JPS60169255A - Duplicated loop communication system - Google Patents

Abstract

PURPOSE:To prevent a transmission delay time at fault from being increased by constituting the system so that each node receives a signal from one of active and spare transmission lines and the signal is transmitted to both the active and spare transmission lines. CONSTITUTION:Five nodes 11-15 are connected by the active loop transmission line 16 and the spare loop transmission line 17. Each node receives a signal from a reception section able to receive a carrier in an active reception section R connected to the active loop transmission line 16 and a spare reception section R' connected to the spare loop transmission line 17, regenerates it and transmits respectively it to the active loop transmission line 16 and the spare loop transmission line 17 from both an active transmission section S and a spare transmission section S'. When no fault takes place in the loop transmission lines 16, 17, each node selects the active reception section R as the reception use.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD OF THE INVENTION The present invention relates to a duplex loop communication system constructed by connecting a plurality of nodes through working and backup loop-shaped transmission lines.

BACKGROUND ART Conventionally, a loop bank control method and a loop switching control method have been known as duplex control methods in a duplex loop communication system.

To explain the former loopback control method with reference to FIG. 1, a plurality of nodes 1 to 6 are connected by a working loop transmission line 6 and a backup loop transmission line 7, and under normal conditions (
As shown in A), mutual communication is performed using the current receiving section R and transmitting section S of each node and the current loop-shaped transmission path 6. on the other hand.

A carrier is transmitted to the backup loop-shaped transmission path 7 via a backup transmitter S° and a receiver R' of each node.

As shown in (B), when a failure occurs in the current loop-shaped transmission line 6 between nodes 1 and 2 and the receiving section R of node 2 detects a carrier disconnection, node 2 It transmits the carrier to the next node 3, and connects its own backup reception section R'' to the working transmission section S. Along with this, the backup reception section R'' of node 1 detects the carrier disconnection,
Connect the current receiving section R and the backup transmitting section S'.

Through such switching control, communication between the nodes is performed through the paths indicated by the arrows in FIG. 9.

After this, a new failure occurs between nodes 4 and 5, switching is performed, and communication between the nodes is performed via the path shown by the arrow in FIG. 9.

However, in the loop bank control method described above, (
If a loop bank is configured as shown in B), the length of the transmission path will be approximately doubled, increasing the signal transmission delay time, and as shown in (C), if a failure occurs at two or more locations, the loop will fail. There is a problem that some nodes will become separated and unable to communicate with each other.

The latter loop switching control method connects the current receiving section and transmitting section in each node with a working loop-shaped transmission path, and connects the backup receiving section and transmitting section in each node with a backup loop-shaped transmission path. They are connected and configured to switch to the backup side if a failure occurs on the working side, but even if a failure occurs between nodes on the working side and backup side of the loop transmission line, no communication will be possible. There is a problem. A command decoding circuit for loop switching control is also required.

Purpose of the Invention The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to prevent transmission delay time from increasing even if a failure occurs, and to prevent transmission delay time from increasing even if a transmission line fails at multiple locations. An object of the present invention is to provide a duplex loop communication system that does not become unable to communicate.

Summary of the Invention The present invention achieves the above object, in which each node receives a signal from either one of the working and backup transmission paths to which a carrier is being sent, and sends the signal to the working and backup transmission paths. is configured to do so.

Examples of the invention Further details of the present invention will be explained below with reference to two examples.

FIG. 2 is a block diagram of a loop communication system to which an embodiment of the present invention is applied. In this system, five nodes 11 to 15 are connected to a working loop transmission line 16 and a backup loop transmission line 17. connected. Each node receives a signal from the active receiving section R connected to the working loop-shaped transmission path 16 and the backup receiving section R' connected to the backup loop-shaped transmission path F, whichever is capable of receiving carriers. Then, this is reproduced to transmit the current transmitter S and the backup transmitter S.

The signal is sent from both to the current loop-shaped transmission line 16 and the standby loop-shaped transmission line 17, respectively.

If no fault has occurred on any of the loop-shaped transmission lines 16 and 17, each node selects the current receiving section R for receiving, as shown in (A).

Therefore, in this case, the signal is transferred along the path shown by the arrow.

As shown in (B), when a failure occurs in the currently used transmission path between nodes 11 and 12, node 12 detects a carrier disconnection in the currently used receiving section R.

The spare receiving section R'' is selected for reception. Therefore, in this case, the signal is transferred along the path shown by the arrow.

