WO2008069487A1

WO2008069487A1 - Switched ethernet-based network system and signal processing method thereof for railway signalling system

Info

Publication number: WO2008069487A1
Application number: PCT/KR2007/006047
Authority: WO
Inventors: Jong Gyu Hwang; Hyun Jeong Jo; Jae Ho Lee; Yong Ki Yoon
Original assignee: Korea Railroad Research Institute
Priority date: 2006-12-08
Filing date: 2007-11-28
Publication date: 2008-06-12
Also published as: KR20080052711A; KR100870712B1

Abstract

A network system for railway signaling using a switched Ethernet technology and a signal processing method are provided. The system includes a multi port Network Interface Card (NIC), a redundant switch, and a redundant bus. The multi port NIC connects with a plurality of railway signaling equipments, redundantly transceives the same data, and transceives only normal data among the data. The redundant switch connects to the NIC, switches data using a buffer, and provides the data to a plurality of the NICs connected. The redundant bus transceives data between the NIC and the redundant switch.

Description

SWITCHED ETHERNET-BASED NETWORK SYSTEM AND SIGNAL PROCESSING METHOD THEREOF FOR RAILWAY

SIGNALLING SYSTEM

Technical Field

[1] The present invention relates to a railway signaling system, and more particularly, to a network-based interface system using a switched Ethernet technology, for providing a network that is easily scalable using the switched Ethernet, performing signal processing with high reliability, and performing failure detection and recovery even at the time a failure occurs.

[2]

Background Art

[3] In general, railway signaling systems are vital systems for controlling a speed and route of a train, preventing a collision and a rear-end collision of trains, and finally assuring safety operation of the train. As such railway signaling equipments perform their own function, they are linked to other control equipments, constituting one signaling system.

[4] Because conventional links between railway signaling equipments are currently mostly based on a point-to-point communication type, when maintenance is performed or a new equipment is added, only one control equipment connects with one signaling equipment. Therefore, there is a drawback that upon extension, it costs a lot as well as takes a long time. In order to provide a solution to this, there is needed an effort to network the link between the railway signaling equipments.

[5] A conventional wiring system based on a point-to-point communication method may be more complicated because a communication cable increases in number due to the increasing number of railway signaling equipments. Despite the fact that the links between the railway signaling equipments should be scalable according to need, this salability is difficult to be achieved.

[6] In recent years, as a control device for a railway signaling system becomes electronics, the needs for network-based interface is of much significance. A high reliable system such as railway signaling system requires a network technology that can meet real-time requirements and reliability.

[7] As described above, the links between the railway signaling systems are presently mostly based on the point-to-point communication type. Hence, this causes a difficulty in maintenance at the time new equipments are added. In order to solve this, the interface between railway signaling equipments uses an Ethernet-based technology, not the conventional point-to-point communication technology. This is advantageous of saving a cost of installation and maintenance owing to sharing of transmission media and providing easy salability such as addition of a new equipment; however, may deteriorate a safety and reliability of data transmission because of the sharing of the transmission media. Thus, there is needed a system guaranteeing a stability of data transmission to apply a network technology to the interface between the railway signaling equipments.

[8]

Disclosure of Invention Technical Problem

[9] Accordingly, the present invention is directed to an interface between railway signaling systems using a switched Ethernet-based technology and a signal processing method thereof that substantially obviate one or more of the problems due to limitations and disadvantages of the related art.

[10] An object of the present invention is to provide a network system for railway signaling using a switched Ethernet technology to complement a random characteristics of collision between transmitted Ethernet frames due to inherent Ethernet protocol logics, in which a redundancy architecture is configured to perform a failure detection and recovery upon a failure of Ethernet-based network, thereby providing an interface between railway signaling systems with assurance of high reliability and safety.

[11] Another object of the present invention is to provide a nework system for railway signaling using a switched Ethernet-based method, for providing a high-reliable redundancy network architecture using a dual or quadruple port Network Interface Card (NIC).

[12]

Technical Solution

[13] To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, there is provided a network system for railway signaling using a switched Ethernet technology. The system includes a multi port Network Interface Card (NIC), a redundant switch, and a redundant bus. The multi port NIC connects with a plurality of railway signaling equipments, redundantly transceives the same data, and transceives only normal data among the data. The redundant switch connects to the NIC, switches data using a buffer, and provides the data to a plurality of the NICs connected. The redundant bus transceives data between the NIC and the redundant switch.

