JP2000078156A - Device and method for displaying system configuration and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To recognize a changed spot clearly at a glance by reading a connecting state after a change and a connecting state before the change out of a storage means and displaying these states while combining them when the change of connecting state is detected. SOLUTION: When the change of connecting state is detected, the connecting states before and after the change are read out of the storage means and displayed while being combined. When a certain power source is turned off, for example, a pass reset is generated and all the nodes connected to a serial bus transmit self identification packets and execute self identification processes. Further, based on the control of central control 101, a system configuration display device 1 executes a topology construction process. Besides, the configuration ROM of each node is read and the information required for displaying the system configuration is provided from the respective nodes. Then, the central control unit 101 stores this information in the prescribed area of a RAM 103 and displays it through a display control part 109 onto a display 108.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system configuration display device, and more particularly, to a system configuration display device and a system configuration display device for displaying a system configuration such as a system including a plurality of devices connected to a serial bus defined by IEEE1394. The present invention relates to a method and a recording medium.

[0002]

2. Description of the Related Art Conventionally, there has been an apparatus such as an IEEE 1394 analyzer having a function of displaying a system configuration in which a plurality of devices are connected by the same interface.

[0003] Devices equipped with an interface specified by IEEE 1394 include a connector insertion / removal, power ON / OFF.
When turned off, a specific signal called a bus reset signal is generated and a process called tree identification is executed. FIG. 9 is an example of a system configuration diagram immediately after executing the tree identification. In IEEE 1394, a connected device is called a node. In the figure, reference numeral 1001 denotes a node A, which has two IEEE 1394 interface ports of port 0 (p0) and port 1 (p1).

[0004] Nodes 1002 and 1003 are Node B,
Node C, which is port 0 (p0) and port 1 (p
It has three IEEE 1394 interface ports: 1) and port 2 (p2). 1004,100
5, 1006 are nodes D, E, and F, respectively.
And one IEEE 139 for each port 0 (p0)
It has four interface ports.

The port 0 of the node A 1001 is connected to the node B 1
The node A is a parent node of the node B, and the node B is a child node of the node A by the tree identification process described above.
Port 1 of node A 1001 is connected to port 0 of node C 1003. Node A is the parent node of node C by the above-described tree identification process, and conversely, node C is a child node of node A.

[0006] Port 1 of node B 1002 is connected to node D 1
The node D is a parent node of the node D, and the node D is a child node of the node B by the above-described tree identification process.
Port 2 of node B 1002 is not connected to anything.

The port 1 of the node C 1003 is connected to the node E 1
The node C is a node of the node E by the above-described tree identification process, and the node E is a child node of the node C.
The port 2 of the node C1003 is connected to the port 0 of the node F1006, and the node C is a parent node of the node F by the above-described tree identification process, and the node F is a child node of the node C. A node to which a plurality of ports are connected is called a branch, and a node to which one port is connected is called a leaf. A node in which all ports are connected to child nodes is called a root. In FIG. 9, node A 1001 is the root, node B 1002 and node C 1003 are branches, and node D 1004, node E 1005, node F
1006 is a leaf.

Next, each node performs a self-identification process. This gives each node an opportunity to select a node unique number called Physical_ID, and allows any connected node to identify itself. Specifically, a signal called a self-identification packet is transmitted to all connected devices according to the following procedure. The self-identification process uses a deterministic selection process,
The root node passes control to the node connected to the connection port with the lowest number and waits until the node sends a signal indicating that it and all of its child nodes have identified themselves. The root node then passes control to the node connected to the port with the next number,
Wait for the processing of that node to end. As described above, when the nodes connected to all the ports of the root node end the processing, the root itself performs self-identification. The child node performs the same process recursively. Accordingly, the order in which the nodes shown in FIG. 9 transmit the self-identification packets is as follows: node D1004, node B1002, node E1005, node F1006, node C1003, node A1001.
It becomes the order of.

FIG. 10 shows a format of the self-identification packet, and FIG. 11 shows an explanation of each part of the self-identification packet shown in FIG. As shown in these figures, the self-identification packet includes the contents indicating the physical ID number of the device, the supported communication speed, the power-related capability, the port connection state, and the like. Here, Physical_ID is the number of self-identification packets received before transmitting the self-identification packet. A node having four or more ports continuously transmits another self-identification packet with m = 1, but a description of such a case is omitted here. 98.304Mbp self-identification packet
s.

