JPS6028173B2 - Terminal station separation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION When a failure such as a transmission/reception failure occurs in any of a plurality of terminal stations constituting a loop transmission processing system, the present invention automatically puts the terminal station involved in the failure into a loop. This relates to a method for separating the transmission line from the transmission line.

What is a loop transmission processing system? As shown in Fig. 1, a master station 1 serves as a central processing unit that performs transmission control and management of a loop transmission line, and terminal stations 2 to 4 are connected to an optical fiber transmission line (hereinafter referred to as , simply referred to as optical transmission line) 5 (5
, ~54) are connected in a loop.

Generally, in signal exchange in this system, an optical signal from the master station 1 or the preceding terminal station is received by the terminal station 2 or the rear & terminal station (however, excluding terminal station 2).
The terminal station that receives the optical signal transmits the reception processing result in the form of an optical signal to the downstream terminal station or the master station 1 as a response to the reception, but the disadvantage of such a system is that the terminal station If a failure of some kind occurs in any of 2 to 4, the loop-shaped optical transmission line will be equivalently and substantially cut off at that part due to the failure, and the system will no longer be able to function. .
A partial failure will spread to the entire system. In this way, the reliability of the entire system is directly influenced by the reliability of each of the terminal stations 2 to 4. For this reason, each terminal station has traditionally been equipped with a fault detection device, and when this fault detection device detects that a fault has occurred in the own terminal station, the own terminal station is disconnected from the loop optical transmission line. Automatic separation is being carried out. Due to this separation, a normal terminal station sends and receives optical signals to and from other normal terminal stations or the master station 1 via a loop-shaped optical transmission line without causing any faults that occur in one part to spread to others. That's what you get. In this way, the fault detection device automatically isolates the terminal station associated with the fault from the loop optical transmission line, and greatly contributes to improving the reliability of the loop optical transmission line and the entire system. Not only is the configuration uneconomical, but because it uses an optical branching coupler for optical reception monitoring, optical losses such as insertion loss and branching loss are relatively large, and there is It has drawbacks such as the inability to increase the transmission distance between the station and the station.

FIG. 2 shows a schematic configuration of an example of a conventional terminal station. According to this, the direct connection between the front side optical transmission line 6 and the rear side optical transmission line 8 and the indirect connection via the terminal station depend on the switching state of the optical switch 7. The optical switch 7 consists of two switches, one for input and one for output, and is in the switching state as shown in the figure in a normal state. Therefore, in such a switching state, the optical signal passing through the front side optical transmission line 6 is transferred to the optical switch 7, the optical fiber 9, the optical branching coupler 1
0, is subjected to photoelectric conversion by the optical receiver 12 via the optical fiber 11 (if necessary, serial-to-parallel conversion may be performed immediately after this by the serial-to-parallel conversion circuit), and then input to the terminal station processing device 13. The data will be subject to appropriate data processing. The result of this data processing is converted into an optical signal by the optical transmitter 14 (if necessary, parallel-to-serial conversion may be performed by a parallel-to-serial conversion circuit immediately before this), and then
Optical fiber 15, optical branching coupler 19, optical fiber 16,
The signal is transmitted to the downstream terminal station or master station via the optical switch 7 and the downstream optical transmission path 8. By the way, the part within the dotted line display frame in Fig. 2 constitutes the above-mentioned fault detection device (hereinafter referred to as the terminal station separation device), and if the terminal station is in a specific state, it is determined that there is a fault. , the switching state of the optical switch 7 is changed based on the determination output so that the front side optical transmission line 6 and the rear side optical transmission line 8 are directly connected.

That is, the reception state signal A is a branched reception optical signal obtained by the optical branching coupler 10 and is sent to the optical reception monitor 1 via the optical fiber 17.
8, and the transmission state signal B is obtained by monitoring the branched transmission optical signal obtained by the optical branching/coupling device 19 with the optical transmission monitor 20 via the optical fiber 20. Based on this, the fault detection circuit 22 determines whether or not a fault has occurred in its own terminal station. This fault detection circuit 22 is constituted by a logic circuit consisting of gates, and its judgment logic is shown in the table below.

