Magnetic flowmeter output verification

• US 7,619,418 B2
• Filed: 04/19/2007
• Issued: 11/17/2009
• 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: Hunter, Kirk A., Foss, Scot R., Schulz, Robert K., Totenhagen, William G.
• Primary Examiner(s): Dole; Timothy J
• Assistant Examiner(s): Baldridge; Benjamin M
• Application Number:
  US11/788,392
• Publication Number:
  US 20080258736A1
• Time in Patent Office: 943 Days
• Field of Search: 324/520, 738/611.7
• US Class Current: 324/520
• 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 providing an output related to flow through the flowtube;

output circuitry coupled to the measurement circuitry and providing a transmitter output that is related to flow through the flowtube to a remote location; and

output verification circuitry coupled to the output circuitry and verifying proper operation of the output circuitry;

wherein the output circuitry includes pulse output circuitry providing a pulse output on electrical wiring in order to transmit flow information; and

wherein the output verification circuitry verifies a pulse output frequency in order to verify proper operation of the pulse output circuitry.

2. The magnetic flowmeter transmitter of claim 1, wherein the output circuitry includes analog output circuitry that provides 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 measures a parameter associated with the analog output and compares the measured parameter to known values for verification.

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

5. The magnetic flowmeter transmitter of claim 1, wherein the output verification circuitry includes pulse counting circuitry that counts pulses from the pulse output and that verifies the pulse output frequency as a function of the counted pulses from the pulse output.

6. The magnetic flowmeter transmitter of claim 5, wherein the output verification circuitry includes pulse count comparison circuitry that compares the counted pulses from the pulse output to a reference pulse count and that verifies proper operation of the pulse output circuitry based upon the comparison.

7. The magnetic flowmeter transmitter of claim 1, wherein the output verification circuitry comprises:

sampling circuitry that provides a sampled frequency signal;

frequency to voltage conversion circuitry that converts a frequency of the sampled frequency signal into a representative voltage;

an analog to digital converter that converts the representative voltage into a representative digital voltage value; and

wherein the pulse output verification circuitry verifies the pulse output frequency as a function of the digital voltage value.

8. The magnetic flowmeter of claim 1, wherein the output verification circuitry further comprises adjustable pulse feedback trigger level circuitry that adjusts a trigger level above which a pulse in the pulse output will be detected.

9. The magnetic flowmeter of claim 8, wherein the adjustable pulse feedback trigger level circuitry adjusts the trigger level as a function of a trigger level adjustment input.

10. The magnetic flowmeter of claim 8, wherein the adjustable pulse feedback circuitry automatically adjusts 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.

11. The magnetic flowmeter transmitter of claim 1, and further comprising pulse waveform analysis circuitry that digitizes the pulse output and that analyzes a pulse output waveform for at least one of rise time, duty cycle and amplitude.

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

measurement circuitry that senses flow through the flowtube and that provides an output related to flow through the flowtube;

output circuitry coupled to the measurement circuitry providing a transmitter output that is related to flow through the flowtube to a remote location; and

output verification circuitry coupled to the output circuitry that verifies proper operation of the output circuitry,

wherein the transmitter is coupled to an analog current loop and wherein the output circuitry provides an analog output on the analog current loop in order to transmit flow information over the analog current loop; and

wherein the output verification circuitry is internal to the transmitter and measures a parameter associated with the analog output and compares the measured parameter to known values for verification.

13. The magnetic flowmeter transmitter of claim 12, wherein the output verification circuitry converts the analog output to an isolated frequency and verifies proper operation of the output circuitry using the isolated frequency.

14. The magnetic flowmeter transmitter of claim 12, wherein the transmitter is coupled to communication wiring and wherein the output circuitry provides a pulse output on the communication wiring in order to transmit flow information.

15. The magnetic flowmeter transmitter of claim 14, wherein the communication wiring is the analog current loop.

16. The magnetic flowmeter transmitter of claim 14, wherein the output verification circuitry verifies a pulse output frequency in order to verify proper operation of the output circuitry.

17. The magnetic flowmeter of claim 14, wherein the output verification circuitry further comprises adjustable pulse feedback trigger level circuitry that adjusts a trigger level above which a pulse in the pulse output will be detected by the output verification circuitry.