In the previous parts 1 and 2, we have discussed the problems of COTS integration and the type of tools that could ease the process. We must have a tool which works from the top down, or we suffer constant delays from waiting for low-level design data-which even once we have it, the system diagnostics will be constrained by the limited scope of the low-level analysis. That is, a bottom-up approach often impedes the communication between system integrator and COTS supplier that is needed to achieve system-level performance in line with the expected or even warranted low-level diagnostics.To tackle the top-down requirements, eXpress maintains a dynamic link between different levels of designs. This allows two things to happen. First, it allows the system to be analyzed as changes are made during the development progresses; and second, it allows low-level design changes to be monitored at the system level. By providing both these capabilities, eXpress allows requirements to be easily passed down from the system level, and the changes they effect can be immediately seen in their system perspective.
Another main concern precluding acceptance of any tool is that it be able to produce understandable results by both engineers and management alike. To achieve this, eXpress provides several options. First of all, indicators that represent low-level signal flow may be turned off to reduce "visual clutter," thus increasing the readability of content-heavy, system-level diagrams. Secondly, eXpress provides a vast number of symbols as well as an import capability so that the elements within a design do not simply appear as boxes, but rather indicate the function performed. Finally, all elements within eXpress are fully reusable to reduce development time and provide engineers with a set of components previously created and validated to eliminate re-entry errors.
To achieve true integration with data supplied by COTS suppliers (or any other subcontracted companies or vendors), eXpress uses a cross-platform/binary-compatible data structure for all of its files. This allows different companies, divisions or work groups to provide Part Libraries, Symbol Libraries, and even complete designs regardless of the hardware used. In fact, in a fully networked environment, SUN UNIX, HP UNIX and PC-based workstations may all access the same files without extra conversion. Existing data from previous efforts residing in other CAD/CAE tools can also be translated through the use of eXpress's import feature which can handle numerous formats, including EDIF-a netlist standard common to most electronic CAD/CAE tools. Also, a DXF import function allows vector-based symbols to be imported from tools such as AutoCAD®, CorelDraw, and Visio.
Finally, what is probably the most challenging aspect of a successful COTS integration is the ability to co-develop the diagnostic strategy along with the product design. eXpress and STAT together provide the ability to perform analysis at any level, whether it be the system, subsystem, or a combination thereof. By reducing STAT's job through extracting only the pertinent information to a given analysis, eXpress also reduces analysis timeætime better spent determining how additional tests can be implemented and whether the COTS hardware can provide it. In fact, to help the Test Engineer determine the most effective use of information available at a given Test Point, eXpress provides the unique capability of being able to mix functional mode and failure mode test information.
By utilizing eXpress and STAT in a top-down environment in which diagnostic and operational features are co-developed, the systems integrator can safely choose to incorporate COTS components without unknowingly assuming hidden risks, costs and liabilities. eXpress and STAT perform their best in making the COTS pill safe to swallow.