[0010] For the sake of simplicity, the communication speed is 98.304M.
bps to S100, 196.608 Mbps to S20
0,393.216 Mbps is abbreviated as S400.
The Physical_ID of the node A 1001 is 5, the Physical_ID of the node B 1002 is 1, and the node C
Physical_ID of 1003 is 4, node D10
04 Physical_ID is 0, node E1005
Physical_ID is 3.

Subsequently, the node having the topology construction process function can estimate the topology from the self-identification packet. As described above, the node D10
04, node E1005 and node F1006 respectively correspond to p0 = 10, p0 in the self-identification packet shown in FIG.
Since a self-identification packet with 1 = 00 and p2 = 00 is transmitted, it can be seen that this is a leaf node that has only port 0 and is connected to the parent node. Node B 1002
Transmits a self-identification packet with p0 = 10, p1 = 11, and p2 = 01, so that port 0 is connected to the parent node, port 1 is connected to the child node, and port 2 is an unconnected branch node. You can see that. Further, by following the deterministic process described above, it can be seen that port 1 is connected to node D1004. Since the node C1003 transmits a self-identification packet in which p = 10, p1 = 11, and p2 = 11, port 0 is a parent node, and ports 1 and 2 are branch nodes connected to child nodes. I understand. Node B10
02, port 1 is connected to node E1005,
It can be seen that port 2 is connected to node F1006. Finally, the node A1001 has p0 = 11, p1
= 11, p2 = 00, so that port 0 and port 1 are connected to the child node, and port 2 is a nonexistent branch node. Further, as described above, port 0 is connected to node B 100
2 shows that port 1 is connected to node C1003.

Further, the communication speed supported by each node is determined from the sp field of the self-identification packet transmitted by each node, and it is possible to obtain information on power from the pwr field.

Each node implements an area called a configuration ROM.
The following information can be obtained from the contents of _Info_Block. FIG. 12 shows Bus_Info_Bl.
This shows the format of the ock. In the figure, the irmc bit is set to 1 when the node is a device having the isochronous resource manager function, and is set to 0 when the node is not a device having the same function. cm
The c bit is set to 1 when the node is a device having the cycle master function, and is set to 0 when the node is a device not having the function. The isc bit is set to 1 when the node is a device that supports the isochronous operation, and is set to 0 when the node is a device that does not support the isochronous operation. The bmc bit is set to 1 when the node is a device having the bus manager function, and is set to 0 when the node does not have the function. The other parts in FIG. 12 are not directly related to the present invention, and thus description thereof is omitted.

When there are a plurality of nodes having an isochronous resource manager function, a node having a cycle master function, and a node having a bus manager function, one node is connected to each of the nodes according to a predetermined rule. , Assigned to the bus manager. In FIG. 9, it is assumed that node A 1001 is assigned to an isochronous resource manager, a cycle master, and a bus manager.

FIG. 13 shows a display example of a conventional system configuration display device obtained based on the above information.

[0016]

However, the above conventional example has the following problems.

(1) When a new device is added as a node, a bus reset occurs, a tree identification process, a self-identification process, and a topology construction process are newly performed as described above, and only the result is displayed. Because
It is difficult to tell which node is the newly added node.

(2) Even if the cable is disconnected from one node, a bus reset occurs, and the tree identification process, the self identification process, and the topology construction process as described above are newly performed, and only the result is displayed. Therefore, it is difficult to know from which node the cable was unplugged.

[0019]

In order to solve the above-mentioned problems, a system configuration display device, a system configuration display method, and a recording medium according to the present invention are mainly characterized by the following configuration.

That is, a system configuration display device for displaying a connection configuration of a plurality of devices includes a recognizing means for recognizing the connection status of all devices connected to the system, and displaying the connection status of all the recognized devices. Display means for storing, the storage means for storing the recognized connection state, and detection means for detecting a change in the connection state of a device connected to the system, wherein the connection state has been changed by the detection means. Is detected, the connection state after the change and the connection state before the change are read out from the storage unit and displayed in combination on the display unit.

Further, the system configuration display device includes an instruction input means for selectively switching between a connection configuration of a past device and a connection configuration of a current device. The connection state stored in the storage means is read out and displayed on the display means.

A system configuration display method for displaying a connection configuration of a plurality of devices includes a recognition step of recognizing a connection status of all devices connected to the system, and displaying a connection status of all the recognized devices. A display step of displaying on the means, a storage step of storing the recognized connection state in a storage means, and a detection step of detecting a change in a connection state of a device connected to the system, and the detection step When detecting that the connection state has changed, the display step reads out the connection state after the change and the connection state before the change from the storage unit and displays them in combination on the display unit.

