JP2001339372A - Redundant system device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a redundant system device that selects/switches a master/a slave with simple control needing only a small load. SOLUTION: Reference frame generating sections 111, 112 generate a multi- frame synchronously with a clock CLK and a pulse P. Frame extract sections 112, 122 extract the multi-frame from a frame data signal from an opposite device. Selectors 113, 123 select the multi-frame of the reference frame generating sections 111, 121 or the frame extract sections 112, 122. Frame generating sections 114, 124 generate a frame data signal from the multi-frame selected by the selectors 113, 123 and transmit the signal to the opposite device. Phase detection sections 115, 125 detect synchronization/asynchronization of the multi- frame of both devices 110, 120. Master/slave control sections 116, 126 autonomously control the master/slave state of its own device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a redundant system, and more particularly, to operating a first system to an n-th system in a self-running mode or a following mode.
The present invention relates to a redundant device for synchronizing these devices.

[0002]

2. Description of the Related Art Conventionally, a master mode (self-propelled mode) has been used.
There is known a redundant device that synchronizes the phases of these devices by causing a device in a slave mode (follow-up mode) to follow the device. Such a synchronization method
Generally, it is called “act determination method”.

FIG. 6 is a block diagram showing an example of a conventional redundant device (in the case of a duplex device).

[0004] As shown in FIG.
0-system device 610, 1-system device 620, control device 6
30.

[0005] Frame data and device status information are transmitted and received between the devices 610 and 620. This frame data is used to synchronize devices 610 and 620, as described below. Further, the control device 630 includes:
It receives the other-system phase detection information from the devices 610 and 620 and transmits a selection signal to the devices 610 and 620. Here, the other-system phase detection information is information indicating a phase detection result, and includes failure information and the like. The selection signal is a signal for setting the devices 610 and 620 as one of a master and a slave. Transmission and reception of the other-system phase detection information and the selection signal are performed by the upper interfaces 616 and 626 in the devices 610 and 620 and the lower interface 631 in the control device 630.

The 0-system device 610 receives an internal reference clock CLK and a frame pulse P (M cycle) from outside. The reference frame generation unit 611 outputs a multi-frame (M) synchronized with the clock CLK and the pulse P.
× N cycles). The reference frame generation unit 61
1 sends disconnect information to the upper interface 616 when the clock CLK or the pulse P is not input. The upper interface 616 sends this disconnection information to the control device 630 as the above-mentioned other system phase detection information. The frame extracting unit 612 extracts a multi-frame (M × N cycle) from the frame data signal (M cycle) received from the device 620. The selector 613 responds to the selection signal described above,
One of the multi-frame output from the reference frame generator 611 or the multi-frame output from the frame extractor 612 is selected. The frame generation unit 614 generates a frame data signal (M cycle) by superimposing the multi-frame selected by the selector 613, and sends it to the device 620. Further, the frame generation unit 614 generates an in-apparatus reference frame signal (M × N cycle) F ₀ in synchronization with the transmitted frame data signal, and sends it to another component (not shown) in the apparatus 610. . The phase detection unit 615 receives the multiframes from the reference frame generation unit 611 and the frame extraction unit 612, respectively, and detects the synchronization / asynchronization of the two and the detection of the frame disconnection. These detection results are sent to the control device 630 as the other-system phase detection information described above.

[0007] The configuration of the system 1 620 is the same as that of the system 610.

The control device 630 uses the other-system phase detection information received from the devices 610 and 620 to
Determine 20 masters / slaves. If the other-system phase detection information includes failure information such as disconnection information, the device having no failure is selected as the master. In addition, both devices 61
When the phases of 0,620 are synchronized, both devices are selected as masters. Then, when a phase shift occurs between both devices 610 and 620 when both devices 610 and 620 are selected as masters, control device 630 temporarily changes one device to a slave and changes the other device to a slave device. By following the phase, the phases of both devices 610, 620 are resynchronized. Then, when the phases of the two devices 610 and 620 are synchronized again, the slave device is changed to the master. The selection of the master / slave is specified by the above selection signal.

Other components in device 610 (not shown)
Operate in synchronization with the phase given by the in-device reference frame signal F ₀ input from the frame generation unit 614. Also, other components in the device 620 (not shown)
Is the same. Therefore, by synchronizing the phase between the devices 610, 620, these devices 610, 6
The operation of each component in the device 20 can be completely synchronized.

