JP2003092587A - Network system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure real time property in communication between networks. SOLUTION: This network system includes LANs B1 and B2 respectively provided with a local controller and a plurality of communication nodes and includes a gate way apparatus F for controlling communication between the LANs B1 and B2 by connecting both of them. The gate device F provided with a data reception part DA1 R which receives data transmitted from the LAN B1 to the LAN B2 and which is provided with a first buffer, and a data transmission part DA2 S which is provided with a second buffer and which transmits data written in this second buffer to the LAN B 2. When data is written in the first buffer, the data written in the first buffer is overwritten on the second buffer without regard to whether data in the second buffer is transmitted to the LAN B2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a network system including a plurality of networks and a gateway device for controlling communication between the networks, and more particularly to a network system constituting an automatic train control device for railways. .

[0002]

2. Description of the Related Art Conventionally, there is known a network system including a plurality of networks to which terminals such as local controllers for transmitting and receiving signals are connected respectively, and a gateway device for controlling communication between these networks. In such a network system,
The gateway device, when transmitting a signal from one network to another network, a first buffer to which data received from one network is written,
Second data to which the data written in the first buffer is transferred
And the buffer written in the second buffer, and the data written in the second buffer is transmitted to the other network.

If new data is written in the first buffer before the data written in the second buffer is transmitted to another network, the second data is written in the oldest order.
Of the old data, and the oldest data is transmitted to the other LAN.

[0004]

In the case of the above conventional technique, even if the gateway device receives new data to be transmitted from one network to the other network,
If old data remains in the second buffer, the older data will be transmitted. For this reason, old data will flow to the other network, and the real-time property of the data will be impaired. For network systems in which real-time property is important for input or output from the peripheral device of the node connected to the network, The above conventional technique cannot be applied.

An object of the present invention is to secure real-time property in communication between networks.

[0006]

As a means for solving the above problems, the present invention provides a gateway device constituting a network system with a data receiving section having a first buffer and a second buffer. A data transmission unit, the data reception unit receives data to be transmitted from one network to the other network from the one network, writes the data in the first buffer, and the data transmission unit in the second buffer. The gateway device is configured to transmit the written data to the other network, and the gateway device changes the data written in the first buffer to the data written in the second buffer. It is configured to be transferred to the second buffer and overwritten regardless of whether it has been sent to the second buffer.

Thus, if the next data arrives before the data written in the second buffer is transmitted to the other network for some reason, the transmission of the previous data is stopped and the newly arrived data is reached. Since it is transmitted to the other network, the latest data always flows on the network, and the real-time property of the network system is improved.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention.
1 shows a configuration of a network system in which a plurality of LANs are connected. The illustrated network system includes local area networks (hereinafter referred to as LANs) B1 and B2, and L.
Local controllers A1 and A2 connected to ANB1 and B2 respectively, and a plurality of communication nodes C1 to Cn and E1 to En also connected to LANB1 and B2 respectively.
And a gateway device F for connecting LANB1 and B2
And are included.

The local controllers A1 and A2 cyclically transmit data frames with function codes, fixed frame lengths, and fixed packet allocation frames to LANB1 and B2.
2 has a function to issue to each. For example, the local controller A1 includes a function code indicating that the communication is addressed to the LANB2 (for example, train position information transmitted by the local controller A1).
2 is a data frame in which data addressed to the communication nodes C1 to Cn is provided, and a data frame in which data addressed to the communication nodes C1 to Cn is written, a local controller A2 to LAN
A data frame having a function code indicating that the communication is addressed to B1 and in which no data is written is repeatedly transmitted to the LANB1 in a predetermined order.

Similarly, the local controller A2 also has an LA
The communication node E1 includes a function code indicating that the communication is addressed to the NB1, the data frame in which the data addressed to the local controller A1 is written, and the function code indicating that the communication is addressed to the communication nodes E1 to En. A data frame in which data for En is written, a data frame in which no data is written, including a function code indicating that the communication is from LANB1 to local controller A2 (for example, train position information transmitted by local controller A1) Are repeatedly transmitted in a predetermined order to the LANB2.

The function code may indicate a destination.

