JPH06104794A - Switching circuit of transmission system having redundant configuration - Google Patents

Abstract

PURPOSE:To attain an exact switching control by preventing the outputs of an existent and preliminary device from colliding with each other by providing a logic circuit which monitors the state of a control signal for each existent and preliminary unit, and executing a control according to a switching signal only in the case of a signal state in which either unit is selected. CONSTITUTION:An input buffer 60 is equipped with an invertor gates 70 and 90, pull-up resistors 80 and 109 are connected between each input edge and each power source, and selection signals (s) and (s)' are inputted from a control package. And also, a logic circuit 10 supplies an enable signal to an output buffer circuit 9 corresponding to the potential of the two selection signals. On the other hand, the circuit 9 is constituted of 16 pieces of three state gates, and a gate function is operated corresponding to each channel signal separated by a separator circuit DMUX 5. Then, only at the time of the signal state in which either unit is selected, the control is executed according to the switching signal. Therefore, the outputs of the existent and preliminary device can be prevented from colliding with each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switching circuit for a working unit and a spare unit in a transmission system having a working / standby redundant configuration, and more particularly to a switching means for improving the accuracy of switching operation. .

[0002]

2. Description of the Related Art Conventionally, in an important communication system, two identical units are provided in the main part so that the communication is not interrupted even if the device fails. The other is used as a backup device and is configured with redundancy so that it immediately switches to the backup device when a failure occurs in the current device, but it is an important issue to prevent a slight interruption during switching. Is. FIG. 3 is a block diagram showing an example of a conventional working / spare switching circuit in a channel signal demultiplexing device used for a switch for multiplex communication, and the channel demultiplexing device shown in this example is, for example, TDM (time division multiplexing) or This is a circuit for separating each channel signal from a main signal MS in which 96 channels have been multiplexed by FDM (Frequency Division Multiplexing) by a separation package and supplying each channel board.

Since this circuit is an important part, as described above, in addition to the normal working unit 1, the unit 2 having the same function is used.
Is provided as a spare unit, and a control package 3 and an alarm package 4 are provided to switch between these two units.
Have and. In this circuit, the multiplexed main signal SM
Are input in parallel to the two separation packages 1 and 2, and 16 channel output terminals a to p and a'to p'are connected by wire or OR for each channel, and channels not shown are shown. The alarm signals q and q'output from the separate packages 1 and 2 are supplied to the alarm package 4, and the switching request signal from the alarm package 4 is also provided. The selection signals s and s'are output from the control package to which r is input, and are supplied to the two separation packages 1 and 2.

The operation of this configuration will be described. Normally, the control package 3 selects a signal s for the active package 1 so that an output is generated only from the active package 1.
At the same time, and at the same time, the selection signal s ′ for the spare package 2 which is in the non-operating state is set to the high potential. Each of the packages 1 and 2 has a failure detecting function, and when a failure is detected in its own package, alarm signals q and q'are generated, and the alarm package 4 which receives the alarm signals generates a switching signal r. To switch the package.

FIG. 4 is a block diagram showing an example of the internal structure of the conventional separation packages 1 and 2. In this figure, an example of the internal structure of the package 1 is shown. DM in this figure
The UX5 is a circuit for separating 96-channel signals from the main signal SM, and generally uses commercially available IC components. At the same time, the UX5 has a failure diagnosis function and outputs an alarm signal q when a failure occurs. ing.

The input buffer 6 is an inverter as shown in FIG.
The pull-up resistor 8 is connected between the input terminal of the target 7 and the power supply, and the low potential of the selection signal s for determining the operating state is converted into a high potential to be used as an enable signal. It is supplied to the output buffer circuit 9. On the other hand, the output buffer circuit 9 comprises 16 3-state gates, and
It functions as a gate corresponding to each of the channel signals separated by X5. That is, when the selection signal s is supplied at a low potential, it is inverted by the input buffer 6 to become a high potential, and each three-state gate of the output buffer circuit is obtained.
Since each gate signal is supplied to the enable terminal of each channel, all the channel signals a to p are input to each channel panel (not shown). Although not shown, each of the 16 main signals a to p has signals of 6 channels sequentially arranged in a time-divisional manner, including a total of 96 channels of time-divisional signals.

