JPH0638614B2 - Multiplexer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to automatic switching from a failure module to a normal module in a multiplexer redundantly configured with a plurality of modules.

[Conventional technology]

FIG. 4 is a block diagram showing a conventional multiplexer. In the figure, reference numeral 1 is a multiplexer, and 2a and 2b are line interface modules (hereinafter referred to as CT), one of which is a working system and the other of which is a standby system. 3 is a line terminating device (hereinafter referred to as DSU), 4 is a switching switch module, 5 is a control module, and the multiplexing device 1 is formed of CTs 2a and 2b, a switching switch module 4, a control module 5, and the like. . 6 is a cable connecting the DSU 3 and the switching module, 7a and 7b are cables connecting the switching switch modules 4 and CTs 2a and 2b respectively, and 8 and 9 are the control modules 5 which monitor and control the switching modules 4 and CT2a and 2b respectively. A signal line 10 for performing the operation is a bus for transferring an input / output signal to / from the DSU 3 and supplying an internal clock.

Next, the operation will be described. The received signal from the DSU 3 is input to the switching switch module 4 via the cable 6. The switching switch module 4 controls the switch SW in the switching switch module 4 in accordance with the control signal sent from the control module 5 via the signal line 8, and either the CT 2a or 2b receives the above-mentioned reception signal. Signals are sent or signals from CT2a or 2b are DS
It is transferred to U3. CT2a, 2
b is a DS sent via the switching switch module 4.
Transfer the signal from U3 to bus 10 and vice versa
The signal from is transferred to the switching switch module 4 in order to be sent to the DSU 3, one of which is currently used and the other is reserved by the control of the control module 5. Working C
T2a (or 2b) is a switching switch module 4
Receives the received signal from and transfers it to bus 10, and vice versa
The signal from 0 is transferred to the switching switch module 4, and the spare CT2b (or 2a) is the bus 1
No signal is sent to 0 and no signal is received from the switching switch module 4, but a signal is received from the bus 10.
The switching switch module 4 of the received signal is transferred. In other words, the current CT2a (or 2
Only b) transfers the received signal from the DSU 3 to the bus 10 or switches the signal from the bus 10 to the switch module 4.
Can be transferred to the DSU 3 via.

Further, the control module 5 disconnects the received signal of the DSU 3 from the CTs 2a, 2b and the switching switch module 4, and the DS.
Alarm information such as transmission signal disconnection to U3, loss of frame synchronism, and bit error is monitored, and switching of CTs 2a and 2b is controlled so as to interlock with the switch SW of the switching switch module 4.

[Problems to be solved by the invention]

Since the conventional multiplexer is configured as described above,
A signal from the DSU 3 or a signal to the DSU 3 must pass through the switching switch module 4, and a failure of the switch SW element in the switching switch module 4 or an electrical failure such as a fuse disconnection or a card missing can be directly transmitted to the signal. The reliability is lowered due to the influence, and in the spare line CT2a (or 2b), since it is necessary to perform the synchronization pull-in from the line signal every time the switching is performed, the switching time becomes long, and further, the control module When the control module 5 is abnormal because the switching is controlled only by 5, C
Both the T modules 2a and 2b and the switching switch 4 cannot be switched, and there is a problem that communication with the DSU 3 is lost.

The present invention has been made to solve the above-mentioned problems, and enables the reception signal from the DSU to be simultaneously received by both the working CT and the standby CT, and an abnormality has occurred in the control module. Even in the case, it is an object to obtain a multiplexing device that realizes that one of CTs is always in use.

[Means for solving problems]

The multiplexer according to the present invention is provided with an adapter for branching a cable from a DSU into a plurality of cables, connects each CT cable from the branch adapter, and connects each CT with its own CT.
In addition, a manual switch for outputting a request signal so as to make it active is provided, and a switching control circuit for performing switching control is provided in the CT.

[Action]

In the multiplexing device according to the present invention, the received signal from the DSU is branched into a plurality of CTs by the branching adapter, and all CTs are always
The reception signal can be received at, and the same frame synchronization state is maintained for the line, and the time when normal data can be sent and received after switching is shortened, and a manual switch is provided for each CT. In addition, priority is given to the switching of the manual switch over the switching from the control module, and even when the control module is abnormal, 1
By providing a switching control circuit in which only one CT is in use, a multiplexing device capable of avoiding a situation in which two or more CTs operate as in use or the current CT does not exist is realized. .

