JPH0113665B2 - - Google Patents

Description

Detailed Description of the Invention The present invention provides a loop that has two pairs of transmission lines, a working transmission line and a protection transmission line, and that performs so-called loop replacement, in which the protection transmission line takes over when a failure occurs in the working transmission line. This invention relates to a transmission system that facilitates the search for failure locations.

In a loop transmission system, the loop transmission line is generally duplicated to improve the reliability of the loop transmission line. However, in the past, when a failure occurred on the working transmission line and the loop was then switched to the protection transmission line, the task of searching for the fault location between stations on the old working transmission line, which had become the protection transmission line, ended. Either you can investigate it later, or you can investigate each connection unit between terminal stations or between a monitoring station and a terminal station, or you can investigate whether the configuration of both the monitoring station and the terminal station is the same as that of the circuit connected to the current transmission line. Alternatively, a method has been considered in which a circuit with the same level of functionality is also provided on the backup transmission line side and investigated using a test program or the like.

However, the first method of conducting an investigation after the work is completed cannot be applied to a non-stop operation system. In the second method, which is performed individually between stations,
It requires a lot of manpower and is time consuming. The third method has the problem that it requires a large amount of material and is not economical.

Therefore, an object of the present invention is to eliminate the above-mentioned problems, and to easily and economically realize failure location search without stopping system operation after loop replacement. Our goal is to provide a loop transmission system that can.

The features of this invention are as follows. In other words, in a loop transmission system in which multiple stations are connected in series through two sets of transmission lines, a working transmission line and a protection transmission line, the first station has a means for sending a specific signal to the protection transmission line, and a means for transmitting a specific signal to the protection transmission line, and means for inquiring about the status of the backup transmission line using the working transmission line from the second station of the station. The second station also includes means for checking the reception status of the specific signal from the backup transmission line, and means for checking the check result in response to the inquiry from the first station using the working transmission line. and means for responding to the station.

Next, embodiments of the present invention will be described in detail using the drawings.

FIG. 1 is a schematic block diagram of a loop transmission system which is an embodiment of the present invention.

A monitoring station 1 that manages the operation of the entire loop transmission system and a plurality of terminal stations 21 to 2n are connected in series by transmission lines 3 and 4. The monitoring station 1 includes a control mechanism 1-1 that controls the status of the entire monitoring station and issues commands to each circuit and mechanism within the monitoring station using a microprogram;
- 1 and which issues an inquiry frame, and the bit parallel data sent from this inquiry frame sending mechanism 1-2 is detected when the monitoring station 1 is able to transmit the data. It has a pair-loop data transmitting/receiving circuit 1-4 that converts data into bit series data and sends it to a signal modulation circuit 1-6 or 1-7. Signal modulation circuit 1-6, 1
-7 are circuits that perform signal conversion for sending data to the transmission lines 3 and 4, respectively.

Changeover switches SW1 and SW2 are connected to the inputs of the signal modulation circuits 1-6 and 1-7, respectively. The changeover switches SW1 and SW2 connect the output of the specific signal generation circuit 1-5 that continuously generates a repeating pattern of 1010..., that is, a dot pattern, to the signal modulation circuits 1-6 and 1-7, respectively, or This is a changeover switch for performing so-called loop switching, which selects whether to connect the outputs of the paired loop transmitting/receiving circuits 1-4 to the signal modulation circuits 1-6, 1-7, respectively. The transmission lines 3 and 4 are opposite circuits, that is, when one is connected to the paired loop data transmission/reception circuit 1-4, the other is connected to the specific signal generation circuit 1-5. Therefore, the one connected to the pair-loop data transmitting/receiving circuit 1-4 side is the working transmission line.

On the other hand, a plurality of terminal stations 21 to 2n connected in series
The data received via the signal demodulation circuit 1-
8 or 1-9, the bit-serial data is converted to bit-parallel data by the pair-loop data transmitting/receiving circuit 1-4, and if the data is addressed to the own station, the response frame receiving mechanism 1 - Transferred to 3. The response frame receiving mechanism 1-3 has a function of analyzing the received data and notifying the control mechanism 1-1 of the result. Changeover switch SW3
is used to determine whether the received data is to be received from transmission line 3 or 4, and is connected to the working transmission line side.

