JPS5950639A - Method for detecting restoration of failure in loop data transmission system - Google Patents

Abstract

PURPOSE:To detect automatically the state of restoration in a failed section, by transmitting a monitor signal to a signal intermitting section by a loop back terminal station and receiving the monitor signal transmitted from the loop back terminal station of opposite party via a signal relay section. CONSTITUTION:When a signal interruption takes place on transmission lines 3d, 4d, a transmission controller 2c connects a signal on a transmission line 4c to a transmission line 3c and a transmission controller 2d connects a signal from a transmission line 3e to a transmission line 4e, respectively, and a monitor controller 1 connects a signal from a transmission line 3a to a transmission line 3h and connects a signal from a transmission line 4h to a transmission line 4a, respectively to constitute the loop back. Monitor signal generating circuits 24c, d keep to transmit the monitor signal to the signal interruption sections 3d, 4d from the controllers 2c, 2d. Further, detecting circuits 25c, 28d monitor whether the monitor signal transmitted from the opposite party is transmitted on the transmission lines 3d, 4d. When the transmission lines 3d, 4d are restored, the circuit 25c, 28d detect the transmission of the monitor signal and recognizes that the signal interruption section is restored.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] The present invention relates to a loop data transmission system, and particularly to a method for detecting failure recovery during loopback.

[Prior art]

Generally, a loop data transmission system has a configuration as shown in FIG. In the same figure, the supervisory control device (C
8T) 1 is necessary for the loop transmission system and performs system failure monitoring and recovery control from failures when locks occur. Transmission control devices (ST) 2a-g connect scattered terminals (not shown) to the loop transmission system. The transmission lines 3a-h and 4a-h connecting the supervisory control device 1 and the transmission control devices 'la-g, respectively, transmit signals in opposite directions and form a loop.

In addition, the transmission system using the transmission lines 3a-h is called the A non-transmission line,
The transmission system using the transmission lines 4a to 4h will be referred to as a B-system transmission line.

Now, if a failure occurs on transmission lines 3d and 4d,
As shown in FIG. 2, a transmission control device 2c.

2d (hereinafter referred to as a loopback terminal station), the signals transmitted from the transmission line 3c are transferred to the transmission line 4cm,
5. A loopback is performed in which the signal transmitted from the transmission line 4e is returned to the transmission line 3e.

By adopting such a loopback configuration, even if a failure occurs in the transmission lines 3d and 4d, the system can be maintained.

However, it is not preferable to continue the loopback configuration, and it is necessary to break the loopback configuration as soon as possible.

The reason for this is that if another failure occurs during the loopback configuration, the transmission control device caught in the failed section will be removed from the management of the supervisory control device.

Therefore, if a failure in the loop transmission path can be repaired through maintenance and inspection, the transmission system itself needs to quickly recognize the recovery in order to reconfigure the network.

However, in the conventional method for making this recognition, after the repair work on the network is completed, the maintenance personnel inputs into the supervisory control device that the repair has been completed.

Therefore, it is necessary to provide the supervisory control device with an interface for inputting the completion of repair, which makes the device complicated.

In addition, since the recovery procedure is executed based on instructions from the operator without checking the electrical connection between the loopback terminal stations, if there is a faulty cable connection, it is necessary to check whether the network has been completely repaired or the loopback configuration has been removed. I had to.

[Purpose of the invention]

An object of the present invention is to provide a method for automatically detecting a recovery state upon completion of recovery from a loopback state of a loop transmission system.

[Features of the invention]

A feature of the present invention is that each loopback terminal station sends a monitoring signal during the signal interruption section, and receives the monitoring signal transmitted from the loopback terminal station on the opposite side of the section via the signal interruption section. The purpose is to detect a failure recovery state.

[Explanation of Examples]

Hereinafter, one embodiment of the present invention will be shown and described in detail.

FIG. 3 is a configuration diagram of a transmission control device to which this embodiment is applied.

In the figure, the transmission control device 2c is roughly divided into a microcomputer 100 and a transmission section including a modulation circuit 26, a demodulation circuit 27, and the like. The signal from the A system transmission line 3c mentioned above is received by the receiving circuit 34, and the signal from the B non-transmission line 4d is received by the receiving circuit 35, and the multiplexer 30 selects which of these transmission lines. The selected signal is selected by a control circuit (LOOP CTL) 29 that determines which signal is selected, and is input to a demodulation circuit 27.

Note that the microcomputer 100 includes a microprocessor (MPU) 17. Read-only memory (ROM) 18 containing a microprogram, memory (RAM) 19 for data buffers, etc. Internal bus 209 communication LSI (
HDLC) 21, general-purpose input/output control LSI (PPI) 2
Consists of 2.

The signal received from the transmission path is sent to the demodulation circuit 27 as a data 27a and a clock 27b on the communication control LSI 21.
and is decoded by the microcomputer 100.

