The requirements imposed by fieldbus users in process automation (PA) for an easy to understand and easy to handle diagnostics concept have been implemented by PROFIBUS. PROFIBUS International (PI) adopted an addendum to the PROFIBUS ?PA Devices? profile that specifies a diagnostics concept which was developed in close cooperation with NAMUR. The requirements of the NAMUR recommendation 107 or the VDI guideline 2650 for a classification of diagnostic events into their status signals have been incorporated.
Process devices according to the PROFIBUS profile ?PA Devices? have the following status signals: Function Check (invalid output signal through malfunction in the field device or its periphery), Maintenance Required (valid output signal, but exhausted wear reserves), Outside of Specification (operation outside of specified operating conditions), and Failure (invalid output signal due to a malfunction in the field device or its periphery). In addition to the listed classification, detailed diagnostic information can be made available. By using suitable functions in the control system or Plant Asset Management system, it allows for enabling an individual notification of different addressees (such as operator and maintenance personnel). PROFIBUS PA uses the measured value communicated together with the measured-value status, which was redefined as part of the specification work, for the transmission of the current status signal.
Another novelty is that the effect of a certain diagnostics event can be set to the status signal in the device. This takes the fact into account that diagnostics events are evaluated differently in the context of the specific application purpose of the device and, therefore, can also lead to different status signals. Detailed information about a diagnostics event in the device are transferred via the PROFIBUS diagnostics internationally standardized in IEC 61158-6 or via readable diagnostics parameters.
The described diagnostics concept decisively contributes to a powerful asset management based on the PROFIBUS technology.