[14] In another aspect, there is provided a signal processing method in a network system for railway signaling. The method includes transceiving data, distinguishing reception data, removing failure data, and outputting only normal data in a multi port NIC, and receiving, by a different redundant switch, data from a railway signaling equipment having the NIC, providing the data to an NIC coupled to a different railway signaling equipment, and transmitting the data to the different signaling equipments. [15]

Advantageous Effects

[16] According to the present invention, a stable network system for railway signaling can be configured such that installation is easy, compatibility is excellent, data is processed in real time, and a wiring system is simplified. [17] Also, according to the present invention, the network system for railway signaling using a switched Ethernet technology transceives data and performs a normal operation even when one device or data fails by applying a redundant bus architecture and a redundant switch, thereby making a fault tolerance possible, securing stability, and improving reliability. [18]

Brief Description of the Drawings [19] FIG. 1 is a conceptual diagram illustrating a conventional Ethernet and a switched

Ethernet; [20] FIG. 2 illustrates a construction of a network system for railway signaling using a switched Ethernet technology according to the present invention; [21] FIG. 3 illustrates an example of a construction of a multi port NIC according to the present invention; and [22] FIG. 4 illustrates an example of actually interfacing railway signaling equipments according to the present invention. [23]

Mode for the Invention [24] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to accompanying drawings. [25] It should be noted that only description necessary for understanding an operation of the invention is made and other description is omitted below. [26] The present invention provides a network system for railway signalling using a switched Ethernet technology, for processing data in real time using the switched

Ethernet, improving a reliability of a whole network by configuring a redundancy parallel architecture, and performing failure detection and recovery. [27] Today, an existing Ethernet protocol is the most common network technology for using at offices. If the Ethernet protocol is applicable to a railway signaling system, a network system for railway signaling can be realized effectively at low cost. The existing Ethernet protocol is to stand by during a random backoff time and then perform retransmission when a collision of transmission frames occurs. However, because a transmission delay is impossible to be exactly expected at existing Ethernet, the existing Ethernet protocol cannot secure a hard real-time. Hence, the existing Ethernet protocol cannot be used for an interface between railway signaling systems that requires a higher safety than any other industrial control systems.

[28] The present invention introduces a switching technology into existing Ethernet technology in order to provide a solution to uncertainty for a transmission delay of a transmission frame at the Ethernet.

[29] The switching technology has been developed and applied mainly for office networking, however, an attempt to apply a switch to an industrial network is tending upwards as the switching technology is widely used and a switch cost goes down.

[30] Unlike a given Ethernet, a switched Ethernet operates as if a dedicated virtual line is set between two communication nodes, thus greatly reducing a probability of collision between transmission frames.

[31] FIG. 1 is a conceptual diagram illustrating a conventional Ethernet and a switched

Ethernet.

[32] In the Ethernet of FIG. IA, if a source station transmits a frame, the frame is transmitted to all stations. Thus, the Ethernet has a problem that a collision occurs at a hub because the source station transmits a frame to all stations connected.

[33] In the switched Ethernet of FIG. IB, because a source station transmits a frame only to a destination station, a collision does not occur even in the event of concurrently transmission to several stations. In detail, the switched Ethernet uses a switching technology, thereby preventing a collision from occurring at a switching hub when two or more stations transmit frames to one destination station.

[34] The switched Ethernet checks whether a reception line of the destination station is in use when a frame is received from a transmission line of the source station.

[35] If the reception line of the destination station is not in use, transmission is immediately initiated. Otherwise, if the reception line is in use, the frame is stored in a buffer of FIG. IB connecting to the destination station and waits until the use of the reception line finishes.

[36] If the switched Ethernet receives a plurality of frames having the same destination station, it stores the frames in the buffer of each port of the switching hub of FIG. IB and then, transmits the frames to the destination station in a reception sequence. This method can prevent a collision from occurring at the switching hub.

[37] In order to apply the switched Ethernet used for an industrial network to the railway control network system requiring stability, the present invention uses a hardware redundancy architecture based on a multi port NIC and a switch dual system architecture, thereby improving reliability.

[38] In the network system for railway signaling, "fault tolerance" represents that a failure occurring from any part or module within the system has no influence upon system operation. A fault tolerance system is aim to maintain a normal system operation with no data loss and destruction though any failure occurs.

[39] In general, the network system for railway signaling making much of safety requires the high-reliable fault tolerance system absolutely.

