The data train keeps chugging along - CompactPCI systems utilized in railway operations

2When the first steam engine rolled along the tracks, people marveled at the innovation of the machine, the technology, the possibilities. As traffic on the rails grew, it became necessary for a more intricate communication system to be in place to avoid collisions, ensure travelers arrived on time, and manage the loads of freight increasingly seen on the railways. Enter embedded computing subsystems, with the ability to manage the vast amounts of data being generated to ensure proper, safe functioning of the railways. These systems not only manage the functions of each train car in modern railway operations, but also help control communications to ensure a safe means of transportation for both those working for the railway as well as those using it for travel. And with the growth of mobile networks, today's computing systems for railways also need to provide data access down to the individual passenger.

Whether transmitting a train’s location back to the central station or providing an updated timetable to a traveling passenger, a railway system relies on accurate, secure data transmission to ensure proper operations. Wireless data transmission may seem simple enough: Essentially, an access point along the track makes an electronic connection to the Internet, the phone network, and other services inside a rolling train (railroad, cable car, underground). But the large amounts of data being moved requires high-speed transmission with subsystems that can withstand rigorous environments as the train rolls down the track.

Reliable transmission of wireless data in a fast-moving means of transportation is considerably more difficult than in a stationary or slow-moving one. However, improved ruggedization incorporated into cost-effective CompactPCI Serial-based systems has enabled railway systems to meet the growing data demands of both railway operations and passenger convenience.

Technology evolves

The original CompactPCI specification, based on the parallel PCI bus system, proved itself in the area of 19” solutions due to its modularity, maintainability, and robustness. The new CompactPCI PlusIO and CompactPCI Serial specifications carry these same benefits, while incorporating a modern serial architecture.

This means PCI Express, SATA, USB, and Ethernet are included on the bus backplane, yet all three specs maintain the same 19” mechanics as well as maintain a dedicated system slot and passive backplane for backward compatibility be-tween the two newer specs and the legacy CompactPCI. CompactPCI PlusIO is the link between CompactPCI and CompactPCI Serial, providing a migration path from old systems that need to incorporate newer, serial technologies.

What makes CompactPCI Serial different from its relatives is the simple fact that it is based solely on serial technology; the parallel bus no longer exists in pure CompactPCI Serial systems. Interesting to note is that neither CompactPCI Serial nor CompactPCI PlusIO need switches and bridges. CompactPCI Serial does, however, use a configuration of one system slot and up to eight peripheral slots, and moves from CompactPCI PlusIO’s simple star architecture to full mesh for Ethernet functions.

CompactPCI Serial uses a new rugged connector with a signal density of up to 184 pin pairs (on 3U) and transmission frequencies of 12 Gbps, exponentially increasing the data throughput and processing capabilities of CompactPCI-based systems. Combined with the other advantages inherent in this technology platform, including robustness and modularity, it proves very useful for the reliable wireless communications needed in the railway industry.

Convenience for passengers

CompactPCI Serial is equipped with all the interfaces necessary to make wireless connections from the rest of the world to the passenger and it supports high-speed data transfers. These types of embedded systems can be used in passenger information systems as content servers or multimedia access units, as well as in passenger and train surveillance for the recording and management of camera data and also for ticketing. They can be combined with diagnosis, maintenance, and service functions for overall control as well, offering a well rounded, easily managed computing system.

Additionally, CompactPCI Serial systems for passenger surveillance enable easy configuration of complex SATA, RAID, or NAS systems for recording camera data. Modern processors support up to eight SATA channels used to control eight robust, hot-pluggable hard-disk shuttles via a standard bus backplane.

Infotainment computers depend on flexible interfaces to communicate to other computer units onboard the train and to the outside world. CompactPCI Serial systems offer up to eight peripheral slot cards (and more using bridges) that can simply be plugged into the system for any desired I/O function and with hot swap support. These may be additional UART, USB, and Ethernet interfaces as well as multimedia connections for several screens and audio on/off, fieldbus connections from CAN bus up to railway-specific MVB and WTB, or switches and gateways between the train bus, wagon bus, and higher-level Ethernet communication.

CompactPCI Serial carriers for PCI Express Mini cards and combined SIM card slots can cover the whole world of high frequency requirements – WLAN, UMTS, GPS, GSM, HSDPA, LTE – up to the railway-specific GSM-Rail. In one current installation, Internet access, train surveillance, and the communication between the wagons are controlled via satellite. A single CompactPCI system houses three independent computer units on separate backplanes and with separate power supplies:

  • A satellite system with three CPU cards
  • A content server with one CPU card and a side card for the RAID system
  • A storage server with four CPU cards

Safe operation

For railway functions that rely on safety, ranging from train control, train protection and control technology, to driverless operation in Automatic Train Operation (ATO) systems, CompactPCI Serial is a worthy platform. Sub-computers on separate backplanes, each with an identical setup of a CPU board, I/O functions, and a PSU of their own, are built into the same rack or distributed over several racks to be connected as redundant, complete systems that monitor each other. Most communicate via Ethernet – again, relying on wireless data transmission for effective operation.

Mass transit vehicles are being equipped with driverless systems more often to increase travel speeds and frequency, lower energy consumption, and increase stopping precision at a station. ATO computers onboard the train are typically based on modular systems because they control a multitude of functions (status data continuously sent to the control center, capture of data from the wayside sensors, etc.) and communicate with wayside equipment. The flexibility and scalability of CompactPCI Serial-based systems prove these platforms to be extremely efficient implementations.

In one driverless underground application, up to 500 mobile and stationary control and management systems are needed to monitor the train on a line. In this case, the control and monitoring system provides a response channel that allows the permanent transmission of status data of the vehicles back to the control center. Reliable wireless communication is key to system operation and train control and is carried out using CompactPCI Serial technology.

Train cars

For most systems, a multitude of single, yet interconnected, functions for vehicle control that generate critical data are often an integral part of the embedded system. These can include the control of the train drive, traction and brakes, the clutches, gearboxes, and anti-skid system, as well as increased braking power through sanding.

In a vehicle handling passenger traffic, there is also the control of the doors, the lighting system, the air conditioning, and possibly the tilting system.

Vehicle operation

Apart from the physical vehicle itself, there are many management functions that relate to the actual operation of the car. In the driver’s cabin, you can find display systems for speed, tank filling level, SIFA, GSM, as well as data loggers. The motor starter, the pre-heating system, and the traction cooling system can be connected to the main supply, with the electric equipment and the battery connected to an auxiliary supply. There are also various systems for train safety operating in conjunction with the wayside train guidance systems.

Control centers

Computer-based operation management systems control the exchange of these volumes of information and facilitate communication between the vehicles operating on the tracks, the control center by the wayside, and stations along the route.

CompactPCI Serial-based subsystems can manage all data transfers between individual trains and the railway company’s central servers via UMTS and/or WLAN, for updates to pending seat reservations, information about the current trip, including potential connections and other services. By incorporating GPS functionality, current trip information is readily available to passengers within the train at any given moment as well (Figure 1).

Figure 1: As the importance of electronics grows in railway communications, cost-effective and scalable solutions become even more critical.

Full steam ahead

Wireless communications are integral to both train operations and passenger convenience. Today’s embedded computing systems used in railway operations must stand the test of time operating under harsh conditions, while handling the increasing amount of wireless data required for effective operation. CompactPCI Serial offers improved capabilities for broader functionality and safety.

Barbara Schmitz is Chief Marketing Officer at MEN Mikro Elektronik.

MEN Mikro Elektronik GmbH

[email protected]