EDDL (Electronic Device Description Language)

DeltaV Whitepaper
June 2012 – Page 1 EDDL Technology

Why Electronic Device Description
Language (EDDL) Technology is the
Right Choice for Smart Plant
Installations
This whitepaper is targeted to readers who are familiar with the device descriptor language (DDL) used for
describing FOUNDATION fieldbus and HART devices. This standard has been enhanced to EDDL to allow a richer,
yet secure, exchange between users and intelligent field devices. You may have been exposed to FDT/DTM and
alternative technology—this whitepaper is not intended to compare the two technologies, but instead is focused
on the technical aspects and merits of EDDL.

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Table of Contents

Introduction .............................................................................................................................. 3

Matching Needs ....................................................................................................................... 3

Empowering Users .................................................................................................................. 4

Operator Information and Interaction .................................................................................... 4

Addressing Engineering Requirements ................................................................................ 6

Maintenance and Upgrades .................................................................................................... 7

Platform and Protocol Independence .................................................................................... 8

Testing & Validation ................................................................................................................ 9

EDDL Architecture ................................................................................................................. 10

EDDL Extensions ................................................................................................................... 11

Conclusion ............................................................................................................................. 12

Appendix A............................................................................................................................. 13

Key features of EDDL technology ...................................................................................... 13

Appendix B ............................................................................................................................. 14

Additional reading .............................................................................................................. 14

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Introduction

When IEC 61804-2 Electronic Device Description Language (EDDL) was approved as an international standard in
March 2004, the EDD source files created using EDDL were already deployed in millions of process industry field
devices.

EDDL is a text-based language for describing the digital communication characteristics of intelligent field
instrumentation and equipment parameters—device status, diagnostic data, and configuration details—in an
operating system and human machine interface (HMI) neutral environment.

Initially developed in 1992 for use as part of the HART Communication Protocol (HART, www.hartcomm.org),
EDDL-based technologies continue to evolve. EDDL is being enhanced to extend the concept of Interoperability
to the HMI and diagnostic data.

Today EDDL technologies form the engineering and operating foundation on which all major digital fieldbus
®
protocols—FOUNDATION™, HART , and Profibus—construct parametric and device descriptions. And, because
EDDL is an open technology with international standard status, it can be easily and effectively applied to any
device and any fieldbus protocol.

The EDDL technology enables a host system manufacturer to create a single engineering environment that can
support any device, from any supplier, using any communications protocol, without the need for custom software
drivers for each device type.

Matching Needs

Technologies and standards appear and disappear all the time. Often, those who buy into the technology du jour
have later been disappointed and incurred the unnecessary expense of replacing a “promising” (but unsupported)
technology.

Today’s process industry users have become very cautious about buying “technology hype,” especially when
faced with choosing a technology that must remain in place for a decade or more.

When discussing digital field automation technology architectures, users state their concerns a hundred different
ways, but in the end, what users seek are assurances that the technology platform they choose provides:

 Freedom of choice in plant floor instrumentation and equipment independent of the host: valves, transmitters,
motor starters, remote I/O, etc.
 Consistency in how plant floor instrumentation and equipment are engineered
 Flexibility and efficiency in how plant-floor data is shared throughout the enterprise
 Ease of maintenance
 Quantified proof that adopting manufacturers have long-term commitments to expand and improve the
underlying technology.

A seldom mentioned, yet extremely important, realization influencing a technology’s success is its dependence on
other technologies. From a product manufacturer’s perspective, the less dependent a technology’s architecture is
on underlying technologies, the better. Not only does such a design help manage risk, but it also frees up
development resources to enhance and improve product features—something end users seek when evaluating
similar products from different manufacturers.

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Overall, the simple elegance, enhanced capabilities, and operating-system- and HMI-neutrality of EDDL
technology equip it to provide solutions that address the engineering and operating questions, concerns, and
needs of both end users and manufacturers.

Empowering Users

Frequently, marketing literature and sales presentations state that end users insist on a single engineering
environment to manage, commission, and configure any field device, from any manufacturer, to any fieldbus
protocol.

Similarly, the engineering environment is often the focus at industry and user group meetings in the form of a
multi-part question: “During a process automation system (PAS)’s lifetime, what percentage of time will/did it take
to:

 Develop the initial database and control logic?
 Perform software maintenance and upgrades?
 Make periodic engineering improvements and enhancements?”

Undoubtedly, engineering, configuring, and managing activities are important. Further, when those activities are
compared to the amount of time operators use the system, experienced users also ask, “How consistent can we
make our HMI systems so our operators can confidently and efficiently use them?”

