ApplicationsJuly 27, 2019

Fast, reliable internet access for trains leverages technology

Modular preLink components with powerful EtherRail cable assemblies for data networks on railways.

New cabling and connector technology is making fast, reliable Internet access possible on trains. A powerful data infrastructure is necessary to deliver the performance that customers expect, and new tool-free assembly and installation options provide PushPull convenience and weight reduction using only a single twisted pair.

Train travelers now expect Internet access that provides a high-performance experience. They want to surf privately during the train journey or use the compartment as a mobile workstation. Railway operators are increasingly offering an appropriate data infrastructure to meet customer requirements.

Importance of system cabling

Rail customers expect reliable Internet access.

Rail customers expect reliable Internet access.

Solutions to ensure reliable and fast Internet in trains relies on new cabling systems and advanced technology solutions.

Data networks in trains and buses can be implemented reliably and in future-proof manner using the preLink system and EtherRail cables that are part of the HARTING technology portfolio, and specially designed for railway requirements. With Ethernet via only one pair of wires, operators can reduce their operating costs and optimize their production with the tool-less PushPull system.

The central component of the preLink system is the termination block, which allows the cable connection to be performed quickly, simply and reliably. The small size of the preLink contact block makes it possible to prefabricate data cables separately from the train car and then install them in the former. A minimum hole diameter of just 12 mm is sufficient to insert and route the cables.

Once the cables have been laid, the appropriate connector is attached, depending on the network device to be connected. Here, both RJ45 and M12 D- and X-coded connectors (socket or pin) are available for data transmission of up to 10 Gbit/s. This unique diversity of mating faces, in conjunction with standardised preLink connection technology, offers unparalleled flexibility and investment security, especially over long periods of use within railway technology scenarios. The system simultaneously simplifies assembly, making it both faster and more reliable.

M12 connector technology

A current innovation that is being implemented in transportation systems is use of M12 sockets, which can now be connected via preLink as well. The newly designed sockets can be used both as a loose cable coupling as well as a housing feedthrough and be securely screwed here. The second innovation is a preLink printed circuit board socket that allows the user to connect pre-assembled preLink cables directly to the printed circuit board without the need for detours.

As a result, there is no need for a permanent detachable connection to a housing via connectors, and Ethernet connections can be quickly and cheaply brought directly to the circuit board. The combination of the modular preLink system and Etherrail cable is the ideal matchup for cabling rolling stock. With easy-to-install connectors and cables, trains can be equipped with future-ready Gigabit Ethernet and make an important contribution towards providing the infrastructure for the mobile workplace of the future.

Single Pair Ethernet

T1 Industrial Jack

Ethernet single twisted pair (SPE)

The goal of Ethernet via Single Twisted Pair cable and small connectors according to IEC 63171-3 is to achieve weight savings while offering identical performance. Under IEEE 802.3bp (1000 BASE-T1), cable lengths up to 40 meters can transmit 1 Gbit/s — while the cable length is about one-third less than conventional 8-wire Ethernet cable.

A standard Ethernet cable with four wire pairs for 1/10 Gbit/s Ethernet weighs about 45 kg per kilometer. In contrast, a Single Pair cable with the same bandwidth weighs only 30 kg per kilometer. Since several kilometers of cable are installed in the cars of passenger trains alone, this offers a considerable savings potential in terms of vehicle weight.

Tool-less installation

HARTING PushPull technology simplifies assembly and service in the railway sector while improving reliability. The solutions consist of the circular M12 PushPull connector in a rugged metal housing, as well as the lightweight, easy-to-use rectangular variant 4 connector. Securely transmitting power, data and signals up to Category 6A presents no difficulties with M12 and with variant 4.

The advantage of PushPull connectors (circular or rectangular versions) lies in the tool-free installation. The connectors are simply gripped and attached. The connectors produce an audible “click” indicating that they have been securely locked and correctly mated – while saving up to 75% of installation time. Both connectors feature robust IP protection class 67 and are tested in accordance with fire protection standard EN 45545-2.

Technology report by HARTING