After this, as shown in (C), a failure also occurs in the current transmission line between nodes 14 and 15.

The node 15 detects a carrier disconnection in the active receiving section R and selects the spare receiving section R'' for reception. Therefore, in this case, the signal is transferred along the path shown by the arrow.

In this way, as long as there are no failures on both the working and backup transmission paths between adjacent nodes, mutual communication between each node will be maintained regardless of how many places on the loop transmission path, both backup and work, a failure occurs. There will be no hindrance to the continuation of the project.

3 is a block diagram showing an example of the configuration of each node in FIG. 2, 21 is a demodulation circuit, 22 is a modulation circuit, 23 is a carrier disconnection detection circuit, 24 is a regenerative relay circuit, 25 is a reception switching circuit, 26 2 is a transmission switching circuit, 27 is a switching logic circuit, and 28 is a carrier generation circuit.

The signals on the working and backup transmission lines 16 and 17 are sent to the demodulation circuit 21.
The received signal is decoded by the receiver switching circuit 25 under the control of the switching logic circuit 27 and then supplied to the receiving input terminal 29 . The carrier disconnection detection circuit 24 connects the active and backup transmission lines 16.
．． Detecting whether a carrier is being transmitted on 17,
The detection result is notified to the switching logic circuit 27. Based on the notification from the carrier disconnection detection circuit 24, the switching logic circuit 27 is a reception switching circuit configured to supply the demodulated signal from this transmission path to the reception input terminal when the carrier is being sent out on the current transmission path 16. 25. On the other hand, when a carrier disconnection on the working transmission line 16 is detected, the switching logic circuit 27 switches the backup transmission 1i! after a predetermined period of time. The reception switching circuit 25 is controlled to supply the demodulated signal from the 817 to the reception input terminal 29.

On the other hand, the output of the demodulation circuit 21 is regenerated by the regenerative relay circuit 14, then supplied to the modulation circuit 22 via the transmission switching circuit 26 under the control of the switching logic circuit 27, where it is modulated and then 16 and the backup transmission line 17. Based on the notification from the carrier disconnection detection circuit 24, the switching logic circuit 27 is a transmission switching circuit configured to supply the modulation circuit 22 with a reproduced signal from this transmission path when a carrier is being sent out on the current transmission path 16. 26. On the other hand, when carrier disconnection on the working transmission path 16 is detected, the switching logic circuit 27 controls the transmission switching circuit 25 to supply the carrier from the carrier generation circuit 28 to the modulation circuit 22, and After a period of time (enough time that other nodes do not recognize carrier disconnection based on this transmission switching operation) has elapsed, the switching of the reception switching circuit 25 as described above is controlled.

The switching logic circuit 27 controls the transmission switching circuit 26 to supply the transmission data on the signal output terminal 30 to the modulation circuit 22 based on the command from the terminal 31. The transmission data that has returned after going around the loop-shaped transmission path is discarded by the transmission switching circuit 26 under the control of the switching logic circuit 27.

In the above embodiment, the switching logic circuit 27 performs various switching controls based on the notification from the carrier disconnection detection circuit 23, but the carrier disconnection detection result is managed by the processor and It is also possible to configure the switching logic circuit to be controlled.

Effects of the Invention As explained in detail above, in the present invention, each node receives a signal from either one of the working and backup transmission paths to which a carrier is being transmitted, and transfers the signal to the working and backup transmission paths. To realize a redundant loop communication system in which transmission delay time does not increase even if a failure occurs, and communication is not disabled even if a transmission path fails at multiple locations, since the transmission line is configured to transmit data at multiple locations. I can do it.

[Brief explanation of drawings]

FIG. 1 is a configuration block diagram of a duplex loop communication system for explaining an embodiment, FIG. 2 is a configuration block diagram of a duplex loop communication system to which an embodiment of the present invention is applied,
FIG. 3 is a block diagram showing an example of the configuration of each node in FIG. 2. 21... Demodulation circuit, 22... Modulation circuit, 23... Carrier disconnection detection circuit, 24... Regenerative relay circuit. 25...Reception switching circuit, 26...Transmission switching circuit, 2
7...Switching logic circuit, 28...Carrier generation circuit.

Claims (1)

[Claims] A duplex loop communication system in which a plurality of nodes are connected by working and backup loop-shaped transmission lines. Each node is characterized in that it receives a signal from either one of the working and protection transmission paths through which a carrier is being transmitted, and sends the signal to both the working and protection transmission paths.
Heavy loop communication system.