JPH09214534A - Transmission line controller - Google Patents

Abstract

(57) Abstract: It is possible to diagnose an abnormality of a transmission line without using a multiple transmission line, and to automatically restore a communication system even when the transmission line is abnormal. A transmission path control device 10 is provided between both ends of a bus-shaped transmission path 12. The transmission path control device 10 transmits a signal transmitted from a communication device (for example, 14a) to the bus-shaped transmission path 1
By receiving from both ends of 2, the normal / abnormal state of the bus-like transmission line 12 is diagnosed. When the bus-like transmission line 12 is normal, the transmission line control device 10 does not execute the operation of sending the received signal to the bus-like transmission line 12, and as a result, the transmission line 12 is kept in the bus-like form. When a disconnection point 22 or the like occurs on the bus-shaped transmission path 12, the transmission path control device 10 detects that the signal is blocked by the disconnection point 22 and connects both ends of the bus-shaped transmission path 12 by , A new bus-like transmission line is formed excluding the disconnection point 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission line control device having a transmission line abnormality diagnosing function.

[0002]

2. Description of the Related Art As one of methods for improving the reliability of transmission lines, there is a method of providing a plurality of transmission lines in parallel between communication devices. In this method, when a communication device transmits a signal to another communication device, the signal is sent to the plurality of transmission lines at substantially the same time. The communication device on the signal receiving side determines that there is no abnormality in the transmission line when there is no significant difference in the timing of signal reception from each transmission line, and if it does, there is an abnormality such as disconnection. It is determined that it has occurred (see Japanese Patent Laid-Open No. 6-152606).

[0003]

Since the above method is premised on a plurality of transmission lines, it cannot be applied to a communication system having one transmission line. A first object of the present invention is to provide a transmission line control device capable of automatically returning a communication system even when a transmission line is abnormal, by improving a connection mode with a transmission line and adding a signal relay function. .
A second object of the present invention is to prevent the redundant signal transmission from occurring regardless of whether the transmission line is normal or abnormal by devising the signal relay function.

[0004]

In order to achieve such an object, the transmission line control device according to the first structure of the present invention is originally composed of two bus-shaped signal transmission lines due to the occurrence of an abnormality. Of the bus-like signal transmission line, and a means for determining by dividing the bus-like signal transmission line by monitoring the signal propagation status, and when it is determined that the bus-like signal transmission line has been divided, And a means for restoring and forming a single bus-shaped signal transmission path from which an abnormal place is excluded by connecting. Therefore, in this configuration, when an abnormality occurs, the positions of both ends of the abnormality change as compared with those before the occurrence of the abnormality, but a single bus-like signal transmission path is restored and formed as before the occurrence of the abnormality. That is, this configuration can be applied to a single bus-shaped signal transmission line unlike the conventional one.

In the transmission path control device according to the second configuration of the present invention, in the first configuration, a signal sent from the communication device connected to the bus-like signal transmission path to the bus-like signal transmission path is transmitted. It is characterized in that it is provided with means for receiving from both ends of the bus-shaped signal transmission path and providing for the above determination, and means for discarding the received signal when it is determined not to be divided. Therefore, in this configuration, even when the bus-shaped signal transmission line is normal, formation of a pseudo ring-shaped transmission line and thus infinite loop transmission, congestion due to return of the received signal (repeat), etc. , Redundant signal transmission does not occur.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of a communication system using a transmission path control device 10 according to an embodiment of the present invention. The communication system shown in this figure is a communication device 1
4a to 14e are connected by a bus-shaped transmission line 12. The transmission path control device 10 according to the embodiment of the present invention is provided between both ends of the bus-shaped transmission path 12. Note that the transmission line 12 shown in FIG. 1 seems to be a ring-shaped transmission line at first glance, but it should be noted that it is actually a bus-shaped transmission line. That is, as will be described later, when the bus-shaped transmission line 12 is normal or abnormal, the transmission line 12 becomes a transmission line on which signals are cyclically transmitted, that is, a ring-shaped transmission line. There is no.

