JPH11261450A - Active/reserve switching system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify a switching control circuit and to reduce a standby time upto a valid switching starting point exceeding a delay time required for a signal amplifier returning to its active state to be in its normal operation state. SOLUTION: A state change detector 41 issues a switching request using a pulse generated only when a signal amplifier 31 changes its normal operation state to a state other than the normal operation state, while a control circuit 70 does not perform switching from an active to a reserve mode when a request other than this switching request is received. Since the signal amplifier 31 returning to the active state does not erroneously generate the switching request even if the state other than the normal operation state continues within the delay time until the amplifier becomes in the normal operation state, the control circuit 70 causes a switching mask to validate the switching by a reset request. Thus, it is possible to eliminate a complicated monitoring, the control circuit and the storage area from the control circuit, and a starting time of the switching validation does not have to take into account the delay time until the signal amplifier 31 become in the normal operation state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active standby switching system in which at least one active device is provided with one standby device, and one active device in a state other than the normal operation is switched to the standby device for operation. The present invention also relates to an active / standby switching system that simplifies switching control to a standby device and can eliminate a standby time until a switching validity start time exceeding a delay time until the active device returns to the normal operation state.

[0002]

2. Description of the Related Art Normally, in an apparatus to which an active / standby switching system is applied, there are roughly three states to be monitored for switching. This will be described with reference to FIG.

The first state is an unmounted state 101 in which the device has not been mounted and deployed at a predetermined position. The second state is a normal operation state 104 in which the device is operating normally, and the third state is a state other than the first and second states.

[0004] Mounting the device causes the unmounted state 101 to become the initial state 102. The initial state 102 automatically shifts to an operation stop state 103 waiting for an operation command. The operation stop state 103 is a state in which operation is possible but is not working, and the operation stop state 103 shifts to a normal operation state 104 by an operation command received from the control circuit, and the normal operation state 104 is changed by a stop instruction received from the control circuit. It returns to the operation stop state 103 and cannot operate.

[0005] The apparatus is in an initial state 102, an operation stop state 1
03 or when an abnormality occurs in the normal operation state 104, the state is shifted to the abnormal stop state 105. Further, when a device reset request is received from the control circuit in the operation stop state 103, the normal operation state 104, or the abnormal stop state 105, the state of the apparatus returns to the initial state 102. When the device is removed in the initial state 102, the operation stop state 103, the normal operation state 104, or the abnormal stop state 105,
The state becomes the unmounted state 101.

Here, an example of an active / standby switching system using the device as a signal amplifier will be described with reference to FIG.

In the illustrated working spare switching system, an input signal input from an input terminal 11 is applied to an input signal switch 2.
1, output from the output terminal 61 via the signal amplifier 31 and the output signal switch 51 as an output signal.
An input signal from the input terminal 12 is transmitted as an output signal from the output terminal 62 via the input signal switch 22, the signal amplifier 32, and the output signal switch 52. This state is referred to as a “normal operation state”.

Next, as shown by a broken line, for example,
It is assumed that the signal amplifier 31 enters an abnormal stop state due to occurrence of an abnormality, and the spare signal amplifier 30 is operating instead. In this case, the input signal from the input terminal 11 is
When the input signal switch 21 and the output signal switch 51 are switched, the signal is transferred via the input signal switch 20 and the spare signal amplifier 30 and sent out from the output terminal 61 as an output signal.

During this time, with respect to the other signal amplifier 32, the input signal switch 22 and the output signal switch 52 are not switched, and the input signal from the output terminal 12 is transferred to the output terminal 62 via the signal amplifier 32. ing. This state is referred to as a “stop state of the signal amplifier 31”.

Further, although not shown, the signal amplifier 3
2, an abnormal stop occurs, the standby signal amplifier 30 is operating instead, and the input signal from the input terminal 12 is switched by the input signal switch 22 and the output signal switch 52. Is transferred via the input signal switch 20 and the backup signal amplifier 30 and sent out as an output signal from the output terminal 62. During this time, the input signal switch 21 and the output signal switch 51 are not switched and the input signal from the output terminal 11 is not switched. Is transferred to the output terminal 61 via the signal amplifier 31. This state is referred to as a “stop state of the signal amplifier 32”.

The switching of the working spare is controlled by the control circuit 170. The control circuit 170 controls the signal amplifier 3 for switching.
The status of each of the signal amplifiers 31 and 32 is monitored by the status recognition means, and the status of each of the signal amplifiers 31 and 32 is set to one of the three states of “unmounted state, normal operation state, and other states” as described above. Recognized, the normal switching is performed in a state other than the normal operation state in order to prevent the abnormal occurrence of the normal operation.

