JPH0479641A - System for detecting faulty location of loop transmission line - Google Patents

Abstract

PURPOSE:To detect a faulty location in a short time by sending fault transmitting signals which are different from each other by stations to be monitored to the 2nd transmission line when the occurrence of a fault is detected on the 1st transmission line so that a monitoring station can identify the stations to be monitored by detecting the fault transmitting signals. CONSTITUTION:When a fault occurs on a transmission line 1, the reception circuit 5 of a station S1 to be monitored immediately after the faulty point A detects the fault and sends a fault detecting signal 10 to a control circuit 3. Upon receiving the signal 10, the circuit 3 transmits a fault transmitting signal 11 to a transmission 2 from a transmission circuit 6a. After receiving the fault transmitting signal, a station Si-1 to be monitored on the upstream side passes the signal and transfers the signal to the transmission line 2 and the signal is transmitted to a monitoring station M after the signal is successively passed to upstream-side stations to be monitored. The fault transmitting signal is transmitted to a monitoring control circuit 4 through the reception circuit 8a of the station M and the station Si to be monitored which has transmitted the fault transmitting signal from the form of the received signal and the position of the faulty point A is discriminated immediately.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for detecting the location of a fault in a loop transmission line, and in particular, the present invention relates to a method for detecting the location of a fault in a loop transmission line, and particularly when a monitoring station and a plurality of monitored stations have two different transmission directions.
This invention relates to a method for detecting the location of a fault in a loop transmission line in a data transmission system connected in a loop with multiple transmission lines.

[Conventional technology]

BACKGROUND ART Conventionally, in this type of data transmission system, fault position detection in a loop transmission line that performs normal data transmission has been performed using the following method.

A monitoring station M' equipped with a monitoring control circuit having a fault monitoring function and a plurality of monitored stations 811 to SI are connected to two transmission lines 1 and 2 having mutually different transmission directions as shown in FIG. In the data transmission system, if a failure occurs in transmission line 1, which is constantly transmitting data, failure point A
The monitored station S'+ (i=1 to n) immediately after transmits a fault signal to the transmission line 2.

To simplify the device, each monitored station is equipped with only a one-way data transmission function, and during normal times, it simply transfers the received alarm signal as is to the transmission line 2 in the opposite direction, and prevents failures. It only has the function of sending out a fault signal when it is detected.

Therefore, the monitoring station M cannot identify the location of the fault just by receiving the fault signal, and first sends a return circuit creation command from the transmission path 1 to the nearest monitored station S11 to have it create a return circuit LI. After that, send a test signal and perform a loop test. If there is no abnormality, a cancellation command is sent to cancel the return loop L1, and then the same loop test is repeated for the next monitored station in order, and the monitored station S'I-
Up to 1, the loop test can be performed without any abnormality, but the monitored station S+
Since the loop test cannot be performed for 1, failure point A
is being detected.

[Problem to be solved by the invention]

In the conventional loop transmission path fault location detection method described above,
It takes time to repeatedly create and release loops,
It has the disadvantage that it cannot respond to urgent data transmission requests.

An object of the present invention is to provide a method for detecting the location of a fault in a loop transmission line that can detect a fault point in a short time without complicating the equipment of each monitored station.

[Means to solve the problem]

The loop transmission path fault location detection method of the present invention uses two transmission paths with different transmission directions: a first transmission path that transmits data during normal times, and a second transmission path that normally only transmits alarms. In a loop transmission path fault location detection method, in which the monitoring station of a data transmission system in which a monitoring station and a plurality of monitored stations are connected in a loop, detects the location of a fault point of the first transmission path. When the monitored station detects that a fault has occurred in the first transmission path on the input side, the second transmission transmits a different fault transmission signal for each monitored station predetermined to enable station identification. The monitoring station is configured to detect the fault communication signal and identify the monitored station that transmitted the fault communication signal.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a system configuration diagram for explaining one embodiment of the present invention. The monitoring station M and the monitored station are connected to the transmission line 1 (first transmission line), which performs data transmission during normal operation, and the transmission line 2 (second transmission line) in the opposite direction, which is normally used only for alarm transmission. 8
1 to Sfl are connected in a loop to form a data transmission system. In this system, when an abnormality occurs at the failure point A on the transmission line 1 for data transmission, the immediately following monitored station SI detects it, and the control circuit 3 transmits the failure in a predetermined station-specific format. A signal 11 is sent to the transmission line 2. This fault transmission signal 11 is detected by the monitoring control circuit 4 of the monitoring station M, and is immediately identified as the fault transmission signal from the monitored station Sl, so that the position of the fault point A can be detected. The format of the fault transmission signal is preferably one that occurs easily and can be easily identified; for example, an intermittent signal with a different repetition period can be used.

