JP3139040B2 - Data transmission system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a loop transmission system, and more particularly to a system for monitoring that a data transmission path is normally operating between transmission devices and performing a bypass control.

[0002]

2. Description of the Related Art Confirming that a data transmission path is normal between transmission apparatuses is a basic procedure of data transmission. One of the methods conventionally used to know the data transmission path or the down state of the other transmission device is that a transmission requesting communication device sends a communication enable / disable inquiry signal at the start of communication, and This is a method in which inquiries are made a predetermined number of times until there is a reply “OK”.

[0003] Also, a method has been performed in which, during communication, detection of reception of a signal from a partner is stopped for a predetermined time or more and an inquiry is made a predetermined number of times. Such a determination result is used for displaying a communication abnormality in each transmission device, and is also used for bypass control of a transmission path in a loop transmission system.

[0004]

As described above, the monitoring of the data transmission path to and from the other transmission device and the subsequent control are performed entirely by software in the conventional methods. However, this type of operation by software imposes a heavy processing load on a processor that controls the transmission apparatus, and has the disadvantage of delaying other processing and reducing the throughput of the effective information amount of the entire transmission network. There are various failure modes that can occur in the transmission system, and the corresponding software must be prepared for all conceivable cases, so that the overhead of case analysis is large and the transition to the bypass mode is slow. If the route abnormality occurs repeatedly and sporadically,
As a result of repeating the round trip and the normal mode, the time allocated to the normal transmission may be almost nil. Such a transmission delay particularly hinders transmission of control data in which real-time property is important, such as control of a plant in a factory or control of a transportation system.

[0005] While a specific bit is reciprocated between the transmission devices, one transmission device inverts the truth value of this bit, thereby generating a continuous alternation of the truth values and detecting the stop of the alternation. A method for performing control on the safe side is disclosed in JP-A-2-39903.

An object of the present invention is to solve the above-mentioned problems of the detour control system performed in the conventional data transmission system and to provide a detour control system having high responsiveness and a small software load. is there.

[0007]

According to the present invention, specific link control information is reciprocated between adjacent transmission devices.
By inverting the truth value of this information in one of the transmission devices, a continuous alternation of the truth value is generated, and when this alternation is stopped, the transmission path is reconfigured by detour control. Was.

[0008]

As a result, even if a failure occurs in either the transmission device or the transmission cable, the truth value of the link control information transmitted from the failure point to the downstream side is always constant. Stop. This effect is obtained no matter how the truth value of the circuit is fixed. Since the truth value inversion processing and the alternation state monitoring function can be easily realized by hardware and can operate at high speed, control when a transmission path is disconnected can be started very quickly.

[0009]

FIG. 1 shows an embodiment of the present invention. In this embodiment, the present invention is applied to a loop transmission system for train control, and a loop indicated by a broken line in the figure shows a path of a logical flow of link control information between both transmission devices (ST). Represents. Actually, the data input from the receiving unit passes through the processing circuit of the transmission function or the transmission processor,
A frame is formed together with a group of information on the application of this system, such as control of train equipment, and the frame is output from the transmission unit. FIG. 2 shows an example of the frame configuration. In this frame configuration, the link control information is referred to as a link control unit, and is placed at the head of a word unit to be transferred, followed by a bit group obtained by dividing the application information group into word units. While the application information goes around the entire train along the solid line loop in FIG. 1, the link control information goes around with the adjacent transmission ST. Here, since the link control information is inverted in one transmission ST, the alternation of the truth value with one cycle time of one round trip of the path of this information passing through the dashed loop in the figure as shown in the figure. appear.

