JPH0720128B2 - Optical communication system failure detection / removal method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fault detection / elimination method for an optical communication system in which a plurality of nodes are connected by an optical transmission line having a star coupler.

(Prior Art and its Problems) Conventionally, there is known a star type optical communication system in which a plurality of nodes are connected by an optical transmission line having a passive star coupler and data is exchanged between the nodes. Fifth
The figure shows the overall configuration of a conventional optical communication system. A plurality of nodes 1, 2a to 2c are connected to each other via an optical transmission line 4 via a passive star coupler 3. In the conventional optical communication system, a specific node 1 among these plurality of nodes 1, 2a to 2c serves as a monitoring station, which constantly monitors the signal state of the optical transmission line 4 to shut off the power supply to the failed node, The failed node is removed from the system to avoid the situation where the entire system becomes incommunicable. More specifically, the node 1 of the monitoring station, as shown in FIG. 6, includes a central control unit 10 that controls the node 1 and a communication control unit 11 that controls the data communication between the nodes. An optical signal from the optical / electrical conversion block 12a and the communication control unit 11 which is connected to the optical transmission line 4 formed of an optical fiber cable and which converts an optical signal input from the optical transmission line into an electric signal is converted into an optical signal. The optical transmission / reception unit 12 is composed of an electric / optical conversion block 12b that outputs a transmission signal to another node to the optical transmission line 4, a power supply 13, and a power switch 14 whose operation is controlled by a central control unit 10. , Central controller 10, communication controller 11, and optical transceiver 12
The optical / electrical conversion block 12a is powered by the power supply 13 directly through the electric wire 15, and the electrical / optical conversion block of the optical transmitter / receiver 12 is
12b is supplied with power from the power supply 13 via the power supply line 16 and the power switch 14.

On the other hand, the other nodes 2a to 2c are, as shown in FIG. 7, a central control unit 10 'that controls each node 2a (2b, 2c).
And a communication control unit 11 ′ that controls the data communication between the nodes.
An optical transmission / reception unit 12 'similar to the optical transmission / reception unit 12 of FIG. 6, which is connected to the optical transmission line 4 and performs electric / optical conversion and optical / electrical conversion of a transmission signal; and a power supply 13', and Power switch
14 ', the central control unit 10' is directly fed from a power source 13 'through a power feed line 15', and the communication control unit 11 'and the optical transmitter / receiver unit 12' connect a power switch 14 'and a power feed line 16'. Powered through. The power switch 14 'of each node 2a (2b, 2c) is connected to the output side of the central control unit 10 of the monitoring station node 1 via the power switch control line 5a (5b, 5c), respectively.
The central control unit 10 of the monitoring station node 1 controls the operation of each.

The central control unit 10 of the monitoring station node 1 uses the optical
The signal state of the optical transmission line 4 input via the electrical conversion block 12a and the communication control unit 11 is constantly monitored, and the optical transmission line 4 is filled with abnormal signals such as continuous light and unsynchronized irregular light emission. If it is determined that communication between the nodes is not possible, the central control unit 10 determines that the power switch control lines 5a to 5c
And 18 sequentially output switch switching signals to sequentially cut off the power supply to each of the communication control units 11 'and the optical transmission / reception units 12' of the nodes 2a to 2c other than the monitoring station node 1 for a fixed time, and then The power supply to the electric / optical conversion block 12b of the optical transmitter / receiver 12 is also cut off for a certain period of time. Then, if the signal state of the optical transmission line 4 during the power supply interruption is normal, the node that interrupted the power supply is identified as the faulty node, and the power supply to the node is held in the stopped state. The faulty node is removed from the system to remove the abnormal signal from the optical transmission line 4, and the system is returned to the communicable state again.

In such a conventional optical communication system, there is a problem that the power switch control lines 5a to 5c need to be wired between the other monitoring station nodes and the other nodes of the power switches 14 and 14 'provided in each node.

