JPS6190533A - System for detecting line fault - Google Patents

Abstract

PURPOSE:To improve the utility of a communication system by allowing each terminal station device to measure a time when a transmitted signal is fed back from a reflected point, inform this time to a supervisory device and allowing the supervisory device to use the time and detect a line faulty location. CONSTITUTION:When a control section 8 of each terminal station device 5 receives a transmitted telegraphic message addressed to itself, a count of a counter section 20 is read, a telegraphic message informing the value and the own device address is constituted, and the result is transmitted to the supervisory device 4. A control section 10 of the device 4 holds a pair of the time value and the terminal station device address. When the required information is received, the control section 10 compares the stored time values, constitute an arrangement list arranging terminal station device addresses corresponding in a prescribed order and stores the list to a storage section 21. When no response comes from, e.g., a terminal station device 5-2, the supervisory device 4 references the said arrangement list, reads the address of a terminal station device 5-3, and transmits a telegraphic message for diagnosis to the terminal station device 5-3. When a normal response is obtained from the device 5-3, it is discriminated that the fault exists in the terminal station device 5-2. When no response comes also from the device 5-3, it is discriminated that the fault exists between corresponding couplers.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a line fault detection method in a so-called C5M^/CD communication network in which a plurality of terminal stations are connected in parallel to a transmission line. .

A C5MA/CD type communication network is widely known as a means of configuring a so-called local area network. Further, as one method in which this method is constructed using an optical transmission line or the like, there is a method using a transmission line folded back in a U-shape.

(Prior art and problems to be solved by the invention) FIG. 2 is a block diagram showing an example of the configuration of a U-shaped communication system.

The transmission path is from the starting end 11 to each coupler 1-3.1-2.1-
1.1-4, turns back at turning point 2, passes through coupler 1-4.1-1-1-3 again, and terminates at transmission line 13.
It forms a U-shape.

A monitoring device 4 and terminal devices 5-1 to 5-3 are connected to each of the couplers 1-1 to 1-4. For example, a signal sent from the transmitter 6 of the terminal device 5-1 is transmitted to the coupler -1.1-4,
After passing through the turning point 2, each coupler connects each terminal device 5-1 to
It arrives at the receiving section 7 of 5-3.

The control section 8 of each terminal device 5-1 to 5-3 monitors the signal received by the receiving section 7 to determine the state of the transmission path for communication between the connected terminal devices 9-1 to 9-3. Determine the CSMA/
In accordance with the CD system protocol, it controls the transmission of signals from the transmitter 6, determines the destination of data received by the receiver 7, and performs controls such as receiving communications addressed to its own station.

The monitoring device 4 is connected to the transmission path by a transmitting section 6 and a receiving section 7 like the terminal device 5-1 etc., and is periodically controlled by the control section 10 in the same manner as the control of the terminal device. Call each terminal device 5-1 to 5-3, and call each terminal device 5-1 to 5-3.
Diagnosis is performed to determine the normality of the terminal equipment and the transmission line depending on whether a normal response is obtained from the terminal equipment.

As a result of the diagnosis, if an abnormality is detected in the terminal equipment, the address of the faulty terminal equipment is notified to other terminal equipment that can communicate with the terminal equipment, so that they do not communicate with each other. Performs processing such as notifying maintenance personnel of the occurrence of an abnormality.

Cases in which an abnormality is detected by this diagnosis can be roughly divided into cases where a failure such as a power outage has occurred in the terminal equipment 5-1 to 5-3, and cases where a disconnection, etc. has occurred in the transmission line. There is.

”□ In the former case, normally only one end station device with a failure will be unable to communicate, and the other end station devices will be able to continue communication normally. However, in the latter case, generally the transmission line Since all the terminal devices connected at a position far from the failure point with respect to the return point 2 become unable to communicate, if they can be identified, it is possible to quickly determine the range of communication inability.

Furthermore, if the location of the failure can be accurately pointed out, including the distinction between the two types described above, it is possible to quickly take measures such as troubleshooting.

However, in the past, there was no means of identifying such failure points.
The only thing left to do was to sequentially diagnose all end station equipment and identify the end stations that were unable to communicate.

[Means for solving problems]

The problem with the above 0 is that the signals are transmitted in opposite directions to each other.
11, a parallel first transmission line and a second transmission line are connected at one end to form a turning point, and the transmission line is configured such that the signal transmitted to the first transmission line is received from the second transmission line. In a communication system in which a monitoring device and a plurality of terminal devices are connected to each other, each terminal device measures the time from when it sends a signal to the first transmission path until it receives the signal from the second transmission path. The monitoring device has means for notifying the monitoring device, and the monitoring device recognizes and memorizes the relative placement of each terminal device with respect to the turnaround point based on the time, and combines the relative placement and the response state of each terminal device. This problem is solved by the line failure detection method of the present invention, which is configured to determine the location of the failure.

