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GDA (Graphical Diagnostic Assistant) Technology
 A Graphical Applications Language and Product  for Performance Monitoring, Quality Control, and Diagnosis

Technical Resources:


A graphical language - GDL

While at Gensym, Greg Stanley conceived of the idea of the Graphical Diagnostic Language (GDL), and developed it along with co-workers Eric Finch and Steve Fraleigh and others.  We productized the result as GDA, an acronym for “Graphical Diagnostic Assistant”,  changed to “Gensym Diagnostic Assistant for marketing reasons.  GDL allowed domain experts to focus on the application logic (for filtering, calculations, statistics, recognizing events and recurring problems, diagnosing problems, managing displays, and taking corrective actions), rather than on programming in some text-based language.

This was one of  the first true graphical languages, along with LabView and GRAFCET that appeared around the same time.  In a true graphical language, a user “programs” starting by drawing diagrams through a graphical user interface, rather than just entering text.  The development environment paradigm is “clone, connect, and configure”.  That is, the user selects (“clones”) program blocks from a palette, connects them, and then configures them.  The graphical objects might represent function blocks like numerical calculators, filters, AND gates, or alarm generators.  Or, they might represent action steps in a procedural sequence.  The connecting arrows represent relationships between objects, such as passing of input/output information for information flow diagrams.  Or, they can represent sequential actions in the case of procedures and workflows.  The highest level of the programming language is graphical - text is entered a properties of the graphical objects.  This differs from traditional programming where only text is entered.

The picture below shows an example GDA screen shot.  The graphical blocks are the “source code” for the logic and actions.  Text fields are only comments.  A property table of detailed configuration information for a program block is available by right clicking on the graphical object.This view happens to show an operator message display as well, although the operator interface did not require looking at the logic diagrams.


A GDA Diagram - User Source Code


GDL was the first to combine information flow diagrams with sequential control (workflow) diagrams

GDL was the first to combine both information flow diagrams and sequential control (workflow) diagrams into one language.  The applications were mainly for monitoring and control of systems monitored through sensors reporting numerical values.  Application developers draw pictures of the logic and actions by connecting objects representing logic gates or action steps, rather than writing expert system rules.  Developers select blocks to collect  historical numerical data, run SPC tests to generate events based on the numerical performance data, reason over the events (event correlation), and then take corrective action.

While the first application in beta form was an emergency response system for the NUPEC Japanese government/industry consortium for nuclear power plant monitoring, GDA has wide applicability for the process industries.  It could be used in other areas for performance monitoring as well. Its capabilities include statistical process control/quality control and fuzzy control, generation of events based on numerical performance data, boolean and fuzzy logic gates. It can also perform automated recovery by sequencing of corrective actions. The ideas are presented in a series of three technical papers:

An Object-Oriented Graphical Language and Environment For Real-Time Fault Diagnosis (pdf)

Using the G2 Diagnostic Assistant for Real-Time Fault Diagnosis (pdf)

Integrating Dataflow and Sequential Control in a Graphical Diagnostic Language (pdf)

Similar technology was also built later by Integration Objects, who then sold it to Emerson.


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