Next, referring to FIG. 8 and FIG. 7, a procedure relating to the "stop state of the signal amplifier 31", that is, a procedure in which the signal amplifier 31 is switched to the spare signal amplifier 30 due to a failure, and A description will be given of a procedure for mounting again and returning to a normal operation state after repair.

The control circuit 170 determines the monitoring timing (3
The state of the signal amplifier 31 is monitored and recognized at the position of the upward arrow generated every cycle 1).

First, when the control circuit 170 detects, at the monitoring timing (31) T0, an abnormally stopped state due to a failure in the signal amplifier 31, that is, a state other than the unmounted state and the normal operation state, the state of the switching system is determined. From the “normal operation state” to the “stop state of the signal amplifier 31”.
Therefore, the control circuit 170 determines the monitoring timing (3
1) The switching mask is invalidated in order to prohibit the switching operation to the already used spare signal amplifier 30 when the signal amplifier 32 is in a state other than the unmounted state and the normal operation state at T0.

After the monitoring timing (31) T0 and before the monitoring timing (31) T1, if the signal amplifier 31 is removed, repaired, and mounted again, the control circuit 17
From 0 until the operation command is received via the control line c31, the signal amplifier 31 is in the operation stopped state, and is in a state other than the unmounted state and the normal operation state.

When receiving a reset request from the reset terminal, the control circuit 170 recognizes the reset pulse at the monitoring timing (31) T1 and sends an operation command to the signal amplifier 31 via the control line c31. As a result, the switching system shifts to the “normal operation state”.

However, even if the signal amplifier 31 receives the operation command at the monitoring timing (31) T1, a delay time is required until the signal amplifier 31 enters a normal operation state. Therefore, at the monitoring timing (31) T2 one cycle later, the signal amplifier 31 is still normal. This is a state other than the operating state. Therefore, when the switching mask is enabled at the monitoring timing (31) T1, the switching to the standby state is performed again at a monitoring timing (31) T2 one cycle later, as a state other than the normal operation state.

To prevent this, if the signal amplifier 31 has shifted to the normal operation state at the monitoring timing (31) T3 where the delay time is, for example, 1.5 cycles, the control circuit 170 sets the delay time to At a monitoring timing (31) T4 having a time corresponding to two cycles exceeding the switching mask, the switching mask is changed from invalid to valid.

Next, referring also to FIG. 9 and FIG. 7, if there is no input signal at the input terminal 12 and the signal amplifier 32 is not mounted, the signal amplifier 31 is removed due to a failure and repaired, and A description will be given of a procedure for returning from the standby state to the working state when the mounted state returns to the normal operation state.

In the initial state, as shown, the signal amplifier 31 is in a state other than the unmounted and normal operation states, the signal amplifier 32 is in the unmounted state, and the switching mask of the control circuit 170 is disabled.

In this state, the control circuit 170, which has received the reset request from the reset terminal, sets the monitoring timing (31).
The reset pulse is recognized by T1, and an operation command is sent to the signal amplifier 31 via the control line c31. As a result, the switching system shifts to the “normal operation state”.

However, even if the signal amplifier 31 receives the operation command at the monitoring timing (31) T1, a delay time is required until the signal amplifier 31 enters the normal operation state. Therefore, the signal amplifier 31 still operates normally at the monitoring timing (31) T2 one cycle later. It is a state other than the state. In this example, the signal amplifier 31 sets the delay time to 1.
Since the operation state has shifted to the normal operation state at the monitoring timing (31) T3 for five cycles, the control circuit 170 switches the switching mask at the monitoring timing (31) T4 having a time corresponding to two cycles exceeding the delay time. Is changed from the switching invalid to the switching valid.

In this series of operations, the control circuit 170
State recognition means so that the signal amplifier 32 is not monitored at the monitoring timing (32) even though there is no input signal at the input terminal 12 and the signal amplifier 32 is not mounted and need not be switched. The signal amplifier 3
2 is recorded and the state is grasped.

The recording of the unmounted state is necessary in addition to the above-described countermeasures for the no-signal channel, when the switching to the spare signal amplifier is performed or when the reset request is erroneously received.

[0025]

The above-mentioned conventional working spare switching system has the following problems.