However, in the method for switching the spare device in use having the above-mentioned structure, the control package 3 shown in FIG.
When the selection signals s and s', which should originally have different low potentials and high potentials, become high potentials, low potentials, or levels are not stable, both of the separation packages 1 and 2 are in the operating state or both It was sometimes in a standby state. When both are in the operating state, the outputs of the two packages are combined and cause a collision, resulting in deformation of the output waveform, which not only causes malfunction but also when used for a long time in this state, the internal output buffer There is also a greater risk of damage. On the other hand, when both are in the standby state, no output is generated. Furthermore, if the control package 3 is removed for replacement, both of the two separation packages 1 and 2 will be in a standby state because the selection signals both have a high potential due to the circuit configuration. There was a point.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems in the conventional active spare switching circuit. Even if a failure occurs in the unit switching device, signals are output from both units. It is an object of the present invention to provide a switching circuit for a transmission system having a redundant configuration capable of eliminating a defect that a signal collision occurs due to being generated or a defect that no signal is output. .

[0009]

SUMMARY OF THE INVENTION In order to achieve this object, the present invention provides a switching circuit for a transmission system, which has a plurality of units having the same function and has a redundant configuration for switching to another unit when a failure occurs in the unit in use. In the above, each unit is provided with a logic circuit for monitoring the states of the switching signals for all the units, and is provided with a means for controlling according to the switching signal only when only one unit is in a signal state selected. There is.

In addition, in the switching circuit of the transmission system in which the unit has two units for working and protection,
Each of the above units is equipped with a logic circuit for monitoring the state of the switching signal for the two units, and is controlled according to the switching signal only when only one of the units is in the selected signal state, and when the two signal values are the same. It is characterized in that it has means for operating the currently selected unit as it is.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A switching circuit for a transmission system having a redundant configuration of the present invention will be described in detail below with reference to the illustrated embodiments. FIG. 1 is a block diagram showing an embodiment of an active spare package switching circuit according to the present invention, in which the same numerals and symbols as those in FIGS. 3 and 4 indicate the same functional blocks.
That is, the main signal SM is TDM (time division multiplex) or FDM.
This is a circuit in which 16 channels are multiplexed by (frequency division multiplexing), and the respective channel signals are separated by the two separation packages 10 and 20 and supplied to each channel board (not shown). This circuit is provided with a spare unit 20 having the same function as the working unit 10 in order to cope with a failure of the package, and has a control package 3 and an alarm package 4 for switching between these two units.

In this circuit, the multiplexed main signal SM
Are input in parallel to the two separation packages 1 and 2, and 16 channel output terminals a to p and a'to p'are connected by wire or OR for each channel, and channels not shown are shown. The alarm signals q and q'are output from the separate packages 1 and 2 and are supplied to the alarm package 4, and the switching request signal from the alarm package is also provided. The selection signals s and s ′ output from the control package to which r is input are the two separate packages 1 and
The point of being supplied to No. 2 is not functionally different from the above-mentioned conventional one. The difference of this embodiment from the conventional circuit is that the selection signals s and s' outputted from the control package 3 are both supplied to the two separation packages 10 and 20. The internal configurations of the separation packages 10 and 20 are different according to the above. That is, FIG. 2 is a block diagram showing an example of the internal structure of the separation packages 10 and 20, and the package 10 will be described here.

