DMIS Certification Program - dmisstandards.org

[Note: This entire document, with hyperlinks to topics and embedded files for Application Profiles and the Certification Process Flowchart, may be downloaded from the Homepage main menu Files/Documents to Download > DMIS Certification > DMIS_Certif_Notice-Revised.doc. Or, you may click on this link.]

Contents:

I. What is DMIS?

II. What is the DMIS Certification Program?

1. What does Conformance to the DMIS Standard Mean?
2. DMIS Conformance Testing.
3. The NIST DMIS Test Suite (NDTS)

III. What is the Certification Process?

IV. What are the Steps for Certification?

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I. What is DMIS?
DMIS (Dimensional Measuring Interface Standard) is both an American National Standard and ISO international standard language for the correct, complete, and unambiguous description of computer-executable dimensional measurement part programs and measurement results. As a standard, DMIS is non-proprietary and represents industry consensus. Dimensional measurement part programs and results are critical to manufacturing Quality Assurance. Since DMIS is a very large standard, it has been divided up into a variety of conformance classes, in order to accommodate the fact that many implementers only need to implement portions, or subsets, of the DMIS standard.

The implementers of DMIS fall into two categories: DMIS producers, and DMIS consumers. DMIS producers generate DMIS input (DMI) files containing a list of DMIS instructions. DMIS consumers read/interpret DMI files to execute actual measurements and produce measurement results such as DMIS output (DMO) files.

DMIS is a successful, dynamic standard because its scope and capabilities have expanded over the years along with technology advances in the metrology industry. However, this success has brought about challenges in the area of compliance of DMIS implementations. Not surprisingly, of those who claim DMIS compliance, the actual compliance varies as widely as the implementations.

In pursuit of better DMIS compliance in the Quality Industry, the Dimensional Metrology Standards Consortium (DMSC, Inc.), called upon NIST to mature their NIST DMIS Test Suite as a key mechanism of a DMIS Certification Program.

II. What is the DMIS Certification Program?

Consider the situation if CMM users insisted on purchasing only CMM software that has DMIS Certification. Part programs would be able to transition through CMM machine and software changes, and be interchangeable with partners and associates around the world; thus having a much higher value, life, and use for the time and cost invested.

The DMIS Certification Program is a process whereby vendors and users of DMIS-based products can verify that these products actually conform to the DMIS Standard, thus enabling the interoperability of programs. Timely, correct, complete, unambiguous, and widely-implemented non-proprietary interface standards save time and money for everyone from customers, to end users, tier suppliers, and vendors.

The benefits of non-proprietary interface standards are realized when end users and tier suppliers demand them and lead efforts to enable them.

1. What does Conformance to the DMIS Standard Mean?
The primary purpose of DMIS is to allow organizations to exchange measurement programs and store measurement data among different dimensional measurement devices and computer applications within their companies, as well as with company divisions, contractors, or other companies and organizations. DMIS is widely used and available for a broad range of measurement systems and applications. However, a DMIS file that is created by one DMIS product may not be fully or correctly interpreted by another DMIS product. Successful DMIS interchange can only be achieved if DMIS applications faithfully implement (1.) the DMIS standard, and (2.) the appropriate, formally recognized DMIS Application Profiles coupled with any addenda.

As DMIS is a very large language, most applications only need to implement subsets of the standard. These subsets are called ‘conformance classes’ which have been defined by the DMSC, Inc . In order to conform to a given conformance class, a system using DMIS must fully implement the subset for that class. Two Application Profiles (APs) have been defined one for Prismatic parts, and one for Thin Walled parts. Seven addenda have also been defined which are rotary tables, multi-carriage, contact scanning, IPV (in-process verification), QIS (quality information systems), measurement uncertainty, and soft-gauging.

Each application profile and addendum may be implemented at one of three levels. According to the DMIS Standard, Level 1 is essential or required to meet the profile’s goals; Level 2 is considered important to meeting the profile’s goals; and Level 3, is beneficial to meeting the profile’s goals. The NIST DMIS Test Suite includes an Excel spreadsheet, developed by the DMIS Standards Committee, that details all of the commands used in the DMIS language, and those which are required for each level of conformance.

The primary benefit of any DMIS profile is the ability to insure interoperability through the use of validation tools against DMIS instances and certification services for applications. Once an application has been certified, behavior of that application is predictable under the constraints of the profile level.