Also, the computer-readable recording medium has a recognition step of recognizing the connection states of all the devices connected to the system, and a display step of displaying the recognized connection states of all the devices on display means. A program for causing a computer to execute a storage step of storing the recognized connection state in storage means, and a detection step of detecting a change in the connection state of a device connected to the system.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described by showing embodiments of the present invention.

<First Embodiment> FIG. 1 is a schematic block diagram of a system configuration display device for representing an embodiment of the first invention.

In FIG. 1, reference numeral 1 denotes a node A connectable to an IEEE 1394 serial bus, which is a system configuration display device embodying the present invention. 101 is a ROM 102
A central control unit for controlling each unit according to the program instructions stored in the central control unit 101;
In the OM, 102, the central controller 101 writes and reads data as needed, reads and stores data from the LINK controller 115 by direct memory access, and reads and stores data in reverse by direct memory access. A RAM for writing data to the memory 115.

Reference numeral 104 denotes a timer for the central controller 101 to perform time measurement as needed, and has a calendar / clock function. A timer for the central controller 101 to read the date, day of the week, and time. A battery for continuing timekeeping even when the power supply unit 120 of the configuration display device 1 is off, 106 is a key input unit including a mouse, 107
Is a key input detecting means for detecting that the key input means 106 has been operated and informing the central controller 101 of the operation.

Reference numeral 108 denotes a display such as a liquid crystal display or a cathode ray tube;
A display control unit for switching a signal to be transmitted to the display unit 8 or converting a signal to be transmitted to the display unit 108;
Reference numeral 10 denotes a speaker for outputting an audio signal, 111 denotes a speaker control unit which is controlled by the central control device 101 and amplifies the audio signal and switches a signal to be output to the speaker 110, and 112 denotes an IEEE1394 serial bus. Ports 0 and 113 for connecting the system configuration display device 1 are also ports 0 and 114 for connecting the system configuration display device 1 to the IEEE 1394 serial bus, and controllers (Physical) for controlling the physical layer defined by IEEE 1394 are used. Layer C
ontroller) (abbreviated as PHY). 115 is I
A controller (Link Layer Controller) for controlling the link layer defined by EEE1394 (L
INK).

Reference numeral 116 is used for the IEEE 1394 isochronous transfer. The FIFO 116 is controlled by the FIFO control unit 117, temporarily stores the isochronous data from the LINK 115, and sends it to the CODEC 118 in the order in which the data is stored.
O and 117 are FIFO control units for storing and extracting isochronous data to and from the FIFO 116,
Reference numeral 118 denotes a CODEC for performing predetermined encoding / decoding of the isochronous data extracted from the FIFO 116
(Abbreviation of CODER / DECODER) 119 is a power supply unit for generating a voltage and a current necessary for operation of each unit in the system configuration display device 1 from a commercial power supply (not shown) and supplying them to each unit. And a power supply circuit unit for supplying power to a node connected from the power supply circuit 113 and a bias voltage to the IEEE1394 ports 112 and 113. 121 is a CPU inside the system configuration display device
It is a bus.

FIG. 2 is a flowchart showing the operation of the present embodiment.

First, when the power supply unit 119 is turned on to supply power to each unit, the PHY 114 generates a bus reset signal to all nodes connected via the ports 112 and 113 (S101). When the bus reset occurs, all nodes connected to the IEEE 1394 serial bus execute the above-described tree identification process (S10).
2) A self-identification packet is transmitted to execute a self-identification process (S103). Further, the system configuration display device 1 executes the above-described topology construction process under the control of the central control device 101 (S104).

The configuration ROM of each node is read, and information necessary for displaying the system configuration is obtained from each node (S106). In the case of the present embodiment, the system configuration display device 1 has an isochronous resource manager function, a cycle master function, an isochronous function, and a bus manager function, and becomes an isochronous resource manager, a cycle master, and a bus manager. I do. System configuration display device 1
The central controller 101 stores the above information in the RAM 103 (S106) and causes the display 108 to display the information via the display controller 109 (S107).

FIG. 3 shows a display example displayed on the display unit 108 here. Reference numeral 108a denotes a screen displayed on the display 108.

