Trasmettere Fieldbus ad elevata frequenza attraverso uno Slip Ring

Trasmettere Fieldbus ad elevata frequenza attraverso uno Slip Ring
Novembre 2016

The continuous request for increasing performance and cost reduction in motion control lead the market to the use of Ethernet based field buses, recently they are overcoming as standard the previous solutions granting better performance and an easier way to reduce time to market in the development of new machines.

A further improvement to simplify the deployment has been done by different brands proposing hybrid cables that can transport power, signals and Ethernet-based buses with only one cable and connector in a daisy chain topology.

It’s clear that this trend and the use of rotating machines to reduce the footprint lead to a whole new challenge to slipring manufacturers like Servotecnica in order to reduce, as much as possible, the impact of an electrical rotary joint over the Ethernet network, being the fact that TIA/ANSI/EIA specifications was intended for cables only.

We had also to say that hybrid cables had less margins (Attenuation, NEXT, ACR, RL, IL, etc…) than a standard, plain CAT5e cable, so the introduction of a slipring can easily be critical to machines manufacturer generally being a bottleneck through which pass all the electrical connections for the rotating part.

There were four major points to overcome:

  • Keep a clean contact over all the rotation (also in case of standard vibrations)
  • Reduce as much as possible the noise generated by power lines presents in the same cable
  • Reduce the crosstalk generated by the Ethernet itself over the different pairs (this problem became bigger as much is bigger the ring used)
  • Keep the same transmission quality over time before the end of life target


Thanks to the use of a gold-gold technology for brushes and rings we can have a clean and uniform contact over the whole rotation and the fiber-brushes grant the correct pressure reducing wear for a long life.

Servotecnica developed standard internal slipring structures depending by sizes and performances needed to grant reliability over time of the transmission also in presence of power lines generating noise. We ran extensive test simulating a complete network and monitoring the behavior over time introducing also unwanted circumstances, trying to verify through a stress simulation the reliability of the electrical rotary joint.

The result of the experiences done with our customers in the field lead us to develop a complete documentation and standard quality controls that can grant the CAT5e conformance of our slipring also with hybrid cables. All our sliprings Ethernet based are 100% tested and certified CAT5e, recently we introduced also some standards 100 Base-T and 1000 Base-T slipring models available in different configurations with additional power channels, for those that need a fast stock solution.

Our long experience can help you to find the best solution for your needs, it doesn’t matter if it will be a standard or a custom solution, we will help you to reach your performance and time target, contact us through our direct offices in Germany and Italy or our distributors in Europe.

SVTS C - Through Bore Sercos Slip Ring SVTS D - Sturdy Sercos Slip Ring
  • Article appeared on:
    Sercos News 2/2016 - the automation bus magazine read online
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