Table This judgment indicates normal transmission/reception status, that is, optical reception monitor 1.
8. The occurrence of a failure can be determined by detecting a transmission/reception state other than when the optical transmission monitor 21 is outputting an output indicating the presence of an optical signal or outputting an output indicating the absence of an optical signal. When either monitor output indicates the presence of an optical signal,
If the other monitor output outputs an output indicating the absence of an optical signal, it is determined that a transmission failure has occurred, and the failure detection circuit 22
is for controlling the switching state of the optical switch 7 by outputting a determination to disconnect the own terminal station from the front and rear optical transmission lines 6 and 8.

If we add a little explanation to the table here, the reception status signal A
, a failure when the transmission status signal B is ON or OFF respectively means that some kind of failure occurs in the optical receiver 12, the terminal station processing unit 13, or the optical transmitter 14, and as a result, the optical transmitter 14 This is the case when the device is placed in a state where it cannot send out optical signals.

Of course, failures that prevent transmission due to destruction of the optical transmitting element itself are also included in such failures. Furthermore, a failure when the reception status signal A and the transmission status signal B are OFF and ON, respectively, is a state in which the optical transmitter 14 is transmitting an optical signal even though there is no reception processing result. means. This failure occurs when a failure occurs in the driver itself that causes the optical transmitting element itself to be forced into an optical transmitting state, or when some processing is executed without permission within the terminal station processing device 13. That's why. If the terminal station is normal, there is a possibility that some kind of failure has occurred, but there is no choice but to assume that it is normal. Even if a failure should occur, it is not a particular problem because the failure can be quickly detected by changing the transmission/reception status later.
As described above, a terminal station where some kind of fault has occurred is immediately separated from the loop optical transmission line by the terminal station separation device, and the fault occurring at that terminal station is not transmitted to other normal terminal stations or the master station. Since it is not propagated, a normal terminal station can still receive optical signals from the master station or previous terminal station, and can transmit the processing results in the form of optical signals to the subsequent terminal station or master station. be.

However, as can be seen from Fig. 2, monitoring the reception status requires an optical transmission monitor and an optical branching coupler, which not only makes the device configuration unnecessarily complicated and uneconomical, but also makes the optical branch Since the coupler is inserted into the optical fiber transmission line, optical losses such as insertion loss and branching loss are large.
This has the disadvantage that it is not possible to maintain a large distance between stations.

In addition, in order to increase the distance between stations when optical loss is large, a semiconductor laser with high output power must be used as a light emitting element in the optical transmitter, but semiconductor lasers have the disadvantage of low reliability. There is. An object of the present invention is generally to provide a terminal station separation method in a loop transmission processing system that can economically isolate the terminal stations constituting the system by means of a loop transmission line in the event of a failure.

That is, the present invention is also directed to a loop-shaped optical transmission processing system, and in the case of a loop-shaped optical transmission processing system, an optical transmission/reception monitor and an optical branching/coupling device are not required, making the terminal station separation device economical. This has been designed to allow for a better configuration. For this purpose, the present invention provides a failure detection circuit, transmits an identification signal unique to the terminal station to the master station when a failure is detected, and sends a unique identification signal indicating that the terminal station or eye station cannot receive the signal. If the master station is located at the master station rather than a specific terminal station, the master station basically separates the terminal station immediately preceding the specific terminal station for a certain period of time using a loop-shaped transmission line. The status will be monitored, and if it is confirmed that the loop transmission line has returned to normal status, the separated terminal station will be connected to the loop transmission line again. Then, the terminal station is separated from the loop transmission line again.
Furthermore, if the loop-shaped transmission line is not restored to normal state, the master station will stop the terminal station separation process for a certain period of time, and during that time, the specific terminal station will be forcibly separated from the loop-shaped transmission line by its internal circuit. It is characterized in that the terminal station related to the occurrence of the failure is isolated.

The present invention will be explained below with reference to FIG.

FIG. 3 shows a schematic configuration of a terminal station according to the present invention, and FIG. 4 is an explanatory diagram showing the configuration of the present invention. In FIG. 4, M is a master station, N is a terminal station, N-1, N -2... indicates the rank of the previous terminal station.

Components that are the same as those shown in FIG. 2 are given the same reference numerals, and the operation of this terminal station will be explained as follows.
That is, the connection of the terminal station to the front side and rear side optical transmission lines 6, 8 is controlled by the switching state of the optical switch 7, which serves as a bypass circuit, and is normally in the state shown in the figure.