The configurations of the terminal stations 21 to 2n are the same for each terminal station, and the configuration shown for the terminal station 22 is taken. Terminal 2
2, the control mechanism 2-1 controls the operation by a microprogram similarly to the control mechanism 1-1 in the monitoring station 1, and is in charge of the overall control of the terminal station 2. The terminal station 22 uses this control mechanism 2-1.
Act according to instructions.

Data from the transmission lines 3 and 4 are demodulated by signal demodulation circuits 2-8 and 2-9, respectively. The signal demodulation circuits 2-8, 2-9 are similar to the signal demodulation circuits 1-8, 1-
It is the same as 9. Signal demodulation circuit 2-8, 2
The data demodulated by -9 is transferred to selector switch SW4.
Accordingly, the side serving as the working transmission line is selected by the changeover switch 4, and is input to the paired loop data transmission/reception circuit 2-4.

The data transmitting/receiving circuit 2-4 converts the input received data from bit-serial data to bit-parallel data, determines whether the data is addressed to the own station, and sends an inquiry frame to the own station. or a data terminal device connected to your own station (hereinafter referred to as
DTE).
If the data is to DTE connection control mechanism 2-10
If the inquiry frame is for the own station, the inquiry frame is transferred to the inquiry frame receiving mechanism 2-3.

The inquiry frame receiving mechanism 2-3 has a function of analyzing the received inquiry frame and notifying the control mechanism 2-1 of its contents.

On the other hand, the specific signal detection circuit 2-5 is connected to the transmission line 3 or 4, which is on the standby side, by a changeover switch SW7, and continuously displays a dot pattern on the connected transmission line for a certain period of time or more. is being sent out, it has a function of turning on the output signal and notifying the control mechanism 2-1.

The control mechanism 2-1 is an inquiry frame receiving mechanism 2-
When receiving information indicating that the standby transmission line status inquiry frame has been received from 3, the signal from the specific signal detection circuit 2-5 is determined, and the result indicates whether or not the dot pattern is being received. It has a function of creating a response frame and instructing the response frame transmission mechanism 2-2 to send the response frame.

The response frame transmission mechanism 2-2 is the control mechanism 2-1.
When a response frame transmission instruction is received from the loop transmission/reception circuit 2, the response frame is temporarily stored,
It has a function to instruct transmission to 4.

When the pair-loop transmitting/receiving circuit 2-4 receives the sending instruction, it sends out a response frame to either the signal modulating circuit 2-6 or 2-7 when it detects the sending possible timing of its own station. As to which circuit to send the signal to, the current transmission line side is selected by the changeover switch SW8.

The changeover switch SW5 is located between the demodulation circuit 2-9 and the signal modulation circuit 2-7, and the changeover switch SW6 is located between the demodulation circuit 2-8 and the signal modulation circuit 2-6. The switch closes the circuit, and the switch on the side of the working transmission line opens the circuit.

The configuration of this embodiment and the functions of each part have been described above.

Next, the operation will be explained based on the embodiment shown in FIG.

The state shown in FIG. 1 shows the state after a failure has occurred in the transmission line 4, which has been used as the working transmission line, and the loop replacement between the working transmission line and the backup transmission line has been performed. Note that it is assumed that the failure location is located at the location marked with an x between the terminal stations 21 and 22.