FIG. 2 shows a functional configuration of the transmission path control device 10. The transmission path control device 10 shown in this figure
Are receiving units 16a and 16b and transmitting units 18a and 18
b, and the control unit 20. The receiving units 16a and 16b are connected to the first or second end of the bus-shaped transmission line 12, and relate to the connection of the signals sent out on the bus-shaped transmission line 12 by any of the communication devices 14a to 14e. Receive through the edge. When receiving the signal via the bus-shaped transmission path 12, the receiving units 16a and 16b supply the received signal to the transmitting unit 18a or 18b, respectively, and notify the control unit 20 of the reception.

When a notification of signal reception is received from one of the receiving units 16a and 16b and then a notification indicating that the same signal is received from the other unit within a predetermined time, the control unit 20 performs bus-like transmission. It is determined that the path 12 is normal, that is, the signal transmission via the transmission path 12 is normally performed, and the operations of the transmission units 18a and 18b are stopped. On the other hand, when the notification of signal reception has arrived from either one of the reception units 16a and 16b, but the notification that the same signal has been received has not arrived from the other, the control unit 20 The transmitting unit (either 18a or 18b) that receives the received signal from the receiving unit that receives the signal is operated to send the signal to the rest of the bus-shaped transmission path 12.

Due to this operation, in the present embodiment,
Even if the bus-like transmission line 12 is not a multiplex transmission line, it is possible to diagnose whether or not there is an abnormality in the transmission line 12,
When an abnormality occurs in the bus-shaped transmission line 12, the transmission line 1 concerned
2 has been achieved, and the effect of preventing redundant signal transmission on the bus-shaped transmission path 12 has been realized. Next, the transmission path control device 10
The reason why such an effect is caused by will be described with an example for the sake of easy understanding.

For example, assume that the bus-like transmission line 12 is functioning normally in the communication system shown in FIG. In this state, it is assumed that one of the communication devices, for example, 14a sends a signal to the bus-shaped transmission line 12. Then, this signal propagates in the left and right directions on the bus-shaped transmission path 12 as indicated by the arrow in the figure. The signals propagating in these different directions eventually reach the transmission path control device 10. The transmission path control device 10, especially the receiving section 16a thereof
And 16b receive these two kinds of signals whose propagation directions are different from each other almost at the same time, that is, with a time difference corresponding to a difference in signal transmission path length and the like. The control unit 20 determines that the bus-shaped transmission path 12 is normal based on the detection of signal reception at such timing, and the transmission units 18a and 18b.
Prohibits the sending operation of (receive signal discard). In this way, if the bus-shaped transmission line 12 is normal, the transmission line 12 is held in its original shape (bus-like) by the operation of the transmission line control device 10. At that time, since the transmission path control device 10 is provided, a situation in which redundant signal transmission such as cyclic transmission and repeat does not occur. That is, the communication device 14a-
From the viewpoint of 14e, the existence of the transmission path control device 10 can be ignored, and the signal transmission in this system is similar to the conventional signal transmission by the bus.

Further, as shown in FIG. 3, any place on the bus-like transmission line 12 (communication devices 14c and 1 in the figure).
It is assumed that a wire break has occurred at a location 22 between 4d). In this case, when the communication device 14a transmits a signal on the bus-shaped transmission path 12, the signal propagating to the left in the figure reaches the transmission path control device 10, but the signal propagating to the right is caused by the disconnection point 22. Therefore, the transmission path control device 10 is blocked and cannot reach the transmission path control device 10, and one of the reception units 16a and 16b cannot receive the signal from the communication device 14a. When the control unit 20 cannot receive the notification that the signal has been received from one receiving unit from the other receiving unit within a predetermined time, some abnormality occurs in the bus-shaped transmission line 12. In addition to notifying the outside to the outside, a command for permitting the transmission operation is given to the transmission unit provided in the subsequent stage of the reception unit that has received the signal. Then, the transmission unit (for example, 18a) receives the signal supplied from the reception unit (for example, 16a) that has received the signal,
The data is sent to the remaining part of the bus-shaped transmission path 12 (for example, the part from the transmission path control device 10 to the disconnection point 22 via the communication devices 14e and 14d).

