Fewer Fieldbus Programming Headaches

Some relief has arrived for those headaches caused by the difficulties associated with working with fieldbuses.

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The industry has developed two technologies that just may streamline the insertion of applications written by device vendors’ experts: an enhanced electronic device description language (EDDL) and the field device tools (FDT) protocol.

“Maintenance users now have a means to understand what is happening to the device or asset in the context of what its vendor has determined is important,” says John Yingst, product manager for asset management at Phoenix-based vendor Honeywell Process Solutions.

Although EDDL has been with fieldbus technology since its inception as a means of describing the devices connected to it, there was no systematic way of categorizing and interpreting the parameters. So each vendor invented its own scheme. DD files, moreover, needed software between them and the devices and were limited in the scope of their interaction with devices. A C-like language, enhanced EDDL creates applications that should be portable among systems that support it. “It makes data access more meaningful just by organizing and presenting information in a more logical and graphical manner,” says Yingst.

FDT, promulgated by the FDT Group, in Diegem, Belgium, is an open interface protocol between the support software for a fieldbus device and the platform of the control system. The FDT-compliant device software (called a device type manager, or DTM) can be written in any language that supports FDT, including EDDL.

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