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PDElib STEP Programming Interface

PDElib STEP Interoperabilty The STEP module of Transcendata's data exchange software library (PDElib) provides the power and versatility to handle a wide variety of today's challenging STEP tasks.  Whether translating geometry and topology or critical configuration management information, PDElib's STEP Interface will give you a time-tested and proven environment to build upon.

Using PDElib and the STEP Interface you can quickly leverage years of STEP knowledge gained from Transcendata's participation in STEP pilot activities and commercial translator development.

What is STEP?

STEP (STandard for the Exchange of Product model data) is an international standard for the computer-interpretable representation and exchange of product data.  The objective is to provide a neutral mechanism capable of describing product data throughout the life cycle of a product, independent of any particular system.  The nature of this description makes it suitable not only for neutral file exchange, but also as a basis for implementing and sharing product databases and archiving.

The information generated about a product during its design, manufacture, utilization, maintenance, and disposal is used for many purposes during the life cycle.  The use may involve many computer systems, including some that may be located in different organizations. In order to support such an environment, organizations need to be able to represent their product information in a common computer-interpretable form that is required to remain complete and consistent when exchanges among different computer systems.

STEP is a series of related parts that define resources, languages models and application protocols (APs) that make up the standard. Through the implementation of APs, STEP is extensible across a wide variety of applications and industries.  In addition to the current set of 14 international standards, work is underway on over 30 additional parts of STEP.  Industry experts in the United States and worldwide expect that efforts to expand the capabilities of STEP will extend into the next century.

ITI TranscenData history with STEP

Transcendata has participated and continues to participate in many STEP activities including:

AutoSTEP U.S. automotive manufacturers and suppliers are using STEP AP203 and AP214 to  exchange product data more effectively.
JAMA Japanese Automotive Manufacturers Association members are using STEP AP203 and AP214 to improve data exchange.
ISAP International STEP Automotive Project involves many of the world's leading automotive manufacturers and suppliers using STEP to improve data integration.
CSTAR Improving data exchange between McDonnell Douglas and suppliers, the C-17 STEP Transfer and Retrieval project is hailed as the first production implementation of STEP.
AWS The Advanced Weapon System program demonstrates subcontractors (Lockheed Fort Worth, Vought Aircraft) delivering data to/from prime contractor (Lockheed Aeronautical Systems) using STEP AP202 and AP203.
STEPNet CAD/CAM/CAE vendors are collaborating to improve the interoperability of commercial STEP-based products.
ENGEN Construction history (CSG) information exchange is the focus of this program. The purpose is to improve solid model exchange without exchanging explicit geometry and topology data.
PreAMP Pre-competitive Advanced Manufacturing Processes was initiated to enable concurrent engineering of Printed Circuit Assemblies (PCA's) using STEP AP210
Design for Analysis Program for STEP AP209 Composite Structure.

STEP Interface Highlights


Part 21 Parser/Formatter EXPRESS Handling Geometry & Topology Support
The STEP ASCII File Parser (SAFP) and STEP ASCII File Formatter (SAFF) subsystems efficiently and reliably read and write STEP physical file (Part 21) data while also performing added syntactical error checking.  Backpointer references are maintained during parsing.  Long and short entity naming conventions are both handled. Pre-compiled data definitions files (ddf) for AP203 and AP214 EXPRESS definitions are included.  If using a user-defined EXPRESS schema, an EXPRESS to ddf compiler is provided to generate the specific ddf.  This allows the STEP interface to be used for any EXPRESS data model. Part 42 geometry and topology data is conveniently mapped between the populated STEP memory model and corresponding neutral entity representations within PDElib Core (GDX subsystem). Once in GDX, complex manipulations may be performed on the data.

Configuration Management Utilities Product Structure Utilities AP203 & AP214 Utilities
The STEP Configuration Management (s041) subsystem allows for the creation, management, and manipulation of Part 41 data.  Automatic creation of the minimum required set of CM entities is supported.  CM data may be parsed from or formatted to Configuration files. The Product Structure/Configuration Management PS/CM (s044) subsystem allows for the definition of individual components and their relationship in an assembly.  Users may parse and traverse assemblies, link components, create an assembly from a tree, etc. Individual subsystems for AP203 and AP214 provide STEP dependent functions for working with the specific entity structures as well as specific product structure and configuration management requirements of these two protocols.

 

Other Key Features

 

Physical File Header Data Physical File Identification
The Header and Data section entities are stored as entities in the model.  Differentiates between internally and externally mapped entities. Since database pointers resulting from a parsed STEP physical file do not correspond to the original Physical File ID, each entity structure contains a field fro the physical file ID as well as one for the SCOPEing entities pfid. The model data access subsystem provides the capability of storing backpointers to referencing entities.  The STEP physical file parser updates backpointers as a file is parsed.

Log Tolerances Entity Mapping
There are three major log file functions: File Stamp will output a user specified title, filename, and current date and time; Data Section will output a listing of the header section entities and entity counts; Error Summary will output a summary of error and processing time data. PDElib tolerances are associated to a particular model.  Tolerances are used by the STEP subsystem when converting STEP geometry to/from PDElib Core. STEP Part 42 geometry and topology entities may be manipulated within the PDElib Geometry Conversion Engine to achieve the best possible translation results between systems.

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