FIG. 8 shows another conventionally known optical communication system.
The node configuration shown in the figure is similar to that of FIG. 7, but differs from that of FIG. 7 in that each node is provided with an abnormality detection circuit 18. That is, in the optical communication system shown in FIG. 8, the operation control of the power switch 14 'is performed by the abnormality detection circuit 18 provided in each node, and the abnormality detection circuit 18 functions as an electrical / optical conversion block of the optical transmitter / receiver 12'. It is connected and constantly monitors for abnormalities such as continuous light emission of the electric / optical conversion block of the own station,
If an abnormality occurs in the optical conversion block, the power switch 14 'of the own station is switched to operate, and the communication control section 11' of the own station.
Also, the power supply to the optical transmission / reception unit 12 'is stopped so that each node itself detects the abnormality and then leaves the system.

This optical communication system does not require a power switch control line wired between a monitoring station node and other nodes as in the system shown in FIGS. 5 to 7, but each node has its own electrical / optical conversion line. It is necessary to have an abnormality detection circuit that constantly monitors the operating state of the block, detects an abnormal signal in the optical transmission line, and turns off the power of the local station. Has the problem of becoming expensive.

The present invention has been made to solve such a problem, and in an optical communication system in which a plurality of nodes are connected by an optical transmission line having a passive star coupler, continuous light emission and synchronization of an electric / optical conversion block can be obtained. An object of the present invention is to provide a fault detection / elimination method for an optical communication system, which can inexpensively and surely prevent a communication failure of the entire system due to an abnormal signal such as irregular light emission.

(Means for Solving the Problems) According to the present invention in order to achieve the above-mentioned object, according to the present invention, each node of a plurality of nodes connected to an optical transmission path logically forming a bus is unique to the node. A central control unit that controls the
A communication control unit that controls data communication between nodes, and an optical signal converting an optical signal input from the optical transmission line into an electrical signal.
Failure detection / elimination method for optical communication system including electric conversion block and optical transmission / reception unit including electric / optical conversion block for converting electric signal to optical signal and outputting transmission signal to other node on optical transmission line In the above, in each node, a first power supply path for supplying power to the optical / electrical conversion block, a second power supply path for supplying power to the electric / optical conversion block, and a central control unit in the middle of the second power supply path, A switching means that is controlled to be switched by any one of the communication control units is provided, and the one control unit of each node is
When it is detected that an abnormal signal continuously occurs in the optical transmission path for the first predetermined time, the switching means is operated to switch the power supply to the electrical / optical conversion block, and the second power supply is unique to the node. After stopping for a predetermined time, while monitoring the signal state of the optical transmission line via the optical / electrical conversion block of the node, and holding the transmission signal output as no signal, supply power to the electric / optical conversion block. Immediately after the power supply is restarted, the presence / absence of an abnormal signal in the optical transmission line is discriminated to detect a fault in the node, and if no fault is detected in the node, the transmission signal is output without signal. After waiting for the elapse of the third predetermined time sufficient to complete the failure detection of all the other nodes while holding the same, the output of the transmission signal is restarted, and when the failure of the node is detected, Electric / optical conversion block Fault detection and removal method of the optical communication system, characterized in that for holding the power supply stopped state subsequent to stop the power supply again the electro-optical conversion block to click is provided.

(Operation) One of the central control unit and the communication control unit of each node constantly monitors the optical signal state input from the optical transmission line via the optical / electrical conversion block of the optical transmission / reception unit to perform optical transmission. When it is detected that an abnormal signal such as continuous light or irregular light emission without synchronization has continuously occurred in the road for the first predetermined time, a unique value preset for each node is set to a different value. By stopping the power supply to the electric / optical conversion block for a predetermined time of 2 and then detecting the failure of the local node, the failure detection of all the nodes is completed.
By holding the transmission signal output to no signal in any node until the predetermined time of, it is possible to reliably perform the determination of whether or not the own node is abnormal without misdiagnosis, When an abnormality of the node of the own station is detected, the power supply to the optical / electrical conversion block of the optical transmission / reception unit of the own station is held and the system is withdrawn from the system. A fault detection / removal program detects a system fault by software and removes it, so that it is possible to inexpensively and surely avoid an inability to communicate with the entire system without separately providing a special abnormality detection circuit. To