As described above, according to the present embodiment, the control unit 20 diagnoses the presence / absence of an abnormality in the bus-shaped transmission line 12 based on the result of monitoring the signal propagation state using the receiving units 16a and 16b, and the presence of abnormality For example, when a diagnosis is made that there is a disconnection point 22), the abnormality occurrence point (for example, the disconnection point 22)
A single bus-like transmission line (excluding the communication device 14c to the communication devices 14b and 14a, the transmission line control device 1 in the example of FIG.
0, a bus-like transmission path from the communication device 14e to the communication device 14d is formed, so that when an abnormality occurs in the bus-like transmission path 12, the system can be automatically restored. Further, when the present embodiment is carried out, it is not necessary to use a multiplex transmission line, so that the system cost becomes low.

[0014]

According to the first aspect of the present invention, when a single bus-shaped signal transmission line is originally divided into two bus-shaped signal transmission lines due to the occurrence of an abnormality, the bus It is possible to apply to a single bus-shaped signal transmission line by connecting both ends of the original signal-shaped signal transmission line to restore and form a single bus-shaped signal transmission line from which an abnormal place is excluded. It is possible to realize abnormality diagnosis and automatic recovery functions.

According to the second configuration of the present invention, further, when the bus-like signal transmission line division due to the occurrence of the abnormality does not occur, the received signal is discarded for the determination of the presence or absence of the abnormality. When the signal transmission path is normal, redundant signal transmission does not occur such as formation of a pseudo ring-shaped transmission path, further infinite loop transmission on the transmission path, and congestion due to return of the received signal (repeat).

[0016]

[Addendum] The present invention has a function of externally notifying when a single bus-shaped signal transmission path is originally divided into two bus-shaped signal transmission paths due to an abnormality. It can be understood as a configuration. Such a function enables a person who maintains the communication system to deal with the abnormality more quickly. Furthermore, the abnormality that can be dealt with by the present invention is not limited to disconnection, and the present invention can deal with various phenomena that hinder normal communication. Furthermore, the present invention is not limited to wireline transmission. In addition, the method for diagnosing the presence / absence of abnormality in the present invention does not need to limit the determination of the presence / absence of signal reception within a predetermined time. The present invention can also be expressed as a transmission path control method, a communication method, a communication system, etc., and those skilled in the art can easily and uniquely make such changes in expression based on the disclosure of the present application. Will.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a communication system using a transmission path control device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a functional configuration of a transmission path control device according to an embodiment of the present invention.

FIG. 3 is a block diagram showing a situation where a disconnection occurs in a bus-shaped transmission line.

[Explanation of symbols]

10 transmission line control device, 12 bus-like transmission line, 14a-
14e communication device, 16a, 16b receiving unit, 18a,
18b Transmitter, 20 Control, 22 Disconnection point.

Claims (2)

[Claims] 1. A means for determining whether or not a single bus-shaped signal transmission path is originally divided into two bus-shaped signal transmission paths due to occurrence of an abnormality by monitoring signal propagation conditions, And a means for restoring and forming a single bus-shaped signal transmission line in which the abnormal place is excluded by connecting both ends of the bus-shaped signal transmission line originally when it is determined that A transmission path control device characterized by the above. 2. The transmission line control device according to claim 1, wherein a signal sent from the communication device connected to the bus-shaped signal transmission line to the bus-shaped signal transmission line is at both ends of the bus-shaped signal transmission line. And a means for discarding the received signal when it is determined that the received signal is not divided, and a transmission path control device.