[Effect]

That is, each terminal device is provided with a means for measuring the time required to receive the signal sent from itself returning via a return point, and the monitoring device is notified of this time.

The monitoring device compares these times and stores, for example, a layout table in which the addresses of each terminal device are arranged in descending order of time. The ranking of this arrangement table is equal to the order of the distance of each terminal device from the turning point.

When an abnormality is detected in a certain terminal equipment through the above-described diagnosis, next, for example, the terminal equipment located next to that terminal equipment at a farther position is indexed from the above-mentioned layout table, and the Diagnose the terminal equipment.

If the terminal equipment is normal, it can be determined that there is no failure in the transmission path.

If the terminal station device is also abnormal, there is a possibility that the transmission path failure has occurred at a position closer to the turning point than the terminal station device that first detected the abnormality. In this case, the possibility of a transmission path failure can be confirmed by diagnosing an even more distant terminal station.

〔Example〕

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

Each terminal device 5-1 to 5-3 includes a timer 20 in addition to the conventional transmitter 6, receiver 7, and controller 8.

The control unit 8 composes and transmits a message addressed to its own station, for example, as the first communication after power is turned on. At this time, the first character of the message is transferred to the transmitter 6 and the timer 20 is started at the same time.

The timer 20 detects the start of transmission of the first bit signal of the message from the transmitter 6 and starts counting, and detects the arrival of the bit signal from the receiver 7 and stops counting.

When the control unit 8 receives the message sent by itself, the control unit 8
It reads out the count value of 0, composes a message notifying the value and its own terminal device address, and sends it to the monitoring device 4.

When the monitoring device 4 receives this message, the control unit 1O holds the pair of time value and terminal device address, and in this way,
Waits for notifications to be received from all terminal devices that should receive notifications.

After receiving the required notifications, the control unit 10 compares the held time values and constructs, for example, a layout table in which the corresponding terminal device addresses are arranged in descending order of the values, and stores it in the storage unit 21. do.

During operation of the communication system, the monitoring device 4 monitors the terminal equipment in the same manner as in the past, for example by periodic diagnosis. As a result, when an abnormality is detected due to, for example, no response from the terminal device 5-2, the arrangement table in the storage unit 21 is referred to, and the position next to the terminal device 5-2 where the abnormality is actually detected (return The address of the terminal device 5-3 located at a far distance from point 2 is read out, a diagnostic message is sent to the terminal device 5-3, and a response from the terminal device is waited for.

If a normal response is obtained from the fourth station device 5-3, it is determined that the fault is in the terminal device 5-2.

If there is no response from the terminal device 5-3,
- Generally speaking, the probability that terminal equipment 5-2 and 5-3, which are independent from each other, will be in trouble at the same time is small, so there is a possibility that a fault such as a disconnection will occur in the coupler or transmission line from coupler 1-2 to coupler 1-1. There is a high possibility that

As described above, the control unit 10 composes a failure notification message according to the determined failure location and transmits it to all end station devices.

In addition, the location where the failure has occurred is displayed to the maintenance personnel in an appropriate manner.

〔Effect of the invention〕

As is clear from the above description, according to the present invention,
! Since the location of a line fault in a communication system can be accurately detected, there is a significant industrial effect of improving the reliability and availability of the communication system.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the configuration of an embodiment of the present invention, and FIG. 2 is a block diagram of an example of the configuration of a conventional system. In the figure, 1-1 to 1-4 are couplers, 2 is a turning point, 4 is a monitoring device, 5-1 to 5-3 are terminal devices, 6 is a transmitter, 7 is a receiver,

Claims (1)

[Claims] Parallel first channels for transmitting signals in opposite directions
The transmission path and the second transmission path are connected at one end to form a turning point, and a monitoring device and a plurality of terminal devices are installed on the transmission path so that the signal transmitted to the first transmission path is received from the second transmission path. In a communication system in which the terminal equipment is connected to each other, each terminal equipment has a means for measuring the time from sending a signal to the first transmission path to receiving the signal from the second transmission path and notifying the monitoring device. The monitoring device recognizes and stores the relative placement of each terminal device with respect to the turning point based on the time, and determines the location of the failure based on the relative placement and the response state of each terminal device. A line fault detection method characterized by comprising: