The Electronic Device Description Language (EDDL) is a universal language for writing Electronic Device Descriptions (EDD) that can access diagnostic, real-time, and asset management information.
EDDL is the international standard for integrating intelligent field devices with systems: IEC 61804-3 and the ISA104 committee just adopted it as an ANSI/ISA standard for use in industrial automation applications.
A demonstration of EDDL will take place at booth 1356. Attendees can see how advanced EDDL enables user interfaces that can be provided in a control systems and handheld devices for accessing diagnostic, real-time asset management information.
Using this technology, it is possible to provide an interoperable environment where information available in sensors and actuators may be accessed by distributed process control systems or handheld communicator to configure, calibrate a device, diagnose problems, and provide data and alarms for user-interface displays.
Over the long life of plants, new device types and versions keep getting added as part of replacements and modifications. Currently, more than 1000 EDD’s are available from 85 different vendors. Thus, to achieve the best results, the latest electronic device descriptions should be used with HART, Profibus, and Foundation fieldbus devices.
Through the use of EDDL technology, it is possible for users to choose best-in-class instruments that can be used on the network no matter what control system the plant is using. Because EDDL is required for Foundation Fieldbus certification and is the only device description language supported by the HART Communication Foundation, EDDL is supported by virtually every Process Control Systems vendor worldwide, and EDD’s are available for any Foundation, HART, and some Profibus based field device.
It is not necessary to understand how EDDL works. However, understanding the technology may be helpful when choosing EDDL. The EDD file created by an instrument or device designer uses EDDL syntax to describe a device and all its parameters in detail. This can include parameters such as process variable, setpoint, high-low limits, ambient temperature, etc. Also, EDDL supports methods, a scripting language based on a subset of ANSI C used to support step-by-step, interactive setup, and calibration procedures. Device designers can define where all the important parameters should appear on an UI display, such as in columns or bar charts, and in which order. Using EDDL, device manufacturers are given an unrestricted opportunity to provide technicians access to their devices, with the full scope of their functions, where all the menus and parameters appear as intended by the manufacturer.
The file written using EDDL is processed (“tokenized”) to a compressed binary to prevent tampering and subsequent problems. The tokenized files are relatively small and therefore files for many types and versions of devices can be stored also in the limited flash memory of a handheld communicator.
EDDL provides a well-defined structure for supporting the most simple to the very complex field device. Since EDD’s are text-based that are interpreted by the host system, these files are independent of operating systems and control platforms. This structure allows the same EDD to have a common look and feel across applications, which reduces the learning curve and supports multiple host applications. Also, this enables field device additions to be incorporated without affecting the runtime stability of the control system.
One of the greatest benefits EDDL provides the process industry is interoperability across multiple hosts, devices, and technologies. This flexibility allows the end user to choose the best combination of price and performance for devices and software. This interoperability simplifies the control system integration process, because all a systems integrator or end user has to specify in the bid process is that all instrumentation and control equipment conform to the International Standard, EDDL. Competitive bids are easier to evaluate because the end user does not have to worry if specific software packages are available to support various devices; with EDDL, all comparable EDDL devices can be supported by all control systems. Finally, interoperability means operators and maintenance personnel can easily find the calibration and diagnostic information needed for a particular device, and all EDDL-compatible devices will provide the necessary information in a “look and feel” of the host system.