Depending on the data source, it’s usually agreed that Operations personnel use the PAS 70-to-85 percent of the
time, with other activities sharing the remaining 15-to-30 percent.

While engineering, installation, development, and improvement activities are fundamental, it’s equally important to
understand how EDDL technology is being enhanced to meet the daily needs of operators and maintenance
personnel.

Operator Information and Interaction

EDDL technology creates source files containing only content relevant to a specific manufacturer’s intelligent field
instrument or device. This is an important aspect of the EDDL technology design philosophy that insists that EDD
files remain OS- and HMI-neutral.

For manufacturers of intelligent field instrumentation and equipment, this philosophy eliminates the need to
expend resources designing and writing software to support operator interfaces—specifying fonts, sizing
windows, selecting colors, etc.—for different manufacturers’ HMI products and platforms.

For end users, EDDL’s neutrality philosophy ensures that operators are provided information with a look and feel
that is consistent with other information being presented.

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Some might argue that content is more
important than consistency; this may be correct
for operating information that users access
several times an hour. However, EDD file
content provides access to “normal” and
“abnormal” operating information. EDD file
content is about access to information contained
in intelligent field devices and equipment, the
sort of information viewed by operators during all
sorts of process operations.

Because abnormal process operations occur
infrequently—every few days, weeks, or
months—presentation consistency does become
important. For example, most of us have
experienced the “use-it-or-lose-it” software
phenomenon: the one where we revisit a
software application we once knew well, only to
find we’ve forgotten a lot of what we once knew.

That’s exactly what the EDDL design philosophy
avoids. Most people would agree that, when
faced with efficiently evaluating and acting on Figure 1 Parameters in a temperature transmitter read
information, a familiar presentation format directly from the EDD without any organization applied.
provides users with considerable confidence that
they are making the correct decisions.

There’s no doubt that a technology for deploying digital field instrumentation or equipment should provide
efficiencies in addressing the development of the initial database and logic, aid maintenance, and support
enhancements. As previously noted, those functions are employed about 15-to-30 percent of the time.

100 - PT

Figure 2 Parameters in a temperature transmitter organized via the enhancements of EDDL and the look and feel of the HMI.

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Most of the time, the efficiency and effectiveness of the technology are being “realized” by process operators and
maintenance technician; therefore, the technology must do its work in a way that makes these individuals
comfortable.

Consider a FOUNDATION fieldbus-based
temperature transmitter as an example. Figure 1
shows the parameters as they would appear on
an HMI, if read directly from the EDD without any
parametric organization applied
100 - PT

Figure 2 shows how those same parameters
could be organized on the HMI by using the EDDL
enhancements. In this case, the host system
supplier has chosen to use dialog boxes with
identifying tabs.

Figure 3 shows an alternate display organization
of the parameters using the exact same EDD. In
this case, an explorer view of the temperature
transmitter contents is shown. With the
enhancements to EDDL, the host system
supplier is provided the flexibility to organize the
parameters of a field device in the manner
optimal for the field device, but consistent with
the look and feel of the host system’s HMI.

EDDL technology is designed to address
engineering, startup and daily operations Figure 3 Same EDD as Figure 2; different look and feel as
determined by the HMI.
requirements, with special emphasis on ensuring that
operators and maintenance technicians are
comfortable using the technology to make critical
operational decisions.

Addressing Engineering Requirements

EDDL technology addresses the engineering requirements of end users and intelligent field device and equipment
manufacturers. Though their reasons differ, the engineering requirements of both groups are similar, each
seeking solutions that:

 Ensure operating system independence
 Support multiple fieldbus protocols
 Avoid special, proprietary, or executable files* for different host system platforms
 Supports multiple country codes and international languages
 Use standardized testing and validation procedures and tools
 Allow efficient configuration entry
 Use a robust, consistent, easy-to-identify revision control methodology
 Include third-party testing and registration
 Ensures that .exe files (or .dll’s) do not interface with one another

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Besides meeting all of these engineering requirements, EDDL technology also has international standards status
as IEC 61804-2.

The EDDL design philosophy provides end users and intelligent field device product manufacturers a consistent
and rich engineering environment.

Maintenance and Upgrades

When control and automation systems adopted “open system” technologies, software maintenance, with
mandatory and voluntary software upgrades, increased dramatically. Today it’s not uncommon to install
mandatory software upgrades and/or OS security patches two or more times a month. However, EDDL neutrality
to OS and HMI technologies eliminates the need for end users to worry about what happens to EDD files as a
result of software upgrades.

