Siemens favors EDDL over DTM/FTD for automation

Mark Hoske, editor-in-chief -- Control Engineering, 11/1/2004

Erlangen, Germany—Siemens will provide Device Type Manager/Field Device Technology (DTM/FDT) technology if customers request it, but is advising against using DTM/FTD for automation, controls, and instrumentation because of lacking economic advantages and higher total lifecycle costs.

Even so, the company says it supports the technology, and, like Profibus International, will use it for complex I/O devices. "The technology should be used if its increased customer benefits can compensate for the considerably higher degree of complexity involved," says Anton Huber, VP and board member of Siemens Automation & Drives, in a statement to Control Engineering.

Huber explains that today's field instruments, with long service life and stable technology, are integrated into the control system using an electronic data sheet, known as Electronic Device Description (EDD). It describes the respective, associated field device, and is generated by Electronic Device Description Language (EDDL). Device and control system manufacturers supported related methodology, language definition, and innovations for many years, he says.

Integrating DTM with plants' existing field instruments will cause "many disadvantages without any substantial benefits," Huber adds. "DTMs are software components, which, for instance, just like device drivers, are implemented in the control system software. In practical use, disturbances and problems with compatibility cannot be avoided. This will lead to numerous, previously unknown, difficulties in connection with the field instruments. Furthermore, in the future, device integration will be defined, in part, by Microsoft technology with its considerably shorter innovation cycles as compared to the investment goods industry."

In response to Siemens statements, Invensys Process Systems' fieldbus technology development director, Scott Bump, says that, "Siemens has clearly made new business decisions regarding their stance on several fieldbus technologies. Siemens has been a strong partner of the FDT Joint Interest Group for years. It has contributed large amounts of work toward the development and marketing of the FDT specifications. Siemens has not made FDT aware of any perceived limitations in the FDT technology, and those limitations were not enumerated in their statement. Hundreds of FDT-based applications created by more than 40 vendors are available on the market today, and are operating successfully in plants around the world.