[0010]

As shown in FIG. 6,
In the conventional redundant device, the control device 63 as a higher-level device is used.
With 0, selection / switching of the master / slave was performed.

For this reason, the conventional redundant device has a disadvantage that the control for selecting / switching between the master and the slave is complicated. This disadvantage becomes more remarkable as the number of systems provided in the redundant system device increases.

Further, the conventional redundant system has a disadvantage that the load on the control unit 630 increases when the number of systems is large. For this reason, control other than the master / slave selection / switching control of the control device 630 may be delayed.

For these reasons, there has been a demand for a redundant system device capable of performing selection / switching of a master / slave by simple and low-load control.

[0014]

According to the present invention, each of the first to n-th devices (n = 2, 3,...) Is operated in a self-propelled mode or a follow-up mode. And a redundant device for synchronizing the same.

An autonomous self-propelling / following system in which each of the first to n-th systems changes the self-propelling state / following state of this apparatus according to the self-propelling state / following state of another apparatus. A control unit is provided.

According to the present invention, since an autonomous self-propelling / following control unit is provided in each system, selection / switching of a master / slave can be performed by simple and low-load control.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the size, shape and arrangement relationship of each component are only schematically shown to the extent that the present invention can be understood, and the numerical conditions described below are merely examples. .

First Embodiment Hereinafter, a redundant system according to a first embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a block diagram schematically showing a configuration of a duplexer according to this embodiment.

As shown in FIG. 1, this duplexer has:
It has a system 0 device 110 and a system 1 device 120.

Frame data and device status information are transmitted and received between the devices 110 and 120. As described later, these devices 110 and 120 autonomously determine their own master / slave.

The 0-system apparatus 110 includes a reference frame generation unit 1
11, a frame extracting unit 112, a selector 113,
A frame generation unit 114, a phase detection unit 115, a master / slave control unit 116, and an upper interface 117
And That is, the 0-system apparatus 110 according to this embodiment includes an autonomous master / slave control unit 116 therein.

The reference frame generation unit 111 externally receives
An internal reference clock CLK and a frame pulse P (M cycle) are input. The reference frame generation unit 111 generates a multi-frame (M × N cycle) in synchronization with the clock CLK and the pulse P. When the clock CLK or the pulse P is not input, the reference frame generation unit 111 transmits the disconnection information to the master / slave control unit 11.
Send to 6.

The frame extracting section 112 extracts a multi-frame (M × N cycle) from the frame data signal (M cycle) received from the device 120. This multi-frame is sent to the selector 113 and the phase detector 115. Further, the frame extracting unit 112 extracts failure information, transition information, and the like of the device 120 from the frame data signal and sends the information to the master / slave control unit 116.

The selector 113 inputs a selection signal from the master / slave control unit 116. And selector 1
Reference numeral 13 denotes a reference frame generation unit 1 according to the selection signal.
One of the multi-frame output from the frame extractor 11 or the multi-frame output from the frame extractor 112 is selected. The selected multi-frame is output to the frame generation unit 11
4

The frame generation unit 114 includes a selector 113
Input the selected multiframe, and also input the fault information and the transition information from the master / slave control unit 116. Then, the frame extracting unit 112 generates a frame data signal (M periods) by superimposing the information and the multi-frame. The generated frame data signal is sent to the device 120. In addition, the frame generation unit 114 synchronizes with a frame data signal to be transmitted and synchronizes one or more types of frame signals (M × N
(Period) F ₀ is generated. These frame signals F ₀ are:
It is sent to other components (not shown) in the device 110.

The phase detector 115 receives multi-frames from the reference frame generator 111 and the frame extractor 112, respectively. Then, the phase detection unit 115
Will detect these multi-frame synchronous / asynchronous detections,
Perform disconnection detection. These detection results are sent to the master / slave control unit 116.