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 11 is a multiplexer, 12 is a branch adapter, 13a and 13b are CTs, and 14 is CT13a and CT1.
3b is a controller for switching, 15 is an encoded reception signal RO sent from the DSU 3 to the branch adapter 12,
Reference numeral 16 denotes a signal R1 obtained by distributing the reception signal RO15 in the branch adapter 12, and 17a denotes CT1 from the branch adapter 12.
3a and 17b are signals R2 and 1 transferred to CT13b.
8a is a coded transmission signal SO from CT13a, 18b is a coded transmission signal SO from CT13b, and 19 is a transmission signal S.
The signals S1 and 20 obtained by combining the O18a or 18b in the branch adapter 12 are the signals S1 from the branch adapter 12 to the DS.
The signals S2, 21a, 21b sent to U3 are CT13.
c is a manual switch provided for 13b, 22 is a bus for exchanging signals between the controller 14 and the CTs 13a, CT13b, and 23 is a bus for supplying input / output signals with the DSU 3, frame pulses, clocks and the like. .

FIG. 2 is a block diagram showing an example of the CT 13a (the CT 13b has the same structure). In the figure, 24 is a code
Decoding circuit, 25 is the reception signal RDO decoded by the encoding / decoding circuit 24, 26 is the reception signal RDO 25, and the multiplexing device 1
Bit synchronization / frame synchronization circuit for transferring to the clock and frame in 1; 27, signal RD1 in which bit synchronization / frame synchronization is taken; 28, signal OPRAH which is significant (level "H") when CT13a is in use , 29 are AND gates, 30 is an output signal R sent to the bus 23
D, 31 are frame pulses FP sent from the bit synchronization / frame synchronization circuit 26, 32 are out of frame synchronization, an alarm generation circuit for detecting a signal disconnection of the decoded reception signal RDO25, a line failure, etc. and generating an alarm, 33
Is an alarm signal ALM generated by the alarm generation circuit 32.
H and 34 are input signals SD fetched from the bus 23, 35 is a coding / decoding circuit 24 for the input signals SD34, and the encoded transmission signal SDO is 36, and the CT 13a is instructed to be active at the level "H" sent from the controller 14. The switching instruction signals CONTAH and 37 are the level "H" sent from the controller 14, and the switching instruction signal CONTBH and 38 for instructing the CT 13b to be in use are the level "H", and the significant state signal MANUAH of the manual switch SW21a is 39 and the level 39 is the level "MANUAH". Status signal MANUBH of the manual switch 21b of CT13b which is significant in H ", 40 is a switching instruction signal CONTAH
36, CONTBH37, status signal MANUAH38,
A switching control circuit which receives the MANUBH 39, controls the switching of the CTs 13a and 13b, and outputs a signal OPRAH28, 4
1 is an AND gate.

Further, FIG. 3 shows a truth table showing theoretical control of the switching control circuit 40.

Next, the operation will be described. The branch adapter 12 branches the received signal RO15 into two identical signals R1 16 and
The branched R1 16 is transferred to the CTs 13a and CT13b, respectively, and the transmission signal 18a or 18b sent out only from the active system of the CTs 13a and 13b, one of which is the active side, is combined into a signal S1 19 to form one signal. The signal S220 is sent to DSU3. That is, the branch adapter 12 divides the signal line for transmitting the reception signal RO15 into two and distributes the signal, and also the transmission signal SO.
It has a function of coupling two signal lines transmitting 18a or 18b into one signal line.

The controller 14 receives the alarm signal ALMH33 from the CTs 13a and 13b via the bus 22,
The switching instruction signals CONTAH36 and CONTBH37 are set to CT13 in order to bring the system having no abnormality or failure in 13b into operation.
a or CT13b, and gives an instruction to switch between the working and the spare.

The coded signal reception RO15 from the DSU 3 is divided into two by the branch adapter 12 and transferred to the CTs 13a and 13b as signals R2 17a and 17b, respectively. In FIG. 2, the signal R2 17a received by CT13a (CT13b also performs the same operation) is input to the encoding / decoding circuit 24 and becomes the decoded reception signal RDO25. The received signal RDO25 is input to the bit synchronization / frame synchronization circuit 26 and the alarm generation circuit 32, and the bit synchronization / frame synchronization circuit 26 transfers the line clock and frame phase to the clock and frame phase of the multiplexer 11. Is performed, and the signal RD1 27 is obtained. Signal R
D13 27 is currently used by the CT 13a, that is, the signal OPRA.
When H28 is at level "H", it is sent from the AND gate 29 to the bus 23 as the output signal RD30. The input signal SD34 from the bus 23 is captured by both CT13a and CT13b. The input signal SD34 becomes the transmission signal SDO35 encoded by the encoding / decoding circuit 24. A
The ND gate 41 is a gate circuit that performs control for preventing collision of the transmission signals SDO35 transmitted from both CTs 13a and 13b. In CT13a, when CT13a is in use, that is, when signal OPRAH28 is at level "H", this is transmitted. It is sent to the branch adapter 12 as a signal SO18a.