In FIG. 1, reference numeral 1 denotes a system configuration display device which is a node A, which is an isochronous resource manager, a cycle master, and a bus manager as described above, and has an isochronous function. The communication speed is up to S200 (in detail, 98.304 Mbps and 196.608 Mbps as described above).
s) Supported. Further, Physical_ID is 5, and port 0 is assigned to port 0 of node B, port 1
Is connected to the port 0 of the node C3.

Node B2 has Physical_ID of 1
It is supported up to S200 and has an isochronous function. Port 0 is connected to port 0 of node A1, port 1 is connected to port 0 of node D4, and port 2 is connected to nothing. It represents. Node C
3 has a Physical_ID of 4, supports up to S200, has an isochronous function, has port 0 connected to port 1 of node A1, port 1 connected to port 0 of node E5, and port 2 connected to port F6 of node F6. 0
Is connected to.

Node D4 has a Physical_ID of 0
This indicates that only S100 is supported and has an isochronous function, and port 0 is connected to port 1 of node B2. Node E5 is Phys
ical_ID is 2, support up to S200,
This means that the port has no isochronous function and port 0 is connected to port 1 of node C3.
Node F6 has Physical_ID = 3 and S2
00 and has an isochronous function, indicating that port 0 is connected to port 2 of node C3.

In this state, communication between arbitrary nodes is possible (S108).

Here, when the power of the node F6 is turned off or the cable is disconnected from the port 0, the node C6 is turned off.
3 causes a bus reset (S109). When the bus reset occurs, all the nodes connected to the IEEE 1394 serial bus execute the above-described tree identification process (S110), transmit a self-identification packet, and execute the self-identification process (S111). Further, the system configuration display device 1 executes the above-described topology construction process under the control of the central control device 101 (S112). Also,
The configuration ROM of each node is read, and information necessary for displaying the system configuration is obtained from each node (S113). In the case of the present embodiment, the system configuration display device 1 has an isochronous resource manager function, a cycle master function, an isochronous function, and a bus manager function, and becomes an isochronous resource manager, a cycle master, and a bus manager. I do. Central control device 10 of system configuration display device 1
1 stores the above information in an area different from the area where the information is stored in the RAM 103 in S106 (S114) and causes the display 108 to display the information via the display controller 109 (S11).
5).

This enables communication between the nodes displayed on the right half of the display screen 108b of the display 108 shown in FIG. 4 (S116).

FIG. 4 shows a display example displayed in step S115.
Shown in

FIG. 4 shows a display screen 108b of the display unit 108, and the right half of the screen is the current system configuration. As can be seen from this, the node A1, which is a system configuration display device, is an isochronous resource manager, a cycle master, and a bus manager as described above, and has an isochronous function. The communication speed is up to S200 (in detail, 98.30 Mbps and 196.608 Mb as described above).
ps) Supported. In addition, Physical_ID
Is 4, which indicates that port 0 is connected to port 0 of node B2 and port 1 is connected to port 0 of node C3.

Node B2 has a Physical_ID of 1
It is supported up to S200 and has an isochronous function. Port 0 is connected to port 0 of node A1, port 1 is connected to port 0 of node D4, and port 2 is connected to nothing. It represents. Node C
3 has a Physical_ID of 3, supports up to S200, has an isochronous function, and has port 0 connected to port 1 of node A1, port 1 connected to port 0 of node E5, and port 2 connected to nothing. It is not done.

Node D4 has Physical_ID of 0
This indicates that only S100 is supported and has an isochronous function, and port 0 is connected to port 1 of node B2. Node E5 is Phys
ical_ID is 2, support up to S200,
This means that the port has no isochronous function and port 0 is connected to port 1 of node C3.

The left half of the display screen 108b displays the system configuration before the last bus reset occurs.
That is, it is the same as the system configuration shown in FIG.

Looking at the display contents of the left half and the right half of the display screen 108b, it can be seen at a glance that the node F has left the system.

As described above, in the present embodiment, there is an effect that a portion that has changed before and after the occurrence of the bus reset can be seen at a glance.

<Second Embodiment> In a second embodiment of the present invention, a past or present system configuration is displayed according to an instruction input from the key input unit 106 shown in FIG. 1. .

It is assumed that a block diagram of a system configuration display device embodying the second embodiment of the present invention is the same as that of FIG.

FIG. 5 is a flowchart showing the operation of the present embodiment.

Steps S201 to S214 are the same as those shown in FIG. 2, that is, the first embodiment, and will not be described.

