FDT/DTM or EDDL for Asset Management using Foundation Fieldbus technology

In order to achieve the full potential of automation benefits, smart devices must be fully integrated into control, engineering and asset management systems. The system must have detailed knowledge of all the parameters and functionality implemented in the smart devices. Different technologies are available to optimize this integration, the most commonly used being FDT/DTM and EDDL.

However, conflicting claims on the benefits and advantages of each technology have created some confusion among end users. It became necessary to clarify the situation by performing a thorough and objective comparison between the two approaches.

The International Instrument Users Association WIB, a neutral and competent party decided to perform this evaluation. They commissioned Shell Global Solutions International (SGSi) to do a comparison of FDT/DTM and EDDL technologies as applied in Foundation Fieldbus (FF) systems, the Foundation Fieldbus providing the field bus communication protocol. This test is a milestone as it provides an objective assessment by an independent laboratory recognized for its competence and experience.

The FDT Group (responsible for the FDT/DTM technology) as well as the Fieldbus Foundation, (representing the ECT group responsible for the EDDL technology), were both invited to support the evaluation. The FDT Group and SGSi co-sponsored this program; the Fieldbus Foundation decided to not participate. The final report is now available and presents their findings and evaluation. If you wish to receive a copy, please ask at\n This e-mail address is being protected from spam bots, you need JavaScript enabled to view it

The SGSi test facility has been used to evaluate the performances of 4 FF devices that support both FDT/DTM and EDDL for a number of device/systems combinations (see the detailed list in table 4). For HART and Profibus many more EDDLs and DTMs are commercially available. The report provides representative screen captures to illustrate the findings in one specific test case, the Metso Neles ND9000 positioner. Similar results are observed for the other cases not presented in this report.

The conclusions are:

The basic claims on the advantages and disadvantages of FDT/DTM and EDDL technology are confirmed using FF technology. A summary of these observations is given in table 1.
FDT/DTM, in concept, offers the enhanced data accessibility and extended functionality as used in commissioning (parameterization) and maintenance of FF smart devices in a very effective manner.
EDDL offers the required data accessibility and functionality as used in commissioning (parameterization) of FF smart devices
Both EDDL and FDT/DTM as applied to FF technology are not mature yet: there is a limited number of FF devices supporting EDDL and/or FDT/DTM; interoperability issues are observed with EDDL and with FDT/DTM; The DTM used for this evaluation had not been through the dtmINSPECTOR test. The dtmINSPECTOR evaluates DTM compliance with FDT standards.

The following recommendations are made:

Systems should support both FDT/DTM and EDDL
DTMs and EDDLs are required for more FF devices
Certification procedures for FDT Frame applications must be implemented.
All DTMs (device/communication/gateway) must be certified using the latest version of the DTM test tool dtmINSPECTOR (current version 2.0).
The style guide for DTMs must be improved to obtain the same menu system (use commissioning and maintenance views)
Vendors should implement more device intelligence in their DTMs

The results published in the report confirm the consistent position of the FDT Group:

FDT/DTM technology allows incorporation of enhanced diagnostics and device intelligence compared to EDDL.
FDT/DTM and EDDL are complementary technologies that perform best in their respective areas of application: EDDL descriptive language is suited for device data access and FDT/DTM programming interface is the recommended platform for advanced asset management applications, intelligent device diagnostics and efficient Human Machine Interface. Based on current technologies and customer requirements, DDs may still be required for the Operator Station in addition to EDDL and DTMs.
Control systems, tools and field devices suppliers should continue supporting both approaches. Vendors should continue to exploit the benefits of each technology including the flexibility and power of FDT/DTM for advanced device functionalities.

This objective test confirms that FDT technology meets the end users’ needs and that it delivers the claimed benefits. It supports our message that FDT technology brings superior benefits to end users and suppliers alike.