Although this is nice, the real power of this dialog is unleashed only after you have calculated diagnostics. When a calculated diagnostic study is loaded into memory for the active model, then the Test Program Optimization dialog looks quite different: Here you see the diagnostic value (Probabilty of use in diagnosing) of each test in the "ATE Testing Procedure" with the tests that were assigned. It also shows the time that will required to run the complete procedure allowing optimization of procedures for isolation.

 

 

 

By default, when a design is linked to a diagnostic study, the Test Program Optimization dialog will be filled with all tests that are included in the calculated diagnostics, alphabetically sorted by how likely each test is to be used to diagnose a failure.

 

Before invoking this dialog, develop a diagnostic sequence that represents your preferred order of testing. Then, on this dialog, the values that appear in the Probability column will indicate the relative likelihood that each test will be used to diagnose a failure. In the example above, the top value is 97.04—this is assigned to the test which will always be performed first (its probability is not 100.0 because 2.96 percent of the expected failures are non-detectable).

 

To assign tests to a particular test program, click on the “Assign” button in the lower left corner of the Test Program Optimization dialog. The following assignment dialog will then appear:

 

 

 

 

 

 

Notice that the number of tests assigned to this test program and the cumulative test time are both displayed at the bottom of the dialog. 5

 

Within a diagnostic study, the candidate lists on the Detection and Isolation panels can now be populated four different ways—all candidates, candidates in test programs, candidates in virtual test sets and candidates in standard test sets.

 

 

You can toggle between the different display modes by clicking on the “T” icon in the upper right corner of the candidates list (Note: this icon only appears if the design contains either virtual test sets or test programs that correspond to the panel’s diagnostic usage).  Currently, test programs are handled by the diagnostics in the same manner as a virtual test set. In future releases of the software, however, test programs will take on a larger role—providing another method for controlling the order in which tests are performed during diagnostics.

 

 

You can toggle between the different display modes by clicking on the “T” icon in the upper right corner of the candidates list (Note: this icon only appears if the design contains either virtual test sets or test programs that correspond to the panel’s diagnostic usage).

 

To evaluate the diagnostic effectiveness of one or more test programs, generate diagnostics using only those test program(s) as candidates for detection and/or isolation. In the example below, you can see that our one-minute test program can detect only a little more than half of the expected failures.

 

 

Because no isolation tests were included in this test program, it should not be surprising that the expected isolation to a single component (using only this test program) is poor. In this particular example, the numbers resulted in fault detection being privileged over fault isolation.

 

In situations where certain isolation tests are among the tests most commonly performed during diagnostics, those isolation tests may be included in the initial test program (in place of some of the later, less useful detection tests). In that case, the probability of isolation would be better, at the expense of the probability of detection. Here is where automated test program assignment is particularly useful, since the comparisons are now considerably more complex (and can no longer be performed by simply viewing cumulative values in a spreadsheet).

 

Currently, test programs are handled by the diagnostics in the same manner as a virtual test set. In future releases of the software, however, test programs will take on a larger role—providing one more method for controlling the order in which tests are performed during diagnostics.