The master / slave control unit 116 inputs disconnection information, a detection result, and the like from the reference frame generation unit 111 and the phase detection unit 115. Further, the master / slave control unit 116 sends a signal from the frame extraction unit 112 to the device 12
Enter 0 information. Then, the master / slave control unit 116 controls the state transition of the device 110 using these pieces of information (described later). As described later, there are three types of states of the device 110: SYNC, HUNT, and RST. Of these, SYNC is in master mode and HU
NT and RST are slave modes. In the master mode, the master / slave control unit 116 causes the selector 113 to select a multi-frame output by the reference frame generation unit 111. On the other hand, in slave mode,
The master / slave control unit 116 supplies the selector 113 with
The multi-frame output from the frame extracting unit 112 is selected. Further, the master / slave control unit 116 sends the failure information (disconnection information, detection result, and the like) and the transition information input from the reference frame generation unit 111 and the phase detection unit 115 to the frame generation unit 114.

The upper interface 117 transmits and receives control information to and from an external device (not shown).

The first system device 120 includes the reference frame generation unit 1
21, a frame extracting unit 122, a selector 123,
A frame generation unit 124, a phase detection unit 125, a master / slave control unit 126, and an upper interface 127
And That is, the first system device 120 also includes the autonomous master / slave control unit 126 therein.

The configuration of the reference frame generator 121, the frame extractor 122, the selector 123, the frame generator 124, the phase detector 125, and the upper interface 127 is the same as that of the reference frame generator 111, frame extraction unit 112, selector 11
3. The configuration is the same as that of the frame generation unit 114, the phase detection unit 115, and the upper interface 117.

The master / slave control unit 126
20 for four states (SYNC, PSYNC, HUNT)
And RST).
Is different from the master / slave control unit 116 of FIG. this house,
SYNC and PSYNC are in master mode and HU
NT and RST are slave modes.

Next, the master / slave control units 116 and 1
The operation of 26 will be described with reference to FIGS.

First, the basic operation principle of the state transition will be described.

As shown in FIG. 2A, the master / slave control unit 116 of the 0-system device 110 has three types of states.
That is, SYNC (synchronizing), HUNT
(Hunting) and RST (reset) are controlled. Here, SYNC is a master mode, and HUNT and RST are slave modes. That is, the selector 113 selects the multi-frame from the reference frame generation unit 111 at the time of SYNC, and
At the time of T and RST, the multi-frame from the frame extracting unit 112 is selected (see FIG. 1).

On the other hand, as shown in FIG. 2B, the master / slave control unit 126 of the first system device 120 has four types of states, namely, SYNC (synchronizing) and PS.
The state transition of YNC (pre-synchronous), HUNT (hunting) and RST (reset) is controlled. Here, SYNC and PSYNC are in the master mode, and HUNT and RST are in the slave mode. That is, the selector 123 selects the SYNC and PS
In the case of YNC, the multiframe from the reference frame generation unit 121 is selected, and in the case of HUNT and RST, the multiframe from the frame extraction unit 122 is selected (see FIG. 1).

Assuming that there is no failure or the like in the devices 110 and 120, the states of the master / slave control units 116 and 126 transition as follows.

In FIG. 2, when the power is turned on, the device 110 is in the RST state, and the device 120 is also in the RS state.
It becomes T state. Further, the device 110 makes a transition to HUNT at the internally generated determination timing (for example, the rising timing of the clock CLK (see FIG. 1)), and the device 120 also makes a transition to HUNT at this determination timing.

As described above, in the act determination method, both devices 110 and 120 are in the slave mode (here, H
In the case of (UNT), one of the devices 110 and 120 is changed to a master mode (here, SYNC), and the slave mode device is made to follow the master mode device so that the two devices 110 and 120 are synchronized. There is a need.
If both devices 110 and 120 are not synchronized despite being in the master mode, the devices 110 and 120 are not synchronized.
20 needs to be changed to the slave mode to achieve synchronization.

For this reason, the master / slave control unit 116 of the 0-system device 110 checks the status of the 1-system device 120 and both the own device 110 and the other device 120 perform HUNT.
If, the state transits to SYNC at the internally generated determination timing. Further, when the master / slave control unit 116 checks the status of the first system device 120 at this determination timing, both the own device 110 and the other device 120
If it is YNC and both devices 110 and 120 are not synchronized, the state transits to HUNT.