Everyone who’s upgraded a computer from Microsoft Windows 98 to Windows 2000 and later to Windows XP
appreciates the complexities of relinking applications, reloading device drivers, reestablishing network
communications, and dealing with incompatible executable files. EDDL technology does not install or create any
executable files in the HMI host application; therefore, EDDL-based technologies eliminate the need to relink
applications or communications, and incompatible EDD files simply don’t exist.

One feature PC users have come to appreciate is the “plug-and-play” technology known as universal serial bus
(USB). From a user’s perspective, USB appears quite simple and, regardless of the device manufacturer or
device type that’s been plugged in, what appears on the user’s screen is consistent for Windows users and
different, yet consistent, for Macintosh users. Behind the scenes, USB shares a number of similarities with EDDL
technology. Both use device-description files and both make use of device-descriptor services embedded in the
host platform that is designed to provide users with a consistent information presentation format.

*Potential for carrying viruses is great.

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Similar to the efforts that produced USB, Example EDDL User Presentation of Radar
representatives of Fieldbus Foundation (FF) Level Gauge Threshold Calibration
www.fieldbus.org, HART Communication
Foundation (HCF) www.hartcomm.org, and
Profibus Nutzerorganisation e.V. (PNO)
www.profibus.com met in February 2003 to extend
the capabilities of the IEC 61804-2, Electronic
Device Description Language standard.

Among EDDL extensions are: improved device data
organization, graphical visualization consistency,
and support for persistent data storage. Echo Curve
(Device data)
From a system administrator’s perspective, the
simplicity, longevity, robustness, and OS and HMI
platform neutrality of field devices conforming to
IEC 61804-2 simplify software maintenance
activities. For already overworked control system Filter
engineers/technicians, eliminating software
maintenance worries is a welcome benefit of
deploying safe, secure, easy-to-use EDDL-based
fieldbus technologies.

For intelligent field device manufacturers, knowing
that EDD files are always operating-system- and
HMI-neutral permits each manufacturer to release a In this EDDL example, a graph is used to present the echo waveform of a radar
new product when the product is ready and not level gauge in order to identify false echo areas and configure appropriate
have to wait until the product completes thresholds. Thanks to EDDL’s uniformity design philosophy, information is
presented to users the same regardless of device manufacturer.
compatibility testing with a variety of different HMI
manufacturers and/or operating system revisions
Figure 3 Example EDDL user presentation of radar level gauge threshold
calibration.

Platform and Protocol Independence

Everyone is aware of the difficulties of getting device software drivers to work following a host platform operating
system upgrade. EDDL was specifically designed for the EDD file to avoid this issue. The IEC 61804-2 standard
is not only operating-system- and HMI-independent, but also fieldbus-communication-protocol-neutral.

It’s this extended neutrality that allows device manufacturers to confidently develop a single EDD source file for a
given fieldbus-based device and be assured that it will safely and consistently perform on a variety of host
application platforms.

From an end-user perspective, it’s equally reassuring to know that a host workstation change from UNIX to LINUX
or from Windows NT to Windows XP or a port to Windows CE does not require modification of the existing EDD
files.

The way EDDL technology retains its platform and protocol independence is really quite simple. Each EDD file is
uniquely numbered and contains only the descriptions needed by the host application. Any methods included in
the EDD file are interpreted by the host application using a method interpreter, thus providing a safe area or
“sandbox” where methods execute.

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Security and reliability are also assured, because the installation of an EDD file does not initiate installation of
Win32-based DLL (dynamic linking library), ActiveX, or similar executable software, thus avoiding the problems
associated with incompatible versions, revised path names, and/or “file missing” error messages.

EDDL technology is designed to encourage worldwide use and includes support for multiple languages as defined
by the International Organization for Standardization (ISO).

Under the EDDL architecture, developers write a single EDD file that incorporates multiple language text strings,
each conforming to ISO 639 for language codes, and ISO 3166 for country codes. The EDD host application
selects the appropriate language from the EDD file to display user information.

Avoiding host application conflicts and maintaining a consistent look and feel are paramount for operators/users.
To this end EDD files do not specify fonts, window sizes, color, or other aspects of the host interface.

Because of the wide number of host application types—PAS with a rich graphic interface to a simple handheld
unit with a limited capability display—the host application generates the screens based on constructs provided by
EDD file content. This permits information contained in the EDD files to seamlessly integrate with a specific host
application’s capabilities.

