1Pierre Zuber, Bombardier Transportation, Pittsburgh, USA The IEC / UIC / IEEE Train Communication Network for time-critical and safe on-board communicationPierre Zuber, Bombardier Transportation, Pittsburgh, USAHubert Kirrmann, ABB Corporate Research, Baden, Switzerland• What is the Train Communication Network ?• Wire Train Bus• Multifunction Vehicle Bus• Real-Time and Deterministic data transfer• Message Services• Available and Safe Architecture• Standardization of Vehicle data• ROSIN -TrainCom - ERRI projects• Conclusion
2The IEC Train Communication Network Train BusVehicle BusVehicle BusVehicle Businternational IEC and IEEE standard for data communication aboard rail vehicles.developped by IEC TC9 (Electric Traction Equipment) with the collaboration of:railways operators:manufacturers:Chinese RailwaysAlstom (FR, GB, BE)DB (Germany)Bombardier - ADtranz (CH, DE, SE)FS (Italy)ANSALDO (IT)JRRI (Japan)CAF (ES)NS (Netherlands)Firema, Ercole Marelli Trazione (IT)RATP (France)Mitsubishi (JP)SNCF (France)Siemens (GB, DE)PKN (Poland)UIC (Union Internationale des Chemins de Fer)Toshiba (JP)UITP (Union Internationale des Transports Publics)Westinghouse Signals (GB)
3Objectives of the TCNDefine interfaces between programmable equipment's,with the aim of achieving plug-compatibility:1) between vehicles2) between equipment aboard a vehicle:
4TCN’s network architecture train busnodenodenodevehicle busdevicesvehicle busvehicle busvehicle busThe Train Communication Network consists of:• a Train Bus which connects the vehicles (Interface 1) and of• a Vehicle Bus which connects the equipments within a vehicle (Interface 2).
5standard communication interface between vehicles Wire Train Bus (WTB)standard communication interface between vehiclesnodenodenodemain applicationopen trains with variable composition such as UIC trainscovered distance860 m, 22 vehicles (including passive, retrofit vehicles)number of nodes32 (some vehicles may have more than one node)data rate1 Mbit/s over shielded, twisted wiresresponse time25 ms cycle timeinaugurationassigns to each node its sequential address and orientationreferencesthousand of vehicles in daily operationconformanceERRI (European Rail Research Institute, Utrecht, NL)
6remote, multiple traction,... vehicle control: WTB trafficdiagnostic computertrain attendantdriver's cablocomotivecoaches for destination Ycoaches for destination Xdriving coachVehicles of different types communicate over the train bus for the purpose of:1)telecontroltraction control:remote, multiple traction,...vehicle control:lights, doors, heating, tilting, ...2)diagnosticsequipment failures,maintenance information3)passenger comfortnext station, delays, connections.seat reservation
7Fritting (voltage pulses) is used to overcome oxidation of contacts WTB wiringWiring over shielded twisted pairs, jumpers or automatic couplers between vehicles.Fritting (voltage pulses) is used to overcome oxidation of contactsSince there are normally two jumpers, wiring is by nature redundantUIC specified a data cable ( 18 pole) compatible with the 13-pole UIC connectorWTB cableredundant nodesvehiclevehiclejumperLine ALine Bclassicclassic2WTB node11WTB nodeWTB node2UIC linesUIC linesjumperLine BLine Atop viewUIC data cable
8MVB - the standard vehicle bus Why standardize the vehicle bus ?MVB is important for:• small equipment manufacturers(reduced bus diversity)• vehicle assemblers(wider choice of suppliers, commissioning)• railways operators(less maintenance and spare parts)All MVB devices are interoperable: there exist no incompatible optionsMVB paves the way to interchangeability of equipment and simplified maintenance.
9Multifunction Vehicle Bus (MVB) “standard interface for plug-compatibility between equipment on-board vehicles”radiopower linecockpitTrain BusdiagnosticsMultifunction Vehicle Busbrakespower electronicsmotor controltrack signalsdata rate1,5 Mbit/sshortest period 1 msdelayshielded twisted pairs and optical fibersmediaup to 255 programmable stationsnumber of stationsup to 4095 simple sensors/actuatorsstatustens of thousand of vehicles in servicetime distributionclock synchronization within a few microsecond
11The MVB can span several vehicles: MVB wiringThe MVB can span several vehicles:Train BusrepeaternodeMVBdevices with short distance busdevicesThe number of devices under this configuration amounts to 4095.The MVB can serve as a train bus in trains with fixed configuration, up to adistance of 200 m (EMD medium) or 2000 m (OGF medium).
