Installing new equipment for any on-board project can be an expensive undertaking and replacing existing cables is extremely costly especially where coupler connections are involved.  In some cases running new cables may not be an option, considering how complex a train system installation can be, there may not be space or budget to run new ethernet lines through existing couplers. In most cases existing cables can be reused and utilised, especially for data communication through the use of powerline technology.  
 
Traditionally, modern railway fleets are designed with Ethernet Train Backbone (ETB) Networks enabling fast and resilient communication between trains. However, not all trains are new, and with many thousands ofolder fleets existing with decades of life left, the need to modernise the on-board communications has never been greater. 
 
Nevertheless, on-board networks are inherently complex. Trains are required to be coupled and re-coupled regularly, often whilst in service, and will swap directions many times throughout the day. During the coupling phase, they will connect both the non-critical (i.e. Passenger Information Systems) and more importantly critical systems (i.e. traction, Door control etc) together in each separate train to form a fully connected and communicating formation known as a consist.  
 
The Inter-vehicle couplers which connect the separate train Units together have a series of pins that are securely fastened for transit. If this connection fails, the train cannot be in service, meaning they are a vital part of the integrity of the overall operation of the railway. During modernisation phases of fleets and on-board train systems, ethernet communication between trains can utilise existing network cables within the auto-coupler, as such careful consideration of train-train communications technologies and methods should be made.  
  
One of the main challenges with legacy couplers is the limited supply of available “spare” connections and appropriate shielding to run high-speed network communications. Existing train wires through the coupler can be allocated to a variety of services and systems such as power or train control. These pairs are likely to be prone to noise and may not be shielded, making them unsuitable for use as data communication pairs but well suited to Ethernet over Powerline technology.

When it comes to Ethernet data communication onboard railway vehicles, physical cabling is required to be shielded CAT5e as a minimum for gigabit communication. Poor cabling practices such as breaks in shielding can cause communication loss or sporadic interference, especially in the electromagnetically noisy train environment. Additionally, if there is voltage on the line, regardless of the quality, Ethernet data communication is not possible.

To achieve communication between trains via couplers, Westermo has designed the Viper-002-PL to connect the network across the coupler in the harshest of environments. In an IP67 housing and utilising M12 connectors, the EN50155 compliant Viper-002-PL is a perfect choice for any on-board networking solution where through coupler communication is required.

The device has two ports. One is a 100Mbit/s copper Ethernet port and the other a 2-wire cable port for communication. Since they work in pairs, the 2-wire cable ports will connect between two Viper-002-PL’s through the on-board coupler. Automatically negotiating with each other, the Viper-002-PL is surge resistant and immune to electrical interference.

After a short negotiation, Ethernet traffic will seamlessly communicate over the coupler, enabling data connectivity through the train. If the train is required to be uncoupled and connected to another train, the Viper-002-PL will l disconnect and reconnect automatically to the new Viper-002-PL in the newly joined vehicle. Importantly the devices can utilise the same “train wires” at each end of the train without x-connectivity and network loops thanks to the unique implementation by Westermo when designing this device specifically for railway vehicle connectivity.  

 
There is one additional feature of the Viper-002-PL that should not be ignored. The connection between couplers is often powered, up to 110VDC. This means that conventional Ethernet traffic cannot tolerate electrical interference on the same wires, meaning it would not be possible for communication. The Viper-002-PL complies to a standard that ensures Ethernet over Powerline communication in the most harsh and complex environments, allowing implementation of ethernet networks via couplers that would otherwise have been difficult and costly to the project.  
 
The Viper-002-PL is a perfect product for any retrofitted on-board system to ensure high quality, secure and robust data communication over train couplers.  
 

Read about Wired Train Coupling (ICL) here