The first problem is that the switching mask time of the control circuit is set to a delay time for returning the normal operation of the active device in order to guarantee a smooth switching operation when the active device is returned from the operation stop state to the normal operation state. It is necessary to set a longer time.

The reason is that the active device is still in a state other than the normal operation state within the return delay time. Therefore, when the switching mask is switched to the switching enable, the standby device is again returned to the standby device at the first self-monitoring timing of the switching enable. Is switched.

The second problem is that it is necessary for the control circuit to record the unmounted state in all the active devices to be switched as recognition means.

The reason for this is that if one of the active devices has returned and the spare device is empty, and the control circuit has switched the switching mask to enable the switching, the active device that has not been operated and is not mounted yet is not recognized. This is because, at the first monitoring timing when the switching is effective, the switching to the spare device is performed in spite of the unmounted state.

An object of the present invention is to solve the above-mentioned problems, to simplify the switching control by eliminating the recording for recognizing the state of the active device by the switching control circuit, and to set the switching effective time of the switching mask. An object of the present invention is to provide a working / standby switching system that can shorten the recovery time from the standby to the working by earliering.

[0031]

According to the present invention, there is provided an active / standby switching system in which one active unit is provided with one standby unit, and the active unit is switched to the standby unit when it is in a state other than normal operation. In the active / standby switching system, there is provided switching control means for detecting a change in the state of the active apparatus and switching the active apparatus whose state has changed from a normal operation state to a state other than the normal operation to the standby apparatus.

In this configuration, when the state change of the active device is detected and the state changes from the normal operation state to a state other than the normal operation, the active device is switched to the standby device. In the state in which the switching does not occur, the switching condition does not occur. In addition, since a switching condition does not occur in a state where a state change does not occur, even when a reset request is issued, it is possible to immediately enable the switching at the monitoring timing of the state change detection.

Further, in an active / standby switching system in which one active device is provided for a plurality of active devices and one active device in a state other than the normal operation is switched to the active device and operated, the status of each active device is determined. Detect changes,
There is provided switching control means for switching one active device whose state has changed from a normal operation state to a state other than the normal operation to the standby device and invalidating (inhibiting) switching of the remaining active devices to the standby device.

Also in this configuration, when the state change of the active device is detected and the state changes from the normal operation state to a state other than the normal operation, the active device is switched to the spare device. In a state where no change occurs, a switching condition does not occur. Further, since a switching condition does not occur in a state where a state change does not occur, even when a reset request is issued, the switching can be immediately enabled by the monitoring timing of the state change detection.

Therefore, upon receiving the reset request, the switching control means immediately releases the invalidity (prohibition) of the switching at the monitoring timing of the state change detection.

Further, in a specific configuration, a switch for switching and connecting one spare device instead of at least one of the active devices, and a switch provided for each of the active devices and corresponding to the active device are provided. A state change detector that outputs a request for switching the active device when detecting that the device has changed from a normal operation state to a state other than the normal operation, and a switching request for the active device is received from the state change detector. At this time, one active device is selected, and a switching instruction for switching the selected active device to the standby device is output to the switch, while invalidation of switching to the standby device for all remaining active devices is output to the switch. The control circuit, upon receiving a reset request, immediately disables the switching of the switch at the monitoring timing of state change detection and enables the switching.

[0037]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention.

In the illustrated working spare switching system, a reset terminal 10, input terminals 11, 12, input signal switches 20, 21, 22 and a spare signal amplifier 3 as a spare device are provided.
0, signal amplifiers 31 and 32, state change detectors 41 and 42, output signal switches 51 and 52, signal terminators 60, output terminals 61 and 62, and a control circuit 70 are provided as active devices. .

The difference from the prior art is that the state change detector 4
The control circuit 70 deletes the function of monitoring and recording the operating state of each of the signal amplifiers 31 and 32 as the active device, and detects the state change only when the state of each of the signal amplifiers 31 and 32 changes. That is, a switching request is received from the devices 41 and 42.

The state shown is for the first channel:
A signal amplifier 31 receives an input signal input from the input terminal 11 via a switching terminal ab of the input signal switch 21;
The output signal is amplified and output as an output signal from the output terminal 61 via the switching terminal gh of the output signal switch 51.
, The signal amplifier 32 converts the input signal input from the input terminal 12 to the switching terminal a- of the input signal switch 22.
b, amplifies the signal, and sends it as an output signal from the output terminal 62 via the switching terminal gh of the output signal switch 52. That is, it is in the “normal operation state”.

