JP2002016610A - Data communication system and control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a data communication system capable of relaxing the performance drop on the entire network even when the frequency to start the bus reset is high. SOLUTION: Concerning the data communication system having a network configuration, in which plural nodes (routes, branches or leaves, for example), are connected in the form of tree structure through an IEEE1394 serial bus, while using the other IEEE1394 serial bus as a bypass line in addition to the IEEE1394 serial bus connecting a certain node with other nodes, a certain node and other nodes are connected and a loop is composed of the original line and that bypass line. This system is provided with a detecting means for detecting the data routes, with which that loop is formed, and a means for selecting one data route to be used for data communication out of the detected data routes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for connecting a plurality of electronic devices by using a data communication bus capable of performing communication by mixing control signals and data, and performing data communication between the devices. And a control method thereof, and a computer-readable memory.

[0002]

2. Description of the Related Art Hard disk drives and printers are the most frequently used personal computer peripherals. These peripherals are digital interfaces (hereafter referred to as general-purpose interfaces for small computers).
A connection is made between personal computers using SCSI or the like which is a digital I / F, and data communication is performed.

A recording / reproducing device such as a digital camera or a digital video camera is also a personal computer (hereinafter referred to as P
C) is one of the peripheral devices as an input means. 2. Description of the Related Art In recent years, technology in the field of capturing still images and moving images captured by a digital camera or video camera into a PC, storing the images on a hard disk, or editing the images on the PC, and then performing color printing with a printer has been advanced. And users are increasing.

[0004] When outputting the captured image data from a PC to a printer or a hard disk, the above-mentioned SCSI is used.
Data communication is performed via the like. In such a case, in order to transmit information having a large data amount such as image data, a digital I / F having a high transfer data rate and versatility is required. Up to 4 digital I / Fs that can meet such demands
Attention has been paid to an IEEE 1394 serial bus capable of transferring data at 00 Mbps.

[0005] The IEEE 1394 serial bus includes:
Device numbers (node IDs) of peripheral devices such as PCs and various digital cameras and video cameras are assigned. In order to connect each device (node) with the power on, the IEEE1394 serial bus is
A means called bus reset is provided.

When the network configuration changes,
For example, when a device (node) is deleted from the network or a new device (node) is added, by starting a bus reset, the configuration of the previous network is reset, and a new network is started. Perform a rebuild.

[0007] When the bus reset is activated, a parent-child relationship is declared between directly connected devices (nodes) in order to detect a new network connection status. When a parent-child relationship is determined between all devices (nodes), one route is determined. Device number (node I
Since D) is assigned from the lowest number, the root is the device (node) with the highest number. In this way, by automatically activating the bus reset, the network configuration at that time can always be set and recognized.

[0008]

However, when the bus reset is activated, the data transfer is suspended, and the data transfer during this time is kept waiting, and the device (node)
The parent-child relationship between them is newly declared each time the bus reset is activated. Therefore, if the bus reset is activated frequently, there is a problem that the performance of the entire network is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a data communication system capable of alleviating a decrease in the performance of the entire network even when a bus reset is frequently activated. To provide.

[0010]

To achieve the above object, the present invention provides a data communication system having a network configuration in which a plurality of nodes are connected in a tree structure via an IEEE 1394 serial bus. In addition to the IEEE 1394 serial bus connecting between the other node and the IEEE 1394 serial bus, another IEEE 1394 serial bus is used as a bypass line to connect the certain node and the other node, and a loop is formed between the original line and the bypass line. And a data communication system characterized by the above configuration. Hereinafter, this is referred to as a first invention.

Another invention is the first invention, wherein:
A configuration in which the data communication system further includes a detection unit that detects a data path in which the loop is formed, and a unit that selects one data path to be used for data communication from the detected data paths. did. The second
Called the invention.

Further, another invention is the second invention, wherein
The detecting means is configured to detect a data path excluding a data path passing through the incommunicable node when one of the nodes becomes incommunicable.

Another aspect of the present invention is a data communication system having a network configuration in which a plurality of nodes are connected in a tree structure via an IEEE 1394 serial bus. Means for detecting a change, means for notifying at least a node that is another node including a parent node and a route of the information on the state change, holding means for holding the notified information, and re-establishment of the network. At the time of construction, a configuration is provided in which a number is set for a newly connected node from the number (ID) next to the already assigned device number (node ID).

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] A first embodiment to which the data communication system of the present invention is applied will be described below. Before that, a general IEEE 1394 bus reset procedure is described. The determination of the device number (node ID) will be described with reference to the drawings.

