FDI – A common solution for device management?
25 September 2012
Suzanne Gill reports on the emerging FDI standard, and finds out why end-users should be taking an interest in this latest set of specifications, which aims to offer a single source integration solution for managing the functionality offered by intelligent devices.
The combined efforts of five of the major automation foundations – FDT Group, Fieldbus Foundation, HART Communication Foundation, PROFIBUS & PROFINET International, and OPC Foundation, has led to the development of a single common solution for Field Device Integration (FDI) and it continues to move this standard forward.
At the 2012 ACHEMA exhibition in Frankfurt the FDI Cooperation, LLC confirmed that FDI is continuing on its path to becoming an international standard under the International Electrotechnical Commission (IEC). A draft of the FDI specification was submitted to the IEC in April 2012 and the outcome of this is now eagerly awaited.
The reasoning behind the development of the specification was perfectly sound. Efficient and economically viable device integration requires multi-protocol, standardised technology that makes device information available across systems and applications from different manufacturers. In the past this has not been available, and the development of such uniform technology has always been inhibited by the different interests of various organisations and automation manufacturers, resulting in the creation of disparate technical solutions.
The current solutions – Electronic Device Description Language (EDDL) in its various formats and Field Device Technology (FDT) – both have their strengths and weaknesses, but to a large extent they overlap, leading to additional expense for both end-users and manufacturers.
A single solution
FDI is said to combine the advantages of FDT with those of EDDL in a single, scalable solution and is applicable for a range of tasks over the lifecycle of the plant, for both simple and complex devices, including configuration, commissioning, remote diagnostics, and calibration. It should be noted that both FDT and EDDL do still exist and continue to be strongly supported. FDI has been added to the mix to offer a way to rationalise information, making life easier for the end-user.
So, the end-user community with either FDT or EDDL-based hosts should be interested in the benefits offered by FDI. It will provide a single source solution for managing functionality and information from intelligent field devices. Users will not need to manage a variety of disparate device descriptions, which will help to reduce the costs associated with maintaining assets in the field.
Commenting on the benefits of FDI at Hannover Messe this year, Larry O’Brien, marketing manager for Fieldbus Foundation said: “Device integration offers a way to view process information from different devices on different networks. End-users today often have a variety of devices from different manufacturers, on different networks. They need a way to view all this information through a single window, and to have all the information put into context, providing them with consistency and a way to visualise information in a common way.”
O’Brien continued: “Plants today generally comprise a mixture of networks and devices. A good plant asset management strategy should be able to tie together information from all the different networks into a single system and put everything into context and that is one of the key things that FDI aims to achieve.”
A key feature of FDI is the added element of OPC integration. “OPC should be viewed as the ‘glue’ that ties everything together, said O’Brien. “So, not only do you have information from many different devices on a variety of networks but it is also necessary to interface with many different subsystems. OPC is the link that is needed to manage the intelligent devices, the plant asset management application and all the other applications that need to be dealt with, in particular integration with higher level systems such as computerised maintenance management systems (CMMS), alarm management systems and the DCS host. There are a variety of applications that all need to be co-ordinated and need to work together to manage the information from the devices. “And its is not just about maintenance. There is information that is crucial for safety that needs to be managed too,” said O’Brien.
FDI can also offer benefits across the plant lifecycle. Traditionally, the focus of technologies such as FDT, EDDL or fieldbus has been on the ability to reduce costs through the engineering, installation and commissioning phases. Looking at the operation and maintenance phases of the plant can be valuable too. “One of the key areas of value for FDI is the elimination of customisation,” said O’Brien. “A great deal of money is spent undertaking custom integration between different applications. With a standard technology, such as FDI, much of this cost can be avoided. As an additional benefit it can provide faster times to start up, which for some projects could be the justification needed for the automation investment.
“Transparency is also crucial. Highly customised solutions often require a great deal of ‘looking after’ which requires a specialised knowledge of the system. With FDI, however, it is not necessary for the control engineer to pay attention to what is going on behind the scenes, allowing them to spend more time on ensuring that the plant continues to be productive.”
The functionality of FDI has now been demonstrated at the Hannover Messe and the ACHEMA exhibition this year, showing how it can be used to integrate Foundation Fieldbus, HART, and PROFIBUS field devices from various manufacturers within an ABB process control system, making use of prototypes of FDI standard host components developed by the FDI Cooperation.
The device package
The device package is key to FDI. The Electronic Device Description (EDD) – the device definition which includes the business logic and the user-interface, a user interface plug-in and various other attachments that go into the device package – can include manuals and certificates or any protocol specific files that need to be added. The EDD is an FDI encoded file format, but is based on the standard Electronic Device Description Language (EDDL). The user interface plug-in uses standard, existing technology.
Another major component is the FDI host, which incorporates three major components – the FDI client, the FDI Server and the communication server (OPC UA) which connects everything together. This basically manages and provides device data, putting everything into context for the end user. It also manages the device packages and processes the business logic from the EDD.
Interoperability was an important consideration, so FDI has backwards compatibility and direct connectivity with both FDT and EDDL. Devices packages can be processed by FDT systems without the need for additional DTMS or EDDs.
Conformance testing is an important requirement to achieve interoperability and to ensure that devices coming onto the market meet the specifications of the standard. Conformance testing for FDI will be performed as an add-on to existing product conformance tests at Fieldbus Foundation, HART Communications foundation, and PROFIBUS and PROFINET International for the respective protocols.
FOUNDATION fieldbus, PROFIBUS, and HART all use EDDL as a core technology, albeit all slightly different variations of the technology. The FDI Cooperation has harmonised EDDL across communication protocols, which enables it to provide single cross-protocol FDI Design and Test Tools, including a common EDD Interpreter. EDDL harmonisation is now complete, and this has facilitated the second step of the project - harmonisation between EDDL and FDT technologies - the ultimate goal of FDI.
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