In the above state, console 1 at monitoring station 1
-10, when the operator inputs a fault location search command, the control mechanism 1-1 instructs the inquiry frame generation mechanism 1-2, the loop data transmission/reception circuit 1-4, and the signal modulation circuit 1. ―
6, an inquiry frame is sent to the terminal station 21 as to whether or not the dot pattern is being received. When the terminal station 21 receives this inquiry frame, the control mechanism 2-1 in the terminal station 21 controls the paired loop data receiving circuit 2-
4. Knowing that the inquiry frame has been received by the inquiry frame receiving mechanism 2-2. By recognizing this inquiry frame, the control mechanism 2-1 judges the output signal of the specific signal detection circuit 2-5, but there is no fault between the terminal station 21 and the monitoring station 1, and the dot pattern is normal. Since it has been received, a response frame indicating "receiving dot pattern" is created and transmitted using the transmission line 3 via the response frame sending mechanism 2-2, pair-loop transmitting/receiving circuit 2-4, and signal modulation circuit 2-6. and responds to monitoring station 1. When the monitoring station 1 receives this response, it is reported to the control mechanism 1-1 via the signal demodulation circuit 1-8, the pair-loop transmitting/receiving circuit 1-4, and the response frame receiving mechanism 1-3. When the control mechanism 1-1 receives this report and recognizes that the dot pattern is normally being received at the terminal station 21, it then similarly inquires of the terminal station 22 whether or not the dot pattern is being received. Since the fault location is located upstream of the terminal station 22, the terminal station 22 returns a frame indicating that "dot pattern is not received" to the monitoring station 1 as a response. In this way, inquiries are sequentially made from the terminal stations 21 to 2n, and at the monitoring station 1, the results are sent to the console 1-1 by the control mechanism 1-1.
10 to notify the operator. At which terminal the operator detects the dot pattern and
Alternatively, by knowing whether or not the fault has been detected, it is possible to identify which section of the transmission path 4 has the fault.

FIG. 2 is a time chart of the above operation. In FIG. 2, inquiries and responses related to fault location detection are shown, and those related to normal data transmission are omitted. Also, inquiries and responses to the terminal stations 23 to 2n are also omitted.

In the above embodiment, a dot pattern, which is the simplest pattern, was used as the specific signal sent to the protection transmission line, but other signals (e.g.
11001100...), etc., it is of course possible. In short, it is sufficient that the signal level does not remain at "0" or "1", that is, a so-called non-communication state.

Furthermore, the configuration shown in Fig. 1 is only one example, and it is easy to analogize other mechanisms that have equivalent functions, such as integration of each mechanism such as the inquiry frame generation mechanism 1 and 2, and conversion of the changeover switch to an electronic switch. It goes without saying that the present invention includes all of these.

Further, although the case where n terminal stations are connected has been described, it goes without saying that only one terminal station may be used.

Further, although the case where there is one monitoring station has been described, it goes without saying that the monitoring station may be connected to an appropriate terminal station position.

The embodiments of this invention have been described above, and the following effects can be obtained by this invention.

Inquiries for fault detection and communication operations for responses can be performed using the current transmission line while normal data transmission is being carried out, making it possible to perform searches while online and realize a loop transmission system that operates 24/7. can.

Since responses to inquiries from the monitoring station are received, remote diagnosis can be performed from the monitoring station, and manpower can be saved.

In addition to the normal operation function, the functions required in the present invention include a specific signal generation function and a specific signal detection function, and the present invention requires only a small amount of circuitry and is highly economical.

It is possible to detect not only disconnection accidents in the transmission line, but also failures in the signal modulation/demodulation circuits of each station and logic circuits connected in series with the transmission line, which fix the polarity to a fixed value.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram of a loop transmission system according to an embodiment of the present invention, and FIG. 2 is a time chart showing a fault location searching operation in the loop transmission system of FIG. Explanation of symbols, 1...Monitoring station, 1-1...Control mechanism, 1-5...Specific signal generation circuit, 21-2n...
... terminal station, 2-1 ... control mechanism, 2-5 ... detection circuit, 3, 4 ... transmission line.

Claims (1)

[Claims] 1. In a loop transmission system in which a plurality of stations form a loop in series with two sets of transmission lines, a working transmission line and a protection transmission line, a first station transmits a specific signal to the protection transmission line. and means for inquiring the remaining second station about the status of the protection transmission line using the working transmission line, and the second station transmits the specified signal from the protection transmission line. A loop transmission system comprising: means for checking a reception state; and means for responding to the inquiry from the first station with the check result using a working transmission line. 2. The loop transmission system according to claim 1, wherein a plurality of said second stations are provided. 3. The loop transmission system according to claim 2, wherein the inquiry means makes an inquiry to each of the second stations sequentially. 4 Any one of claims 1 to 3
3. The loop transmission system according to 1., wherein the specific signal sending means sends out a repeating pattern of "1" and "0".