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

First, FIG. 2 shows a connection relation of each node of an optical communication system for carrying out the method of the present invention, where n nodes from the first node N1 to the nth node Nn are radially arranged via the passive star coupler 3. They are connected by an optical transmission line 4. The optical communication system for carrying out the method of the present invention does not require a specific node as a monitoring station node, and each node is basically configured as shown in FIG. The node configuration shown in FIG. 3 is similar to the node configuration of FIG. 6 described above, except that the power switch controller 18 from the output side of the central controller 10 is connected only to the power switch 14 of its own station. The only difference is that the other parts are configured in the same manner as in FIG. 6, so
Parts corresponding to those in FIG. 6 are designated by the same reference numerals, and detailed description thereof will be omitted.

Next, with reference to FIG. 1 and FIG. 4, a fault detection and removal procedure executed by each of the nodes N1 to Nn will be described. Each node N1 ~
The central control unit 10 of Nn monitors the signal state of the optical transmission line 4 via the optical / electrical conversion block 12a of the optical transmission / reception unit 12 and the communication control unit 11, and the continuous state of the optical transmission line 4 is synchronized. It is determined whether or not an abnormal signal such as irregular light emission that cannot be taken occurs, and this abnormal signal occupies the optical transmission line 4 and causes a failure that disables communication between nodes (step 20). When one of the nodes (for example, assume that the node N2 has failed) that constitutes the optical communication system fails and outputs continuous light to the optical transmission line 4, for example, each node outputs an abnormal signal. It is determined whether or not a failure has occurred in the optical transmission line 4 based on whether or not a certain continuous light has continued for the first predetermined time To or longer. If the determination in step 20 is affirmative (Yes), that is,
When continuous light is continuously generated in the optical transmission line 4 for a first predetermined time To or longer, the central control unit 10 interrupts communication with other nodes, that is, the transmission signal output is made non-signal and the power supply is turned off. A switching signal is output to the power switch 14 via the switch control line 18 to turn off the power switch 14 to stop the power supply to the electrical / optical conversion block 12b of the optical transceiver 12 (step 21).

Since each of the nodes N1 to Nn executes failure detection according to the procedure of the flowchart of FIG. 1, when a failure occurs in the optical transmission line 4, each of the nodes N1 to Nn detects the failure and detects its own. Since the power supply to the electrical / optical conversion block of the station is stopped, considering the difference in program execution timing, etc., at least the predetermined time after the predetermined time To has passed from the time when the abnormal signal occurred (time p1 in Fig. 4). Within t0 (p2 in Fig. 4)
Within the time point), all the nodes N1 to Nn will complete the stop of the power supply to the electro-optical conversion block, and at the latest.
At the time of p2, there is no optical signal in the optical transmission line 4 and there is no signal (see FIG. 4).

Next, it is determined whether or not a unique time (second predetermined time) τi pre-assigned to the own station has elapsed from the time when the power supply to the own station was stopped (step 22), and if it has not elapsed, the time elapses. Until step S22, the step 22 is repeatedly executed until the predetermined time τi elapses. Where τi is the i-th node Ni
Is a predetermined time, and its value is set by the following equation.

τi = i × (t1 + t3 + t5) Then, t1 is an appropriate predetermined value (t1> t0) longer than the predetermined time t0, and t3 and t5 are also appropriate predetermined values (t3> tlarger than predetermined times t2 and t4 described later). t2, t5> t4) are set.

When the determination result in step 22 is affirmative, that is, when the predetermined time τi peculiar to the own station elapses, the central control unit 10 outputs a switching signal to the power switch control line 18 while keeping the transmission signal output as no signal, and supplies the power. The switch 14 is turned on to restart the power supply to the electric / optical conversion block 12b. (Step 23). Then, the optical / electrical conversion block 12a monitors the signal state of the optical transmission line 4 for a predetermined time t2, and determines whether or not an abnormal signal has occurred in the optical transmission line 4 within the subsequent predetermined time t4 (step twenty four). The predetermined times t2 and t4 are set to a value sufficient to be able to surely discriminate whether or not an abnormal signal has occurred in the optical transmission line 4 by distinguishing it from a signal such as noise and the like without fail.