On the other hand, from the microcomputer 100 to the communication control LS
The signal transmitted via I21 is modulated by modulation circuit 26. Then, via the multiplexers 31 and 32 controlled by the control circuit 29, the transmission of the A-system transmission line 3 (the i circuit 33 and the transmission circuit 36 of the B-system transmission line 4 is carried out, and the signals are transmitted to the respective transmission lines. be done.

The configuration of the supervisory control device 1 is shown in FIG. This is also the same as the transmission control device in terms of data transmission and reception operations. However, in addition to transmitting and receiving data, the supervisory control device also includes a connection command generation circuit (CON GEN) 23 and a supervisory signal generation circuit (SVS GEN) 24e4 for connecting a microcomputer to the transmission line side of each transmission control device. T-More 1
These signals are selected by multiplexers 31 and 32 so that the 1C received IN data is not only input to the demodulation circuit 27 but also simply repeated.

The detection circuits (DETB, DETA) 25 and 28 detect which waveform of the received signal on both transmission lines is as shown in FIG.
9 determines which transmission path to select.

Note that FIG. 5 shows a Manchester code and is a data signal. 5 is a monitoring signal having a cycle four times that of the data signal. The data signal and the monitoring signal are thus distinguished so that they can be easily distinguished by hardware.

6 (4), (B), and (C5) represent the format of the data signal flowing through the system. FIG.
) shows a network configuration frame for controlling the network configuration, and 0 in the same figure shows a microcomputer connection frame.

In Figure 6, 03), (C), F is the start flag.

DA is the address field of the destination transmission control device.

C is a control field indicating a data function.

8A is the address field of the sending transmission control device.

11t, cheetah field, F'C8 is a frame check sequence, F is an end flag, LC is a loop command including a loopback command, 1st return, make-up command, 9 recovery response, SYN is a special synchronization pattern, CON is a microcomputer connection command. is.

Figure 7 (4) and a3) show the transmission circuit configuration after loopback assembly, and the transmission control devices 2c and 2d in Figure 7 (8) are extracted from the basic configuration of the configuration shown in Figure 3. It is depicted as Similarly, FIG. 0 also shows the basic configuration of the supervisory control device.

In Figure (4), @, a signal disconnection occurs on transmission lines 3d and 4d, and transmission control device 2c transfers the signal from transmission line 4c to transmission line 3C, and transmission control device 2d transfers the signal from transmission line 3e. The supervisory control device 1 connects the signal from the transmission path 3a to the transmission path 3h, and connects the signal from the transmission path 4h to the transmission path 4a to form a loopback configuration. .

In this embodiment, each signal disconnection section 3d is output from the supervisory signal generation circuits 24C and 24d provided in the transmission control device 2C12d.
, 4d continues to send the monitoring signal shown in FIG. 50. Furthermore, the detection circuits (
DETA, DETB) 25c and 28d monitor whether a monitoring signal sent from the shore is transmitted on the transmission lines 4d and 3d, respectively.

Now, assuming that the transmission line 3d or 4d in the signal cut-off section is restored, the detection circuit (DETA, DETB) 25c.

28d detects that the supervisory signal has been transmitted.

The above contents are temporarily stored in the respective detection circuits, and are input at a certain timing to the microcomputers provided in the transmission control devices 2c and 2ct, respectively. In this way, the transmission control device 2c.

2d can know that the signal interruption period has been recovered.

Next, the entire system performs an operation to know this in the 8th step.
The following description focuses on the program flow of the supervisory control device 1 shown in the figure. This figure shows a program flow of recovery adjustment processing from the time of loopback configuration to the time of recovery.

In the figure, in step 201, a network configuration frame (Fig. 6@) is transmitted to the loopback terminal station (transmission control device 2C), and a recovery timing command is sent.

In step 202, the loopback terminal station (10) wait for their response signal.

In step 203, the recovery response (terminal station status) in the network configuration frame LC, which is the response signal, is checked to detect whether the recovery of the signal interruption section has been completed, and if it has not been recovered, the process returns to step 204. If so, the process branches to step 208.

Step 204. Step 205. Step 206 is
Step 201 respectively. Step 202゜Step 203
The loopback terminal station (transmission control device 2d)
) is also processed in the same way.

In step 207, in order to perform other processing than the recovery interim processing, the recovery interim processing is temporarily suspended and waits for a certain amount of time. Then, the process returns to step 201 and repeats the process.

In step 208, in order to cancel the loopback and enter the single-system operation mode, a monitoring signal (FIG. 5(B)) is first sent from both systems of the network. At this time, the transmission control device that has received the supervisory signal enters a repeat mode in which it simply repeats the system signal. Then, the repeat mode is entered one after another (11), and all transmission control devices enter the repeat mode.

In step 209, the multiplexer 31 or 32 of the supervisory control device 1 is selected to enter the single-system operation mode.