[40] One of key function capable of maintaining fault tolerance is to process always two or more duplicates of data. In detail, if data is generated in an application program, the data is stored in always two memories and then transmitted. The fault tolerance can be kept with no influence upon a different system in such a manner that though data stored in a memory of any module is defective, the data is transmitted with two or more memories continuously kept and normal data is searched through a data comparison at a data receiving side.

[41] The present invention uses a new NIC having a dual or quadruple port

[42] for fault tolerance. The present invention has a plurality of communication

[43] ports and communication lines so as to construct a network system having a

[44] characteristic of fault tolerance.

[45] The present invention provides a stable network system for railway signaling configured to repeatedly transceive the same data using the multi port NIC and redundantly connect a plurality of switches to repeatedly transceive the same data with the multi port NIC. Also, the network system for railway signaling is configured to transceive, by even one station, the same data with the plurality of switches and provide a redundant bus in preparation for the occurrence of an error in a communication line at the time data is transceived.

[46] FIG. 2 shows a schematic construction of a network system for railway signaling using a switched Ethernet technology that can satisfy the above requirements.

[47] Referring to FIG. 2A, each slave station includes a dual port NIC 20. The dual port

NIC 20 transceives the same message through a redundant switch 30.

[48] The switched Ethernet represents a combination of the NIC 20 and the switch 30.

[49] For example, the same message is transceived between a port 1 (Pl) of a slave station

1 and a switch 1 and between a port 2 (P2) of the slave station 1 and a switch 2.

[50] The two switches 1 and 2 transceive the same message with the master 40.

[51] In such a method, the NIC 20, which is one slave station, transceives the same message through a dual port, thereby realizing a stable dual architecture.

[52] Upon the receipt of an erroneous message, the NIC 20 can remove the erroneous message through a message comparison and transceives a normal message. [53] In detail, a reception station outputs a result value using the normal message in cases where there is the erroneous message as a result of comparing two messages received from the switches 1 and 2.

[54] FIG. 2B shows an example of a network system for railway signaling for securing a characteristic of fault tolerance that is more improved through an extension of a multi port into a quadruple port.

[55] Redundant bus architecture maintains a stable system operation because data can be transceived via a normal bus though a communication bus fails.

[56] In a quadruple port NIC 20, each slave station transceives the same message with a redundant switch 30 through two or four redundant buses.

[57] In FIG. 2B, though any one of bus lines 1 and 2 fails, data can be transceived normally because a slave station 1 transceives data with the redundant switch 30 through redundant buses each connecting to a port 1 and a port 2.

[58] In FIG. 2B, the slave station 1 can transceive the same message with one redundant switch 30 since bus lines connecting to the port 1 and a port 3 connect with one redundant switch 30. Thus, the quadruple port NIC 20 can more improve a characteristic of fault tolerance compared to the dual port NIC.

[59] In the present invention, the reason why two redundant switches 30 are applied is to safely process data even though one switch 30 fails upon communication relay between the master station 40 and the slave station 20.

[60] In detail, the slave station 1 transceives data with a different slave station at the port 1 and the port 2 through the switches 1 and 2. Thus, a message can be normally transceived between the slave stations though any one of the switches 1 and 2 fails.

[61] In conclusion, the network system for railway signaling can be kept in safe against a failure occurring from each constituent element and a high-reliable network architecture simply recoverable can be secured by the multi port NIC 20, the redundant bus, the plurality of switches 30, and a failure detection and output data decision algorithm.

[62] FIG. 3 shows an example of a construction of a multi port NIC according

[63] to the present invention.

[64] The network system for railway signaling can simplify a conventional complex wiring system based on a point-to-point communication, provide a solution to a maintenance problem, and provide an advantage of easy scalability.

[65] Thus, the network system for railway signaling using the switched Ethernet technology that is a complement of the conventional Ethernet can lead to greater system performance improvement than the point-to-point communication.

[66] FIG. 3 shows an NIC having a CPU (ATmegal23L) 22 for controlling an Ethernet, a switch 24, and two ports (RS232) 26 that are most compatible with existing railway control equipments. [67] At present, the railway signaling systems mostly have the RS232 port 26 but not an

Ethernet port. [68] The present invention is also applicable to the existing railway signaling systems without system modification by employing the RS232 port 26 of FIG. 3 installed in most of the railway signaling equipments. [69] The multi port NIC of FIG. 3 has four or more ports connecting with the switch 24 and includes a plurality of the RS232 ports 26. The plurality of RS232 ports 26 can be also coupled with the railway signaling equipments. [70] The CPU 22 receives serial data from the railway signalling equipments through the