If the determination result of step 24 is negative (No), it means that there is no abnormality in the electrical / optical conversion block 12b of the local node, and it is determined that the fault cause of the optical transmission line 4 is not in the local node. , The steps after step 25 described below are executed while the electric / optical conversion block 12b of the local node is supplied with power. In this case, the optical transmission line 4 is kept in a no signal state.

On the other hand, when the faulty node N2 executes the step 23, the abnormal signal S2 appears again on the optical transmission line 4 (at the time point p3 in FIG. 4 (a)), and the determination result of the step 24 becomes affirmative. In this case, the central control unit 10 of the node N2 turns off the power switch 14 within a predetermined time t4 following the predetermined time t2 to turn on the electric power again.
By stopping the power supply to the optical conversion block 12b and fixing this state, the own station is separated from the system. When the power supply to the electrical / optical conversion block 12b of the faulty node N2 is stopped, the fault signal is eliminated from the optical transmission line 4 (Fig. 4 (a)).
(At the time of p4), the optical transmission line 4 becomes a signalless state again.

Other nodes that have no abnormality, after performing the determination in step 24,
It is determined whether or not the third predetermined time T1 has elapsed from the time when the own station detected the occurrence of a fault signal on the optical transmission line 4 (step 25), and the elapse of the predetermined time T1 is waited (see FIG. a) p5
Point), restart communication with other nodes (step 2)
6). Failure detection for all nodes is time (n +
1) × (t1 + t3 + t5) should have been over, and the predetermined time T1 is this time (n + 1) × (t1 + t3
It is set to an appropriate predetermined value larger than + t5). Note that t3 and t5 are the predetermined time described in steps 24 and 27 above.
Since it is set to an appropriate predetermined value that is larger than t2 and t4, two or more nodes simultaneously execute step 23 in the failure detection performed after the elapse of the predetermined time τi peculiar to each node given by the above equation. Then, the situation of starting power supply to each electric / optical conversion block 12b is avoided, whereby each node sequentially competes with the fault detection of other nodes for fault detection of its own node from the first node N1. It will be possible to execute without fail.

Although the power switch 14 is connected to the central control unit 10 and the operation control of the power switch 14 is performed by the central control unit 10 in the above-described embodiment, the present invention is not limited to this, and the central control is not limited thereto. The first by the signal control unit 11 instead of the unit 10.
The signal control unit 11 may control the operation of the power switch 14 by executing the control program necessary for the fault detection and removal shown in the flowchart of the drawing.

Further, in the above-described embodiment, only the electric / optical switching block 12b of the optical transmitter / receiver 12 is controlled to be turned on / off by the power switch 14, but the optical / electrical switching block 12a is also powered via the power switch 14. , Electrical / optical switching block 12b
Also, the power supply to the optical / electrical exchange block 12a may be controlled to be turned on / off at the same time.

(Effects of the Invention) As described in detail above, according to the failure detection / removal method of the optical communication system of the present invention, the first power feeding path for feeding the optical / electrical conversion block to each node, and the electrical / optical conversion are provided. A second power supply path for supplying power to the block, and a switch means that is controlled to be switched by one of the central control unit and the communication control unit are provided in the middle of the second power supply path, and the one of the nodes The control unit of the
When it is detected that the power is continuously generated for a predetermined time, the switching means is operated to stop the power supply to the electric / optical conversion block for a second predetermined time unique to the node, and then the While monitoring the signal state of the optical transmission line via the electric conversion block, and holding the transmission signal output as no signal, the power supply to the electric / optical conversion block is restarted, and immediately after the power supply is restarted in the optical transmission line. The failure detection of the relevant node is performed by determining whether or not the abnormal signal of is generated, and when the failure of the relevant node is not detected, the failure detection of all other nodes is performed while keeping the transmission signal output as no signal. After waiting the elapse of the third predetermined time period, which is sufficient for completion, the output of the transmission signal is restarted, and when the failure of the relevant node is detected, the power supply to the electrical / optical conversion block is stopped again and thereafter Electric / optical conversion block Since the power supply stop status of the optical signal system is maintained, when the optical transmission line of the optical signal system is monitored by a specific monitoring station node, the power switch control line for wiring between the monitoring station and other nodes becomes unnecessary. In addition, since the one control unit executes the abnormality detection and removal program to detect the system failure by software and removes it, there is no need to install an abnormality detection circuit, and the entire system communicates with the failed node. It has an excellent effect that it is possible to avoid the situation in which it cannot be performed reliably and inexpensively.