FIG. 6 shows a display example of the system configuration displayed in step S207 in this embodiment, and FIG.
In FIG. 15, an example of a new system configuration after the bus reset generated in step S209 is shown in FIG. 6, reference numeral 108c denotes a display screen displayed on the display unit 108 in step S207, which is the same as the display example of the system configuration shown in FIG. In FIG. 7, reference numeral 108d denotes a display screen displayed on the display unit 108 in step S215. The left arrow key 131 is for displaying the previous system configuration.
32 is for displaying the next system configuration. However, since this is the first display in step S207, there is no previous or later system configuration display, and thus arrow keys 131 and 132
Is in a non-display state (broken line) and is invalid even if a click operation is performed. The display state is indicated by a solid line, and the screen display is switched in response to a click operation.

In the display example of FIG. 7 displayed in step S215, since there is one previous system configuration, the left arrow key 131 is displayed and the right arrow key 13 is displayed.
2 is a non-display state.

In FIG. 7, a node G7 having three ports, which does not have the isochronous function, is added up to S400. Port 0 of node G7 is connected to port 2 of node B2, and nothing is connected to port 1 and port 2 of node G7. Further, the Physical_ID of each node has changed as shown in FIG. The Physical_ID of the node A is 6, the Physical_ID of the node B is 2, and the node C is
Physical_ID of the node 5 is Physic_ID of the node D.
cal_ID is 0, Physical_ID of node E
Is 3, the Physical_ID of the node F is 4, and the Physical_ID of the node G is 1.

In this state, communication between arbitrary nodes is possible. Here, when the left arrow key 131 is clicked (S217), the central control device 101 detects this by the key input detecting means 107 and reads the immediately preceding system configuration data from a predetermined area of the RAM 103 (S21).
8), the content is displayed on the display unit 108 (S21).
9). An example of the display is 108e shown in FIG. That is, the display returns to the display of the same content as the display content displayed in step S207. The display contents of the display screen 108c shown in FIG. 6 and the display screen 108e shown in FIG. 8 are the same. The only difference is that the right arrow key 132 is shown in FIG. 8 and is enabled.

As described above, in the present embodiment, the right arrow key 132 on the display screen 108e shown in FIG.
Is clicked, the central controller 101 detects this by the key input detecting means 107, reads out the next system configuration data from the predetermined area of the RAM 103 (S
218), the content is displayed on the display unit 108 (S2).
19). This returns to the display of FIG. 7 again. The display screen 108e of FIG. 8 and the display screen 1 shown in FIG.
08d clearly shows that the node G is newly added and is connected to the node B, that is, the difference from the previous state.

When a bus reset occurs again due to addition of a node or insertion / removal of a connector (S220),
Step S210 and subsequent steps are repeated.

In the present embodiment, it is possible to store and display system configuration data from a plurality of times before, depending on the capacity of the RAM 103 and the like.

<Third Embodiment> The present invention has been described with reference to the IEEE.
Although the present invention has been described with reference to the E1394 serial bus system, the present invention can be applied to a system configuration display device of a system other than the IEEE1394 serial bus system.

For example, the present invention is applicable not only to a wired system but also to a wireless system.

[0060]

[Other Embodiments] Even if the present invention is applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), an apparatus (for example, a copying machine) Machine, facsimile machine, etc.).

An object of the present invention is to provide a storage medium storing a program code of software for realizing the functions of the above-described embodiments to a system or an apparatus, and to provide a computer (or CPU) of the system or apparatus.
And MPU) read and execute the program code stored in the storage medium.

In this case, the program code itself read from the storage medium implements the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention.

As a storage medium for supplying the program code, for example, a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD
-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.

When the computer executes the readout program code, not only the functions of the above-described embodiment are realized, but also the OS (Operating System) running on the computer based on the instruction of the program code. ) May perform some or all of the actual processing, and the processing may realize the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written into a memory provided on a function expansion board inserted into the computer or a function expansion unit connected to the computer, based on the instructions of the program code, It goes without saying that the CPU included in the function expansion board or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

When the present invention is applied to the storage medium, the storage medium stores program codes corresponding to the above-described flowcharts. Each module shown will be stored in a storage medium.

That is, at least “recognition module 1
410, the display module 1420, the storage module 1430, and the detection module 1440 may be stored in the storage medium.

[0068]

As described above, according to the present invention, I
In an IEEE 1394 serial bus system or the like, the connection status of all connected devices can be displayed in a system before and after a bus reset occurs due to insertion / removal of a connector of a device or power ON / OFF of a connected device. The changed part can be recognized at a glance.

