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Full duplex mode with just one fiber: new fiber optic media converters with WDM technology

Two optical fibers are normally required for Ethernet data transmission via fiber optics. The new Fast Ethernet media converters feature special technology: only a single optical fiber is required for optical communication.

Optical transmission using wavelength division multiplex

WDM technology  

Bidirectional data transmission using WDM technology

WDM stands for wavelength division multiplex. This multiplex method uses both 1310 nm and 1550 nm wavelengths.

This enables data to be transmitted and received simultaneously (bidirectionally) on a single-mode fiber – without restricting the transmission quality and bandwidth. Two devices are used for connection via a single optical fiber. Device A transmits data at 1310 nm on the TX channel and device B receives data at the same wavelength on the RX channel. When the roles are reversed, 1550 nm is used in the other direction. Connection is therefore only possible between device A and device B. The devices are available as a set (A and B device).

Thanks to WDM technology, the bandwidth in existing fiber optic networks can be doubled by using two WDM media converter pairs. The existing installed cable is split into two independent network connections. For new installations this means that costs can be reduced by saving on cable fibers and connectors.

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Optical transmission with WDM in rotating applications

For rotating applications  

Single-fiber media converters are particularly suitable for rotating applications.

Another advantage of media converters with WDM technology comes into play when used in rotating applications. Inexpensive fiber optic connection via optical rotary transformers is possible for the first time. In the case of rotating applications such as revolving transfer machines or wind power plants, the challenge lies in transferring power and signals between the fixed and rotating part of the system. So far electromechanical slip ring assemblies have been used predominantly for data transfer. However, in applications involving the transfer of high levels of power, electromagnetic interference can occur, to which fiber optic technology is resistant.

WDM media converters, which work with a single optical fiber, make the use of an optical rotary transformer an attractive prospect. These so-called optical rotary joints are wear-free and already available from many manufacturers. Due to the simplified structure, the price for devices with a single fiber is significantly lower compared to optical rotary transformers with several fibers. In addition to wind power plants, many other applications benefit from the advantages of optical rotary transformers. For example, media converters with WDM technology are used in radar systems, maritime drive systems, revolving transfer machines, plus the automotive and packaging industry.

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Redundancy via light and copper in rotating applications

Redundant data communication  

Redundant data communication

It is particularly important for wind power systems that high-performance data communication between hub and gondola is guaranteed. This is where a redundant network offers advantages. Independent transmission paths are used for data communication.

Standard Ethernet data transmission is based on two WDM media converters. For fiber optic transmission, an optical rotary transformer with a single fiber is used, which is integrated in the axis of the existing copper slip ring. This transmission path is resistant to EMI, electrically isolated, and maintenance-free. The redundant path is constructed with the aid of Ethernet extenders. The existing copper slip ring is used for the SHDSL connection and redundancy management is ensured via managed switches.

The new WDM media converters make it possible to ensure cost-effective, high-performance, and reliable data communication. In conjunction with the SHDSL extenders from Phoenix Contact that communicate via the conventional copper connection of the slip ring, it is now possible to create a future-oriented redundant network solution.

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Practical diagnostic functions with link management

LFP and FEF functions  

In the event of a network interruption: the transmission path is switched off

Media converters from Phoenix Contact offer comprehensive diagnostic options. The integrated LFP (link fault pass through) and FEF (far end fault) link management functions provide permanent connection monitoring. This ensures high system availability. The link on the fiber optic connection switches off if the connection is lost on the copper side of the media converter. The media converter on the other side registers the aborted link via the fiber optic path and likewise interrupts the connection for its twisted pair segment.

The entire connection over the optical path is therefore as transparent is it would be were communication purely copper-based. Both sides of the network connection can therefore detect a lost link immediately and respond accordingly. In the case of a redundant connection, the devices can switch over to it immediately. In addition, when the FEF function signals a lost link to the media converters, this also enables the faulty segment to be localized.

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Further information
  • Full duplex mode with just one fiber: new fiber optic media converters with WDM technology


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