STEP Application Protocols
A list of the STEP Application Protocols (AP) as of June 2004 is given in Fig.2. The ability to support many protocols within one framework is one of the key strengths of STEP. All the protocols are all built on the same set of Integrate Resources (IR's) so they all use the same definitions for the same information. For example, AP-203 and AP-214 use the same definitions for three dimensional geometry, assembly data and basic product information. Therefore CAD vendors can support both with one piece of code.
Part 201 Explicit Drafting Part 202 Associative Drafting Part 203 Configuration Controlled Design Part 204 Mechanical Design Using Boundary Representation Part 205 Mechanical Design Using Surface Representation Part 206 Mechanical Design Using Wireframe Representation Part 207 Sheet Metal Dies and Blocks Part 208 Life Cycle Product Change Process Part 209 Design Through Analysis of Composite and Metallic Structures Part 210 Electronic Printed Circuit Assembly, Design and Manufacturing Part 211 Electronics Test Diagnostics and Remanufacture Part 212 Electrotechnical Plants Part 213 Numerical Control Process Plans for Machined Parts Part 214 Core Data for Automotive Mechanical Design Processes Part 215 Ship Arrangement Part 216 Ship Molded Forms Part 217 Ship Piping Part 218 Ship Structures Part 219 Dimensional Inspection Process Planning for CMMs Part 220 Printed Circuit Assembly Manufacturing Planning Part 221 Functional Data and Schematic Representation for Process Plans Part 222 Design Engineering to Manufacturing for Composite Structures Part 223 Exchange of Design and Manufacturing DPD for Composites Part 224 Mechanical Product Definition for Process Planning Part 225 Structural Building Elements Using Explicit Shape Rep Part 226 Shipbuilding Mechanical Systems Part 227 Plant Spatial Configuration Part 228 Building Services Part 229 Design and Manufacturing Information for Forged Parts Part 230 Building Structure frame steelwork Part 231 Process Engineering Data Part 232 Technical Data Packaging Part 233 Systems Engineering Data Representation Part 234 Ship Operational logs, records and messages Part 235 Materials Information for products Part 236 Furniture product and project Part 237 Computational Fluid Dynamics Part 238 Integrated CNC Machining Part 239 Product Life Cycle Support Part 240 Process Planning
Each Application Protocol includes a scope describing its purpose, an activity diagram describing the functions that an engineer needs to perform within that scope, and an Application Requirement Model describing the information requirements of those activities. These information requirements are then mapped into the common set of Integrated Resources and the result is a data exchange standard for the activities within the scope.
The ultimate goal is for STEP to cover the entire life cycle, from conceptual design to final disposal, for all kinds of products. However, it will be a number of years before this goal is reached. The most tangible advantage of STEP to users today is the ability to exchange design data as solid models and assemblies of solid models. Other data exchange standards, such as the newer versions of IGES, also support the exchange of solid models, but less well.
STEP led the way with three dimensional data exchange by organizing an implementation forum for the CAD vendors so that they could continually improve the quality of the solid model data exchanges. The history of this success is relatively interesting because it show that the initial reluctance of vendors to implement user-defined standards can be overcome with enough perseverance.
At first, in 1996, there was a significant body of opinion that solid model geometry data could not be exchanged between systems using a neutral standard. However, in 1997 Ford, Allied Signal and STEP Tools, Inc. demonstrated the first successful data exchange of 3D geometry using STEP. Once this basic capability had been demonstrated a pilot project, called AeroSTEP, was organized by Boeing and its Aircraft engine vendors to test the first translators by exchanging data about where an engine fits onto the airframe. This project started out by exchanging simple faceted models but eventually demonstrated the exchange of models with great complexity.
The AeroSTEP project made it clear that STEP data exchange of solid model data was both feasible and valuable. As a result, vendor neutral implementation forums were formed in Europe, the Far East and the USA and the quality of the translators was raised to the level that allowed anyone, including ordinary users in small organizations, to use STEP for data exchange of solid models after about 2001.