However, assuming that the master / slave control unit 126 of the first system device 120 performs exactly the same control operation as the master / slave control unit 116 of the zero system device 110, the two devices 110 and 120 are synchronized. Can not. If the control operations of both control units 116 and 126 are the same, when both devices 110 and 120 are HUNT,
This is because the two devices 110 and 120 repeat the operation of simultaneously transitioning to SYNC at the internally generated determination timing and simultaneously transitioning to HUNT at the next determination timing.

Therefore, in this embodiment, when the 0-system device 110 is HUNT, the master / slave control unit 126 of the 1-system device 120 transitions to PSYNC once. Then, at the internally generated determination timing, the master / slave control unit 126 again checks the status of the 0-system device 110, and if the 0-system device 110 is HUNT, transitions to SYNC, and the 0-system device 110 If it is, the state transits to HUNT. In this embodiment, the first system 1
When 20 has transitioned to PSYNC, it is decided to stop following the 0-system device 110. In that sense, PS
YNC is a type of master mode.

Next, the master / slave control units 116, 1
Details of the control operation performed by the control unit 26 will be described.

As described above, when the power is turned on, the device 110 enters the RST state, and
Also enter the RST state (see item a in FIG. 3). At this time, the devices 110 and 120 transmit, as device status information, information indicating that the device is RST, information indicating that the phase detection result is asynchronous, and the like to the other device (FIG. 4).
reference).

Next, the master / slave control units 116 and 1
26, in step S1, detects that the state of the own device is RST, and determines the HU
Transition to NT (item b in FIG. 3). Also at this time, the device 11
0 and 120 are transmitted to the other device as device status information.
It transmits information indicating that the own device is HUNT, information indicating that the phase detection result is asynchronous, and the like (see FIG. 4).

In step S2, master / slave control section 116 detects that own apparatus 110 is HUNT. In this case, the master / slave control unit 116 has no fault in its own device 110 and the other device 120 and has the other device 1
If 20 is HUNT or RST, transition is made to SYNC (see item f in FIG. 3). On the other hand, when there is no failure in the own device 110 and there is a failure in the other device 120, the state transits to SYNC (see e in FIG. 3). If there is a failure in the own device 110, the master / slave control unit 116
Maintain NT. In the case of transition to SYNC, the master / slave control unit 116 transmits to the other device 120, as device status information, information indicating that the own device 110 is SYNC, information indicating that the phase detection result is asynchronous, and the like. (See FIG. 4).

In step S2, master / slave control unit 126 detects that device 120 is a HUNT. In this case, the master / slave control unit 126
Is PSY if there is no failure in the own device 120 and the other device 110 and the other device 110 is HUNT or RST.
The state transits to NC (see item h in FIG. 3). On the other hand, own device 12
0 has no fault and the other device 110 has a fault,
The state transits to PSYNC (see item g in FIG. 3). If there is a failure in the own device 120, the master / slave control unit 1
26 maintains HUNT. When transitioning to PSYNC, the master / slave control unit 126
Then, as the device status information, information indicating that the own device 120 is PSYNC, information indicating that the phase detection result is asynchronous, and the like are transmitted (see FIG. 4).

In step S3, master / slave control section 116 detects that own apparatus 110 is SYNC. If the own device 110 is SYNC, the master / slave control unit 116 checks whether there is a failure in the own device 110 and the other device 120, the state of the other device 120, the disconnection information of the other device 120, and the detection result of the phase detection unit 115. I do. And there is no failure of the own device 110 and the other device 120,
The transition to HUNT is made only when the other device 120 is SYNC or PSYNC, the other device 120 is not in the disconnected state, and the phase is asynchronous (see item c in FIG. 3). In the case of step S3, since the other device 120 is PSYNC,
Device 110 is maintained at SYNC. In the case where SYNC is maintained, the master / slave control unit 116 transmits the status of the own device 120 to the other device 120 as device status information.
C, information indicating that the phase detection result is asynchronous, and the like are transmitted (see FIG. 4).

