JPH0113777B2 - - Google Patents

Description

[Detailed Description of the Invention] (1) Technical Field of the Invention The present invention deals with failures in loop transmission paths in a communication system in which a monitoring station and a plurality of monitored stations are connected by two transmission paths with different transmission directions. Regarding position detection method.

(2) Background of the technology Conventionally, a monitoring station (hereinafter referred to as a master station) and a monitored station (hereinafter referred to as a slave station) each having a fault monitoring device are connected to two loop transmission paths with different transmission directions. For example, in a data highway transmission system, when a failure occurs in the loop transmission path, the failure monitoring device of the main station detects this and sends a loopback circuit creation signal to the slave station near the main station. -Create a loop between slave stations, then send a test signal from the master station to perform a loop test. If the result is OK, the loop test is sequentially performed on the next slave station to search for the point of failure.

The test method described above has the drawback that it takes time to repeatedly create and release the loop, and it cannot respond to urgent data transmission responses.

For this reason, there is a need for a method for detecting the location of a fault in a loop transmission line, which can restore the fault in the transmission line in a short period of time.

(3) Prior art and problems Figure 1 shows a main station 4 having a fault monitoring device 3 on transmission line 1 of system A and transmission line 2 of system B, and each slave station 5-1, 5 connected to the main station. -2...5-n is a schematic diagram of a conventional data highway.

The data signal () sent from the main station 4 is transmitted to the transmission path 1, the data signal () sent from the main station 4 is transmitted to the transmission path 2, and the data signal () sent from the main station 4 is transmitted to the transmission path 2.
It is transmitted in the direction of 1 to 5-n or 5-n to 5-1. In this case, a carrier wave (clock pulse) for fault detection is detected from the data signal.

Now, if a failure occurs at point A on the transmission path, main station 4
An abnormality in the carrier wave is detected in the fault monitoring device 3 (hereinafter referred to as SV) of the main station 4, and a signal to create a loop in the return circuit is output from the SV3 to the slave stations 5-1 and 5-n closest to the main station 4. and loop 6-1,6
-Make n. Then, a test signal is sent from the main station 4 to check the transmission path between the main station and the slave station. If there is no failure, loops 6-1 and 6-n are released,
Next, slave stations 5-2, 5, which are the next in rank from the main station 4.
-(n-1) (not shown) and check the transmission path using the same method as above.

The checks are performed sequentially as described above to confirm the location of the fault point (A) between slave stations 5-i and 5-(i-1).

In the above test, a fault is detected in SV3, and then the transmission path between the main station and each slave station is checked sequentially. At this time, the transmission path loop is repeatedly created and released, so the failure point is detected. and recovery work will take a considerable amount of time.

Therefore, it has the disadvantage that it cannot handle urgent data transmission.

(4) Purpose of the Invention In view of the above-mentioned drawbacks of the conventional example, the present invention provides a novel method for detecting the fault position of a loop transmission line, which uses the other transmission line to detect the fault point when one transmission line fails. With the goal.

(5) Structure of the Invention According to the present invention, a monitoring station and a plurality of monitored stations are connected in a loop through two transmission lines having different transmission directions, and the monitoring station is connected via one of the transmission lines. In a system where data transmission and the status of the monitored station are monitored through periodic polling between the station and the monitored station, when a failure occurs in one transmission path, the monitored station following the failure location When a reception status abnormality is detected in the monitored station, switching from one transmission path to another is performed within the relevant monitored station, and the monitoring station that also detected the abnormality switches to the monitored station that is in front of the fault location. A transmission line switching command is sent via one transmission line, each monitored station switches from one transmission line to another transmission line, and then the monitored station is sent from the monitoring station via the switched transmission line. When polling, the monitoring station confirms the location of the fault on the transmission path based on a transmission path reception status abnormality command from the monitored station that was after the location of the fault on the transmission path before switching. This is achieved by a loop transmission path fault location detection method.

(6) Examples of the invention The present invention will be described below based on the drawings. Fig. 2 is a schematic explanatory diagram of the present invention, Fig. 3a is a block diagram showing the configuration of a main station and a slave station, and Fig. 3b is an SV of the present invention.
Show frame. In FIG. 2, polling is performed periodically between the main station and each slave station.

In the above state, the frame circuit 8 of the main station 7 in FIG.
A frame having the SV frame shown in FIG. 3b is then sent to the transmission line 1 of the A system.

The structure of the SV frame is as shown in the example in FIG. 3b, where it is placed after F of the frame having a frame pattern at the beginning, and data is placed after the SV frame. S.V.
The frame consists of NDA, NDC, and NDR.
NDA is the slave station address, NDC is the control command,
For example, it controls a transmission line changeover switch.
NDR is slave station data and carries the operating status of each slave station.
In the present invention, the reception status is recorded, for example, clock disconnection,
It consists of data such as synchronization loss, level abnormality, etc.