The gateway device also includes a data receiving unit D _A1R having a first buffer for receiving data to be transmitted from LANB1 to LANB2, and a second buffer, and stores the data written in the second buffer. LAN
Data transmission unit D _A2S for transmitting to B2, and LANB
Data receiving section D _A2R having a first buffer for receiving data to be transmitted from the second buffer to the LANB1, and a data transmitting section D having a second buffer and transmitting the data written in the second buffer to the LANB1. _{And A1S} . The gateway device also has a function of transferring the data written in the first buffer to the second buffer.

Each of the LANs B1 and B2 has a ring structure in which a local controller, a communication node, and a gateway device are sequentially connected. The local controller transmits a data frame to be transmitted to a downstream network, and the communication node, Each of the gateway devices is configured to transmit the data frame received from the upstream network to the downstream network. When the local controller receives the transmitted data frame from the network on the upstream side, the local controller performs processing corresponding to the received data frame and then deletes it (does not return to LANB1).

In the system of FIG. 1, the gateway device F receives the data frame on the LANB1, determines the function code of the data frame, and uses the data to be transmitted to the LANB2 (for example, train position information transmitted by the local controller A1). A data frame with a function code indicating that there is is detected. A data frame without a function code indicating that it is data to be transmitted to LANB2 is directly returned to LANB1. LANB2
For a data frame with a function code indicating that it is data to be transmitted to the data frame, the data of the packet of the data frame is written to the first buffer of the data receiving unit _DA1R , and the data frame itself is LA.
Returned to NB1. This data is immediately transferred to and written in the second buffer of the data transmission unit D _A2S .

On the other hand, the data transmission unit D _A2S is a LANB
2 has received a data frame and discriminates the function code of the data frame, and has a function code indicating that the communication is from LANB1 to the local controller A2 (for example, train position information transmitted by the local controller A1). Detect unwritten data frames. Other data frames are LANB2 as they are
Returned to. The data transmission unit D _A2S writes the data of the second buffer to a portion (packet) where the data of the detected data frame is not written,
Send (return) to ANB2.

The gateway device F transfers the data (for example, train position information transmitted by the local controller A1) transmitted to the LANB1 from the local controller A1 to the local controller A2 (that is, LANB2) by the above-described procedure to the LANB2. .

Further, in the gateway device F, new data is transferred to the data transmitting unit D _A2S , that is, even before the data written in the second buffer is transmitted to the LANB2. First of _A1R
When the data is written in the buffer, the data is written over the second buffer of the data transmission unit D _A2S . That is, the data before being overwritten is LA
New data that is erased and overwritten without being transmitted on NB2 is transmitted on LANB2. As a result, the latest data always flows on the network, improving the real-time property of the network system, and a network system using a plurality of LANs in which real-time property is important for input or output from the peripheral device of the node. Will be applicable to.

A second embodiment in which the present invention is applied to an automatic train control system will be described below. The structure of this embodiment is shown in FIG. The network system shown is
ATC logic units R1 and R2 of triple fail-safe configuration, which are terminals for cyclically issuing a frame with a function code, a fixed frame length, and a fixed packet allocation frame, and an AT
A dual loop network (hereinafter ATC-
(Called LAN) S1, S2 and ATC-LANS1, S2
A plurality of communication nodes (not shown) arranged on the upper part 2 and a gateway device T of a dual system fail-safe configuration, which is connected to the ATC-LANS 1 and S2 and exchanges information between the ATC logic units R1 and R2. It is configured to include.

The ATC-LANS1 and S2 are laid along a railroad track, and are ATC-LANS1 and ATC-LAN.
S2 is connected via the gateway apparatus T.
At each railway station, a communication node (communication control device) is placed on the ATC-LAN, and the communication node forms a transmission path with a transmitter / receiver group via an equipment room network. Each transceiver is connected to each track circuit of the line through a protector and a wayside cable. That is, the ATC logic unit is ATC-LA.
It transmits signals to and receives signals from each track circuit on the line through the N, communication node, equipment room network, transceiver, protector and wayside cable.

ATC-LANS1 and S2 are both
The ATC logic unit, the communication node, and the gateway device are connected in order to form a ring structure. The ATC logic unit transmits the data frame to be transmitted to the ATC-LAN (network) on the downstream side. ,
In each case, the data frame is received from the upstream network, the function code is determined, and the necessary data is extracted.
Alternatively, the data frame added and received is transmitted (returned) to the network on the downstream side.
When the ATC logic unit receives the data frame transmitted to the downstream network from the upstream network, it extracts the necessary data from the received data frame,
Erase (do not return to ATC-LAN).