In step S3, the master / slave control unit 126 detects that the own device 120 is PSYNC. If the device 120 is PSYNC, the master /
The slave control unit 126 includes the own device 120 and the other device 1
The presence / absence of the fault and the status of the other device 110 are checked. Then, when there is no failure in the own device 120 and the other device 110 and the other device 110 is SYNC or PSYNC, the state transits to HUNT (see item l in FIG. 3). HU
When transitioning to NT, the master / slave control unit 126
Is transmitted to the other device 110 as device status information.
Information indicating that 0 is a HUNT, information indicating that the phase detection result is asynchronous, and the like are transmitted (see FIG. 4).
On the other hand, if there is no failure in the own device 120 and the other device 110 and the other device 110 is HUNT or RST, or if there is no failure in the own device 120 and there is a failure in the other device 110, the device 120 transitions to SYNC. (G term in FIG. 3,
See section h).

In step 4, the master / slave control unit 116 detects that the own device 110 is SYNC. Then, under the same control as in step 3, the device 110 is maintained at SYNC (see item c in FIG. 3), and device status information is transmitted to the other device 120 (see FIG. 4).

In step 4, the master / slave control unit 126 detects that the own device 120 is a HUNT. In this case, the other device 110 is set to SYNC or PS
Since it is a YNC and the devices 110 and 120 are not synchronized, none of the items g, h and k in FIG. Thus, device 120 is maintained at HUNT, and device 120 follows device 110. Thereafter, when the devices 110 and 120 are synchronized, the device 120
The state transits to NC (see k in FIG. 3). When transitioning to SYNC, the master / slave control unit 126
At 0, information indicating that the own apparatus 120 is SYNC, information indicating that the phase detection result is synchronous, and the like are transmitted as apparatus state information.

In step S5, the devices 110, 120
Are both SYNC. In this case, both devices 110,
120 is SY except when a phase shift occurs (that is, when the phase shifts out of synchronization) and when a failure occurs.
Maintain NC. If a phase shift occurs, the device 11
Both 0 and 120 transition to HUNT (see item c in FIG. 3), and the master / slave control units 116 and 126 execute the above-described control after step S2. Also, the device value 11
When a failure occurs in 0 and 120, the device in which the failure has occurred shifts to HUNT (see item d in FIG. 3).

As described above, according to the redundant system of this embodiment, the autonomous master / slave control unit 11
6, 126, the devices 110 and 120 can be synchronized by selecting / switching between master / slave. Therefore, the act determination control can be simplified, and the processing speed of the act determination control and other control can be improved.

In this embodiment, the case of a duplexer has been described as an example. However, the present invention can be applied to a triple or more tripler. In the case of a triple or more apparatus, the m-th apparatus (3 ≦ m ≦ n) is provided with m−1 stages of PSYNC. And the m-th device is the first device.
State transition is performed according to the states of the system to the (m-1) th system.
As a result, the own device can simultaneously execute S from the HUNT simultaneously with other devices.
Transition to YNC can be prevented, and synchronization between devices can be performed.

Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIG.

This embodiment is an example in which the duplexer shown in the first embodiment is applied to DMA (Direct Memory Access) transfer.

As shown in FIG. 5, the device according to this embodiment includes memory boards 510 and 520 and control device 5.
30 and a bus 540.

The memory board 510 corresponds to the 0-system device 110 shown in the first embodiment.
An MA controller 512 and a master / slave determination circuit 513 are provided. Here, the master / slave determination circuit 513 is provided for each component 111 of the 0-system device 110 in FIG.
To 117 are provided. Further, the DMA controller 512 receives a signal for synchronization from a frame generation unit (corresponding to the frame generation unit 114 in FIG. 1) in the master / slave determination circuit 513, and operates in synchronization with this signal. In the first embodiment described above,
The frame F is used as a signal for synchronization in the device 110.
_{Although 0} is used, the signal for synchronization in the memory board 510 need not be a frame, but may be a level signal or multiplexed data.

Similarly, the memory board 520 corresponds to the first device 120 shown in the first embodiment,
1, a DMA controller 522, and a master / slave determination circuit 523. Here, the master / slave determination circuit 523 includes the same components as the components 121 to 127 of the first system device 120 in FIG. Also, D
The MA controller 522 includes a frame generation unit (the frame generation unit 12 in FIG. 1) in the master / slave determination circuit 523.
4), and operates in synchronization with this signal. In the above-described first embodiment, the frame F ₀ is used as a signal for synchronization in the device 120. However, the signal for synchronization in the memory board 520 does not need to be a frame. It may be a level signal or multiplexed data.

The control device 530 includes a memory board 510,
The entire device including the 520 is controlled. However, the control device 53
0 indicates that the memory boards 510, 520
Is not controlled.