FIG. 1 shows a connection form of a system constituted by a network using a general IEEE 1394 serial bus. In the figure, device A is a node called a root, device B, device C, and device D are nodes called branches, and device E, device F, device G, and device H are nodes called leaves. Each connected device (node) is given a device number (node ID).

When there is a change in the network configuration, for example, insertion / removal of a connection device (node) or power ON / OFF
When a change occurs due to an increase or decrease in the number of devices (nodes) due to OFF or the like and it is necessary to recognize a new network configuration, each device (node) that has detected the change uses the IE.
A bus reset signal is transmitted on the EE1394 serial bus to enter a mode for recognizing a new network configuration. The method of detecting the change at this time is performed by detecting a change in the bias voltage on the IEEE 1394 port board. The above is the activation of the bus reset.

After the bus reset, each device (node)
In order to construct a new network configuration, a mode is entered in which each device (node) is provided with a device number (node ID). The general procedure from the bus reset to the determination of the device number (node ID) will be described with reference to the flowchart of FIG.

In the figure, when it is detected that a bus reset has been activated in the network (step S20)
1) From the reset state of the network, a parent-child relationship is declared between all connected devices (nodes) that are directly connected in order to detect the connection status of a new network (step S202). When the declaration of the parent-child relationship is determined between all devices (nodes) (step S203), one route is determined (step S204). However, until the parent-child relationship is determined between all the devices (nodes), the parent-child relationship is declared in step S202, and the route is not determined. After the route is determined, the device number (node I) is assigned to each device (node).
A setting work for allocating D) is performed (step S20).
5). When device numbers (node IDs) are allocated to all devices (nodes) in a predetermined node order (step S2)
06), the new network configuration is recognized, and data transfer can be performed (step S20).
7). In the state of step S207, the state of detecting the activation of the bus reset is detected again. When the activation of the bus reset is detected, the processing proceeds from step S201 to step S201.
The setting operation up to 206 is repeated.

The above is a description of the flowchart of FIG. 2. The part from the bus reset to the route determination in the flowchart of FIG.
FIGS. 3 and 4 show flowcharts of the procedure up to the end of the setting in more detail.

First, the flowchart of FIG. 3 will be described (from bus reset to route determination).

When the activation of the bus reset is detected (step S301), the network configuration is reset once. As a first step of re-recognizing the reset network connection status, a flag is set for each device (node) as a leaf (step S302).
Next, each device (node) checks how many ports of its own are connected to other device blades (step S).
303). In order to declare a parent-child relationship in accordance with the result of the number of ports, the number of undefined (undetermined parent-child) ports is checked (step S304). Immediately after the bus reset, the number of ports is equal to the number of undefined ports.
As the parent-child relationship is determined, step S3
The number of undefined ports detected at 04 changes.

Immediately after a bus reset, only the leaf can declare a parent-child relationship first. A leaf can be known by confirming the number of ports in step S303 (number of undefined ports = 1) (step S3).
04). The leaf declares "I am a child and the other is a parent" to the device (node) connected thereto, and ends the operation (step S305).

In step S303, the device (node) that has a plurality of ports and is recognized as a branch is
Immediately after the bus reset, the number of undefined ports> 1 (step S304). Therefore, a flag of branch is first set (step S306), and the process waits for acceptance of “parent” in the parent-child relationship declaration from the leaf (step S307).

The leaf makes a declaration of the parent-child relationship, and the branch that has received the declaration in step S307 appropriately returns to step S3.
04, the number of undefined ports is confirmed. If the number of undefined ports is 1, the device (node) connected to the remaining port is referred to in step S305 as "I am a child, partner Can be declared a parent.

After the second time, even if the number of undefined ports is confirmed in step S304, for a branch having two or more ports, the process waits again in step S307 to accept a "parent" from a leaf or another branch. .

Finally, any one branch or exceptional leaf (due to the fact that it could not declare a child and did not operate quickly) becomes 0 (zero) in the confirmation of the undefined port in step S304. Then, the parent-child relationship declaration of the entire network is completed, and a flag as a root is set (step S30).
8) Recognition as a root is performed (step S30)
9).

In this way, the process from the bus reset shown in FIG. 3 to the declaration of the parent-child relationship between all devices (nodes) in the network and the determination of the route are completed.

Next, the flowchart of FIG. 4 will be described (from the determination of the route to the end of the setting of the device number (node ID)).

Since information on flags of respective devices (nodes) such as the procedure up to FIG. 3, the leaf, the branch, and the route is set, each is classified based on the information (step S401).

