A Proposal for a Standard Calibration Data Format

Michael Johnston and Andrew Chapman

Abstract

As technology advances in the Metrology and Calibration industries, our ability to develop new software packages that automate the gathering and retention of data increases. Our collective devotion within these industries to tried and true methods has led us to overlook the potential for tracking calibration metadata in a much more meaningful and robust way.

To allow this change in the calibration paradigm, the first step is to establish a standard format for the recording and sharing of this data and collectively building our software around this principle; there are certain pieces of information that can and should be collected for every calibration we perform.

Expanding on the existing work of VDI/VDE-2623, this paper proposes a Standard Calibration Data Format for use in future software packages to unify the industry and provide improved metrological data.

Introduction

For nearly 30 years, Fluke MET/CAL® has been a significant part of the automation of calibration procedures. This breadth of history places Fluke in a unique position to help in establishing the way forward in the unification of calibration data retention and exchange. In both the MET/TRACK and MET/TEAM asset management systems that have served as the database side of MET/CAL, specific aspects of a calibration are retained and can be reported or exported through various means. Across the calibration industry, however, no standardization of this reporting or exporting format exists, leaving users to either create their own tools for combining data sources or maintaining multiple databases separately.

In 2012, the Association of German Engineers developed VDI/VDE-2623, wherein they define and establish a Calibration Data Exchange Format (VDI/VDE-2623, 2012). Numerous papers have been presented at NCSLi, MSC, and in metrology publications calling for a unification of data formats for things like calibration data and scopes of accreditation as part of the Measurement Information Infrastructure Initiative (MII Initiative Knowledge Base, n.d.). The framework has been laid by these efforts, but none have pushed forward to the next step: defining a standard format and driving its implementation.

In this paper, we will offer a proposal for this standard format so that we can begin to move forward and unify the industry around it, with the hope of ultimately creating a new ISO standard.

History

As software’s role has grown in the calibration industry, a variety of calibration runtime and asset management options have been available. Each of these have introduced their own methods for retaining or sharing data. This has led to minimal interaction between multiple systems being used by a given lab, forcing users to maintain multiple data sets separately or create their own methods to combine them. Fluke’s MET/CAL has been one of the causes of this problem, storing all its data in Fluke’s own asset manager. Users that have a different primary asset manager maintain duplicate data for the sole purpose of running procedures in the MET/CAL Runtime and then must view their historic data in another system.

As more competitors join the market, the segregation of data amplifies. The industry has not had a significant focus on resolving this problem. This is likely in part because any solution would require the various participants in the market to form a cooperative stance and accept data generated by their competitors while allowing their data to be accepted as well.

When considering this problem, the Association of German Engineers recognizes the need to exchange calibration data, not only between customers and calibration providers, but also between departments and between calibration laboratories. In the introduction to VDI/VDE-2623 they state, “Against this background it becomes urgently necessary to define a uniform and universal format for exchanging data in the management of measuring and test equipment.”

In researching for this endeavor, the authors were unable to find anything remotely comparable to the efforts made by the Association toward a format that would be usable industry-wide. A recent article published in Cal Lab Magazine offered a suggestion for a data format, focusing on the concept of a set of minimal data set to be offered alongside the normal calibration data that typically comes in an uneditable form like a PDF or printed.

It is our opinion that an approach based upon VDI/VDE-2623 will provide a more useful exchange of data by not limiting ourselves to just the calibration data, but data and metadata related to the full calibration process.

VDI/VDE-2623

In defining their scope for the standard, the Association of German Engineers stated:

“In this guideline a definition is given of the exchange of data which are required and generated during a calibration process. This should make it possible for measuring and test equipment data to be exchanged securely and rapidly between different systems (departments, companies, plants, and so on). The aim here is to collect and collate relevant data for any measuring and test equipment required for the management of measuring and test equipment and thus for process and quality assurance.”

VDI/VDE-2623 establishes a rigid Extensible Markup Language (XML) data structure with both required and optional fields. While some of the data covered by this standard may not be applicable in every situation, using the work already conducted in developing the data structure is ideal for moving this effort forward in a meaningful way.

Proposal

Our purposed solution and standard for calibration data is a defined construction in nine parts. These categories describe each field that is mandatory in VDI/VDE 2623 as well as those required by ISO 17025:2017 and ANSI Z540.3. Some terms used in this proposal will match terms used in other standards, while other terms may be new or adapted from currently existing software packages.

Each category requires a count of expected fields that matches the total fields used in the category, including additional subfields. Additional subfields may be used to add optional data that is listed in the VDI standard, company data that is needed, or extraneous descriptions. Additionally, the total of all the fields used must match the listed expected fields for the entire data package found in the Order category. The proposed data categories are as follows:

Order – This category lists the total expected fields in the data package, and must match the total fields used throughout the package.