The history of the connection status of the devices can be stored and displayed, and the current device connection status or the past device connection status can be displayed by the instruction input means.

Since the history of the connection status of the devices can be stored and displayed, even if any abnormality or failure occurs in the system, the connection status of the device can be displayed retroactively to find out the cause of the abnormality or failure. Becomes possible.

[0071]

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of a system configuration display device according to a first embodiment.

FIG. 2 is a flowchart illustrating an operation procedure according to the first embodiment.

FIG. 3 is a display example of a system configuration according to the first embodiment;

FIG. 4 is a display example of a system configuration according to the first embodiment.

FIG. 5 is a flowchart showing an operation procedure according to the second embodiment.

FIG. 6 is a display example of a system configuration according to a second embodiment.

FIG. 7 is a display example of a system configuration according to a second embodiment.

FIG. 8 is a display example of a system configuration according to the second embodiment.

FIG. 9 is an example of a system configuration diagram at the time of termination of tree identification according to the related art.

FIG. 10 is a format diagram of a self-identification packet according to the related art.

FIG. 11 is an explanatory diagram of each part of a self-identification packet according to the related art.

FIG. 12 shows a configuration RO according to the related art.
M is the format of Bus_Info_Block.

FIG. 13 is a display example of a system configuration according to the related art.

FIG. 14 is a diagram showing a memory map of a recording medium.

[Explanation of symbols]

 1 System Configuration Display Device (Node A) 2 Node B 3 Node C 4 Node D 5 Node E 6 Node F 7 Node G 101 Central Controller 103 RAM 106 Key Input Unit 107 Key Input Detection Means 108 Display 109 Display Control Unit 112 Port 0 113 Port 1 114 Physical Layer Controller (PHY) 115 Link Layer Controller (LINK) 108a Display screen 108b Display screen 108c Display screen 108d Display screen 108e Display screen 131 Left arrow key 132 Right arrow key

Claims (10)

[Claims] 1. A system configuration display device for displaying a connection configuration of a plurality of devices, comprising: recognition means for recognizing a connection status of all devices connected to the system; and a connection status of all the recognized devices. Display means for displaying, a storage means for storing the recognized connection state, and a detection means for detecting a change in the connection state of a device connected to the system, wherein the connection state is changed by the detection means. When detecting that the connection state has been changed, the connection state after the change and the connection state before the change are read out from the storage means and displayed in combination on the display means. 2. An apparatus according to claim 1, further comprising an instruction input unit configured to selectively switch a connection configuration of a device in the past and a connection configuration of a current device, and stored in the storage unit in accordance with an instruction input from the instruction input unit. 2. The system configuration display device according to claim 1, wherein a connection state is read and displayed on the display unit. 3. The system configuration display device according to claim 1, wherein the devices are connected by an IEEE 1394 serial bus. 4. The system configuration display device according to claim 1, wherein said recognition means recognizes a connection state of a device connected by an IEEE1394 serial bus. 5. The system configuration display device according to claim 1, wherein said detecting means detects a change in a connection state of a device connected by an IEEE 1394 serial bus. 6. A system configuration display method for displaying a connection configuration of a plurality of devices, comprising: a recognition step of recognizing a connection status of all devices connected to the system; and a connection status of all the recognized devices. A display step of displaying on the display means, a storage step of storing the recognized connection state in the storage means, and a detection step of detecting a change in the connection state of the device connected to the system. When detecting that the connection state has changed by the step, the display step reads out the connection state after the change and the connection state before the change from the storage unit and displays the combination on the display unit in combination. System configuration display method. 7. An instruction input step for selectively switching a connection configuration of a device in the past and a connection configuration of a current device, wherein the display step is performed according to an instruction input from the instruction input step. Read the connection state stored in
7. The system configuration display method according to claim 6, wherein the information is displayed on the display unit. 8. The system configuration display method according to claim 6, wherein said recognizing step recognizes a connection state of a device connected by an IEEE 1394 serial bus. 9. The system configuration display method according to claim 6, wherein said detecting step detects a change in a connection state of a device connected by an IEEE 1394 serial bus. 10. A recognition step of recognizing connection states of all devices connected to the system, a display step of displaying the recognized connection states of all devices on display means, and storing the recognized connection state. A computer-readable recording medium comprising a program for causing a computer to execute a storage step of storing in a means, and a detection step of detecting a change in a connection state of a device connected to the system. .