In the "normal operation state", the switching terminals ac of the input signal switches 21 and 22 are open. In the input signal switch 20, it is assumed that the switching terminal df is connected and the switching terminal ef is open. Switching of these switching contacts is performed by the control circuit 70 through the control lines c20 and c2.
This is performed according to the respective instructions of 1 and 22.

In the spare signal amplifier 30, since the switching terminals ac of the input signal switching devices 21 and 22 are open, the input signals from the switching terminals d and e of the input signal switching device 20 via the switching terminal f are No output signal switch 5
The signal terminator 6 is connected in series with the switching contacts jk of 1,52.
Connected to 0. Auxiliary signal amplifier 30 is controlled in operation by an operation command or a stop command received from control circuit 70 via control line c30.

The signal amplifier 31 has a self-failure detecting function, and outputs information indicating that it is in a normal operation state to the state change detector 4.
When the state changes from the normal operation state to another state due to an abnormality or the like, the state change detector 41 is notified of information indicating that the state is other than the normal operation state. The signal amplifier 31 is controlled in operation by an operation command or a stop command received from the control circuit 70 via the control line c31.

Similarly, the signal amplifier 32 has a self-failure detecting function, and notifies the state change detector 42 of information indicating that it is in a normal operation state. When the state has changed to, the state change detector 42 is notified of information indicating that the state is other than the normal operation state. The signal amplifier 32 is controlled in operation by an operation command or a stop command received from the control circuit 70 via the control line c32.

The state change detector 41 receives information from the signal amplifier 31 that it is in a normal operation state, and sends a switch request pulse to the control circuit when it receives information that has changed to another state. I do. Similarly, the state change detector 42
Receives information from the signal amplifier 32 that it is in a normal operation state, and sends a switching request pulse to the control circuit when it receives information that has changed to another state.

The output signal switch 51 transfers a signal received from the signal amplifier 31 via a switching contact gh and a signal received from the standby signal amplifier 30 via a switching contact jk. According to the switching instruction received from the circuit 70 via the control line c51, the signal received from the signal amplifier 31 is switched to the switching contact gk, and the signal received from the spare signal amplifier 30 is switched to the switching contact jh.

Next, the "stop state of the signal amplifier 31" will be described with reference to FIG.

The difference from the state shown in FIG. 1 is that the input signal switch 21 receives the switching instruction from the control circuit 70 via the control line c21, opens the switching terminals ab, and connects the switching terminals ac. That is, the output signal switch 51 is connected to the control circuit 7.
0 to the switching terminal g via the control line c51.
−h, jk is open and the switching terminals gk, jh are connected.

The input signal switch 22 is connected to the control circuit 70
, The switching is inhibited by receiving the instruction of invalidating the switching via the control line c22, and the output signal switch 52 also receives the instruction of invalidating the switching via the control line c52 from the control circuit 70 and inhibits the switching. is there.

Therefore, in the first channel, the signal amplifier 31 is removed for repair, and the input terminal 11
Is input to the standby signal amplifier 30 via the switching terminals ac of the input signal switching device 21 and the switching terminals df of the input signal switching device 20, and is amplified and output from the output signal switching device 51. It is transmitted as an output signal from the output terminal 61 via the switching terminal jh.

In the second channel, as in FIG. 1, the signal amplifier 32 receives an input signal input from the input terminal 12 through the switching terminals ab of the input signal switch 22, amplifies the output signal, The output signal is transmitted from the output terminal 62 via the switching terminal gh of the switch 52 as an output signal. Switch terminals ab of input signal switch 22 and output signal switch 52
Since the switching of each of the switching terminals gh has been disabled, even if the signal amplifier 32 fails, it cannot be connected to the standby signal amplifier 30 operating in the first channel.

The "stop state of the signal amplifier 32" is the same as the "stop state of the signal amplifier 31" except that the first channel and the second channel are interchanged. Omitted.

Next, referring to FIGS. 1 and 2 and FIG. 3, the "normal operation state" shown in FIG. 1 is shifted to the "signal amplifier 31 stopped state" in FIG. The procedure for returning to the “normal operation state” will be described.

As shown in FIG. 3, "normal operation state"
When the signal amplifier 31 changes from the normal operation state to the abnormal stop state due to a failure, the state change detector 41 sends a switching request to the control circuit 70 with a pulse for one cycle of the monitoring timing (41). The control circuit 70 detects a switching request received from the state change detector 41 at the monitoring timing (41) T0 for the signal amplifier 31.

