The Fieldbus Foundation (FF), Hart Communication Foundation (HCF) and Profibus Nutzerorganisation eV (PNO), have completed the initial phase of development for key extensions to Electronic Device Descriptions (EDD) defined in the International Electrotechnical Commission (IEC) 61804-2 standard.
IEC 61804-2 is the only international standard for device descriptions. Within Foundation Fieldbus, an EDD is referred to as a Device Description (DD).
The EDD enhancements, which were defined by a working group that included participants from ABB, Emerson Process Management, Endresss+Hauser, FlowServe, Honeywell, Siemens, Yokogawa, and FF and HCF staff, are included in a draft specification that all three control industry organisations will validate in a lab environment and integrate within their respective technologies.
Building on the current IEC 61804-2 standard, the working group extended EDD to provide graphical visualisation of data, improved data organisation, and persistent data storage
‘We achieved our initial goal of development of a common draft specification for advanced visualization that maintains the proven integrity of EDD technology, and most importantly, retains its greatest advantage: operating system and protocol independence. EDD, approved by the IEC as Draft International Standard 61804-2, is already the de facto standard for countless installations around the globe. Our extensions have built on the IEC standard and allow for implementation of additional functionality for complex devices,’ said Fieldbus Foundation Director of Technology Development Dave Glanzer.
With over 15 million EDD-based Foundation Fieldbus, Hart and Profibus devices installed worldwide, EDD is widely used in the automation industry. The EDD provides a structured text language that is operating system and hardware platform independent.
Automation device suppliers use EDD to provide information on parameters and other data in a device. The host reads the EDD to integrate, configure, setup, operate, diagnose and maintain the automation devices.
The EDD extensions are built upon the existing IEC standard. This approach has many benefits. For example, device developers do not need to deal with the burden of designing and programming a graphic display system that must run under a variety of platforms and environments, from large Human-Machine Interfaces (HMIs) to the small handheld.
Instead, they can use common graphic display capabilities provided by commands in the EDD. Since many host systems today already implement EDD-based graphic display systems, devices using the extended EDD have a common look and feel with existing devices. This permits uniform integration, configuration/setup, operation and diagnostics/maintenance – all very important in an interoperable, multi-vendor environment.
EDD also provides operating system and platform independence, which eliminates the need for special ‘plug-in’ executable code that is costly to develop and can jeopardise the host’s control over the human interface and operating environment. In addition, extended EDDs follow proven test and registration procedures, including the same strict revision control policies as today’s EDDs, thus eliminating problems in the field.
The EDD extensions enable device developers to logically organise the large number of parameters in complex devices. They also allow the inclusion of images (e.g. jpg files) to aid the user in device configuration.
With extensions to any standard, it is important to maintain compatibility with existing technology. The implementation of EDD extensions are designed to be completely compatible with the existing technology.
For field device developers, there is no need to learn a new, operating system-dependent programming language, since EDD is not tied to any specific platform. For simple devices, developers can continue to write EDD like they do today using the existing or extended DD Tokeniser tool. For more complex devices, developers can build upon their existing EDDs (cut/paste) to create an advanced EDD using the extended DD Tokeniser tool.
On the host side, the host supplier simply integrates the updated DD Services which can read existing and extended EDDs.
‘The three organisations will now move forward independently with validating the draft specification to ensure compliance and usability of the extensions,’ added Glanzer.