System and method for performing autoranging in a measurement device

• US 6,542,838 B1
• Filed: 05/12/2000
• Issued: 04/01/2003
• Est. Priority Date: 05/12/2000
• Status: Expired due to Term

• Current Assignee: National Instruments Corporation (Emerson Electric Company)
• Original Assignee: National Instruments Corporation (Emerson Electric Company)
• Inventors: Silva, Mark, Haddad, Michel
• Primary Examiner(s): Barlow, John
• Assistant Examiner(s): BHAT, ADITYA S
• Application Number:
  US09/569,862
• Time in Patent Office: 1,054 Days
• Field of Search: 702/88, 702/82, 341/139, 341/155, 364/481, 364/561, 368/118, 375/102, 738/612.8, 324/457
• US Class Current: 702/88
• CPC Class Codes: G01D 3/024 for range change; Arrangements for substituting one sensing member by another
• CPC Class Codes: G01R 15/09 Autoranging circuits

Abstract

A system and method that configures a measurement device to a correct measurement range. The system and method implements an autoranging technique, preferably in software, that automatically determines a measurement range based on a measurement. Once an initial measurement is received, the initial measurement is compared with the current measurement range. If the current measurement range is the correct measurement range for the initial measurement, then the measurement device is already configured at the correct measurement range. However, if the current measurement range is found not to be the correct measurement range, then a new measurement range is determined based on the initial measurement. A new measurement is then taken using the new measurement range to ensure the new measurement range is the correct measurement range. The process repeats itself by comparing the new measurement with the new measurement range to see if the new measurement range, is the correct range. If the new measurement range is not the correct measurement range, then the process continues until a correct measurement range is found.

Claims

1. A method for automatically configuring a measurement device to a correct measurement range, comprising:

receiving a first measurement;

comparing the first measurement with a first measurement range;

determining if the first measurement range is the correct measurement range in response to said comparing;

determining a new measurement range based on the first measurement if the first measurement range is not the correct measurement range, wherein said determining comprises comparing the first measurement with one or more smaller measurement ranges to determine the new measurement range;

wherein said comparing, said determining if the first measurement is in the correct measurement range, and said determining a new measurement range are automatically performed in response to receiving the first measurement.

2. The method as recited in claim 1, wherein said determining a new measurement range based on the first measurement comprises:

iteratively comparing the first measurement with the one or more smaller measurement ranges until a final measurement range is identified, such that the first measurement is greater than a certain percentage of the final measurement range;

wherein the new measurement range is a next higher measurement range relative to the final measurement range.

3. The method as recited in claim 2, wherein said iteratively comparing is performed in software.

4. The method as recited in claim 1, wherein the new measurement range is identified when the first measurement is greater than a certain percentage of a next smaller measurement range relative to the new measurement range.

5. The method as recited in claim 1, wherein said determining a new measurement range based on the first measurement comprises:

comparing the first measurement with a next smaller measurement range relative to the first measurement range;

(a) wherein if the first measurement is less than a certain percentage of the next smaller measurement range, then;

(a)(1) comparing the first measurement with a following smaller measurement range relative to the next smaller measurement range;

(b) wherein the following smaller measurement range becomes the next smaller measurement range and steps (a)-(b) are performed one or more times until the first measurement is greater than a certain percentage of the next smaller measurement range;

wherein, when the first measurement is greater than a certain percentage of the next smaller measurement range, then the new measurement range is a next higher measurement range with respect to the next smaller measurement range.

6. The method as recited in claim 1, wherein said determining a new measurement range based on the first measurement comprises:

determining if the first measurement is greater than the first measurement range;

wherein, if the first measurement is greater than the first measurement range, then the method comprises;

adjusting the first measurement range to be a highest measurement range of the measurement device; and

receiving a second measurement, comparing the second measurement with the highest measurement range, determining if the highest measurement range is the correct measurement range in response to said comparing, and determining a new measurement range based on the second measurement if the highest measurement range is not the correct measurement range;

wherein, if the first measurement is less than the first measurement range, then the method comprises;

comparing the first measurement with one or more smaller measurement ranges until a final measurement range is identified, such that the first measurement is greater than a certain percentage of the final measurement range;

wherein the new measurement range is a next higher measurement range relative to the final measurement range.

7. The method as recited in claim 1, wherein the method further comprises:

receiving a second measurement using the new measurement range;

determining if the new measurement range is the correct measurement range in response to the second measurement.

8. The method as recited in claim 7, wherein the method further comprises:

determining a second new measurement range based on the second measurement if the new measurement range is not the correct measurement range; and

configuring the measurement device with the second new measurement range after said determining the second new measurement range.

9. The method as recited in claim 7, wherein the method further comprises:

configuring the measurement device with the new measurement range if the new measurement range is determined to be the correct measurement range in response to the second measurement.

