A new data exchange format, IDX, promises to improve electromechanical design collaboration.

Electromechanical product designers face constant competitive pressure to reduce development costs, improve design cycle times, and eliminate errors that can lead to costly rework. Nowhere is this challenge more apparent than in the integration of PCB layout with mechanical design, where sharing design information efficiently and reliably has long been a bottleneck in the overall electromechanical product design process.

It’s a tough problem to solve. Not only does the shared information have to bridge the 2D to 3D gap, the amount and type of information that needs to be shared varies from design to design and company to company. Plus, the information requirements often change throughout the design process.

For nearly 20 years, the Intermediate Data Format (IDF) has been the preferred file format for exchanging basic design information between the ECAD and MCAD systems that PCB layout designers and mechanical designers use to design electromechanical products. Unlike drawing data formats like DXF and IGES, the IDF preserves design intent during the exchange process, resulting in significant productivity improvements.

But the IDF is not a panacea. Design information that can be shared through the IDF is limited to the board shape, basic component shapes and locations, basic hole definitions and locations, and keep-in/keep-out areas. More significant, IDF files can only represent “snapshots” of the design at any point in time; the IDF does not support incremental changes throughout the design process.

A new data format, known as IDX for “Incremental Data eXchange,” has been developed to overcome the limitations of the IDF and provide a new level of collaboration between board layout and mechanical design.

History of IDX

IDX grew out of discussions between Mentor Graphics and Parametric Technology Corp. and their customers about ways to enable more collaborative use of their respective tools on designing electromechanical products. Faced with the challenges of designing smaller, more complex products, the customers were asking for a design collaboration solution that could not be developed around the IDF.

As a result of these discussions, they engaged the ProSTEP iViP Association, a standards development consortium based in Germany, to develop a new data exchange format for ECAD/MCAD design collaboration and make it available to the entire CAD vendor and OEM community. A project group was established, and work on the new format began in 2006.

The project group created a data model for ECAD/MCAD collaboration called the EDMD (Electronic Data Mechanical Data). The EDMD data model borrows from STEP (Standard for the Exchange of Product model data), an international standard, specifically, Application Protocol (AP) 214 “Core Data Model for Automotive Mechanical Design Processes” and AP 210 “Electronic Assembly, Interconnection, and Packaging Design.” In addition, a goal of the project group was to incorporate the concepts and content of IDF 3.0 in the initial data model.

ProSTEP released an initial version (1.2) of the EDMD in 2008. The current release of the EDMD, version 2.0, was completed and published as “ProSTEP iViP Recommendation PSI 5” in May 2010. The recommendation includes an XML file representation of the EDMD data model. The XML files have an extension of .idx, which is where IDX gets its name.

Some of the key features of IDX that are not found in the IDF are:

  • XML representation. The EDMD data model is defined with XML schemas, and IDX files are XML documents. This makes IDX flexible and extensible. New features, such as support for etch shapes or traces, can be added in future releases of IDX without affecting current implementations. Plus, XML is familiar to many developers, so there is less reinventing the wheel to support IDX file exchange in their CAD products.
  • Unique design object identifiers. Every design object has a unique identifier in IDX – not just electrical component instances (uniquely identified by reference designator in the IDF) but holes, keep-outs, mechanical components, and other design objects as well. Unique object identifiers are the key to tracking and managing changes in a collaborative design environment.
  • Incremental exchange. IDX can represent an initial “baseline” design state, as well as incremental changes to that state and subsequent states. Incremental exchange reduces the amount of design information shared between PCB layout and mechanical design during the design cycle. More important, IDX gives designers the ability to identify what changes are being proposed and evaluate the effect of those changes before accepting them.
  • Change history. Each design change represented in an IDX file can include a history of who originated the change, when it was made, a comment explaining why it was made, who reviewed the change, whether the change was accepted or rejected, and a comment explaining why it was accepted or rejected. This history is a key element of the collaborative design process.

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