Network devices also play another key role in securing a robust network transmission within the station, between stations to the operations control center, and mobile centers. They include Ethernet switches, extenders, routers, and media converters, and are mostly located inside the stations and by the waysides. According to Louis Chen, Technical Team Manager of Sales Department at EtherWAN Systems, “They must comply with industry standards for railway — EN50121-4, EN50155, and EN61375, which clearly certify some key specifications particularly for electromagnetic protection, endurance of impact, shock, vibration, and temperature, in a railway environment.”
Network devices also play another key role in securing a robust network transmission within the station, between stations to the operations control center, and mobile centers. They include Ethernet switches, extenders, routers, and media converters, and are mostly located inside the stations and by the waysides. According to Louis Chen, Technical Team Manager of Sales Department at
EtherWAN Systems, “They must comply with industry standards for railway — EN50121-4, EN50155, and EN61375, which clearly certify some key specifications particularly for electromagnetic protection, endurance of impact, shock, vibration, and temperature, in a railway environment.”
The most challenging part for Ethernet solutions is to ensure resilience connection by the wayside of the railway. The industrial Ethernet switches support the redundant path topologies, mostly ring topology, along with a resiliency protocol, to minimize the risk of connection breakdowns. “EtherWAN’s proprietary ring self-healing technology can even provide less than 15 milliseconds of fault recovery time,” said Chen. In addition, the managed industrial Ethernet switch should also be able to manage the transmission priority of multiple information whenever there is limited network bandwidth or connection is weak. For instance, it should always prioritize the transmission of emergency/alarm signals.
In addition, in outdoor environments, like tunnels, where waterproof products are considered, Chen also suggests replacing the common RJ45 connector with M12 ones, to resist high electrostatic discharge (ESD) and prevent the cable from going off, for the best reliability in a harsh environment. Chen also pointed out in some countries where there are a high number of lightning strikes, extra surge protection for PoE devices is quite important.
To further ensure reliability, Chen said meeting the common industrial standards might not be enough. He emphasized, “When working in a high-temperature environment, the temperature tested by EtherWAN products and accessories all have to be below and meet the three-year MTBF (Mean Time Between Failure) regulated threshold value, to guarantee their reliability without MTBF compromised.”
PoE devices
With the maturity of the power-over-Ethernet (PoE) technology, managed network switches are now able to provide power to all connected IP devices, such as IP intercoms, IP cameras, IP access control, even digital signage for passenger information boards.
The industry usually provides PoE switches with 15.4/30-watts power per port. However, “in view of the high power consumption from the extra heater or IR for the IP cameras, which are usually located in some bad-lighting environments or harsh weather, we suggest using the PoE switch with 60-watts per port, instead, which provides twice as much power as the IEEE 802.3at standard and is ideal for outdoor surveillance deployment under extreme cold conditions,” said Chen.
Yoda Communications, another specialized Ethernet solution provider, utilizes its strength in telecommunications to deliver multiple network devices for various environments. Long Chang, Associate VP of Sales and Marketing Division at Yoda Communications, further pointed out that the company provides a PoE power meter, a tester to accurately measure the remaining power at the end point where the network device is connected. It provides a handy tool for PoE field installation, and supports IEEE 802.3af, legacy PoE, and 4-pair PoE (60-watts) equipment. This can further measure the power needed for the system.
Chen further added, the company has a special design for its PoE switch, and each PoE port can be manually set for on-off control to efficiently manage the power consumption for each device. With this design, at a wide variety of power capacity, the systems integrators can flexibly design their IP infrastructure using this PoE switch at just-enough power capacity.