12TCN combinations Open train WTB (standard) MVB MVB 0 node 860 m (without repeater)WTB(standard)MVBMVB0 node0 vehicle bus1 vehicle bus2 vehicle busses(conduction vehicle)(standard MVB)(standard & not)Connected train setsWTBMVB(standard)1 vehicle busnot standard vehicle bus200 m (without repeater)Closed trainMVB or otherMVBMVB(not standard)1 vehicle bus0 vehicle bus200 m without repeater
13TCN protocolsboth the train and the vehicle bus use the same protocols- deterministic (periodic) transmissionof time-critical process variables- reliable, demand-driven messages inpoint-to-point andmulticastVariablesMessagesApplicationApplicationInterfaceInterfacecommonPresentationNetworkManagementSessionTransportNetworkMultifunctionWire TrainotherVehicle BusBusbus
14Train and Vehicle Bus Operation State VariableMessagesState of the PlantEvents of the PlantResponse at human speed: > 0.5 sResponse in ms... commands, position, speed• Diagnostics, event recorder• Initialization, calibrationPeriodic TransmissionOn-Demand TransmissionSpurious data losses will be compensated at the next cycleFlow control & error recovery protocol for catching all eventsBasic PeriodBasic PeriodPeriodic DataeventtimeSporadic DataSporadic datadeterminism is the condition for safe and available operation
15WTB and MVB: Integrity and availability principles Both WTB and MVB comply with IEC integrity (HD = 4 on TWP, 8 on fiber)A study at Carnegie Mellon University fully confirmed TCN’s integrity.The TCN architecture allows to build a network without a single point of failure.Duplicated physical layer is the default, single line is also possible.
16Further standardization TCN laid the ground for standardization of data interchange not only betweenvehicles but also between vehicle and ground (signaling) and radio links
17UIC (International Railways Union) train data Electrical and data link interoperability is necessary, but not sufficient for interoperabilityOnce vehicles are able to communicate, they exchange their identification and capabilities:e.g.“I am a traction vehicle, my weight is 50 T, my length 23 m,….“I support diagnostic data, passenger information, multiple traction,…”The “mapping server” in each executes the protocol for cross-identification of the vehiclesTo ensure “plug-and-roll”, UIC defined all traffic on the WTB:UIC556vehicle dataUIC557diagnostic dataUIC647traction dataUIC176passenger infooperator-specificUIC556 cross-identification, process and message data formatsIEC / IEEE 1473 train and vehicle bus, process and message protocols
18To this purpose, safety protocols on top of TCN have been developed ETCS - EurocabMVB is used as the vital on-board bus for Eurocab (European Train Control System).To this purpose, safety protocols on top of TCN have been developedDataClockVitalRadioLoggerComputerMVBMan-Speed andBrakeMachineTrackBaliseDistanceTractionInterfaceInterface(s)InterfaceMeasurementInterface
19Safety protocols were developed for 2/3, 1/2 or coded processors, Safe ArchitectureVital and non-vital devices of different origin can interoperate over the same MVB.Single channel, dual redundant and triple redundant devices can interoperate.Safety protocols were developed for 2/3, 1/2 or coded processors,provide time-stamping, authentication and value check over cyclic services.codeddiversetriple modularand/orand/ormonoprocessorprogrammingredundancyintelligentABABABCdevices(applicationFcFcFF2F1F2FFF1programs)untrusted busdumb devices(no applicationprogramming)and/orand/orsimplex sensor/actorduplicated sensor/actortriplicated sensor/actor
20ROSIN - European Program air conditioningpowerlightdoorsbrakesDevice: Door controlMade by: WestinghouseYear: 1995Revision: 1998 May 19Parameters: position, status, indication, ......Maintenance messages:....1996 Jun 25 10:43 23" low air pressureUniversal Maintenance Tool1996 Jun 26 10:55 09" emergency open1996 Jun 26 11:01 17" manual reclose....This multi-year (and multi-million $) project of European Union based on TCN.It defined data interchange for passenger vehicles, freight trains, radio links,…This work supported the parallel standardization in UIC 556 / 557
21RoMain - Rosin Maintenance Remote web access over radio was demonstrated on the Eusko trainoperatorsmanufacturersremoteInternet ExplorerNetscapeRoMain clientsADtranzserverERRIserversAnsaldoSecure TCP/IPserverNetworkROSIN serverradio proxyRoGatenodenodeBus ABus ABus B