For intelligent device manufacturers, the platform and communication protocol independence of the IEC 61804-2
Electronic Device Description Language standard ensures that:

 Specifications exist for defining the architecture of the application, syntax (form), semantics
(meaning), and user interface structure
 Capabilities exist to implement a single version of a product-specific EDD file containing the device’s
configuration, maintenance, and functionality
 Flexibility exists for deploying the same product, and its associated EDD file, on different fieldbus
protocols

For end users, knowing that manufacturers of IEC 61804-2-conforming devices are developing, testing, and
maintaining a minimum number of EDD files provides additional peace of mind when facing PAS upgrades,
patches, and even operating system changes.

Testing & Validation

As an international standard, EDDL technology marks a major advancement toward achieving interoperability of
intelligent field instrumentation incorporating different fieldbus protocols.

EDD file testing is a multi-part activity. The intelligent field device manufacturer conducts the first series of tests.
The second series of tests is conducted by the appropriate protocol organization—Fieldbus Foundation (FF),
HART Communication Foundation (HCF), or Profibus Nutzerorganisation e.V (PNO)—with each organization
applying similar EDD file testing and registration procedures.

For example, after an intelligent field device manufacturer creates an EDD source file for use with FF protocol, the
developer uses a tokenizer tool to validate the syntax, dependencies, and other protocol and language rules.
Once all checks are verified and validated, the tokenizer tool generates an EDD binary file that organizes the
information into a format accessible by host HMI applications. Besides providing a compressed, easier to transfer
file, the binary format provides protection against accidental changes using a simple text editor.

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The manufacturer then submits the EDD binary file to FF for additional testing and registration.

Before FF registers the submitted EDD binary file, it is subjected to a series of tests using FF’s Interoperability
Test Kit (ITK).

The first test loads the EDD binary into a test system to validate that correct identification information exists.

Next the file is subjected to multiple test cases to ensure that the EDD file content matches its device and follows
protocol rules for maintaining interoperability between hosts and device.

Finally, FF logs the EDD file information, including name, date, size, and the 32-bit cyclic redundancy checksum
value. These become the files available for download from the FOUNDATION’S website at www.fieldbus.org.

For end users and intelligent field device manufactures, the simple elegance of EDDL technology, combined with
the testing and validation tools developed and maintained by each fieldbus organization, provide an
unprecedented level of confidence that robust, protocol interoperable solutions perform as designed and desired.
It reflects over 10 years of accumulated experience.

EDDL Architecture

The architecture of EDDL technology makes it easy to use multiple communication protocols within the same HMI
host application, requires no custom tools for configuration, and maintains a common look and feel for operators
and maintenance technicians, regardless of the intelligent field instrumentation or equipment being viewed. The
EDDL technology enables a host system manufacturer to create a single engineering environment that can
support any device, from any supplier, using any communications protocol, without the need for custom software
drivers for each device type.

With HMI host systems ranging from large process automation systems, with rich graphic displays, to simple
handheld devices with limited display capabilities, EDDL’s consistent-look-and-feel philosophy represents a great
advantage when it comes to operator and maintenance personnel user training.

Because EDDL technology was designed to eliminate the need for special or proprietary files in host systems, a
single EDD file created for a full-featured PAS works equally well in the handheld device.

This important design feature eliminates the expense and burden for intelligent field instrument manufacturers to
create, test, register, and maintain different files for different HMI host systems, or a different operating system for
a different revision of the same host system.

For users, this feature of EDDL technology greatly simplifies changing, adding, upgrading, and evolving HMI host
systems.

Verification that EDDL design philosophy works occurred in 2002 when Infraserv Hochst established a multi-
vendor laboratory, incorporating six FOUNDATION fieldbus host systems and 42 field devices from 11 instrument
suppliers.

Infraserv Hochst developed and applied a variety of tests to evaluate the interoperability of the FOUNDATION
fieldbus technology.

In its final report, delivered to the NAMUR General Assembly in Lahnstein, Germany, Infraserv Hochst stated that
100% of the EDD files worked correctly between each host system and the respective devices. Infraserv Hochst’s
tests further validate an important aspect of EDDL technology: that system-wide interoperability is best achieved
using a well-defined specification and rigorous testing procedures.

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EDDL Extensions

In February 2003, representatives of, FF, HCF, and PNO met in a collaborative project to extend the capabilities
of the IEC 61804-2 standard.

The scope of the cooperative project is to add robust organization and graphical visualization of device data as
well as support for persistent data storage features to IEC 61804-2. Sophisticated devices with hundreds of
configuration, calibration, and diagnostic parameters, such as control valves, radar level gauges, and variable
frequency drives, will greatly benefit from the new user interface enhancements.

Once implemented, the new extensions will further unify the HMI environment and eliminate the need for custom
configuration software packages.

