JPH0113664B2 - - Google Patents

Description

[Detailed description of the invention]

A. Industrial Field of Application The present invention provides a method for automatically transmitting loop transmission to the terminal station associated with the failure when a failure such as a transmission/reception failure occurs in any of the plurality of terminal stations configuring the loop transmission processing system. This relates to a method for separating the road from the road. B. PRIOR TECHNOLOGY What is a loop transmission processing system? As shown in FIG. They are connected in a loop through transmission lines (hereinafter simply referred to as optical transmission lines) 5 (5 ₁ to 5 ₄ ). In general, in signal transmission and reception in this system, an optical signal from master station 1 or a preceding terminal station is received by terminal station 2 or a succeeding terminal station (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. It will be done. A partial failure will spread to the entire system. In this way, the reliability of the entire system is 2 to 4 terminal stations.
It depends directly on the individual's level of trust. 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 can send and receive optical signals to and from other normal terminal stations or the master station via a loop-shaped optical transmission line without causing any faults that occur in one part to spread to others. It can be done. 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. However, since the separation control is performed by a fault detection device, the hardware configuration becomes unnecessarily complicated and separation control cannot be performed economically. 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 are made by the optical switch 7.
It depends on the switching state. 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 sent to the optical receiver 1 via the optical switch 7, the optical fiber 9, the optical branching coupler 10, and the optical fiber 11.
2 (if necessary, serial-to-parallel conversion may be performed immediately by a serial-to-parallel conversion circuit), and then input to the terminal station processing device 13 where it undergoes appropriate data processing. It is a matter of fact. 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 the optical fiber 15 is converted into an optical signal. Branch coupler 19, optical fiber 16, optical switch 7, rear optical transmission line 8
It is transmitted to the downstream terminal station or master station via the . By the way, the part within the dotted line display frame in Fig. 2 constitutes the fault detection device (hereinafter referred to as the terminal station separation device) mentioned above, and if the terminal station is in a specific state, it is determined to be a fault. Based on the determination output, the switching state of the optical switch 7 is changed 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 obtained by monitoring the branched reception optical signal obtained by the optical branching/coupling device 10 via the optical fiber 17 with the optical reception monitor 18, and the transmission state signal B is obtained by the optical branching/coupling device 19. The resulting branched transmission optical signals are monitored by the optical transmission monitor 20 via the optical fiber 20, and these transmission/reception status signals A and B are obtained.
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 determination indicates whether the transmission and reception are normal, that is, whether the optical reception monitor 18 and optical transmission monitor 21 are both outputting an output indicating the presence of an optical signal, or both are outputting an output indicating the absence of an optical signal. The occurrence of a failure is determined by detecting the transmission/reception status other than when the optical signal is present. If the terminal station 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 makes this determination in order to disconnect its own terminal station from the preceding and succeeding optical transmission lines 6 and 8. The output is used to control the switching state of the optical switch 7. Here, to add a little explanation to the table, reception status signal A and transmission status signal B are ON and OFF, respectively.
A failure in this case means that some kind of failure occurs in the optical receiver 12, the terminal station processing device 13, or the optical transmitter 14, resulting in the optical transmitter 14 being unable to send out optical signals. This is the case. 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 state signal A and the transmission state 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. This applies to If the terminal station is normal, there is a possibility that some kind of failure has occurred, but there is no other choice but to dismiss it as 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 in which 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 in that terminal station is transmitted to other normal terminal stations and the master station. Therefore, a normal terminal station can still receive the optical signal from the master station or previous terminal station, and can transmit the processing result in the form of an optical signal to the subsequent terminal station or master station. That's why. C. Problems to be Solved by the Invention However, in the system shown in FIG. 2, it is necessary to provide a transmission/reception monitor for each terminal station, which makes the equipment of each terminal station large and expensive. In particular, when using optical fiber as a transmission line, since it is inserted into the optical fiber transmission line, there are large optical losses such as insertion loss and branching loss, which makes it impossible 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 a large output power must be used as a light emitting element in the optical transmitter.
Semiconductor lasers have the disadvantage of low reliability. In addition to these drawbacks, there is also the problem that maintenance management is difficult because there is no means for returning the terminal station after it is separated from the transmission path. It is an object of the present invention to make a device for separating terminal stations compact, to easily restore the separated terminal stations, and to facilitate maintenance management. D Example The present invention will be explained below with reference to FIGS. 3 to 5. First, FIG. 3 shows the system configuration of an example of a loop-shaped transmission processing system according to the present invention. In the present invention, the transmission processing system is duplicated, and as shown in the figure, a master station 23 and a terminal station 24
~26 and loop-shaped transmission line 28 (28 ₁ ~28
₄ ) A loop-shaped transmission processing system system consisting of a master station 23', terminal stations 24' to 26', and loop-shaped transmission lines 28'(28' ₁ to 28') having the same configuration as this transmission processing system system. ₄ ) A loop-shaped transmission processing system consisting of:
The outline of these loop-shaped transmission processing systems is almost the same as that shown in FIG. 1, but the difference is that each terminal station 24-26, 24'-2
6' is not equipped with a terminal station separation device having a random logic configuration as shown in FIG.
~26,24'~26' loop-shaped transmission line 28,2
Separation control from 8' is performed by a system-common terminal station separation device 27 that can exchange signals with the master stations 23, 23'. By the way, in the present invention, since the terminal stations are separated from the loop-shaped transmission path as described above, it is not possible to send and receive signals between the terminal stations 24, 24', 25, 25', 26, and 26'. be made to be. FIG. 4 shows an example of the configuration of a pair of terminal stations 24, 24', but other terminal stations 25, 25',
The same can be said of the 26, 26' pair. According to this, terminal station 2
4 and 24' have the same configuration, and under normal conditions, signals from the front side transmission lines 28 ₁ and 28' ₁ (assumed to be composed of optical fibers in this example) are sent to optical switches 24 ₄ and 24'. ₄ , is processed by the processing units 24 ₂ , 24' ₂ via the receiving units 24 ₁ , 24' ₁ , and the processing results are sent to the transmitting units 24 ₃ , 24' ₃ and the optical switches 24 ₄ , 24' ₄ as reception responses. via the rear transmission line 28 ₂ ,
_28'2 . That is, the optical switches 24 ₄ and 24' ₄ are normally in the switching state as shown. While the optical switches 24 ₄ , 24' ₄ are in this switching state, each of the processing units 24 ₂ , 24' ₂ transmits the reception status signals c, c' at its own terminal station along with the terminal station-specific code to the processing unit 24' of the other party. ₂ , 24 ₂ , transmitting units 24' ₃ , 24 ₃ , and further terminal stations 25',
