However, many of the requirements for advanced setup and diagnostics of sophisticated devices like vibration transmitters were not fully addressed by the traditional device descriptions (DD) originally developed to support handheld devices.
EDDL (www.eddl.org) is a universal integration solution recommended in NAMUR NE 124 “Wireless Automation Requirements”. It builds upon the traditional DD and addresses the requirements specified in NAMUR Recommendation NE 105 “Specifications for Integrating Fieldbus Devices in Engineering Tools for Field Devices”. Enhanced EDDL (IEC 61804-3) now also provides graphic display defined by the device manufacturer not available in traditional DD.
Using EDDL to prepare a control system for installation of a new device, users need only to copy the EDDL file is into the system. This file is compressed text from the device manufacturer telling the system how to read and display data from the device, as well as how to write to the device. It also includes manufacturer expert guidance in the form of step-by-step wizards and help text.
System security is maintained as there is no need to reveal ‘administrator’ level passwords to those that need to load files on the system to commission new devices. This facet of EDDL makes it easy for administrators to keep the control system up to date and compatible with new devices.
Unlike EDDL, many other device integration solutions are based on software drivers and are therefore affected by the ongoing changes in Windows versions and service packs. As a result, they often require license keys, and installation may affect robustness of other programs.
Accessing Intelligence via WirelessHart
Although many plants use Hart devices, these devices are often not digitally integrated because the legacy control systems do not support Hart communication. These plants only use the analog 4-20 mA signal. Therefore technicians cannot do remote setup and diagnostics from the control room.
For such installations, a wireless adapter is one avenue by which users can digitally integrate Hart devices into the control system. To do this, a user needs only to screw a WirelessHart adaptor into the conduit entry of the device and connect to its terminals. Wireless adapters and wireless transmitters around the plant will self organize into a network. The system can then accesses process variables and diagnostics, and even enable setup, through a wireless gateway.
Because both traditional DD and enhanced EDDL are independent of the underlying communication architecture, the same DD file used by some systems to communicate to a device directly over the wires is also used when communicating with the device through a WirelessHart adapter. This means that a WirelessHart adapter can be used with old or new Hart devices from all manufacturers.
Using wireless adapters, it is possible to unlock features of a device which were previously unavailable in the control system. For example, partial stroke testing (PST) may be initiated on safety shutdown valves as well as the meter verification of flowmeters for lowering the cost of calibration. New diagnostic and setup capability can also be used to improve control valve performance.
Edited by Renee Robbins Bassett, Managing Editor, [email protected], from a submitted paper. The full article can be found at bit.ly/awslant_003.
Authors of submitted paper:
Jonas Berge, Emerson Process Management, Singapore
Ludwig Winkel, Siemens, Germany
Jim Jamison, EnCana Corp. Ltd., USA
Amit Ajmeri, Yokogawa Corp. of America, USA