The ATC logic unit is a source and a receiver of reachable track circuit information and train protection information. The data such as reachable track circuit information and train protection information generated by the ATC logic unit R1 arrives at the adjacent ATC logic unit R2 via the dual fail-safe non-failsafe gateway device T, and the received contents are validated. Sex is checked. Data such as reachable track circuit information and train protection information are always sent to the body of the message containing serial number data whose value changes every time in order to guarantee that the latest information is always transmitted regardless of whether the control contents have changed. , Software generated CRC (cyclic code)
Is given. This allows the ATC logic unit to fail-safely detect a failure or transmission error in which old state information is accumulated in the intermediate non-fail-safe device.

FIG. 3 shows a path of output data to the adjacent ATC logic section in the concrete system configuration. ATC logic unit R1
Sends data such as train reachable track circuit information and train protection information to the ATC-LANS1 and sends the ATC logic unit R2 via the gateway device T and ATC-LANS2.
Send to.

The gateway device T is ATC-LANS.
Data receiving unit D _{R1R for extracting} data from _A.
-LANS2 sends the data to the data transmitting unit _{D R2S}
And a data receiving section _{DR2R for} taking out data from the ATC-LANS2 and a data transmitting section _DR1S for sending out data to the ATC-LANS1. The data receiver D _R1R includes a first buffer for writing data, and the data transmitter D _R2S includes a data receiver D _R1S.
A second buffer into which the data transferred from the first buffer of _R1R is written is provided. Similarly, the data receiving unit D _R2R includes a first buffer for writing data, and the data transmitting unit D _R1S includes the data receiving unit D _R2R.
The second buffer into which the data transferred from the first buffer is written.

The data receiving unit D _R1R is an ATC-LAN.
The data frame is received from S1, the function code of the received data frame is discriminated, and the data frame with the function code indicating that it is the data to be transmitted to the ATC logic unit R2 is detected. When a data frame with a function code indicating that it is data to be transmitted to the ATC logic unit R2 is detected, the data of the packet of the data frame is written in the first buffer. The data written in the first buffer is immediately transferred to the second buffer of the data transmission unit D _{R 2S} and written therein. Each received data frame is transmitted (returned) to ATC-LANS1 again.

On the other hand, the data transmission unit D _R2S has the ATC-
A data frame is received from LANS2, the function code of the received data frame is determined, and ATC-LANS
1 (that is, the ATC logic unit R1), a data frame with a function code indicating that the data is received is detected. The data frame to which the function code indicating that the data is received from the ATC-LANS1 is not added is directly returned to the ATC-LANS2. The data transmission unit D _R2S is ATC-LANS1 (that is, A
When a data frame with a function code indicating that it is data to be received from the TC logic unit R1) is detected, the data in the second buffer is written into an empty packet at a predetermined position of this data frame, and ATC- Send (return) to LANS2. The ATC logic unit R2 is ATC-LA.
When this data frame is received from NS2, the function code recognizes that it is data transmitted from the ATC logic unit R1, and performs necessary processing.

The gateway device T includes a data receiving section D.
_When the data is written in the first buffer of _R1R , the data of the first buffer is written _regardless of _whether the data written in the second buffer of data transmission unit D _R2S has already been transmitted to ATC-LANS2. _Is transferred to the second buffer of the data transmission unit _DR2S and overwritten. That is, the data before being overwritten in the second buffer is erased without being transmitted to ATC-LANS2, and the overwritten data is transmitted to ATC-LANS2.

Data receiving section D _R2R and data transmitting section D
_R1S is from ATC-LANS2 to ATC-LANS1
The data transmitted to the data receiving unit D
Performing operations similar to those of the _R1R and the data transmission unit _{D R2S.}

As described above, the ATC-LAN of the automatic train control device is laid along the railroad track, and, for example,
Each ATC logic unit recognizes the train position based on the information obtained from the track circuit via the transceiver. The recognized train position information is also transmitted to the ATC logic unit of the adjacent ATC-LAN via the gateway device, but in order to maintain safe operation, the train position needs to be transmitted in real time as much as possible. Two adjacent ATC-
The cycles of the data frames flowing to the LAN are not necessarily synchronized, and if new train position information is obtained before the previously detected train position information is transmitted to the adjacent ATC logic unit, the previous train position Instead, it is desirable that new train positions be communicated.