22IEEE standardisationThe IEEE Rail Transit Vehicle Interface Standard Committee influenced TCNWG1 adopted TCN as IEEE 1473 Type T and defined interoperation with foreign components.WG9 is working on information interchange standards and collaborates with UICWTBWTB nodeother busLVBMVBMLMVBMVBstationgatewayAdministratorstationMVBLSBOperation of mixed systems in the USA showed the importance of strict definition of interchanged data and how money spared by off-the-shelf is wasted in costly adaptations
23TRAINCOMTrainComThe successful ROSIN project was followed by another European project: TrainCom.TrainCom considers in particular:- locomotive interoperability (multiple traction) in collaboration with UIC 647- GSM radio linksMORANEERTMS kernelTrainCom
24AcknowledgementsTo all engineers of ABB, Adtranz, AEG, Alstom, Duagon, ERRI, Firema, I.PRO.M, Siemens,…To the railways people in UIC which dedicated years of work in the standard groups
25TCN source code is available on www.traincom.org Conclusion•TCN imposed itself as the standard communication network in railways•UIC did a great job in the definition of the application data, the industry couldreadily support this effort in the ROSIN and TrainCom projects. IEEE RTVISCWG9 has adopted UIC 556 as the basis for IEEE 1473-T train busdata communication.•TCN is a suite of communication and application protocols tailored for therailways, not just a field bus.•TCN is an open technology - there are no royalties, patents or copyrights. Anyone can build a TCN according to specs - chips are available.TCN source code is available on•TCN (MVB) has been adopted in electrical substations and printing machines capitalizing on the work done by the railways community.•Work on TCN is not finished - UIC, TrainCom and IEEE RTVISC WG9 are at work…
27Why not Ethernet instead of WTB ? Ethernet uses a star topography (point-to-point to a hub). A train has a linear topography.Ethernet would need special hubs which recognizes right and left in each vehicle.Hubs would be a single point of failure, a battery failure in a vehicle would stop the bus.Hubs cannot be used for freight vehicles (no battery in the vehicles).In spite of providing 100 times more speed then WTB, Ethernet real-time response is not better, because of overhead associated with transmitting numerous, small data items.Ethernet is just a level 2 (up to data link) specification mutual identification of vehicles are yet to be developed.IP and UDP are too slow for time-critical data (traction data), reconfiguration in case of failure takes several minutes.there is no alternative to WTB as a train bus
28Process Data transmission by source-addressed broadcast Phase1:The bus master broadcasts the identifier of a variable to be transmitted:subscribedsubscribeddevicedevicesubscribed devicesbusdevicesmastersinksourcesinksink(slaves)busvariable identifierPhase 2:The device which sources that variable responds with a slave framecontaining the value, all devices subscribed as sink receive that frame.subscribedsubscribeddevicedevicesubscribed devicesbusdevicesmastersinksourcesinksink(slaves)busvariable value
29The concept of real-time, distributed database cycliccycliccycliccyclicalgorithmsalgorithmsalgorithmsalgorithmscyclicapplicationapplicationapplicationapplicationpoll1234bussourcemasterportPortsPortsPortsPortsTrafficPeriodicListStoressinksinkportportbusbusbusbusbuscontrollercontrollercontrollercontrollercontrollerbusport addressport dataBus traffic and application cycles are asynchronous to each other.Bus and applications interface through a shared memory, the traffic store.Cyclic bus traffic blends with IEC style of programming
30Hard Real-Time and Soft Real-Time 1 element2 elements in seriese.g. vehicle bus and train buse.g. vehicle busprobabilityprobabilityt1t2t1t2t4t3t2+t4hard(cyclic)bounded !response timet1+t3still bounded !t3probabilityt1t2t1soft(event-driven)response timet1+t3unbounded !unbounded !Determinism is not a bus, but a system issue.4
31Locomotive 465 Frame Occupancy % periodic timeAlready today, long frames dominatenumber of devices: 37 ( including 2 bus administrators)37 of 16 bits65 frames of 64 bits30 frames of 128 bits18 of 3249 frames of 256 bitsoccupancy is proportional to surfacetotal = 92%period16 ms32 ms64 ms1282561024