The internal operation of the transmission ST will be described with reference to FIG. In FIG. 3, T is a transmitting circuit, R is a receiving circuit, F1,
F2 is a buffer file of application information, 10
6 is an inverting circuit, 107 and 108 are bypass switches, 109
And 110 are an alternation detection circuit, and 111 is a bypass control circuit.
The transmission circuit T collectively transmits the application information and the link control information into one word as shown in FIG. The receiving circuit R separates the received word into application information and link control information. The link control information on the right side is inverted in truth value by the inversion circuit 106 and sent back to the transmission ST which is a pair on the right side, and the link control information on the left side is directly transferred to the ST on the left side. Since the STs on both sides have the same structure, the link control information on the left is inverted in the ST on the left. Therefore, if the STs on both sides, the STs, and the transmission path between them are all normal, the left and right link control information maintains the alternating state as shown in FIG. In this state, the alternation detection circuits 109 and 110 generate a left link detection signal and a right link detection signal, respectively. By these signals, the detour control circuit 111 causes the detour switches 107, 108
In the direction shown in the figure to allow the application information to pass in the forward direction. The signal to the on-board equipment group on the car on which the ST is mounted is selected and output from one of the buffer files storing the application information, and the signal from the on-board equipment to other devices such as the driver's cab is output from the file. , And are transferred to the adjacent ST.

Here, if a failure occurs in any location of the transmission line or the adjacent transmission ST, the link control information after the failure location is fixed to a constant value, so that no alternation occurs in any location in FIG. . Now, suppose that the transmission path on the right side is disconnected. Then, the right link detection signal disappears, and the detour control circuit 1
Numeral 11 defeats the left detour switch 107 in the opposite direction to the illustration to divert the application information received from the left to the left. Conversely, when the transmission path is restored, the detour switch is changed back.

In the case of the train control system shown in FIG. 1, if the transmission route is interrupted during traveling and it takes too much time to reconfigure the route thereafter, the transmission timing of various command signals may be delayed or deviated. There is a possibility that an improper behavior of the train may occur even in a car with a normal ST or transmission route. Therefore, it is desirable that the speed of switching to the detour and the recovery be as high as possible.
Since 06, 109, 110, and 111 have simple functions, they can be easily operated at high speed by being manufactured with hardware.

[0013]

As described above, according to the present invention, it is possible to easily determine the state of a transmission path between adjacent transmission devices in a loop transmission system and to perform control such as forming a detour at a high speed. Therefore, in particular, in a transmission system used for the purpose of performing real-time control of a train or the like, when a transmission line failure occurs, control interruption and timing deviation are reduced,
It is easy to ensure safety.

[Brief description of the drawings]

FIG. 1 is a diagram of a system to which the present invention is applied.

FIG. 2 is a diagram of an embodiment of the present invention.

FIG. 3 is a diagram of an embodiment of the present invention.

[Explanation of symbols]

106: polarity reversing unit, 107, 108: detour switch,
109, 110: Alternating current detection circuit, 111: detour control circuit, F1, F2: buffer memory.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-58644 (JP, A) JP-A-62-277952 (JP, A) JP-A-3-265247 (JP, A) JP-A-63-1987 312743 (JP, A) JP-A-61-30839 (JP, A)

Claims (3)

(57) [Claims] An alternate transmission / reception of a word including link control information is repeated between two adjacent transmission devices in a loop transmission system, and the polarity of the link control information is inverted before transmission of this word in any one of the transmission devices. Means, one or both of the transmission devices are provided with alternation determination means for the truth value of the link control information, and in the transmission device that has detected the alternation stop, the transmission device transfers the truth value from another transmission device other than the paired transmission device. A data transmission system characterized by diverting incoming data in the direction of the transmission device. (2) Two adjacent transmissions in a loop transmission system
Alternate transmission and reception of words containing link control information between transmitters
Repeat to confirm that the transmission equipment is normal
In a data transmission system that transfers data by The transmission device transmits the link control information before transmitting the word.
Circuit that inverts the polarity of the link, and the truth value of the link control information
Alternation detection circuit that detects whether or not
And when the alternation detection circuit detects alternation stop,
Transfer from a transmission device other than the paired transmission device.
A detour circuit for diverting the transmitted data in the direction of the transmission device.
A data transmission system composed of: (3) Multiple transmission devices are routed via transmission cables.
Data transmission system configured to be connected in a loop
At The transmission device is configured to transmit the data to which the abnormality of the transmission device is to be transferred.
Link control information to be combined with the truth of the link control information
A transmitting circuit that alternates and transmits the value, and
From the transmission device connected to the other side of the link information
A receiving circuit for receiving the transmitted link control information;
The link control information transmitted by the transmission circuit and the reception
Has been changed by the link control information received from the
Data transmission composed of an alternation detection circuit for detecting
system.