The optical switch 7 receives an initial power-on command m issued when the system is placed in the initial state, such as when the power is turned on, through the OR gate 27.
Normally, it is in the switching state as shown in the figure, but if some kind of failure occurs in the terminal station, the separation command from the OR gate 28 causes the optical transmission to be switched off. The lines 6, 8 are operated to be bypassed via the optical switch 7. Therefore, in normal times, the optical signal from the front side optical transmission line 6 is photoelectrically converted by the optical receiver 12 via the optical switch 7 and the optical fiber 9, and then inputted to the terminal station processing device 13 and processed as appropriate. This is something that will undergo data processing. The result of this data processing is converted into an optical signal by the optical transmitter 14 via the changeover switch 24 as the transmitted signal c and preferably the processed signal b, and then sent through the optical fiber 16, the optical switch 7, and the rear optical transmission line 8. The data is then transmitted to the downstream terminal station or master station via the network. However, it is clear that if a transmission failure occurs in the immediately preceding terminal station or if a reception failure occurs in the terminal station shown in the figure, it becomes impossible to receive the optical signal.

In order to detect this, a failure detection circuit 2 having an input disconnection detector and a terminal station address sending circuit is provided.
It is 3.

The failure detection circuit 23 constantly monitors the received signal a output from the optical receiver 12, and if it detects that the detection input is disconnected because the received signal a does not exist for a certain period of time or more, the failure detection circuit 23 outputs a switching command d. The switching state of the changeover switch 24 is controlled, and the terminal station-specific identification signal eterminal station address signal is transmitted to the changeover switch 24, the optical transmitter 14, and the succeeding terminal station (however, if the terminal station is the last one) ), and transmits the timer start/reset command f to the master station.
The timer (TR) 25 is activated by the timer (TR).
Therefore, when the timer 25 times out after a predetermined time, the output g is given as a separation command to the optical switch 7 via the OR gate 28, and the terminal station is separated from the optical transmission lines 6 and 8. However, separation of terminal stations is also performed by the above control. As already mentioned, the master station cannot receive data from a terminal station that is unable to receive data.
An identification signal unique to that terminal station is transmitted to the station, but the signal master station estimates the location of the failure by identifying the receiving identification terminal station address, and the master station immediately precedes the terminal station in the unreceivable state. This is the case when a certain terminal station is subjected to separate control bypass control. As described above, the master station is formed of a terminal station address identification section that identifies the address of the terminal station, a bypass control section that bypasses the preceding terminal station for a certain period of time, and a transmission monitoring section.

There are two types of separation control: When a master station directly or indirectly sends a command to that effect to the immediately preceding terminal station, the immediately preceding terminal station is temporarily or semi-permanently separated from the transmission path. It is intended to encourage

If the terminal station shown in Figure 3 is imitated with the one immediately preceding it,
When the failure detection processing circuit 23 extracts and detects the temporary separation command from the received signal a, it separates the terminal station by giving the temporary terminal station separation command 1 to the optical switch 7 via the OR gate 28, and then waits for a predetermined period of time after this separation. After the elapsed time, the time-up output j from the timer (TB) 26 is given to the optical switch 7 via the OR gate 27 to cancel the separation of the terminal stations that had been continued until then, and when the separation command is extracted and detected. , the terminal station separation command h is given to the optical switch 7 via the OR gate 28, so that the terminal station will not be separated unless an input command is input.

Therefore, by estimating the location of the failure and performing the isolation control and temporary isolation control described above for appropriate terminal stations, it is possible to easily and reliably remove the terminal station where the failure has occurred from the transmission line, and also economically. This makes it possible to separate the particles.

The temporary terminal station separation command i also serves as a start signal for the timer 26, and the time-up output j of the timer 26 serves as its own reset signal.

In the following, control for separating a terminal station related to a failure from a transmission path with respect to a specific failure will be explained as follows. 01 In the case of terminal station reception failure If terminal stations 2 to 4 in FIG. 1 have the configuration shown in FIG. When a reception failure occurs, separation of the terminal stations related to the occurrence of the failure is performed as follows.