26', 25, 26 and the master stations 23', 23 to notify the terminal station separation device 27. FIG. 5 shows the relationship between the master stations 23, 23' and the terminal station separation device 27. Normally, the master stations 23, 23' receive signals sent via the rear transmission lines 28 ₄ , 28' ₄ to the receiving unit 23, 23'.
3 ₁ , 23' ₁ in the processing units 23 ₂ , 23' ₂ , and transmits the processing results and new signals to the front transmission lines 28 ₁ , 28' ₁ as necessary. Each terminal station 24-26, 24'-2 from the signal
When receiving state signals c and c' from 6' are extracted, the terminal station separation device 2 receives them as extracted state signals d and d'.
7. The terminal station separation device 27 selects each terminal station 24 to 26, 2 from the extracted state signals d and d'.
The reception status of terminal stations 4' to 26' is constantly monitored, and if it is detected that there is an extraction status signal indicating that reception is not possible, a specific terminal station included in the normal system is The terminal station is used to control the separation and return of the partner terminal station that is paired with the terminal station. That is, the terminal station control command e (or e') to which a specific terminal station unique code is attached is transmitted to the specific terminal station via the master station 23 or 23'. Assuming here that the specific terminal station is the terminal station 24, the processing unit ₂₄₂ detects that the terminal station control command e is addressed to the own terminal station, and sends the detected output to the terminal station separation command a. as terminal station 2
4', _the optical switch 24' ₄ is switched so that the transmission lines 28' ₁ and 28' ₂ are directly connected.
is separated from the loop-shaped transmission line 28'. Furthermore, if the terminal station 24 receives the terminal station control command e while the terminal station 24' is separated and gives its detection output to the optical switch 24' ₄ as the terminal station return command b, the optical switch 24' ₄ to the original switching state and terminal station 2
4' can also be connected to the loop-shaped transmission line 28' again. Note that the signals a' to c' output from the processing section _24'2 correspond to the signals a to c output from the processing section ₂₄₂ . The present invention attempts to separate a terminal station related to the occurrence of a failure from a loop-shaped transmission path by appropriately performing separation control and recovery control of the terminal station as described above. This will be explained in detail below with examples. (1) When a reception status signal indicating that reception is not possible from the most advanced terminal station is received by the terminal station separation device For example, if a reception failure has occurred in the terminal station 24,
A reception status signal containing the code of the station 24 and information on non-reception of the signal is sent from the processing unit 24 ₂ of this station 24 to the processing unit 24' ₂ of the other terminal station 24 paired with it. The status signal is transmitted from the terminal stations 24' to 2
6' and the master station 23' to the terminal station separation device 27. On the other hand, since a reception failure has occurred in the terminal station 24, no signal is transmitted from the terminal station 24 to the transmission path ₂₈₂ . As a result, the terminal station 25,2
Since terminal stations 25 and 2 are not receiving signals, terminal stations 25 and 2
Similarly, a signal reception status signal including the code of each station and information on non-reception of the signal is transmitted from the processing unit of 6 to the processing units of the terminal stations 25' and 26', respectively, to the terminal station separation device 27 via the master station 23'. be done. To simplify the explanation, the loop transmission processing system including the terminal station 24 will be referred to as system A, and the loop transmission processing system including the terminal station 24' will be referred to as system B. In this example, from system A to the terminal station No signal is transmitted to the separation device 27, and therefore it is first determined that an abnormality has occurred in the A system. Then, through the B system, the terminal station 24
Information indicating that the signal is not being received is transmitted, and the failure section is determined based on this information. In this case, there is a possibility that there is a transmission failure in the master station 23 or a reception failure in the terminal station 24, but since the present invention does not assume a failure in the master station, it is determined that there is a reception failure in the terminal station 24. Therefore, in such a case, the terminal station separation device 27 selects the master station 2 so that the terminal station 24 is separated from the transmission paths 28 ₁ and 28 ₂ .
3', a terminal station control command as a terminal station separation command is given to the terminal station 24'. As a result, the terminal station 24 can be separated from the transmission lines 28 ₁ and 28 ₂ , and after the master 23 confirms that the system has been restored, the master station 23 and the terminal stations 25 and 28
This allows processing to be restarted in between. When the terminal station 24' becomes unable to receive data, the terminal station separation device 27 connects the terminal station 2 to the terminal station 24' via the master station 23.
The terminal station control command is sent to the terminal station 4, and the terminal station 24 gives it to the terminal station 24' as a terminal station separation command. (2) When a receiving status signal indicating that reception is not possible is received from a terminal station other than the foremost terminal station. Such a case is, for example, terminal stations 25, 26, and 26 in FIG. This is the case when either 25' or 26' becomes unreceivable. For example, when a signal to that effect is sent from the terminal station 25 to the terminal station separating device 27 via the terminal stations 25', 26' and the master station 23', the terminal station 27 sends a signal to the terminal station 2, which is the immediately preceding station.
It is presumed that a failure has occurred in the transmitting section of the terminal station 24 or the receiving section of the terminal station 25. First, the terminal station 24 is separated and the system status is monitored. Depending on the monitoring results, the terminal station 24 After the terminal station 25 is restored, the terminal station 25 is separated. The terminal station 24 is separated by a terminal station separation device 27 in the terminal station 24'.
This is done by giving a terminal station control command as a separation command, but while the terminal station 24' is separated, the master station 23 monitors the system status, and if the system returns to normal, it is left as is. It is something to keep. However, if the system is not restored normally, after the terminal station 24 is restored via the terminal station 24',
The terminal station separation device 27 controls the terminal station 25 to be separated via the terminal station 25'. E. Effects of the Invention In the present invention, the transmission system is duplexed, a reception status signal is given from one to the other between a pair of mutually corresponding terminal stations, and the two transmission systems are connected through the other transmission system. It is transmitted to a terminal station separation device common to the system. Then, the terminal station separation device determines that an abnormality has occurred in one transmission system when no transmission signal is sent from one transmission system, and further determines the fault area based on the reception status signal from the normal transmission system. The terminal stations included in that section are separated. Therefore, according to the present invention, each terminal station is equipped with a device for detecting that no signal is being received, and a switch 24 ₄ , 24' ₄ in response to a separation or return command.
The equipment configuration of the terminal station becomes compact, as it is only necessary to provide an interface to operate the terminal station.
This method is very economical when compared to the case where the conventional method is applied to a system in which the transmission system is duplicated. Furthermore, since the terminal station separation device can be realized by software processing of the CPU, it can be achieved by adding to the software functions of the central processing unit, etc., and does not require any special hardware. Furthermore, even after the terminal station is separated from the transmission path, it can be easily restored, making maintenance management easy.

