Comparing EDDL and HTML in an Automation Minutes Podcast

Earlier this week, I listened to Gary Mintchell‘s personal podcast, Automation Minutes Episode 59 (iTunes | RSS feed). Gary interviews Emerson’s Jonas Berge, a member of the ISA104, Electronic Device Description Language (EDDL) standards committee. EDDL is also recognized globally by international standard IEC 61804-3. A few weeks earlier, Gary had interviewed a member of the FDT (a competing standard) marketing committee.

Jonas provides a detailed summary of what EDDL means to process manufacturers. It’s a standard to display information in intelligent field devices communicating via HART, WirelessHART, Foundation fieldbus and Profibus back to the device management software and automation system. EDDL files are standards-based compressed text files that reside in the device management software to provide a consistent view to devices from different manufacturers for setup, calibration, diagnostics, etc. Through the EDDL file, the device manufacturer tells the system what command to send to get information from the device, how to decode it, and how this manufacturer would like to present the data.

Jonas offers a great analogy of how EDDL is like HTML. Both are text-based files. Client software (device management software and web browser) renders both, both are platform independent since they are text files and not installed programs, and both are version independent again since they are not installable programs. And similar to how devices like PCs, MACs and smart phones render HTML pages, PCs and handheld devices with device management software render smart device information.

Also, in how HTML supports sophisticated displays, EDDL supports sophisticated ways to render valve signatures, vibration spectrums, radar level “echo curves”, dial gauges, historical trends, and step-by-step “wizard” procedures. Jonas points out that these graphical enhancements were added to the EDDL standard in 2006 to address the NAMUR NE 105 requirement to support access to full functionality in complex devices in the way the device manufacturers want this functionality to be displayed. These complex devices include valve positioners, variable speed drives, machinery health transmitters, wireless gateways, and bus diagnostic modules to name a few.

The design basis behind the EDDL standard is that the device manufacturer knows best what information their devices contain and how it should be displayed. The device manufacturers can make the full functionality of their devices visible and available on any system. The device management software suppliers know best how to provide a consistent view of trends, gauges, step-by-step procedures, etc.

For plant staff members who manage the device management software, the EDDL files do not become obsolete as the operating system is revised or security patches are added. Since these are text-based files, multiple versions can exist together within the device management software to address the plant realities of different devices, from different vendors, communicating with different digital protocols.

The information presented from these various devices have a common look and feel for the instrument technician and others who access the information. And the integrated diagnostics provided by the EDDL standard meet the NAMUR NE 91 requirements.

I captured a quick video at the recent ISA Expo 2008 in Houston, Texas. I just received some photos and ISA104 / EDDL Booth Report that show systems from ABB, Emerson, Invensys, and Siemens interoperating with advanced valve positioners and transmitters from Emerson, Endress+Hauser, Invensys, Masoneilan, MTL, Metso, Samson, and Siemens. These pictures demonstrate this interoperability in action:

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Posted Friday, October 31st, 2008 under Foundation Fieldbus, Interoperability, Measurement, Profibus, Technologies.

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