Now, when a failure occurs at point (A)' of transmission line 1, an abnormal reception state is detected at slave stations 5'-i to 5'-n and main station 7, and the detected data is transmitted to slave stations 5'-i. ~
Each of the control circuits 10-i to 10-n of 5'-n creates NDR data for the SV frame, and the switches 11-i to 11-n are independently controlled by the control circuits 10-i to 10-n. 11-n to switch from transmission line 1 to transmission line 2. At this time, the main station 7 also detects an abnormality in the reception state of the transmission line 1, so the main station 7 inputs a transmission line switching signal to the frame circuit 8 from the SV9. In the frame circuit 8, a command for switching from the transmission line 1 to the transmission line 2 is placed in the control command of the SV frame, that is, the NDC. The command is sent from the main station 7 to the transmission line 1. The address NDA of this SV frame is addressed to all slave stations, and it is detected at all slave stations preceding the fault location (A'), 5'-1 to 5'-i-1 in the figure. , the control command NDC is the control circuit 10-
1 to 10-i-1, and the control circuit 10-1
~10-i-1 controls switch 11-1~
11-i-1 to switch from transmission line 1 to transmission line 2. Note that, as described above, 5'-i to 5'-n have already been independently switched to the transmission line 2. After all the slave stations have switched to transmission path 2, the main station 7
Put a polling command in the NDC of the frame,
Also, polling of the slave stations is performed by sequentially loading the addresses of the slave stations on the NDA. Through this polling, the main station 7 receives an NDR indicating that the transmission path reception status is abnormal from the slave stations 5'-i to 5'-n.
It is learned that a transmission path abnormality has occurred between (i-1) and 5'-i.

Figure 3a shows an embodiment of the invention. At the main station 7 in Figure a, a frame with an SV frame shown in Figure b is output from the frame circuit 8 and passed through the SV9 to the transmitter 12.
-0 to transmission line 1. Each slave station 5'-1
~5'-n operate according to frame data.

Now, if a failure occurs at point (A)' of transmission line 1,
The fault is detected in the slave stations 5'-i to 5'-n.
For purposes of explanation, slave station 5-i will be described. The fault is received by the receiver 13-i and sent to the control circuit 10-i. 10-i independently controls switch 11-i to switch from transmission line 1 (A) to transmission line 2 (B).
After switching the transmission path at the slave station after the fault location, and switching the transmission path at the slave station before the fault location under the control of the master station,
Polling is performed between the main station and the slave station via the switched transmission path, but at that time the slave station 5'-i
The operation is as follows. That is, the receiver 13'
The slave station address NDA is detected from the SV frame (NDC instructs polling) of the received frame received at -i, and the NDA detection signal is input to the control circuit 10-i.

As a result, the control circuit 10-i transmits fault data.
Transmitter 1 is placed on the NDR via switch 11-i.
2'-i to the receiver 1 of the main station 7 via the transmission line 2.
3'-0, and fault data is detected at SV9. The location of the fault is confirmed from this detection data.

Also, as mentioned above, when a failure occurs at point (A)' of transmission path 1, slave stations 5'-i to 5'-n autonomously switch the transmission path from 1 to 2, but slave station 5 '-1~5'-(i
-1) is switched by a command from the main station.
The procedure is shown below.

For all slave stations 5'-1 to 5'-(i-1) located before the fault location (A') from SV9 of main station 7, switch to transmission line 2 via transmission line 1. The SV frame containing this control command is created by the frame circuit 8. The SV frame carrying the control command is sent to the slave station and
The NDC is input to the control circuits 10-1 to 10-i-1 (Fig. 2) of the slave stations 5'-1 to 5'-i-1, and the switches 11-1 to 11 are controlled by the NDC.
1-i-1 (FIG. 2) to switch transmission line 1 to transmission line 2.

After the transmission path is switched in this way, the main station 7 starts polling the slave stations using the transmission path 1.

(7) Effects of the invention According to the present invention, regarding one-sided transmission path failure,
Faults can be detected without the need for turning back the transmission line, so the fault location detection time can be shortened, and the complicated algorithm of searching for turning back the transmission line can be freed, which has the advantage of reducing the size of the control program. have

[Brief explanation of drawings]

FIG. 1 is a diagram showing a conventional fault location detection method.
FIG. 2 shows an embodiment of the present invention, and FIG. 3 shows an SV frame, etc. In the figure, 1 and 2 are transmission paths, 3 and 9 are fault monitoring devices (SV), 4 and 7 are main stations, 5-1 to 5-n, 5'-1
~5'-n is a slave station, 6-1 to 6-n are return circuits (loop), 8 is a frame circuit, 10-1 to 10-
n is a control circuit, 11-1 to 11-n are switch circuits, 12-0 to 12-n and 12'-0 to 1
2'-n (not shown) is a transmitter, 13-0 to 13
-n and 13'-0 to 13'-n (not shown) indicate receivers.

Claims (1)

[Claims] 1 Via two transmission lines with different transmission directions,
A monitoring station and multiple monitored stations are connected in a loop,
In a system where data transmission and the status of the monitored station are monitored by periodic polling between the monitoring station and the monitored station via either transmission path, when a fault occurs in one transmission path, the location of the fault is determined. When a reception status abnormality is detected in a subsequent monitored station, switching from one transmission path to another is performed within the monitored station, and the monitoring station that also detected the abnormality is switched from one transmission path to another. A transmission line switching command is sent via one transmission line to the monitored station located at When polling from the monitoring station to the monitored station via , the monitoring station detects the location of the fault on the transmission path due to a transmission path reception status abnormality command from the monitored station that was after the fault location on the transmission path before switching. A method for detecting the location of a fault in a loop transmission line, characterized in that the following is confirmed.