The switching control circuit 40 receives the switching instruction signals CONTAH36 and CONTBH37 from the controller 14 and the status signals MANUAH38 and MANUBH39 from the manual switches 21a and 21b, and receives the CTs 13a and C13.
The circuit for controlling the switching of T13b performs the logical operation shown in the explanatory view of FIG. That is, the following three states are realized.

First, the first state will be described. Controller 12
Is a switching instruction signal CONTAH in a normal control state.
Either 36 or CONTBH37 is set to level "H"
Is sent to CT13a and CT13b. At this time, if the manual switches 21a and 21b are in the OFF state, that is, if the status signals MANUAH38 and MANUBH39 are both at the level "L", the switching control circuit 40 switches the working / standby switching based on the instructions of the switching instruction signals CONTAH36 and CONTBH37. I do. Accordingly, when the switching instruction signal CONTAH36 is at the level "H", CT13
When a is the active system and conversely the switching instruction signal CONTBH37 is at level "H", the CT 13b is the active system.

Next, the second state will be described. Manual switch 21
When the manual switch 21a is turned on by switching between a and 21b, that is, when the status signal MANUAH38 becomes level "H", the CT 13a becomes the active system, and when the manual switch 21b is turned on, that is, the status signal MAN.
When the UBH 39 reaches the level "H", the CT 13b becomes the active system. At this time, the instructions of the switching instruction signals CONTAH36 and CONTBH37 from the controller 12 are ignored.

Next, the third state will be described. If the control of the controller 12 cannot be executed normally, or if the manual switch 2
When control is impossible or a setting error occurs, such as when both 1a and 21b are in the ON state, the switching control circuit 40 sets either CT13a or CT13b as the active system. The selection of CT13a and CT13b is performed according to the priority order set by the switching control circuit 40.

In the above embodiment, the case where the number of CTs is two has been described, but the number of CTs may be three or more, and the manual switches 21a and 21b may be controlled remotely.

〔The invention's effect〕

As described above, according to the present invention, a branch adapter is provided between the DSU and the CT so that the received signal from the DSU is distributed by a plurality of signal lines and is commonly supplied to each CT. Since the signal line is configured so that it can be connected to the DSU by connecting it to one, it can be configured with a connector that simply connects the signal line and the cable without the need for switching with a branch adapter and the supply of power. Since it is not affected by the electrical failure of, all the CTs can always operate in the same frame phase with respect to the line in order to supply the received signal to each CT, and every time it switches. Since it is not necessary to perform the synchronization pull-in, the disturbance of the signal output to the bus at the time of switching can be suppressed to a low level, and by providing the switching control circuit, the normal state of CONT is naturally abnormal, and there are multiple Since one of the CTs operates as the current one, the input / output with the bus and the transmission / reception with the DSU can be maintained in a normal state. Furthermore, by providing a manual switch, regardless of the state of the controller. Since CT switching is performed, it is possible to obtain an effect that forced switching can be performed without the controller's instruction.

[Brief description of drawings]

FIG. 1 is a block diagram showing a multiplexer according to an embodiment of the present invention, FIG. 2 is a block diagram showing an example of the CT, and FIG. 3 is an explanation showing a control logic performed by a switching control circuit in the CT. Figure,
FIG. 4 is a block diagram showing a conventional multiplexer. 3 is a DSU, 11 is a multiplexer, 12 is a branch adapter,
Reference numerals 13a and 13b are CTs, 14 is a controller, 32 is an alarm generation circuit, and 40 is a switching control circuit. The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A multiplexer comprising a plurality of line interface modules connected to one line terminating device, wherein one of the line interface modules is a working system and the other is a standby system. It is arranged between the line terminating device and the line interface module, and simultaneously supplies the received signal from the line terminating device to each of the line interface modules, and also transmits from each of the line interface modules. A branch adapter that collects signals into one signal line and transfers them to the line terminating device, a manual switch that instructs the switching of the line interface module to the active one by a manual operation, and a line adapter of each line interface module. A controller that monitors the status and outputs a switching instruction signal is provided, and each line interface module is A switching control circuit is provided for performing switching control by receiving a status signal from the manual switch and a switching instruction signal from the controller, and each of the switching control circuits, when only one of the status signals is significant, If a line interface module with a significant status signal is in use and another is a spare, and all the status signals are insignificant and only one of the switching instruction signals is significant, a line interface module with a significant switching control signal is selected. When a plurality of the status signals are significant, or active and others are reserved, or when all the status signals are insignificant and a plurality of the switching control signals are significant, they are predetermined in the line interface modules. If the line interface module with the highest priority is currently used and the others are reserved and all the status signals and switching control signals are insignificant, all line interfaces are The highest working line in tough Ace modular Yule of the priorities in Ace modular Yule, multiplexer, characterized by performing control to another reserved.