10. The method as recited in claim 7, wherein said determining a new measurement range is repeated at most one time.

11. The method as recited in claim 6, wherein the first measurement range is not the correct measurement range if:

the first measurement is greater than the first measurement range;

or

the first measurement is less than a pre-determined percentage of the next lower measurement range.

12. The method as recited in claim 6, wherein the correct measurement range is a range where measurements are less than the correct measurement range and are greater than a pre-determined percentage of the next lower measurement range.

13. The method as recited in claim 6, wherein the first measurement range is one of a default measurement range or a last measurement range.

14. The method as recited in claim 1, wherein the new measurement range is designated as the correct measurement range, the method further comprising:

configuring the measurement device with the new measurement range after said determining the new measurement range based on the first measurement.

15. The method as recited in claim 14, further comprising:

configuring the measurement device with the first measurement range if the first measurement range is the correct measurement range.

16. The method as recited in claim 1, wherein the method is implemented by a measurement system comprising the measurement device and a computer system;

wherein the computer system automatically performs said comparing, said determining if the first measurement is in the correct measurement range, and said determining a new measurement range in response to receiving the first measurement.

17. The method as recited in claim 1, wherein the measurement device includes a plurality of channels;

the method further comprising maintaining information regarding a last used range on a channel-by-channel basis for each of the plurality of channels;

wherein said information regarding the last used range is useable in returning to a last range for a respective channel for faster autoranging of the respective channel.

18. A measurement system which performs autoranging on a measurement device, comprising:

a measurement device for measuring signals, wherein the measurement device includes a plurality of measurement ranges;

a computer system coupled to the measurement device, wherein the computer system includes a memory medium and a processor coupled to the memory medium, wherein the memory medium stores an autoranging software program for configuring the measurement device with a correct measurement range;

wherein the measurement device is operable to receive a first measurement;

wherein, in response to the first measurement, the processor is operable to execute the autoranging software program to;

compare the first measurement with a first measurement range;

determine if the first measurement range is the correct measurement range in response to the comparison; and

determine a new measurement range based on the first measurement by comparing the first measurement with a next smaller measurement range relative to the first measurement range if the first measurement range is not the correct measurement range.

19. The measurement system as recited in claim 18, wherein, in determining a new measurement range based on the first measurement, the processor is operable to execute the autoranging software program to:

iteratively compare the first measurement with one or more smaller measurement ranges until a final measurement range is identified, such that the first measurement is greater than a certain percentage of the final measurement range;

wherein the new measurement range is a next higher measurement range relative to the final measurement range.

20. The measurement system as recited in claim 18, wherein, in determining a new measurement range based on the first measurement, the processor is operable to execute the autoranging software program to:

compare the first measurement with one or more smaller measurement ranges to determine the new measurement range, wherein the hew measurement range is identified when the first measurement is greater than a certain percentage of a next smaller measurement range relative to the new measurement range.

21. The measurement system as recited in claim 18, wherein, in determining a new measurement range based on the first measurement, the processor is operable to execute the autoranging software program to:

compare the first measurement with the next smaller measurement range relative to the first measurement range;

(a) wherein if the first measurement is less than a certain percentage of the next smaller measurement range, then;

(a)(1) compare the first measurement with a following smaller measurement range relative to the next smaller measurement range;

(b) wherein the following smaller measurement range becomes the next smaller measurement range and (a)-(b) are performed one or more times until the first measurement is greater than a certain percentage of the next smaller measurement range;

wherein, when the first measurement is greater than a certain percentage of the next smaller measurement range, then the new measurement range is a next higher measurement range with respect to the next smaller measurement range.

22. The measurement system as recited in claim 18, wherein, in determining a new measurement range based on the first measurement, the processor is operable to execute the autoranging software program to:

determine if the first measurement is greater than the first measurement range;

wherein, if the first measurement is greater than the first measurement range, then the processor is operable to execute the autoranging software program to;

adjust the first measurement range to be a highest measurement range of the measurement device;

receive a second measurement;

compare the second measurement with the highest measurement range;

determine if the highest measurement range is the correct measurement range in response to said comparison; and

determine a new measurement range based on the second measurement if the highest measurement range is not the correct measurement range, wherein, in determining a new measurement range, the processor is operable to execute the autoranging software program to;

compare the second measurement with one or more smaller measurement ranges until a final measurement range is identified, such that the second measurement is greater than a certain percentage of the final measurement range;

wherein the new measurement range is a next higher measurement range relative to the final measurement range.

23. The measurement system as recited in claim 18, wherein the processor is operable to execute the autoranging software program to further:

configure the measurement device with the new measurement range after determining the new measurement range based on the first measurement.

24. The measurement system as recited in claim 18, wherein the processor is operable to execute the autoranging software program to further:

configure the measurement device with the first measurement range if the first measurement range is the correct measurement range.