Diagnostic systems are used by technicians and professionals in virtually all industries to perform basic and advanced system testing functions. For example, in the automotive, trucking, heavy equipment and aircraft industries, diagnostic test systems provide for vehicle onboard computer fault or trouble code display, interactive diagnostics, multiscope and multimeter functions, and electronic service manuals. In the medical industry, diagnostic systems provide for monitoring body functions and diagnosis of medical conditions, as well as system diagnostics to detect anomalies in the medical equipment.
In many industries, diagnostic systems play an increasingly important role in manufacturing processes, as well as in maintenance and repair throughout the lifetime of the equipment or product. Some diagnostic systems are based on personal computer technology and feature user-friendly, menu-driven diagnostic applications. These systems assist technicians and professionals at all levels in performing system diagnostics on a real-time basis.
With the advent of the microprocessor, virtually all modern vehicles have come to utilize onboard computers to control and monitor engine and electrical system functions. Such vehicle onboard computers typically interface with a multiplicity of sensors and transducers, which continuously detect vehicle and engine operational parameters and provide representative electrical signals to the onboard computer. The data collected and processed by the onboard computer can be useful in the diagnosis of vehicle engine and electrical system malfunctions. Thus, the vehicle onboard computer typically includes a communication port connector that allows certain of the collected data to be transmitted to an independent computer analyzer, which may process the data, store the data, or present the data in a visual format that can be interpreted by vehicle maintenance and repair technicians.
In conjunction with these technological developments, a variety of specialized computer analyzers, or vehicle diagnostic tools, have been developed and marketed to provide vehicle maintenance and repair technicians access to the data available from the vehicle onboard computers. The current technology includes a variety of hand-held vehicle diagnostic tools, frequently referred to as scan tools, with considerable processing capabilities, typically incorporating an integral display and capable of displaying the onboard computer data in a variety of graphical formats that allow vehicle technicians to view and interpret the data.
A typical diagnostic system includes a display on which instructions for diagnostic procedures are displayed. The system also includes a system interface that allows the operator to view real-time operational feedback and diagnostic information. Thus, the operator may view, for example, vehicle engine speed in revolutions per minute, or battery voltage during start cranking; or, with regard to the medical field, a patient's heartbeat rate or blood pressure. With such a system, a relatively inexperienced operator may perform advanced diagnostic procedures and diagnose complex operational or medical problems.
However, if an operator or technician is unable to detect an operational problem and the onboard computer has not detected a fault condition, a potential failure condition may in some cases go unnoticed. Accordingly, it is desirable to provide a method and apparatus that can be executed on diagnostic systems to collect historical operational data corresponding to normal and failure conditions, analyze the data and compare the results of the data analysis to test data gathered from a specific test subject in order to diagnose potential failure conditions that otherwise might be overlooked.