FIG. 2 is a block diagram showing the configuration of a monitoring station and a monitored station according to an embodiment of the present invention.

When a fault occurs in the transmission line 1 in operation, the receiving circuit 5 of the monitored station SI immediately after the fault point A detects this and the control circuit 3
A fault detection signal 10 is sent to

When the control circuit 3 receives the fault detection signal 10, it transmits the fault transmission signal 11 from the transmitting circuit 6a to the transmission line 2. A monitored station 5l-8 (not shown) on the upstream side (upstream side of data transmission path 1 and downstream side of transmission path 2) that receives this signal has a receiving circuit 5a and a transmitting circuit 6a connected by a switching circuit 7. Therefore, the fault transmission signal passes through as it is and is transferred to the transmission line 2, and is sequentially transmitted to the monitoring station M via the monitored station further upstream. This fault transmission signal is transmitted to the receiving circuit 8 of the monitoring station M.
The monitored station SI that transmitted the fault transmission signal is identified by the format of the received fault transmission signal, and the position of the fault point A is immediately determined.

FIG. 3 is a signal waveform diagram of the main parts explaining the above-mentioned operation. When a fault occurs in the transmission line 1 on the input side of the monitored station S, the input signal of the transmission line 1 disappears, a fault detection signal 10 is output, and a fault transmission signal 11 is sent out a little later than that. This signal is output to the transmission line 2, passes through each upstream monitored station, and is transmitted to the input of the transmission line 2 of the monitoring station M with a slight delay, and the monitoring control circuit 4 identifies the transmitted monitored station.

When the detection of the location of the failure point A is completed, the monitoring station M issues a transmission path switching instruction to the monitored station SI-1 via the transmission path 1. The monitored station S l-+ that received this
returns the data signal input from the transmission line 1 to the transmission line 2 by switching the B side contact of the switching circuit 7,
The faulty location is deleted. Note that when the faulty monitored station Sl transmits the fault transmission signal 11, the C-side contact of the switching circuit 7 is switched to transfer the signal from the transmission line 2 from the transmission circuit 6 via the information processing section of the control circuit 3. Fold back to transmission line 1. Here, if the monitoring station M transfers the signal on the transmission line 2 from the receiving circuit 8a to the transmitting circuit 9a,
A loop transmission path excluding failure point A is constructed.

In the above embodiment, the failure transmission signals generated by the monitored station are explained as intermittent signals with different repetition periods, but the station identification code used for data transmission is used, and when a failure occurs, a fixed length clock and station identification code are used. The codes may be transmitted alternately, and if the monitoring station is provided with a simple decoding circuit similar to the data transmission system, this can be implemented with only slight changes to the equipment of the monitored station.

In addition, the switching circuit 7 restores the data transmission path after the point of failure is detected.
Although it has been explained that the transmission path is looped back at the monitored stations before and after the point of failure, it is also possible to recover from the failure by replacing the transmission paths 1 and 2.

〔Effect of the invention〕

As explained in detail above, the present invention provides a means for generating a fault transmission signal in a format that allows easy station identification in each monitored station, and the monitoring station identifies this, so that the fault can be located easily with a simple configuration. This has the effect of allowing detection to be performed in a short time. Furthermore, the control program for fault position detection can also be simplified.

[Brief explanation of the drawing]

FIG. 1 is a system configuration diagram for explaining an embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of a monitoring station and a monitored station according to an embodiment of the present invention, and FIG. 3 is a system configuration diagram for explaining an embodiment of the present invention. FIG. 4 is a waveform diagram of signals of various parts to explain the operation of one embodiment. FIG. 4 is an explanatory diagram of a conventional fault position detection method for a loop transmission line. 1.2...Transmission line, 3...Control circuit,
4...Monitoring control circuit, 5+ 5a, 8.8a・
...Reception circuit, 8) Eta, 9,9a...
・Transmission circuit, 7...Switching circuit, 8...
Response control circuit, failure detection signal for 10..., 11...
...Failure transmission signal, A...Failure point, LI...
...Return circuit, M, M', old...monitoring station, Sl+
S'...Monitored station.

Claims (1)

[Claims] A monitoring station and multiple monitored stations are connected in a loop through two transmission lines with different transmission directions: a first transmission line that transmits data during normal times, and a second transmission line that only transmits alarms during normal times. the first monitoring station of the connected data transmission system;
In a loop transmission path fault location detection method for detecting the location of a fault point on a transmission path, when each monitored station detects that a fault has occurred in the first transmission path on the input side, the station identification is performed. The monitored station transmits a different fault transmission signal to the second transmission path, which is determined in advance for each monitored station, and the monitoring station detects the fault transmission signal and transmits the fault transmission signal. A loop transmission path fault location detection method characterized by identifying.