They also want technology delivering the power to integrate devices to achieve optimum control strategies, while providing consistency and ease of use when developing human interfaces across multiple systems and platforms—all while preserving investments and avoiding future obsolescence.
The control industry took a step in meeting the needs of the user community when the International Electrotechnical Commission (IEC) approved the IEC 61804-2 Electronic Device Description Language (EDDL) standard. An underlying technology in millions of field instruments installed worldwide, EDDL is a text-based language for describing the digital communication characteristics of intelligent devices and equipment parameters in an operating system and human-machine interface (HMI) neutral environment. Automation device suppliers use Electronic Device Descriptions (EDDs) to provide information on parameters and other data in a device. The host reads the EDD to integrate, configure, set up, operate, diagnose and maintain the automation devices.
Because EDDL is an open technology and an international standard, it can be easily and effectively applied to any device and any fieldbus protocol. EDDL enables host system manufacturers 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.
Organizations cooperate
In 2003, the Fieldbus Foundation (www.fieldbus.org), Hart Communication Foundation (www.hartcomm.org) and Profibus Nutzerorganisation e.V. (www.profibus.com), three leading organizations that use EDDL, formed a cooperative joint working group to extend the capabilities of the technology. The working group developed extensions enabling robust organization and graphical visualization of device data, and providing support for persistent data storage. The extensions are available to all three organizations to integrate within their respective control network technologies, with the commitment of being added to the IEC 61804-2 standard upon completion.
Major automation equipment suppliers strongly support EDDL in its native form, and played a key role in enhancing the technology. Emerson Process Management (www.emerson process.com) and Siemens Automation & Drives Group (www2.automation.siemens.com), for example, identified EDDL as the basis for future product development. With typical lifecycles of more than 20 years, today’s plants require stable technology such as EDDL that is decoupled from the revision of the control system or underlying operating system.
NAMUR (www.namur.be) is the end-user association for German chemical/pharmaceutical producers. NAMUR’s NE 105, “Specifications for Integrating Fieldbus Devices in Engineering Tools for Field Devices,” includes requirements for investment safety with fieldbus systems. Key benefits of EDDL technology meet the NAMUR requirements—most notably, platform and protocol independence, and reliable device revision control.
Because EDDL technology eliminates the need for special, proprietary and operating system-specific host application files, the same EDD is used with a large distributed control system (DCS) as with a simple handheld configurator. Device suppliers are no longer required to develop, test and maintain different files to support different host applications. This eliminates the economic barriers for smaller device manufacturers to enter the fieldbus market. End-users benefit from access to a wider range of instrumentation choices.
The Fieldbus Foundation’s device registration process provides robust testing and registration of both device interoperability and device EDD to guarantee quality and compatibility. Coupled with the tight revision control properties of EDD, users are assured that their investment today will provide long-term support over the plant life cycle.
Stephen Mitschke, [email protected], is product manager-fieldbus products, at Fieldbus Foundation.