For example, assuming that a reception failure occurs in the terminal station 3, the optical transmitter 12 in the terminal station 3 will not be able to receive the optical signal, and therefore the received signal a will also no longer exist. This will result in the detection of the

Therefore, the failure detection circuit 23 activates the timer 25 and at the same time transmits the identification signal unique to the terminal station 3 to the changeover switch 24.
The signal is transmitted to the master station 1 via the optical transmitter 14 and the downstream terminal station 4. By the way, while terminal station 3 is performing the above processing, terminal station 4 cannot receive any signals, so it will start the same processing as terminal station 3, but it will not be able to receive the identification signal from terminal station 3. Since the internal processing is reset by reception, no particular problem occurs. When the master station 1 receives the identification signal from the terminal station 3, by decoding the unique code contained in the identification signal, the master station 1 can know that the signal is from the terminal station 3, but Therefore, it can be easily determined that the failure occurs in the transmitting section of the terminal station 2 or the receiving section of the terminal station 3. The terminal station separation control by the master station 1 begins by temporarily separating the terminal station 2 from the transmission path. After the temporary separation command from the master station 1 is received by the optical receiver 12 in the terminal station 2, the failure detection processing circuit 23 detects that the command is a command to that effect.
When identified by , the timer 26 is activated and at the same time the optical switch 7 is controlled via the OR gate 28 to isolate the terminal station 2 . As already mentioned, this separation continues until the timer 26 times out, but while the terminal station 2 is separated in this way, the master station 1 monitors the loop-shaped transmission path with the transmission monitoring section. By doing so, it is possible to know whether a transmission failure has occurred in the terminal station 2 or not. That is, if it is confirmed by the master station 1 that the transmission line system has returned to normal state, there is a transmission failure in terminal station 2, and if it is confirmed that the transmission line system has not returned to normal state, it is confirmed that the transmission line system has returned to normal state. It can be determined that a reception failure has occurred in the terminal station 3. In this case, since the terminal station 3 has a reception failure, the transmission line system will not be restored to a normal state, and the master station 1 will lock the failure detection process that it had been performing for a certain period of time. , the terminal station 3 can be separated from the transmission path. The time limit of the timer 26 in the terminal station 2 and the time limit of the timer 25 in the terminal station 3 are appropriately set so that the separation of the terminal station 2 is released while the failure detection process is locked, and the terminal station 3 is separated afterwards. It's a good thing to have.
After the terminal station 3 is separated from the transmission path, the loop-shaped transmission path system is restored to a normal state, and processing is restarted without the terminal station 3. Although the above example concerns the terminal station 3, it is clear that other terminal stations 4 can be similarly considered.

If the terminal station 2 at the forefront has a reception failure, the terminal station 2
However, the temporary separation command is not sent to the terminal station that sends the identification signal. Therefore, the terminal station 2 is forcibly separated from the transmission path only by the internal circuit when the timer 25 times out. In this case, of course, if it is necessary to unify the control, a temporary separation command may be given to the terminal station 2. However, since the terminal station 2 has a reception failure, it cannot receive the temporary separation command and is therefore not temporarily separated. Therefore, the master station 1 locks the failure detection process for a certain period of time after confirming that the transmission path is not restored to the normal state. '21 Case of terminal station transmission failure' Assuming that a transmission failure occurs at terminal station 2, in this case terminal station 3 will be in a state where it cannot receive data.
In the case of [1}, timer 2 is set at terminal station 3 on the same machine.
5 is activated, and a unique identification signal is transmitted from the terminal station 3 to the master station 1 via the downstream terminal station 4.

As a result, the master station 1 can easily estimate whether there is a reception failure in the terminal station 3 or a transmission failure in the terminal station 2 based on the reception identification signal, and in the same way as in case [1]. First, a temporary separation command is sent to the terminal station 2, and the transmission line system is monitored while the terminal station 2 is temporarily separated. In this case, since the terminal station 2 has a transmission failure, it is clear that if the terminal station 2 is separated, the transmission line system will return to a normal state. Therefore, the master station 1 waits for the terminal station 2 to be reconnected to the transmission line system and then issues a separation command to the terminal station 2. When a separation command is given to the terminal station 2, the failure detection processing circuit 23 in the terminal station 2 identifies this fact and gives the terminal station separation command h to the optical switch 7 via the OR gate 28. is again separated from the transmission line system. In this case, the timer 25 is started in the terminal station 3, but the transmission line system returns to normal state and the optical signal is exchanged before the timer expires, so the optical receiver 12 receives the optical signal. At that point, the timer 25 is immediately reset. Even if a transmission failure occurs in the terminal station 3, the terminal station 3 can be separated in the above manner, but what happens when a transmission failure occurs in the last terminal station 4?