Further, since it is a system in which each multiplex node autonomously controls without needing to provide a special monitoring node, it is possible to avoid the inconvenience of not being able to cope with the abnormality of the monitoring node.

[Brief description of drawings]

1 to 4 show an embodiment of the present invention, FIG. 1 is a flow chart showing a fault detection / removal procedure of an optical communication system according to the method of the present invention, and FIG.
An overall configuration diagram of an optical communication system in which a plurality of nodes are connected by an optical transmission line having a star coupler, FIG. 3 is an avoidance diagram showing an internal configuration of each node shown in FIG. 2, and FIG. 4 is an optical transmission line. Timing chart showing changes over time in the signal state and on / off state of the electrical / optical conversion block of each node, fifth
FIG. 8 to FIG. 8 are explanatory views of a conventional optical communication system.
FIG. 6 is an overall configuration diagram of a conventional star-type optical communication system, 6th
5 is a circuit diagram showing the internal configuration of the monitoring station node 1 of FIG.
FIG. 7 is a circuit diagram showing an internal configuration of a node other than the monitoring station node of FIG. 5, and FIG. 8 is an internal configuration of each node of another conventional optical communication system having an abnormality detection circuit in each node. It is a circuit diagram showing. 3 ... Passive star coupler, 4 ... Optical transmission line, 10 ...
Central control unit, 11 ... Communication control unit, 12 ... Optical transmission / reception unit, 12
a ... Optical / electrical conversion block, 12b ... electrical / optical conversion block, 13 ... power supply, 14 ... power switch, 15 ... feeding line (first feeding path), 16 ... feeding line (second) Power supply path), 18 ... power switch control line, N1 to Nn ... nodes.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location 9372-5K H04B 9/00 K (72) Inventor Kei Inoue 2-9-15 Futaba, Shinagawa-ku, Tokyo No. Furukawa Electric Co., Ltd. Central Research Laboratory (72) Inventor Shoji Hara 2-9-15 Futaba, Shinagawa-ku, Tokyo Furukawa Electric Co., Ltd. Central Research Laboratory

Claims (1)

[Claims] 1. A central control unit for controlling each node of a plurality of nodes connected to an optical transmission line that logically constitutes a bus and a communication control for controlling data communication between the nodes. Section, an optical / electrical conversion block for converting an optical signal input from the optical transmission line into an electrical signal, and an electrical / optical conversion for converting the electrical signal into an optical signal and outputting a transmission signal to another node to the optical transmission line. In a method of detecting and removing a fault in an optical communication system including an optical transceiver unit including blocks, a first power feeding path that feeds the optical / electrical conversion block to each node, and a power feeding to the electrical / optical conversion block A second power feeding path and a switch means which is controlled to be switched by one of the central control unit and the communication control unit are provided in the middle of the second power feeding path, and the one control unit of each node is provided. , Abnormality signal to the optical transmission path first
When it is detected that it has occurred for a predetermined time, the switching means is operated to switch the power supply to the electric / optical conversion block for a second predetermined time specific to the node, and then the While monitoring the signal state of the optical transmission line via the optical / electrical conversion block, and holding the transmission signal output as no signal, the power supply to the electrical / optical conversion block is restarted, and immediately after the restart of the power supply. The presence / absence of an abnormal signal in the optical transmission line is determined to detect a fault in the node, and when no fault is detected in the node, the transmission signal output is held as a non-signal and all other signals are output. After waiting for the elapse of the third predetermined time period, which is sufficient for detecting the failure of the node, the output of the transmission signal is restarted, and when the failure of the node is detected, the power is supplied to the electro-optical conversion block. Stop again Fault detection and removal method of the optical communication system, characterized in that for holding the power supply stop state of the rear the electro-optical conversion block.