According to the above embodiment, each time new data is obtained, it is written in the second buffer regardless of whether the train position written in the second buffer is transmitted to ATC-LANS2. Is ATC-L
Since it is transmitted to the ANS2, the latest train position data can always be transmitted to the adjacent ATC-LANS2, that is, the ATC logic unit. Further, even if the data written in the second buffer is not transmitted at a timing when it should be transmitted for some reason, the data newly written in the first buffer is immediately overwritten in the second buffer. At the next transmission timing, new data will be transmitted, and the real-time property is maintained.

Although the gateway device T, which is an intermediate route for data, has a non-failsafe structure, it is a failsafe device that allows the origin of information and the final receiver to judge the validity of the information as failsafe. Even if the device T does not have a function of checking or creating data, this network system has a fail-safe structure for the entire network.

In the above embodiment, two networks (ATC-LAN) are connected by one gateway device to form a network system. However, in the automatic train control system, a large number (three or more) of ATC-LANs are connected. LAN
Are sequentially connected by gateway devices to form a long system, and at a location along the branch point of the railway, three or more gateway devices are connected to one ATC-LAN, and each gateway device has the following ATC-LA
It has a configuration in which Ns are coupled. The present invention can be similarly applied to such a complicated network system.

Each of the above embodiments is an example in which a ring-shaped network is connected by a gateway device to form a network system. However, even when a bus type network is used, the gateway device connects the networks to each other. If so, the present invention can be applied to obtain similar effects.

[0034]

According to the present invention, the latest data always flows on the network, and the real-time property of the network system is improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a first exemplary embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a second exemplary embodiment of the present invention.

FIG. 3 is a block diagram showing details of a portion of FIG.

[Explanation of symbols]

A1, A2 Local controllers B1, B2 LAN C1 to Cn, E1 to En Communication nodes D _A1R , D _A2R data receiver D _A1S , D _A2S data transmitter D _R1R , D _R2R data receiver D _R1S , D _R2S data transmitter F gateway device R1, R2 ATC logic unit S1, S2 ATC-LANT gateway device

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masao Watanabe             1070 Ichimo, Hitachinaka City, Ibaraki Prefecture Stock Association             Hitachi, Ltd. Transportation Systems Division Mito Transportation             System headquarters (72) Inventor Junichi Sumino             2-2-2 Yoyogi, Shibuya-ku, Tokyo Tohnichi             Inside the passenger railway (72) Inventor Tsutomu Ishikawa             2-2-2 Yoyogi, Shibuya-ku, Tokyo Tohnichi             Inside the passenger railway F term (reference) 5K033 BA06 CB08 DA05 DB13

Claims (3)

[Claims] 1. A plurality of networks to which terminals for transmitting and receiving signals are respectively connected, and a gateway device for receiving a signal flowing through one of the plurality of networks and transmitting it to another network, The gateway device writes the data received from one network in the first buffer, transfers the data written in the first buffer to the second buffer, writes the data, and writes the data in the second buffer. In a network system configured to send data to the other network, the gateway device is configured so that when new data is written in the first buffer, data written in the second buffer is Whether the data in the first buffer is transmitted to the other network or not, A network system characterized by being configured to overwrite a second buffer. 2. The network system according to claim 1, wherein the terminal transmitting and receiving signals to and from the network is
To the network, a data frame having a frame in which data to be transmitted is written and a function code indicating the type of data to be written is cycled in a state in which data is written or a state in which no data is written. Data to which the gateway device identifies the function code of the data frame flowing through the one network and is attached with the function code indicating that the data frame is to be transmitted to the other network. When the frame is found, the data of the data frame is written in the first buffer, while the function code of the data frame flowing through the other network is identified, and it is shown that the data is received from the one network. When you find a data frame with a function code, the data frame Network system characterized by being configured so as to be transmitted to the other network elaborate write data of said second buffer beam. 3. The network system according to claim 2, wherein the terminal that transmits and receives a signal is an ATC logic unit of an automatic train control device that is configured to transmit and receive information for train control, and the plurality of networks. Is a dual-loop network including a plurality of communication nodes and a transmitting / receiving device connected to each communication node, and the transmitting / receiving devices are each connected to a track circuit. system.