In this case, there is a problem because no identification signal is transmitted to the master station 1. In such a case, the master station 1 assumes that the transmission and reception of optical signals between stations will take place within a certain period of time, and that the master station 1 detects that the optical signal transmission from the terminal station 4 has been interrupted for a certain period of time or more. After knowing the
The state of the transmission line system will be monitored by giving a temporary separation command to the system. If the terminal station 4 is separated, the transmission line system is restored to a normal state, so the separation command is given after waiting for the terminal station 4 to be reconnected to the transmission line system. '31 In case of terminal station transmission/reception failure For example, assuming that terminal station 3 has transmission/reception failure at the same time, the optical receiver 12 in terminal station 3 is in a state where it cannot receive data, so it activates the timer 25 and at the same time sends a unique identification signal. It will be transmitted to master station 1.

However, it is clear that this identification signal cannot actually be transmitted to the master station 1 via the terminal station 4 since the optical transmitter 14 is also out of order. Therefore, in this case, since the terminal station 4 is also placed in a non-receivable state, the timer 25 is actually started in the terminal station 4 as well. When the master station 1 receives the identification signal from the terminal station 4, it is determined whether the fault has occurred in the receiving section of the terminal station 4 or not.
Or, since it is presumed to be the transmitter of the terminal station 3, the master station 1 first gives a temporary separation command to the terminal station 3, but the terminal station 3 cannot be separated because it has a reception failure. is clear. Therefore, after confirming in the transmission line monitoring after sending the temporary separation command that the transmission line is not restored to a normal state, the master station 1 locks the failure detection process for a certain period of time. If the timer 25 in the terminal station 3 times up while the failure detection process is locked, the terminal station 3 is automatically and forcibly separated from the transmission line, and the transmission line system is also restored. If the transmission line system is restored to normal state, the terminal station 4 can receive the optical signal from the terminal station 2, and the timer 25 in the terminal station 4 will be reset before the time is up, so no problem will occur. do not have. However, if the last terminal station 4 has a transmission/reception failure, no identification signal will be transmitted to the master station 1, which is a problem.

In this case, since the situation is the same as in '21 when the terminal station 4 has a transmission failure, similar processing will be sought. Now, as is clear from the above explanation, the relationship between the time limits of the timers 25 (TR) and 26 (TB) in each terminal station and the lock time of the failure detection process needs to be set as follows.

Timer TB (common to each terminal station) <<Timer TR2<Timer T
R3<Timer TR4<Failure detection processing lock time However, the number as a subscript indicates that it is compatible with the terminal station.

The reason for setting in this way is obvious, so no particular explanation is required. Although the core and loop-shaped transmission lines have been described so far as being made of optical fibers, it is clear that the present invention can also be applied to cases where electric wires are used instead of optical fibers.

As explained above, according to the present invention, the configuration of the terminal station separation device is simplified, and a terminal station related to a failure can be easily and reliably separated.

In addition, in the case of the present invention, the transmission of the identification signal is controlled depending on whether or not the received signal is actually output by the receiver, so when applying the present invention to a loop-shaped optical transmission processing system, it is not necessary in the past. This has the effect of eliminating the need for optical transmission/reception monitors and optical branching/coupling devices.

[Brief explanation of the drawing]

FIG. 1 is a system configuration diagram of an example of a loop-shaped transmission processing system, FIG. 2 is a schematic configuration diagram of an example of a terminal station in a subordinate system, and FIG. 3 is an example of a terminal station according to the present invention. FIG. 4 is an explanatory diagram showing the configuration of the present invention. 1... Master station, 2-4... Terminal station, 5 (5,-54
)...Transmission path, 7...Optical switch, 12...Optical receiver, 13...Terminal station processing device, 14...Optical transmitter, 2
3... Failure detection processing circuit, 24... Changeover switch,
25, 26...timer, 27, 28...or gate. 1st
Figure 2 Figure 3 Sickle Figure 4

Claims (1)

[Claims] 1. A plurality of terminal stations are connected to a master station in a loop via a transmission path, and the master station includes a transmission monitoring section, a terminal station bypass control section, and a terminal address identification section. In a loop transmission system, each terminal station has a bypass circuit, a terminal station address sending circuit, and an input disconnection detector, and each terminal station has a bypass circuit, a terminal station address sending circuit, and an input disconnection detector. (a) When one terminal station detects an input disconnection, it sends the address of the terminal station to the master station. (b) The master station identifies the address of the terminal station, instructs the preceding terminal station to bypass for a certain period of time, and monitors the transmission path. (c) If the transmission path becomes normal due to the bypass, the preceding terminal station is bypassed, and if the transmission path remains abnormal, the station that transmitted the address is bypassed.