[Brief explanation of drawings]

FIG. 1 is a system configuration diagram of an example of a loop-shaped transmission processing system, FIG. 2 is a schematic diagram of an example of a conventional terminal station, and FIG. 3 is a diagram of a loop-shaped transmission processing system according to the present invention. FIG. 4 is a system configuration diagram of an example of a pair of terminal stations in the loop-shaped transmission processing system, and FIG. 5 is a diagram of the master station configuration and terminal station separation in the same loop-shaped transmission processing system. It is a diagram showing the relationship with the device. 23, 23'...Master station, 24-26, 2
4' to 26'...Terminal stations, 27...Terminal station separation device.

Claims (1)

[Scope of Claims] 1. A transmission processing system consisting of a master station and a plurality of terminal stations connected in a loop via a transmission line is duplicated, and the terminal stations are processed based on signals from each master station. A terminal station separation means for determining the status is provided, and between a pair of mutually corresponding terminal stations, a reception status signal indicating the reception status of one station and the code of the station is given from the one station to the other station. Furthermore, this signal is transmitted to the terminal station separation means through the transmission processing system to which the other station belongs, and the terminal station separation means determines whether there is an abnormality in either system based on the presence or absence of transmission signals from the two transmission processing systems. In addition to determining whether a failure has occurred, the fault section is also determined based on the reception status signal sent through the normal system, and the terminal stations included in the fault section are separated from the system through the normal system. A command is transmitted, and if the system still does not return to normal, a return command is transmitted to the terminal stations that have already been separated to return them to the system, and the isolation is performed to other terminal stations included in the faulty section. A method for separating terminal stations in a loop transmission processing system characterized by issuing commands.