In this figure, the DMUX 5 is a circuit for separating the 16-channel signal from the main signal SM, and a commercially available IC component is generally used. At the same time, the DMUX 5 has a failure diagnosing function. Is output. As shown in the figure, the input buffer 60 is different from the conventional one and has two inverter targets 70 and 90, and pull-up resistors 80 and 100 are connected between the respective input terminals and the power source. The above-mentioned control package
The selection signals s and s'from the circuit 3 are input. Again 110
Is a newly added logic circuit and supplies it to the output buffer circuit 9 as an enable signal described later corresponding to the potentials of the two selection signals. On the other hand, the output buffer circuit 9 is composed of 16 3-state gates and corresponds to each channel signal separated by the DMUX 5.
Function as That is, when the enable signal is supplied to the enable terminals of the respective 3-state gates of the output buffer circuit at a high potential by the combination of the selection signals s and s', the respective gates become conductive. All channel signals a to p are input to each channel panel (not shown).

FIG. 3 is a diagram showing the output truth value of the logic circuit 110. As shown in the figure, the inputs of the two inputs corresponding to the combination of the high potential (H) and the low potential (L) are shown. If both 1 and 2 (which correspond to the high and low potentials of the selection signals s and s') are high or low, the previous state is maintained and the input 1 is at high potential. When the input 2 is at a low potential, the logic circuit output, that is, the enable signal, is set at a high potential, and each gate of the output buffer 9 is turned on. When the input 1 is at a low potential and the input 2 is at a high potential, the logic circuit output is at a low potential and the gate of the output buffer is cut off. Note that the separation package 20 is shown in FIG.
The logic output is inverted, and when the input 1 is low potential and the input 2 is high potential, the output is high potential, and when the input 1 is high potential and the input 2 is low potential, the low potential is output. It is assumed that

According to this structure, when the selection signal S has a low potential and S'is a high potential, the signal input to the logic circuit has a high potential at the input 1 and a low potential at the input 2. In the separation package 10, the enable signal has a high potential, so that the output of this package is selected. At the same time, in the separation package 20, the inverted potential is applied, so that the output buffer is cut off.

On the contrary, when the selection signal s is high potential and s'is low potential, the separation package 10 is cut off and 20 is selected. Since the other operations are the same as those of the conventional one, detailed description thereof will be omitted. According to this operation, even when both the selection signals have the high potential or the low potential as described above, only one of the separation packages is selected. The problem will be solved.

[0017]

According to the present invention having the above-described structure, even if the switching device fails and both the selection signal potentials become high potential or low potential, either one of the working block and the spare block is selected. As a result, the outputs of the working / spare devices do not collide with each other, and accurate switching control can be performed.

[Brief description of drawings]

FIG. 1 is a block diagram showing a working / standby unit switching device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an internal configuration example of a working / spare unit used in the present invention.

FIG. 3 is a diagram showing a logic circuit truth value used in the present invention.

FIG. 4 is a block diagram of a conventional working / standby unit switching circuit.

FIG. 5 is a diagram showing an internal configuration of a conventional working / spare unit.

[Explanation of symbols]

1, 10 Working unit (separate package), 2, 20
Spare unit (separate package), 3 control unit, 4 alarm package, 5 DMUX, 6, 6
0 input buffer, 7, 70, 90 inverter gate, 8, 80 100 pull-up resistor, 9 output buffer circuit, 110 logic circuit.

Claims (2)

[Claims] 1. A switching circuit of a transmission system, comprising a plurality of units having the same function, and having a redundant configuration for switching to another unit when a failure occurs in the unit in use, wherein each of the units corresponds to all units. A switching circuit for a transmission system having a redundant configuration, which is provided with a logic circuit for monitoring the state of the switching signal, and has means for controlling according to the switching signal only in the signal state in which only one unit is selected. . 2. A switching circuit for a transmission system, comprising two units having an identical function, an active unit and a spare unit, and having a redundant configuration for switching to another unit when a failure occurs in the unit in use. The unit is equipped with a logic circuit that monitors the status of the switching signal for the two units, and controls according to the switching signal only when only one unit is selected, and when the two signal values are the same, the current selection is made. A switching circuit for a transmission system having a redundant configuration, characterized in that it has means for operating the above unit as it is.