Technical Items – This category houses details about the device under test, standards in use, and all additional references. All assets in use for the maintenance or calibration event need to be associated to a unique identifier.

Order ID – Order ID describes the specific details about where, when and who will be doing the calibration of maintenance.

Buyer – This category describes the device provider or owner details, like address and names.

Supplier Data – This category houses all details about the calibration laboratory, company name and addresses.

Inspection Plan – This category describes the specific procedure that will be performed during the calibration or maintenance.

Inspection Plan Characteristics – Inspection Plan Characteristics describes what data and how much data is expected to be collected.

Calibration Results – This category houses the collected results per section.

Additional Data Fields – This final category is designed to house any additional data that the device designer, procedure creator, accreditation or law requires.

For a detailed look at the required data fields in each category, see Appendix A. We have explored several possibilities for formats in which to implement this standard data structure. While XML is a popular structure and is what the VDI standard uses, we found that a potential alternative, External Machine Interface (EMI) may present a more flexible use case. EMI is used primarily in Short Message Service (SMS) applications, but its string-based format is simpler and could be used to generate any other format required. EMI uses hexadecimal or ASCII encoding, meaning it is based on established conventional technology. It would also be encryptable, which is an additional positive attribute.

Conclusion

The benefits of a universal format for calibration data are numerous. Increasing the exchangeability of data between calibration software packages makes it easier for servicing facilities to retain their records without unnecessary data bifurcation. A simple way to provide electronic data to customers improves their ability to analyze their calibration data to make smarter decisions about their equipment. By building on the work already done by the Association of German Engineers, we can take a major step toward an international unification that meets the requirements of our collective quality standards. Our proposal presents a simple, flexible, and complete solution that will enable these benefits.

Appendix A

1. Order
   
   1. Expected fields
2. Technical Items (Assets: DUT’s and Standards)
   
   1. Expected fields count
   2. Header for technical list
   3. “Master Data”
      1. Unique ID
      2. Description
      3. Manufacture
      4. Model number
      5. SN
      6. Supplier ID
      7. Properties
         
         1. Amount of additional Properties
         2. Value of property
      8. Secondary IDs
      9. Accessories
         
         1. Amount of Accessories
         2. Value of accessories
            1. 6b1, 6b2,6b3, 6b4
      10. Sub-items
          
          1. Amount of sub-items
          2. Value of sub-items
             1. 6b1, 6b2,6b3, 6b4
      11. Traceability of standard
          
          1. Unique ID – 6b1, 6b2,6b3, 6b4
          2. Last calibration date
          3. Next calibration due date
          4. Service hash ID of calibration, 8a
      12. Additional fields as needed
3. Order ID (Work Order Number)
   
   1. Expected fields count
   2. Date/Time (Service Date/time)
   3. ISO 639-1 (language)
   4. Interface Version
   5. Creator (Technician)
   6. Purchaser/Buyer (Customer ID)
   7. Supplier (Cal Lab)
   8. Additional fields as needed
4. Buyer (unique customer ID)
   
   1. Expected fields count
   2. Company name (facility)
   3. Street address
   4. Zip Code
   5. City/State
   6. Additional fields as needed
5. Supplier Data
   
   1. Expected fields count
   2. Supplier (lab unique identifier)
   3. Company name
   4. Supplier street address
   5. Zip Code
   6. City/State
   7. Country
   8. Additional fields as needed
6. Inspection Plan (Service)
   
   1. Expected fields count
   2. Service Type Description
   3. Accreditation
   4. Service Type ID (Procedure Name or ID#)
   5. Date/time
   6. Additional fields as needed
7. Inspection Plan Characteristics
   
   1. Expected fields count
   2. Service Type ID (hash of ST, and a run ID and date)
      
      1. 6c
      2. 3a
   3. Description
   4. Service Type
   5. Amount of tests
   6. Amount of test points
   7. Nominal Value
   8. Upper Limit
   9. Lower Limit
   10. Units
   11. Comment
   12. Additional fields as needed
8. Calibration Results
   
   1. Expected fields count
   2. Service Type ID (hash of ST, and a run ID) PK
   3. Section I#ID
   4. Result
      
      1. Result value
      2. Unit
      3. Uncertainty
      4. Unit uncertainty
      5. Coverage factor
      6. Date/time
      7. Comment
   5. Temp
      
      1. Unit
   6. Humidity
      
      1. Unit
   7. Location of test
      
      1. Supplier (Calibration Lab) PK
   8. Primary Technician
   9. Additional fields as needed
9. Additional data fields as needed
   1. Expected amount of fields
   2. Additional fields as needed

References

(2012). Format for data exchange in management of measuring and test equipment. Association of German Engineers. VDI/VDE-2623.

MII Initiative Knowledge Base. (n.d.). Retrieved March 18, 2017, from MII Initiative: http://miiknowledge.wikidot.com/start