Each device (node) has a device number (node I
As a procedure for allocating D), the setting can be performed first from the leaf. Device numbers (node IDs) are set in ascending order of leaf → branch → route (node number = 0). First, the number N (N is a natural number) of leaves existing in the network is set (step S402). Thereafter, each leaf requests the root to assign a device number (node ID) (step S403). If there are a plurality of such requests, the route performs arbitration (operation of arbitration into one) (step S404), and assigns a device number (node ID) to one device (node) that has won the arbitration.
The failed device (node) is notified of the result of the failure (step S405). If the acquisition of the device number (node ID) has failed, the leaf issues a device number (node ID) request again and repeats the same operation (step S406).

From the leaf to which the device number (node ID) is assigned, the device number (node I
D) Information is broadcast and transferred to all devices (nodes) in the network (step S407). When the broadcast of one device number (node ID) information ends, the number of remaining leaves is reduced by one (step S4).
08). Here, if the remaining number is 1 or more (step S409), the operation of requesting the device number (node ID) in step S403 is repeated, and finally, all the leaves have the device number (node ID) information. After the broadcast, N = 0, and the process proceeds to the setting of the device number (node ID) of the branch.

The device number (node ID) of the branch is set in the same manner as the leaf.

The number M of branches existing in the network
(M is a natural number) is set (step S410). Thereafter, each branch requests the root to allocate a device number (node ID) (step S41).
1). On the other hand, the route performs arbitration (arbitration) (step S412), and sequentially allocates device numbers (node IDs) from the next youngest number assigned to the leaf, starting from the branch that has won the word stop. The route is
Device number (node ID) information or a failure result notification is issued to the branch that issued the request (step S413), and the branch for which acquisition of the device number (node ID) has failed fails again with the device number (node ID) request. Then, the same operation is repeated (step S414). From the branch to which the device number (node ID) is allocated, the device number (node ID) information of the device (node) is transferred by broadcast to all the devices (nodes) in the network (step S415). When the broadcasting of one device number (node ID) information ends, the number of remaining branches is reduced by one (step S416). Here, when the remaining number is 1 or more (step S417), the operation from the device number (node ID) request operation of step S311 is repeated, and finally all branches broadcast the device number (node ID) information. Until you do. When the device numbers (node IDs) are assigned to all the branches, M = 0, and the setting of the device numbers (node IDs) of the branches ends.

At this point, the device (node) for which the device number (node ID) information has not been finally obtained is only the root. Is set as the device number (node ID) (step S418), and the root device number (node ID) information is broadcast (step S419).

The above is the general procedure of the bus reset and the determination of the device number (node ID).

Next, a data communication system according to the first embodiment of the present invention will be described with reference to the drawings.

FIG. 5 shows the IEEE according to the first embodiment.
1 shows a connection configuration of a system configured by a network using an E1394 serial bus. In the figure, device A is a root, device C is a branch, and device B and device D are leaves. The device number (node ID) indicates that the device D has the node No. 0, device C is node No. 1. Device B is a node No. 2, and the device A is the node No. 3.
Here, device A and device B are connected by connection AB, and device A
The device C and the device C are connected by a connection AC, and the device C and the device D are connected by a connection CD.

Assume that a bus reset has been activated in this network. Then, device D and device A are connected AD
Assume that they are connected by Normally, such a loop connection is not allowed, but the reconfiguration of the network configuration at that time will be described with reference to the flowchart of FIG.

In the figure, when it is detected that the bus reset has been activated (step S601), each device (node) connected to the network declares a parent-child relationship (step S602).

Each device (node) declares a parent-child relationship,
When the parent-child relationship of all devices (nodes) is determined (step S
603), a route (in this case, device A) is determined (step S604).

At this time, regarding the data route from the device A to the device D, which is the route, there are two routes, that is, the route from the connection AC to the connection CD and the route from the connection AD, resulting in a loop connection. When the device A detects this loop connection (step S605), it selects a connection AC → connection CD route or connection AD route (step S60).
6). Here, it is assumed that the route of connection AC → connection CD is selected.

Next, a node ID is set for each device (step S607). When ID setting for all devices is completed (step S608), data transfer is started (step S609).

Here, it is assumed that a bus reset has been activated by connecting a new device or the like (step S60).
1).

If the device C does not declare a parent-child relationship due to a failure or the like, the loop connection as in the previous case is not detected (step S605), and the connection AD is executed for the data path between the device A and the device D. Holds.

As described above, according to the data communication system according to the present embodiment, in a network constituted by the IEEE 1394 serial bus, a loop connection is permitted, so that a device (node) which is a branch fails. However, the connection to the device (node) at the subsequent leaf is guaranteed, and the reliability of the data transfer path of the entire network can be increased.

[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 including one device (for example, , A copying machine, a facsimile machine, etc.).

