Siemens favors EDDL over DTM/FTD for automation
Erlangen, Germany—Siemens will provide DTM/FTD (Device Type Manager/Field Device Technology) technology if customers request it, but advises against DTM/FTD use for automation, controls, and instrumentation, citing lack of economic advantages and higher total lifecycle costs.
Erlangen, Germany— Siemens will provide DTM/FTD (Device Type Manager/Field Device Technology) technology if customers request, but advises against DTM/FTD use for automation, controls, and instrumentation, citing lack of economic advantages and higher total lifecycle costs.
Even so, the company says it supports the technology, and, like Profibus International, will use it for I/O devices of high complexity. “The technology should be used if its increased customer benefits can compensate for the considerably higher degree of complexity involved,” says Anton S. Huber, vice president, and board member of Siemens Automation & Drives, in a statement provided 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, the Electronic Device Description (EDD). It describes the respective field device and is generated by means of Electronic Device Description Language (EDDL). Related methodology, language definition, and innovations have been supported by device and control system manufacturers for many years, he says, with emphasis on continuity and compatibility.
Integrating DTM with plants’ existing field instruments will cause “many disadvantages without any substantial benefits,” Huber explains. “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 the device integration is going to be defined in part by Microsoft technology with its considerably shorter innovation cycles as compared to the investment goods industry.”
In the future, users will have to pay, directly or indirectly, for their field instruments’ additional software-related costs, which are difficult to quantify today, Huber says. Therefore, “DTM upgrades and new releases... are going to generate additional costs throughout the entire life cycle of the field instrument.” In addition, he says, complexity and expense will increase as DTM versions from field device manufacturers keep pace with control system upgrades. Huber adds that the FDT interface is not offered as a standard—neither for the PCS 7 nor for the Simatic S7. “Presently it does not have any commercial relevance. However, we will provide it if the customer requests it,” he says.
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. They have 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 operating successfully in plants around the world.”
Control Engineering Daily News Desk
Mark T. Hoske, editor-in-chief, and Jim Montague, news editor
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