Condition Monitoring with PROFIBUS PA

News from Profibus / Profinet – Part 10 Condition Monitoring with PROFIBUS PA

21.11.2014Editor: Gabriele Ilg

Production facilities in the process industry have very demanding requirements when it comes to safeguarding availability, safety, and efficient maintenance. Condition monitoring responds to these requirements by adopting a holistic approach that is leveraged to acquire and evaluate pertinent, comprehensive information from the field. PROFIBUS PA offers unprecedented performance to owners and operators alike.

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Now it was the youngster who felt out of place. But there were also other things in his company that he had a vested interest in along with the informal reunion that he organized. And they all revolved around IT. The older man noticed that he was getting into a heated debate but nevertheless addressed the topic once again — this time, more carefully. “In my day, automation engineers such as myself and IT staff wanted nothing to do with each other. We simply shared no common ground. The IT experts didn't know what we really did and had no way of helping us.” “Things couldn't be more different now”, replied the youngster as he made his way to the podium…

Self-Monitoring and Field Device Diagnostics

NAMUR recommendation NE 107 entitled “Self-Monitoring and Diagnosis of Field Devices” describes diagnostic possibilities as they relate to field devices. Not only can field devices supply critical information such as mea-surement and control values, but also other important clues that point to the operational status of the devices and help plant operators or maintenance personnel implement targeted measures in response. Since a flood of information hinders more than it helps, however, the NE 107 recommendation outlines the basic aspects of self-monitoring and diagnosis as well as defines a collective or condensed status reporting scheme that encompasses “fault”, “functional check”, “outside specification”, and “maintenance required” as performance indicators with the “NAMUR stoplight system”. All of these requirements have been implemented in the 3.02 profile designated for PROFIBUS PA; a status byte that is automatically transferred along with every process value spells out whether one of the four deviations from the target requirement currently exists.

As Simple As Possible, As Exacting As Required

The variety of diagnostic information acquired and computed by the field devices is coordinated at status byte level by the manufacturer in such a way that the plant operator is provided with an accurate depiction of how reliable and credible the measurement signal is. It goes without saying that service and maintenance personnel require more information in the event of a malfunction and can access detailed status reports by fielding an acyclic query. This makes it possible to perform maintenance when it is needed and in the best possible fashion. Tests conducted by manufacturers and users have revealed that the new functions offered by PROFIBUS PA profile 3.02 improve conditions for everyone involved in plant operation. Handling and interfacing are practical, condition monitoring and asset management are simplified, and field devices can also be replaced without compromising the availability of the remaining machine assemblies.

The man with the beard frequently used to inspect his plant to detect and pinpoint any irregularities or impending faults. Although he possessed something of a “sixth sense” and was able to resolve many problems himself before they turned into something much worse, he also had to admit that the new condition monitoring methods that the youngster talked about were much more efficient than his now outdated detective work. A second bolt of lightning that shook the window and the thunder that followed also reminded the man with the beard that he sometimes had to cut his inspection tour short…

To be continued: Part 11

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Further parts of our Profibus series:

Part 1: PROFIBUS – a Proven Technology

Part 2: PROFIBUS — Diagnostics the Easy Way

Part 3: Profibus — Device Management the Easy Way

Part 4: PROFIBUS — for Stable Process Control

Part 5: PROFIBUS — Certification Ensures Compatibility

Part 6: PROFIBUS — Simple and Safe in Explosion Hazard Zones

Part 7: PROFIBUS — Lowering Lifecycle Costs

Part 8: PROFIBUS Simplifies Device Management

Part 9: How PROFIBUS Makes Network Planning a Breeze