Through the use of familiar dialog boxes, text, dynamic variables, pictures, charts, and archived data are
presented to users in a consistent, familiar format. Graphs, such as control valve signatures, may incorporate
pan/zoom functionality for inspecting specific detail. Additionally, EDDL extensions support user interaction with
device content, such as permitting adjusting filter values.

By providing a standard, platform-independent means for displaying graphical information, device suppliers using
EDDL technology can focus resources on increasing product features to better meet user requirements and know
that developed solutions will be consistently delivered across a variety of platforms and operating systems.

One EDDL extension that end users asked to be included is the support for persistent data storage. This new
feature permits device manufacturers to instruct the host application to store device or local data. This
implementation method relieves the intelligent device manufacturer of having to learn the underlying file system
nuances of different host applications; how data is stored is left up to the host application.

Persistent data storage enables a variety of new applications using EDDL technology. For example, valve
diagnostic software, developed using EDDL technology, can archive valve signatures for later review by support
personnel.

The benefit of IEC 61804-2’s neutrality is again revealed with the addition of the new EDDL extensions.

For example, an intelligent field instrumentation manufacturer who previously developed products for use on the
FF protocol isn’t required to begin using the new EDDL tokenizer, viewer, and services tools until its products
begin using the new EDDL extensions. In fact, for simple devices, EDD file developers may continue writing
EDDL files the same way they do today, using either the existing tools or a new tool.

For more complex devices, developers can use an existing EDD file as the starting point to create the extended
EDD file. EDDL is being enhanced, but it is maintaining backward compatibility with the millions of devices that
have been installed over the past 10 years.

Because an extended EDD file contains additional field device information, PAS host systems must be updated
with a new EDDL host services module. It is available from the respective fieldbus protocol organization and can
be procured by all PAS suppliers. More importantly, the host service module provides backward compatibility for
plant floor devices using older EDD files.

This simple, yet eloquent, ability to extend EDDL technology without “touching” existing EDD files provides end
users the much sought-after peace of mind that deploying a new intelligent field instrument with extensions
carries minimum risk.

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Conclusion

With EDDL technology used by millions of installed field instruments, EDDL is the process industry de facto
standard for ensuring that information about intelligent field devices is consistently available for use by operators,
engineers, and maintenance technicians. And the beauty of it is, the EDD source file created for instrument
number one works right alongside the EDD source file for instrument number 5 million, or 10 million, and so on—
never once requiring an upgrade, revision, or patch of any kind.

Name another software technology that can make that claim!

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Appendix A

Key features of EDDL technology
Device Descriptor Language (DDL) technology first appeared in 1990 and, because of its flexibility and reliability,
it has become a significant technology in many industries including telecommunications, mainframe and personal
computing applications, and instrumentation and control.

The HART Communication Protocol (HART) first began using DDL technology in 1992. HART’s advancement of
the DDL technology eventually led to the development of the International Electrotechnical Commission’s IEC
61804-2 standard, Electronic Device Description Language (EDDL).

Key elements that continue to make EDDL technology a secure, reliable workhorse for instrumentation and
control applications include:

Operating system independence. EDD files do not contain specific operating system commands or instructions;
therefore, they remain transportable and operating-system-independent.

Consistency and uniformity. EDDL technology’s architecture supports multiple protocols within the same host
application and requires no custom tools to maintain a common look and feel.

Single engineering environment. EDDL technology enables a host system manufacturer to create a single
engineering environment that can support any device, from any supplier, using any communications protocol,
without the need for custom software drivers for each device type.

Revision control. Device revision is used to identify the revision level of a device. This permits manufacturers to
improve an existing device’s implementation, such as adding support for additional parameters or enhanced
diagnostics.

Testing and registration. Testing includes validating the syntax, dependencies, and other protocol and language
rules using toolkits and registering the EDD binary file with the appropriate fieldbus organization.

International standard support. EDDL technology is an international standard approved by the International
Electrotechnical Commission (IEC) and is available as standard number 61804-2. It also makes use of ISO
standards for language and country codes.

Security. EDDL files are ASCII-based and, as such, are less likely to bear virus attachments as .exe and .dll files.

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Appendix B

Additional reading

Visit the following web sites to learn more about the use of EDDL technology and fieldbus protocols.

 ARC Advisory Group www.arcweb.com
 Fieldbus Foundation www.fieldbus.org
 HART Communication Foundation www.hartcomm.org
 International Electrotechnical Commission http://www.iec.ch
 Profibus Nutzerorganisation e.V. www.profibus.com

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EDDL (Electronic Device Description Language)

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