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Diagnostics The Key to the Use of Device Diagnostics as a Natural Part of Device Maintenance and Plant Operation

Editor: Dr. Jörg Kempf

Leading process plants demand access to diagnostics in no more than three clicks. This is made possible using Electronic Device Description Language (EDDL), a non-intrusive device integration technology enabling device diagnostics from operator stations. The new enhanced EDDL standard enables the device manufacturer to decide how the device menu system and graphics is displayed in the system and provide expert guidance and wizards simplifying use and improving interoperability.

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Device integration timeline
Device integration timeline
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Meeting user requirements

The EDDL device integration technology, originally called DD when first introduced in 1992, is the language for a compressed text file loaded on the system that declares how data in intelligent field devices is accessed and displayed. Traditional DD enabled setup and diagnostics of different types of devices from different manufacturers from the same single software or communicator, the key to interoperability trusted by manufacturers and users for well over a decade. It became an international standard (IEC 61804) in 2004.

Traditional DD

Traditional DD had several important characteristics. For instance, it drives handheld field communicators, workshop laptop/tablet, asset management systems, and control systems. Since it is a standard independent of Microsoft Windows, the system and device investment is protected over many years of plant operation as the device support files are not affected by Windows version, .NET framework, service packs, or security patches. There is no need to obtain new drivers when the system is upgraded.

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Similarly, the system is not made obsolete by the addition of files for new device versions. The DD files are interoperability tested by independent third-parties together with the device. Because every version of every device type from every device manufacturer has its own file, the addition of new types or versions does not affect existing devices.

The device files are compressed text, not driver programs, and they do not conflict with system software or require software installation. ‘Administrator’ level passwords are not required to commission a new device, which helps to maintain system security. Administrators can keep systems and handhelds up to date by simply loading the files on the system, saving time. This non-intrusive trait ensures easy system administration and robust operation.

The files have no license key or administration overhead, further saving time. The information in the file is also used for automatic configuration of OPC servers making all information in any device externally accessible to other applications for special tasks. These are important characteristics that are not found in other device integration technologies.

Wizards (aka methods) guide technicians step-by-step through procedures like set up and calibration, ensuring steps are not missed. A plausibility check prevents gross errors.

New enhanced EDDL

However, traditional DD did not support graphics and subsequently could not fully support “complex” devices like valve positioners and radar level transmitters. Graphical enhancements, a user friendly menu system, and the ability to store test results were therefore added to the standard. This includes multi-pen trend, multi-waveform graph, and histograms etc. Therefore EDDL now fully supports access to functionality in these devices, such as advanced set up and diagnostics. The content & structure of device information to be displayed, and where on the system screen it appears, is decided by the device manufacturer who knows the device best. The device manufacturer’s experts also include know-how in the form of illustrations, wizards, and help text to aid set up and acting on diagnostics.

Graphics without compromise

At the same time, the consistent look and feel is maintained among devices of different types, from different manufacturers, using different protocols, because EDDL technology inherently enforces consistency. Send, help, print, zoom, and cancel etc. work the same for all devices. This makes EDDL-based device management software, as part of asset management solution (AMS) suites, intuitive and easy to learn. EDDL achieves all this while retaining all the valued characteristics of traditional DD such as investment protection, no device version conflicts, robustness, easy system update, and no license keys, thus meeting all requirements of Namur NE 105. This was independently verified in a test by BIS Prozesstechnik (formerly Infraserv Hoechst).

Supporting all tasks

Thanks to the enhancements, EDDL based software now supports all phases of the plant life cycle including operations and maintenance tasks such as set up of advanced devices and troubleshooting using advanced diagnostics.

Integrated smart diagnostics

In the past, device diagnostics were displayed on a separate dedicated maintenance console. The problem though was that no one was stationed at this workstation because technicians are in the field, so no action was taken on alerts. Therefore device diagnostics did not help technicians; the device management software fell into disuse, and maintenance returned to reactive mode.

However, by integrating device diagnostics in the operator consoles as per the Namur NE 91 suggestion, the device alerts serve as early warning to operators. The operators don’t repair devices, but on failure they have minutes or hours of advance notice to act before their process is affected. They can avoid process upsets by putting loops in manual or manually operating valves.

Diagnostics are effortless. When the alert appears it only takes a single click to open the faceplate of the device to see an overview of the problem. A second click opens detailed diagnostics in the device management software. Once the process is taken care of, the operator can alert a technician to fix the problem. A third click provides manufacturer know-how to resolve the problem. This way, device diagnostics become very helpful for both the operations and maintenance teams, and therefore are included as a natural part of daily work practices. Other solutions would require more clicks and typing.

Alarm flooding is prevented by prioritising devices and diagnostics according to EEMUA 191 recommendations. Therefore, operators are only alerted to faults affecting the process. Predictive diagnostics concerning problems which have not yet materialised are only reported to maintenance technicians. EDDL is unique in that it is the only device integration solution sufficiently robust and non-interfering to be used on the DCS itself, not as an isolated system, to enable device diagnostics in operator consoles. There is no other means to achieve a comparable result.

Upgrade correctly

Many millions of devices and thousands of systems interoperate and enable worker productivity, thanks to traditional DD. Upgrading systems and communicators can further increase worker efficiency, which translates into better plant performance and lower maintenance costs. It is not necessary to switch technology. Just upgrade your existing DD solution to enhanced EDDL to enable use of the power of field intelligence to improve plant performance.

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