DSB Uses 6KQs For 'Ethernet Backbone' In Trains

Danish state rail operator DSB is using 6KQ Ethernet switches from Garrettcom to give its trains an 'Ethernet backbone'. The 6KQ switches realise VLANs for various internal train systems, providing network connections for in-carriage IP-enabled security and surveillance equipment, infotainment systems and passenger-counting technology. The 6KQ met DSB's need for a compact, cost-effective 10-port Ethernet switch with gigabit bandwidth, in a hardened package with the assurance of EN50155 certification for railway applications.

A 6KQ switch is mounted in each carriage and the switches are linked in a bus topology, providing an Ethernet backbone along the length of the train. The switches provide central points in each carriage into which the IP-enabled equipment can be readily connected. The backbone is also connected to a WLAN gateway, responsible for handling the network traffic between the train and the outside world. Network packages are transmitted and received via an antenna installed on the roof of the carriage.

The switches are all powered from an auxiliary 110V DC system, installed through each coach, and are managed using Garrettcom's MNS-6K software, making it simple to realise optimal network traffic for all subsystems. Train and network operators are looking to provide passengers with an improved journey experience, focusing on safety, security and efficiency. Much of this can be addressed with modern CCTV and video-recording technology. CCTV cameras mounted in the carriages and linked to video recorders form an effective surveillance system that acts as a deterrent against crime and anti-social behaviour, including attacks, vandalism and graffiti damage.

The CCTV cameras are linked to the video recorders over Ethernet via the 6KQ switches. Log files of the recorded data are transmitted from the video-surveillance system server to a central office via the WLAN. The WLAN also transmits the train's position information in real time. It also provides passengers with a free internet connection as part of the infotainment system. Ethernet-enabled cameras are mounted in the carriage doorways and register the number of passengers entering and exiting the train at each station.

Not only does this indicate when carriages are full, but the data generated is also being used in statistical analysis to identify passenger trends and behaviour and so help in the planning of improved train schedules. Key in the choice of the 6KQ switch for this application was its ability to be powered directly from the 110V auxiliary supply, eliminating the need for costly voltage converters. The 6KQ also meets the requirements of EN50155, the standard for electronic railroad applications. EN50155 introduces stringent demands for reliability, covering humidity, extended temperature range (-40C to +85C), shock, vibration and power fluctuations.

In addition, EN50155 prohibits the use of fans in train electronics: only passive cooling technologies are permitted. The 6KQ meets all these requirements. In particular, it is sealed to IP53 for dust- and water-resistance and features a unique case design for maximum heat dissipation, eliminating the need for fan cooling. EN50155 as a precautionary measure suggests the use of protective coatings for PCBs in electronic products to counteract corrosive atmospheres that are often present in railroad applications. Garrettcom offers conformal coating as an optional add-on to ensure continuous operation.

The 6KQ is a rugged field switch developed to meet user requirements for small form-factor gigabit Ethernet switches in demanding applications. It offers a maximum of 12 ports and can be configured with user-selected combinations of 10 and 100Mb and gigabit fibre ports of any connector type. Copper port options include 10/100/1000 RJ-45, as well as up to eight 10/100 PoE (power over Ethernet) ports. To meet the needs of demanding industrial Ethernet applications, the 6KQ can handle stressful workload mixtures of high-burst data traffic and priority streaming traffic.


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