Hereinafter, the operation of the apparatus shown in FIG. 5 will be described.

In the DMA transfer, the control device 530 is not used, and the DMA controllers 512 and 522
Is controlled, data is directly transferred between the memories 511 and 521. Basically, the memory board 51
The master sends out data among 0 and 520, and the slave receives and stores data.

As described above, the DMA controller 512
Operates in synchronization with the master / slave determination circuit 513,
The DMA controller 522 operates in synchronization with the master / slave determination circuit 523. Therefore, when the master / slave determination circuits 513 and 523 are synchronized through the state transition as described in the first embodiment, the DMA controller 512 and the DMA controller 522 are synchronized.

That is, according to the apparatus shown in FIG. 5, the control device 530 does not need to control the data transfer and does not need to control the act determination of the memory boards 510 and 520. Therefore, the load on control device 530 becomes very small.

Also, the control device 530
When making an act decision of 0,520, it is necessary to use the bus 540 for master / slave control.
That is, when control device 530 makes an act determination, it is necessary to suspend DMA transfer for master / slave control. On the other hand, in this embodiment, since the act determination is performed autonomously, there is no need to interrupt the DMA transfer, and therefore, the speed of the DMA transfer can be substantially increased.

[0066]

As described above in detail, according to the present invention, it is possible to provide a redundant system device capable of selecting / switching between a master and a slave by a simple and low-load control.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a redundant device according to a first embodiment.

FIG. 2 is a conceptual diagram for explaining an operation of the redundant device according to the first embodiment.

FIG. 3 is a table for explaining the operation of the redundant device according to the first embodiment;

FIG. 4 is a conceptual diagram for explaining an operation of the redundant system device according to the first embodiment.

FIG. 5 is a block diagram illustrating a configuration of a redundant device according to a second embodiment;

FIG. 6 is a block diagram showing a configuration of a conventional redundant system device.

[Explanation of symbols]

 110 0 system device 120 1 system device 111, 121 Reference frame generator 112, 122 Frame extractor 113, 123 Selector 114, 124 Frame generator 115, 125 Phase detector 116, 126 Master / slave controller 117, 127 Upper interface

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Mutsumi Takahashi 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. F term (reference) 5K047 AA02 AA15 GG56 KK19

Claims (5)

[Claims] A first to n-th devices (n = 2, 3,...)
.) Are operated in the self-running mode or the following mode, thereby synchronizing these devices. In the redundant system device, each of the first to n-th devices is provided with the self-propelled state / following state of this device. A redundant system device comprising an autonomous self-propelled / following control unit that changes a state according to a self-propelled / following state of another device. 2. The system according to claim 1, wherein the first to n-th devices do not simultaneously perform at least one of a transition from a self-propelled state to a following state or a transition from a following state to a self-propelled state. 2. The redundant device according to claim 1, wherein the follow-up control unit performs control. 3. The self-propelled / following control unit of the first system device, the first system device is in a following state, and the other systems are all in a following state. Means for causing the device to transition to a self-propelled state; and wherein the first system device is in a self-propelled state, any of the other system devices is in a self-propelled state, and these self-propelled devices are asynchronous. Means for causing the first device to transition to the following state at a certain time; and the self-propelled / following control unit of the second device, wherein the second device is in the following state and the other system Means for shifting the second system device to the self-propelled standby state when all of the devices are in the following state;
Means for causing the second device to transition to the self-running state if the system device is in the following state, and causing the second system device to transition to the following state if the first system device is in the self-running state; When the system device is in the self-running state, any of the other devices is in the self-running state, and the devices in the self-running state are asynchronous, the second system device is shifted to the following state. 3. The redundant device according to claim 2, comprising: 4. The self-propelled drive of an m-th device (3 ≦ m ≦ n)
A tracking control unit including the (m-1) th stage of the self-propelled standby state, wherein the other system device is configured not to simultaneously transition from the following state to the self-propelled state at the same time as the first to m-1th devices. 4. The redundant device according to claim 3, wherein transition is made between these free-running spare states according to the state of the redundant system. 5. The redundancy according to claim 1, wherein the first to n-th devices are used for synchronization between controllers performing direct memory access transfer. System equipment.