In step 210, a microcomputer connection frame (FIG. 6 (Q)) is sent to the system selected in the previous step.

The transmission control device that receives the connection frame determines that the system from which the connection frame was sent is the system selected by the supervisory control device, and connects its own microcomputer to this system. Furthermore, by sending a connection frame to the next transmission control device, the microcomputers of all transmission control devices are connected to this system.

At step 211, it is confirmed that the microcomputer connection frame has completed one cycle, and a POL signal (signal indicating the idle state of the system) is sent out, and the operation mode is entered.

FIG. 9 is a program flowchart showing the response processing of the loopback terminal station to the processing of steps 201 and 204 (FIG. 8).

(12) The response processing program is started when the network configuration frame from the supervisory control device 1 is received.

In step 221, it is determined whether there is a recovery delay command in the network configuration frame. If not, the program exits, and if so, the process moves to step 222.

In step 222, the detection circuit (DETA).

DETB) to the recovery status of the signal interruption section via PPI (
status).

In step 223, the network configuration frame (FIG. 6(r)
3) Set the status in the recovery response of ).

In step 224, a network configuration frame is transmitted to the supervisory control device 1.

According to this embodiment, since the transmission control device itself monitors failure recovery after loopback, there is no need for maintenance personnel to issue a command for network reconfiguration. Furthermore, there is no need to provide an interface for this purpose.

Furthermore, there is an effect that maintenance failures due to poor contact of cables, etc. will not occur.

In addition, at the loopback terminal station, the microcomputer 100 inquires at a predetermined period about the recovery status of the faulty section stored in the detection circuit (13) (DETA, DETB), and if it has recovered, the error message shown in FIG. 6 (4) is sent. Information indicating recovery may be written in the data field of the frame shown in , and sent to the supervisory control device. By doing this, there is no need to inquire about the recovery status from the supervisory control device as shown in the previous embodiment, and there is no need to send the network configuration frame (Fig. 6e) that occurs at a predetermined period to the system. System load can be reduced.

[Effects of the Present Invention] According to the present invention, it is possible to automatically know the recovery state of a faulty section.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an example of a general loop data transmission system to which the present invention is applied, Fig. 2 is a diagram showing a loopback state, and Figs. 3 and 4 are diagrams showing the failure recovery method of the present invention. The supervisory control device (ST) and transmission control device (C8
T) is a configuration diagram of an embodiment of the present invention, and FIGS. 5(4) and (2) are diagrams of the signal waveforms used in the present invention. An example diagram of the transmission format used in Figure 7, @
8 is a basic circuit for explaining the operation of the present invention, and FIGS. 8 and 9 are flowcharts of C8T and ST for explaining the recovery operation. 24... Monitoring signal generation circuit, 25. 28... Detection circuit, 26... Modulation circuit, 27... Demodulation circuit, 29.
...Control circuit, MC100...Microcomputer. (15) T 1 Surface M2 Figure 'H7 Figure 6η (13) χδ Figure 17 Continuation of figure 1 page 0 Inventor Sei Yasumoto - Hitachi University, Omika Factory, 5-2-1, Mika-cho, Hitachi, Ltd. 0 authors Masakazu Okada 5-2-1 Hitachi University Mika-cho, Hitachi, Ltd. Omika Factory 0 authors Hiroshi Tomizawa Hitachi University, Ltd. Omika Factory 5-2-1 Hitachi University Mika-cho

Claims (1)

[Scope of Claims] 1. A loop-shaped transmission line of two systems with different transmission directions, a plurality of transmission control devices and one monitoring control device connected to the two-system transmission path, and the two-system transmission in the same section. In a control method for a loop data transmission system that takes a loopback configuration in which when a fault occurs in both systems, a transmission control device adjacent to the faulty section transmits a signal coming from one system back to the other system, comprising: The opposing transmission control devices adjacent to the section transmit monitoring signals to each other via the faulty section, and monitor the monitoring signal sent via the faulty section, and at least one of the transmission control devices transmits the monitoring signal. A method for detecting failure recovery in a loop type data transmission system, characterized in that, when reception is received, it is determined that the system on the receiving side of the failure section has recovered. 2. A fault recovery detection method for a loop data transmission system as set forth in claim 1, characterized in that the monitoring signal is a signal different from a normal data signal. 3. Permissible scope of claims The loop data transmission system according to claim 1, characterized in that when a transmission control device adjacent to the faulty section recognizes recovery of one system, it reports to the supervisory control device. Disaster recovery detection method. 4. In the statement of claim 1, the supervisory control device sends a signal to a transmission control device adjacent to the faulty section at a predetermined period, inquiring whether the faulty section has recovered or not. and the transmission control device returns a recovery status in response to the inquiry signal. 5. A fault recovery detection method for a loop data transmission system as set forth in claim 4, wherein the monitoring and control device transmits the inquiry signal one system at a time.