2. DMIS Conformance Testing
DMIS conformance testing is a way of determining if a DMIS compliant product correctly implements the DMIS standard with its associated Application Profile. Strictly speaking, the DMIS standard is an exchange file format. However, the term "DMIS" is often used to include a generator (a hardware and software system with which a user can produce DMIS input files), an executor (a hardware and software system that reads DMIS input files, does what they say to do, and writes DMIS output files), as well as the metafiles (the actual DMIS input and output files). Together, the generator, metafiles, and executor form a total DMIS system.

Conformance to DMIS is therefore defined in terms of conformance to a particular Application Profile of DMIS. Thus, the DMIS standard, in conjunction with an Application Profile, is necessary in order to test conformance of a total DMIS system.

3. The NIST DMIS Test Suite (NDTS)
The NIST DMIS Test Suite provides utilities and test files for conducting conformance tests on DMIS input files (.dmi), computer systems that generate DMIS input files, and computer systems that execute DMIS input files. However, for the current DMIS Certification, submitted programs will be tested only for conformance to proper DMIS syntax; that is, the correct use of commands and structure in the DMIS language. The testing process will not analyze input programs for semantics nor for execution performance; that is, the test will not try to evaluate what the program statements ‘mean,’ nor verify that the program does what it is supposed to do.

The NIST DMIS Test Suite, which now applies to DMIS 5.1, is intended to be useful to both developers and users of DMIS systems, and in fact for developers of additional DMIS Test Suites and other parsers. The purpose of the NIST DMIS Test Suite is to help developers and users easily conform to the DMIS language.

One (or more) of the parsers in the Test Suite may be used to parse DMIS input files produced by a commercial system. This test will determine if the syntax of the files is correct. The parsers in the Test Suite will provide a description of each error found, and will continue through the errors in order to make a complete report.

The NDTS currently includes the following items useful for testing*:

A. Test utilities (executable software programs) for DMIS producers for each of several important conformance classes. Each test utility tests if a DMI file is syntactically correct, but does not currently test if anything in the DMI file is semantically correct (meaningful). Syntactic correctness means DMIS-compliant command structure as well as DMIS-compliant spelling of commands and their parameters. Each test utility provides a description of each definite error found, and warnings of other possible errors.

B. Test DMI files (to test the parser). These files contain a complete set of syntactically correct DMIS commands for particular conformance classes. Test DMI files are currently offered only for the same DMIS conformance classes as those for which test utilities are available. These files can now be used by DMIS consumer implementations to test whether the consumer implementation can read all allowed commands in a conformance class and (to a lesser extent) whether the consumer implementation will reject syntactically incorrect commands. Correct use of the language carries substantial weight in terms of transportability and interoperability.
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* The NDTS also includes non-testing items intended to make it easier to build implementations.

III. What is the Certification Process?
A DMIS Certification Process Flowchart has been developed during the evaluation of the NIST DMIS Test Suite. The flowchart document identifies the personnel in the Role-based Process Flow Diagram, and their respective actions and decisions. For each individual ‘Role’ there are ‘functions’ (actions and/or decisions) that must be completed. The Excel flowchart addresses the implementation of these functions; that is, how these functions and processes might be accomplished.

IV. What are the Steps in Certification?
1. All submittals for DMIS Certification will be tested for completeness and correctness; i.e., the submitted files must be able to use all commands within the stated Conformance Level; and, the syntax of the DMI files must be correct. Therefore it will behoove the submitter to download the latest version of the NIST DMIS Test Suite (NTDS) from the NIST Website, and to test their own DMIS files before submittal. [NOTE: the NIST DMIS Test Suite contains an Excel Spreadsheet of all the available Application Profiles.]

(The latest version of this Test Suite is 2.1.3, which may not yet be posted on the NIST Website.) At least one of the parsers for each operating system (Linux, Sun, or Windows) will parse an entire set of files, and will list all the errors and warnings for each of those files along with a list of all the commands used, the percentage of the total commands used, and the commands not used for the given Conformance Class.

2. The submitter should then download and complete the DMIS Certification Application Form from this Website (orange main menu to the right) then send the Form with payment according to the instructions on the Form. The Certification is good for one year, and each certified company will be posted on the DMSC, Inc. Website for public viewing, thus verifying that the Certification is currently valid.

3. Once the files have been tested using the NIST DMIS Test Suite, the submitter will be notified of the results. If the submitted files pass the test, the submitter will be provided the DMIS Certificate, artwork for the DMIS Certified Sticker, and a license to display the sticker on the submitter’s products. The submitter should purchase the stickers from any of several producers that will suit individual company specifications as to size and materials; however, the content of the sticker must not be changed.

4. The Certification is good for one year, and during that year the Certified company may submit a reasonable number of files for certification, or re-certification.

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