e.g. mechanical
• CPC Class Codes: G01F 15/068 with electrical means G01F15/063 takes precedence
• CPC Class Codes: G01F 25/10 of flowmeters

Abstract

A magnetic flowmeter transmitter includes a flowtube and measurement circuitry which provides an output related to flow through the flowtube. Output circuitry, such as analog and pulse output circuitry, provides transmitter output(s) related to flow through the flowtube. Output verification circuitry of the transmitter is coupled to the output circuitry and provides verification of proper operation of the output circuitry by analyzing the output signals.

Claims

1. A magnetic flowmeter transmitter comprising:

a flowtube;

measurement circuitry configured to provide an output related to flow through the flowtube;

output circuitry coupled to the measurement circuitry and configured to provide a transmitter output related to flow through the flowtube; and

output verification circuitry coupled to the output circuitry and configured to verify proper operation of the output circuitry.

2. The magnetic flowmeter transmitter of claim 1, wherein the output circuitry includes analog output circuitry configured to provide an analog output by controlling an analog current loop in order to transmit flow information over the analog current loop.

3. The magnetic flowmeter transmitter of claim 2, wherein the output verification circuitry is configured to measure a parameter associated with the analog output and to compare the measured parameter to known values for verification.

4. The magnetic flowmeter transmitter of claim 2, wherein the output verification circuitry is configured to convert the analog output to an isolated frequency and to verify proper operation of the analog output circuitry using the isolated frequency.

5. The magnetic flowmeter transmitter of claim 1, wherein the output circuitry includes pulse output circuitry configured to provide a pulse output on electrical wiring in order to transmit flow information.

6. The magnetic flowmeter transmitter of claim 5, wherein the output verification circuitry is configured to verify a pulse output frequency in order to verify proper operation of the pulse output circuitry.

9. The magnetic flowmeter transmitter of claim 6, wherein the output verification circuitry comprises:

sampling circuitry configured to provide a sampled frequency signal;

frequency to voltage conversion circuitry configured to convert a frequency of the sampled frequency signal into a representative voltage;

an analog to digital converter configured to convert the representative voltage into a representative digital voltage value; and

wherein the pulse output verification circuitry is configured to verify the pulse output frequency as a function of the digital voltage value.

10. The magnetic flowmeter of claim 6, wherein the output verification circuitry further comprises adjustable pulse feedback trigger level circuitry configured to adjust a trigger level above which a pulse in the pulse output will be detected.

11. The magnetic flowmeter of claim 10, wherein the adjustable pulse feedback trigger level circuitry is configured to adjust the trigger level as a function of a trigger level adjustment input.

12. The magnetic flowmeter of claim 10, wherein the adjustable pulse feedback circuitry is configured to automatically adjust to different trigger levels in order to evaluate parasitic capacitances on the electrical wiring or to determine if the electrical wiring is in a desired condition.

13. The magnetic flowmeter transmitter of claim 5, and further comprising pulse waveform analysis circuitry configured to digitize the pulse output and to analyze a pulse output waveform for at least one of rise time, duty cycle and amplitude.

7. The magnetic flowmeter transmitter of 6, wherein the output verification circuitry includes pulse counting circuitry configured to count pulses from the pulse output and to verify the pulse output frequency as a function of the counted pulses from the pulse output.

8. The magnetic flowmeter transmitter of claim 7, wherein the output verification circuitry includes pulse count comparison circuitry configured to compare the counted pulses from the pulse output to a reference pulse count and to verify proper operation of the pulse output circuitry based upon the comparison.

14. A magnetic flowmeter transmitter for monitoring flow through a flowtube, the magnetic flowmeter transmitter comprising:

measurement circuitry configured to sense flow through the flowtube and to provide an output related to flow through the flowtube;

output circuitry coupled to the measurement circuitry and configured to provide a transmitter output related to flow through the flowtube; and

output verification circuitry coupled to the output circuitry and configured to verify proper operation of the output circuitry.

15. The magnetic flowmeter transmitter of claim 14, wherein the transmitter is configured to be coupled to an analog current loop and wherein the output circuitry is configured to provide an analog output on the analog current loop in order to transmit flow information over the analog current loop.

16. The magnetic flowmeter transmitter of claim 15, wherein the output verification circuitry is internal to the transmitter and is configured to measure a parameter associated with the analog output and to compare the measured parameter to known values for verification.

17. The magnetic flowmeter transmitter of claim 16, wherein the output verification circuitry is configured to convert the analog output to an isolated frequency and to verify proper operation of the output circuitry using the isolated frequency.

18. The magnetic flowmeter transmitter of claim 15, wherein the transmitter is configured to be coupled to communication wiring and wherein the output circuitry is configured to provide a pulse output on the communication wiring in order to transmit flow information.

19. The magnetic flowmeter transmitter of claim 18, wherein the communication wiring is the analog current loop.

20. The magnetic flowmeter transmitter of claim 18, wherein the output verification circuitry is configured to verify a pulse output frequency in order to verify proper operation of the output circuitry.

21. The magnetic flowmeter of claim 18, wherein the output verification circuitry further comprises adjustable pulse feedback trigger level circuitry configured to adjust a trigger level above which a pulse in the pulse output will be detected by the output verification circuitry.