RS232 port, converts the serial data into an Ethernet frame, and outputs the converted frame to an Ethernet multi port. Alternately, the CPU 22 receives an Ethernet frame through the Ethernet multi port, converts the Ethernet frame into serial data, transmits the converted data to the railway control equipment through the RS232 port. The CPU

26 controls a general operation of the NIC. [71] A process of processing data in the network system for railway signaling is described below with reference to FIGS. 1 to 3. [72] First, the master station 40 transmits data. The different redundant switches 30 each receive the same data from the master station 40 and provide the data to the NIC 20 coupled with the plurality of railway signaling equipments. [73] The plurality of NICs 20 each transmit data, which is a result value received from the railway signaling equipment, to the different redundant switches 30. The redundant switches 30 each provide reception data to the master station 40 of the network system for railway signaling. [74] The NIC 20 receives data at the multi port, removes fail data by comparison, and outputs only normal data. [75] FIG. 4 illustrates an example in which railway signaling equipments are actually interfaced using a multi port NIC, a switch, and a dual communication bus. [76] In FIG. 4, two switches 20, a plurality of dual port NICs 30, and railway control equipments 50 connect with each other. FIG. 4 shows an example of a connection in which the railway control equipments 50 connecting to the dual port NICs 30 are a

Local Data Transmission System (LTDS), maintenance equipments, and an Electronic

Interlocking System (EIS) equipment. [77] A network is stably established because one dual port NIC 30 transceives the same data with two switches 20 and transceives the data with the railway signaling equipment 50 connected. [78] FIG. 4 shows a railway signaling system using the dual port NIC 30, but a more stable and high reliable network can be built in cases where a railway signaling system is established using the quadruple port NIC.

[79] Even when the switch, the input/output port NIC, or the transmission bus fails, the network system for railway signaling can perform a stable operation in the railway signaling equipment using the redundant switch 20, the multi port NIC 30, and the redundant multi transmission bus. Hence, the high reliable network system for railway signaling having the characteristic of fault tolerance is established.

[80]

Industrial Applicability

[81] According to the present invention, a stable network system for railway signaling can be configured such that installation is easy, compatibility is excellent, data is processed in real time, and a wiring configuration is simplified.

[82] Also, according to the present invention, the network system for railway signaling using a switched Ethernet technology transceives data and performs a normal operation even when one device or data fails by applying a redundant bus architecture and a redundant switch, thereby making a fault tolerance possible, securing stability, and improving reliability.

[83] While the present invention has been described and illustrated herein with reference to the preferred embodiments thereof, it will be apparent to those skilled in the art that various modifications and variations can be made therein without departing from the spirit and scope of the invention. Thus, it is intended that the present invention covers the modifications and variations of this invention that come within the scope of the appended claims and their equivalents.

Claims

[1] A network system for railway signaling using a switched Ethernet technology, comprising: a multi port Network Interface Card (NIC) connecting with a plurality of railway signaling equipments, redundantly transceiving the same data, and transceiving only normal data among the data; a redundant switch connecting to the NIC, switching data using a buffer, and providing the data to a plurality of the NICs connected; and a redundant bus for transceiving data between the NIC and the redundant switch.

[2] The system of claim 1, wherein the NIC comprises: a dual or quadruple input/output port connecting with the switch; a plurality of RS232 ports connecting to the plurality of railway signaling equipments; and a Central Processing Unit (CPU) for controlling and converting data transceived through the input/output port and the RS232 ports.

[3] The system of claim 1, wherein the NIC couples the plurality of railway signaling equipments through the redundant switch.

[4] A signal processing method in a network system for railway signaling, the method comprising: transceiving data, distinguishing reception data, removing failure data, and outputting only normal data in a multi port NIC; and receiving, by a different redundant switch, data from a railway signaling equipment having the NIC, providing the data to an NIC coupled to a different railway control equipment, and transmitting the data to the different signaling equipment.

[5] The method of claim 4, wherein the multi port NIC has an RS232 port to couple with the railway signaling equipment, and wherein upon receiving serial transmission data from a railway signaling equipment through the RS232 port, the multi port NIC converts the serial transmission data into an Ethernet frame and outputs the converted Ethernet frame to an Ethernet multi port and upon receiving an Ethernet frame through the Ethernet multi port, the multi port NIC converts the Ethernet frame into serial data and outputs the converted serial data to a railway control equipment through the RS232 port.

[6] The method of claim 4, wherein the network system for railway signaling processes data through a redundant communication bus.