The control circuit 70 instructs via the control lines c21 and c51 in accordance with the switching request received from the state change detector 41, and the input signal switch 21 and the output signal switch 5
1 is switched from the connection of FIG. 1 to the connection of FIG.
2 and c52, the switching instruction to the input signal switch 22 and the output signal switch 52 is prohibited, and the "signal amplifier 31
Is stopped. "

Thereafter, the signal amplifier 31 is replaced or removed and mounted after the repair, and is put into an operation stop state waiting for an operation command.

When the control circuit 70 receives the reset request from the reset terminal 10, the reset pulse is detected by the monitoring timing (41) T1 of the signal amplifier 31 based on the "stop state of the signal amplifier 31", and the switching mask is switched from invalid to invalid. The switch is switched to the valid state to return to the “normal operation state”, and an operation command is sent to the signal amplifier 31 via the control line c31. After receiving the operation command, the signal amplifier 31 returns to the normal operation state at the monitoring timing (41) T3 after a delay time of, for example, 1.5 cycles, as in the related art.

As described above, the monitoring timing (41) T1
, The control circuit 70 sets the switching mask to be effective.
Since the signal amplifier 31 does not cause a change in state from a normal operation state to a state other than the normal operation state, the control circuit 70 sets the monitoring timing (41) T2 one cycle later than the monitoring timing (41) T1 and the signal amplifier 31
Is in a state other than the normal operation state, the state change detector 4
1 does not receive the switching request. The condition under which the start time of the switching validity can be advanced is effective when there are a plurality of active devices as described later.

Next, referring to FIG. 1 and FIG. 4, the condition that the second channel is not operated and the non-input signal at the input terminal 12 or the unmounted state of the signal amplifier 32 continues. Now, a procedure for shifting to the "stop state of the signal amplifier 31" and returning to the "normal operation state" will be described.

From the "normal operation state", the signal amplifier 31 changes from the normal operation state to the abnormally stopped state due to a failure, and from the operation of shifting to the "stop state of the signal amplifier 31" at the monitoring timing (41) T0, to the monitoring timing (41). The operation up to the return to the normal operation state at T3 is the same as that in FIG.

As described above, the monitoring timing (41) T1
, The control circuit 70 sets the switching mask to be effective.
The signal amplifier 32 is in a state other than the normal operation state because it is not mounted, and the state change from the normal operation state to a state other than the normal operation state does not occur.
Therefore, the switching request by the monitoring timing (42) is not received from the state change detector 42 even during the switching valid period of the switching mask after the monitoring timing (41) T1.

Therefore, it is unnecessary for the control circuit 70 to record the unmounted state of each of the signal amplifiers 31 and 32, which are working devices.

Next, FIG. 5 shows a case where a plurality of input terminals 11 from the first to n-th channels are used instead of the two channels shown in FIG.
~ 1n, input signal switches 21 ~ 2n, signal amplifiers 31 ~
3n, state change detectors 41 to 4n, output signal switch 51
FIG. 1 shows a block diagram of a working standby switching system including .about.5n and output terminals 61-6n.

The difference between FIG. 1 and the internal configuration is that input signal switch 29 and control circuit 79 corresponding to n channels are provided.
It is. In the input signal switch 29, the spare signal amplifier 30
From a control circuit 79 which receives, via a control line c29, one of n switching terminals d to e connected to a switching terminal c of each of the input signal switches 21 to 2n corresponding to n channels. Connect according to the instructions of.

As shown in FIG. 2 and described with reference to FIG. 4, when the “normal operation state” has shifted to the “stop state of the signal amplifier 31”, for example, the signal amplifier 3n
Therefore, even if an abnormality occurs and a switching request is generated from the state change detector 4n, the control circuit 79 does not perform the switching operation since the switching mask is invalidated. Therefore, there is no adverse effect on the signal of the first channel operated by the backup signal amplifier 30. Since an alarm is generated in the signal amplifier 3n, appropriate measures are taken.

The signal amplifier 31 is mounted and the control circuit 79
Receives the reset request, the monitoring timing (4
1) Since the switching mask is immediately switched to valid at T1, when the signal amplifier 3n is abnormal after this timing, the switching operation is performed to the standby signal amplifier 30 without waiting for the signal amplifier 31 to return to the normal operation state. , "The signal amplifier 3n is stopped". That is, the standby time of the conventional switching mask can be reduced to zero.

In the above description, the working spare device is a signal amplifier, but may be another type of device.

[0069]

As described above, according to the present invention, the following effects can be obtained.

