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News from Profibus / Profinet – Part 2 Profibus — Diagnostics the Easy Way

Author / Editor: Profibus Nutzerorganisation / Dr. Jörg Kempf

Fieldbus communication has brought about a paradigm shift in automation technology. Communication used to be one-way and each line carried only a single analogue signal. Fieldbus communication uses digital technology and it is bi-directional. As a result, field devices have become an integral part of the overall system and they provide the basis for comprehensive asset management ...

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(Picture: Profibus Nutzerorganisation)

The old man felt a blister forming on his tongue. The coffee being served at the event where former system operators and members of the maintenance & service team at “his” company had got together again was really hot. Still, he smiled inwardly. He had been impressed by the presentation given by the young systems engineer summarizing the proven track record of Profibus and he knew that “his” facility was in good hands. Despite that however, he could not refrain from making a few comments.

In the old days, it was easy to check the pneumatic input signals at the press of the thumb. Also, he had often used his tongue to verify the 4-20 mA signal and he wanted to show the blister on his tongue to prove it. This was the right time to do that. The young engineer had paused and was looking out at the audience. The old man spoke up and criticized the fact that in contrast to the way things used to be, you never know where you are with these modern fieldbus systems. We simply do not have the right sensory organ to detect the signals. The eyes, ears, thumbs and tongue are no help. He stuck out his tongue at everyone. The blister was plainly visible …

Fieldbus communication has brought about a paradigm shift in automation technology. Communication used to be one-way and each line carried only a single analogue signal. Fieldbus communication uses digital technology and it is bi-directional. As a result, field devices have become an integral part of the overall system and they provide the basis for comprehensive asset management.

Simple Network Diagnostics

A fieldbus network is essentially the nervous system out on the production floor and is in itself a vital asset in the automation landscape. So it makes good sense to keep an eye on the state of this asset, and nowadays nothing could be easier. A number of manufacturers offer diagnostic tools for the Profibus physical layer. The choice includes mobile devices for service technicians as well as stationary equipment supplying data which can be displayed at any time in the control station, e.g. on the service console. The diagnostic tools provide valuable assistance during commissioning, maintenance and ongoing operation. They make predictive maintenance and asset management possible in the field and from a central location.

Planning with no Hassle

Fieldbus technology optimizes system design, configuration and installation. Hundreds of separate cables are reduced to just a few cables or only a single one. Commissioning takes less time and device setup can be accomplished from a central location. Reversed polarity and incorrect allocation between signals and devices are a thing of the past. Every signal bears the “stamp” of its device and can be uniquely identified and characterized. Measurement precision is also better. The values generated in digital transducers are no longer converted to analogue signals. None of the original measurement precision is lost when the data is transmitted. There is no possibility that corruption during transmission will remain unnoticed. Also, communication is not limited to process data. Diagnostic and status information allow the user to make a correct judgment on the trustworthiness of the process signals.

The old man reached for his cup again. He felt the blister on his tongue as the coffee passed over it. Did the others really believe his story about using his tongue as a test instrument? At any rate, the young engineer responded with the right answers to his questions and pointed out that there is no longer a need to take instrumentation out into the field to collect diagnostic data …

To be continued: Part 3

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