The Diagnostician is a revolutionary approach to achieving fault isolation in a manufacturing test or field maintenance environment. The Diagnostician is a software module which sits under any client program and provides diagnostics-related services during testing or troubleshooting of a system or item. Model-Based reasoning is used to correlate test results to a diagnostic model of the item, thus providing fault call-out. The diagnostic model is created from CAD outputs by the Diagnostic Profiler development environment.

Use of the Diagnostician greatly simplifies test programming, since the programmer does not have to consider fault trees and fault propagation. The programmer simply writes those tests which determine whether signals at various measurement points are pass or fail. During test development, the Diagnostic Profiler helps the programmer determine the effectiveness of his tests in terms of fault isolation resolution and ambiguity group composition.

The Diagnostician software is structured in a DLL library as a series of functions. These functions can be called by any application to provide a seamless diagnostic capability. The structuring of the Diagnostician into DLL functions provides great application flexibility and tailoring, since users can call those functions which their application needs, when they're needed. The Diagnostician operates as a true server, providing automatic fault isolation services to any client program which calls upon its functions.

The Client Program, such as a LabVIEW test program or the ATEasy Test Executive makes all Diagnostician functions available to the application test program. The application reports all test results to the Diagnostician, which performs inferencing based upon the diagnostic model. Fault Call-Out or Ambiguity Group is passed to the client program which reports the indicted components to either back to the client program, or to the screen or to a log file specified by the programmer.

Any client program, when integrated with the Diagnostician, can become a Test/Diagnostic Executive, offering the test programmer diagnostic solutions they never before enjoyed.

The test program developer has a variety of options in the use of the Diagnostician depending on the test philosophy. These are configured through a series of implementation options. These options are:

Diagnostician Control - Under this mode, Diagnostician functions are initiated upon execution of the test program. The Diagnostician will drive the test execution by determining the group of tests to most efficiently isolate to the failed component. Only those tests identified by the Diagnostician as having diagnostic significance will be executed.

Go/No-Go Control - Under this mode, all Go/No-Go tests are executed by the client program. If there is a failure, then the Diagnostician will be initiated and the test results will be reported. The Diagnostician will indict an ambiguity group and test execution will terminate. This mode assumes that there are no additional fault isolation tests available for the Diagnostician to execute.

Mixed Control Mode - Under this mode, the client program will execute the Go/No-Go tests, and upon failure, initiate Diagnostician functions and pass to it the test results. The Diagnostician will then identify fault isolation tests to be executed. This mode has two options:

Using the Diagnostician, the test programmer will no longer be required to determine the best diagnostic test flow to isolate to the faulty component. Diagnostics will be accomplished automatically by the Diagnostician.

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Last modified: December 27, 2001