The first effect is that the switching control circuit does not need to record the unmounted information of the signal amplifier which is the active device, and the switching control circuit can be simplified.

The reason is that a switching request by a pulse is made only when the state of the signal amplifier changes from a normal operating state to a state other than the normal operating state, and the switching from the working mode to the standby mode is not performed except for this switching request. This is because complicated monitoring, control circuits and storage areas can be deleted from the control circuit.

The second effect is that when returning from the standby mode to the working mode, it is possible to eliminate the waiting time until the switching mask switching start time exceeding the delay time until the signal amplifier for the working mode returns to the normal operation state. .

The reason for this is that, similarly to the above-mentioned reason, a switching request by a pulse is made only when the signal amplifier changes from a normal operating state to a state other than the normal operating state, and other than this switching request, switching from working to standby is performed. Is not performed,
This is because a switching request is not erroneously generated even if a state other than the normal operation state is continued within the delay time until the signal amplifier for returning to the normal operation enters the normal operation state.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram showing an embodiment in a case where the “signal amplifier 31 is stopped” in FIG. 1;

FIG. 3 is a time chart showing an embodiment relating to an operation of switching to a spare in one signal amplifier of FIG. 1;

FIG. 4 is a time chart showing an embodiment relating to a switching operation with a spare in another signal amplifier in an example in which one signal amplifier of FIG. 1 is not mounted.

FIG. 5 is a block diagram showing another embodiment of the present invention which is different from FIG. 1;

FIG. 6 is a block diagram illustrating an operation state of the active device.

FIG. 7 is a block diagram showing an example of the related art.

FIG. 8 is a time chart showing an example of an operation of switching one of the signal amplifiers shown in FIG. 7 to a standby state;

9 is a time chart showing an example of a switching operation of another signal amplifier with a spare in an example in which one signal amplifier of FIG. 7 is not mounted.

[Explanation of symbols]

 Reference Signs List 10 reset terminal 11, 12, 1n input terminal 20, 21, 22, 29, 2n input signal switch 30 standby signal amplifier (standby device) 31, 32, 3n signal amplifier (active device) 41, 42, 4n state change detection Devices 51, 52, 5n Output signal switch 60 Signal terminator 61, 62, 6n Output terminal 70, 79, 170 Control circuit

Claims (6)

[Claims] 1. An active / standby switching system in which one active device is provided with one standby device and the active device is switched to the standby device when the active device is in a state other than the normal operation, the status change of the active device is performed. An active / standby switching system comprising: a switching control unit that detects and switches an active device that has changed from a normal operation state to a state other than a normal operation to the standby device. 2. An active / standby switching system in which one standby apparatus is provided for a plurality of active apparatuses and one of the active apparatuses in a state other than the normal operation is switched to the standby apparatus for operation, and a state change of each of the active apparatuses is performed. And switching control means for switching one active device whose state has changed from the normal operation state to a state other than the normal operation to the standby device and disabling the switching for the standby devices of the remaining active devices. Active spare switching system. 3. The active standby switching system according to claim 2, wherein the switching control means, upon receiving a reset request, immediately disables the switching at a monitoring timing of state change detection. 4. An active / standby switching system in which one active unit is provided with one standby unit, and the active unit in a state other than the normal operation is switched to the standby unit and operated.
A switching device for switching and connecting a spare device instead of an active device;
A state change detector that is provided corresponding to the active device and that outputs a request to switch the active device when detecting that the corresponding active device has changed state from a normal operation state to a state other than a normal operation; A switching circuit for instructing the switch to switch the active device to the standby device when a switching request for the active device is received from a state change detector. 5. In an active / standby switching system in which one standby apparatus is provided for a plurality of active apparatuses and one of the active apparatuses in a state other than the normal operation is switched to the standby apparatus and operated, A switching device that switches and connects one standby device instead of one, and is provided corresponding to each of the active devices, and when it is detected that the corresponding active device has changed from a normal operation state to a state other than a normal operation state A state change detector that outputs a request for switching the active device to the active device, and selects one active device when a request for switching to the active device is received from the state change detector, and switches the selected active device to the standby device. A control circuit for outputting a switching instruction to the switching device, and outputting to the switching device invalidity of switching of all remaining active devices to the standby device. Spare switching system. 6. The active standby switching system according to claim 5, wherein the control circuit, upon receiving a reset request, immediately switches the switching disable of the switching unit to the switching enable at the monitoring timing of the state change detection.