Pepperl+Fuchs Blog

Fieldbus Physical Layer Diagnostics Saves the Day!

Posted by Andreas Hennecke on Tue, Mar 17, 2015

...and, the goose!

As I was reading John Rezabek's recent article "Can Improved Physical Layer Diagnostics Save Christmas Dinner?", a few thoughts came to mind.

John pointed out that keeping the installation — junction boxes, instrument housings — sealed from moisture ingress is one of the big challenges for both fieldbus and 4 mA … 20 mA installations.


I often hear from users that fieldbus-based instrumentation performs so reliably that when it's time to replace equipment, it's been so long that the maintenance people have forgotten the differences they need to keep in mind when exchanging a fieldbus instrument! That is actually a nice compliment for fieldbus technology, although it can contribute to a slowed maintenance process.

To remind people about those minute differences, and to help speed up that instrumentation changeover, here are a few tips:

  • Set device address in the workshop
  • Download settings if necessary
  • The O-ring seal of the housing – don’t lose it!
  • Shield and screen must be re-attached / cut back according to the specific grounding concept
  • Add the particulars for your plant here...

A diagram showing where to connect or NOT connect screens is also an essential detail.  It is important to observe this diagram when working with fieldbus installations. Is this information publically known by the maintenance crew?

There are more ways to protect against typical fault occurrences: When a contact bounce occurs during equipment replacement, modern-day device couplers such as Segment Protectors and FieldBarriers switch off the affected spur, and the plant remains in operation.

Where heavy rain or pressure washing is an issue, an enclosure leakage sensor (ELS-1) can help detect water ingress in critical places. The sensor, via Advanced Diagnostics, will report that water before it builds up and does irreparable damage. This means you can respond in a timely and controlled fashion — and not interrupt your holiday plans.

Handheld diagnostic tools such as the new FieldConnex FDH-1 can provide an advantage in maintenance work, since you can check and make sure that the installation is in optimal condition after work is complete. The embedded expert system and built-in display on the FDH-1 provide guidance and immediate feedback about the quality of the installation.

Keeping these things in mind will help you enjoy family time, and save that goose dinner!

Read the full article here: Can Improved Physical Layer Diagnostics Save Christmas Dinner?

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Topics: Fieldbus

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