Is FDT good for fieldbus and device networks?

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What Is FDT/DTM Anyway?

FDT/DTM technology is made up of two basic components: 

• The Frame Application: this is the Device Management Environment.
• The Device Type Manager (DTM): this is a software component that simply operates as a “driver.”

DTMs can be further classified into two categories:

• CommDTMs are software components/applications that enable the Device Management Environment, called a Frame Application, to access different fieldbuses. This approach makes the Device Management Environment open to all fieldbuses. Just add the required CommDTM. CommDTMs for HART, Profibus, Foundation Fieldbus’ transducer blocks and Interbus S already exist, and are being developed for AS-interface, DeviceNet, Profinet and Modbus.
• Device DTMs again are software components/applications, but these DTMs enable users to configure the associated device within the Device Management Environment. These DTMs are the individual “device drivers” that allow users to configure, diagnose, and manage the field device. The DTM is often compared to the drivers loaded into computer operating systems to support external devices such as printers. These don’t just to allow the printer to operate, but also help diagnose and troubleshoot faults (ink cartridge low, align print head, etc.). The DTM offers this same support for field devices connected to a control system (control valve stuck, signature change, etc.).

The chart below shows how EDDL and FDT/DTMs combine to communicate between the field device and the “host-based” software, be it a configuration tool or asset management system.

THE MATING DANCE OF EDDL AND FDT/DTM
Combining to communicate, whether it's a configuration tool or an asset management system.

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End-Users Wanted

TAKING a page from the success of end user councils, originally established by the Fieldbus Foundation, and now adopted by other groups including OPC, FDT Group held its first End User Group Forum in October 2005 in Amsterdam. The event was attended by more than 40 participants, including representatives from 14 end user and engineering companies. Those attending the event learned more about FDT technology, and also provided input on requirements to make it better in the future. Based on the success of this initial meeting, similar events will be held in 2006.

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About the Author

Ian Verhappen is an ISA Fellow and Director of ICE-Pros Inc. an independent Instrumentation and Systems Engineering firm focused on Fieldbus technology, process analyzer systems and oil sands technology. Verhappen can be reached at Ian.Verhappen@ICE-Pros.com or via the web at www.ICE-Pros.com.