An object of the present invention is to provide a storage medium (or a recording medium) storing a program code of software for realizing the functions of the above-described embodiments to a system or an apparatus, and a computer of the system or the apparatus. Needless to say, this can also be achieved by (or a CPU or MPU) reading and executing the program code stored in the storage medium.

In this case, the program code itself read from the storage medium realizes 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 operating system (OS) running on the computer based on the instruction of the program code. ) May include some or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, based on the instruction 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 flowchart (FIG. 6).

[0053]

As described above, according to the first aspect of the present invention,
According to the data communication system according to the above, in the IEEE1394 serial bus composed of a host device such as a personal computer and a peripheral device such as a hard disk and a printer, a network connection by loop connection is permitted, and a data transfer path of the entire network is guaranteed. Thus, the reliability can be improved.

According to the data communication system according to the second aspect, an IEEE 13 comprising a network composed of a host device such as a personal computer and peripheral devices such as a hard disk and a printer.
In the case of a 94 serial bus, when a network is reset by a bus reset, loop connection, that is, a plurality of data paths are detected, and one data path is selected from the loop paths. It is possible to construct a simple network.

According to the data communication system of the third aspect, the IEEE 13 comprising a host device such as a personal computer and a peripheral device such as a hard disk and a printer.
In the 94 serial bus, when a network is reconstructed by a bus reset, if there is a device (node) that is not connected to the network due to a failure or the like among a plurality of data paths, the other data paths are selected. It is possible to connect a device (node) connected to a device (node) that is not connected to the network to the network.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a connection configuration of a system configured with a network using a general IEEE 1394 serial bus.

FIG. 2 is a flowchart showing a general procedure from a bus reset to determination of a device number (node ID) in an IEEE 1394 serial bus.

FIG. 3 is a flowchart detailing a procedure from a bus reset to a route determination in an IEEE 1394 serial bus.

FIG. 4 is a flowchart detailing a procedure from the determination of a route to the end of device number (node ID) setting on an IEEE 1394 serial bus.

FIG. 5 is a diagram illustrating a connection configuration of a system configured with a network using an IEEE 1394 serial bus according to the first embodiment;

FIG. 6 is a flowchart illustrating a procedure for reconstructing a network after a bus reset is activated on the IEEE 1394 serial bus according to the first embodiment.

Claims (10)

[Claims] 1. A data communication system having a network configuration in which a plurality of nodes are connected in a tree structure via an IEEE 1394 serial bus, wherein an IEEE 13 connection between a certain node and another node is provided.
Data communication characterized by connecting the certain node and the other node by using another IEEE 1394 serial bus as a bypass line in addition to the 94 serial bus, and forming a loop with the original line and the bypass line. system. 2. The data communication system according to claim 1, further comprising: a detecting unit configured to detect a data path in which the loop is formed, and a unit configured to select one data path used for data communication from the detected data paths. The data communication system according to claim 1, further comprising: 3. The communication device according to claim 2, wherein when one of the nodes becomes incapable of communication, the detection means detects a data path excluding a data path passing through the incommunicable node. A data communication system as described. 4. In a data communication system having a network configuration in which a plurality of nodes are connected in a tree structure via an IEEE 1394 serial bus, each node detects a state change of a partner node connected to itself. And, the information of the state change, at least, a means for notifying a node which is another node including a parent node and a route, a holding means for holding the notified information, and when reconfiguring the network, A data communication system comprising means for setting a number to a newly connected node from a number (ID) next to an already assigned device number (node ID). 5. A data communication system having a network configuration in which a plurality of nodes are connected in a tree structure via an IEEE 1394 serial bus, wherein the data communication system includes an IEEE 1394 serial bus connecting a certain node to another node. In addition, in the control method of a data communication system in which another IEEE 1394 serial bus is used as a bypass line to connect the certain node and the other node and a loop is formed by an original line and the bypass line, A method for controlling a data communication system, comprising: a detecting step of detecting a data path in which is formed, and a step of selecting one data path to be used for data communication from the detected data paths. 6. The method according to claim 5, wherein the detecting step detects a data path excluding a data path passing through the incommunicable node when one of the nodes becomes incommunicable. The control method of the data communication system according to the above. 7. A method for controlling a data communication system having a network configuration in which a plurality of nodes are connected in a tree structure via an IEEE 1394 serial bus, wherein each of the nodes detects a state change of a partner node connected to itself. Detecting, at least notifying the state change information to a node that is another node including a parent node and a route; holding a step of holding the notified information; and reconstructing the network. A step of setting the number of the newly connected node from the number (ID) next to the already assigned device number (node ID). Method. 8. A data communication system having a network configuration in which a plurality of nodes are connected in a tree structure via an IEEE 1394 serial bus, wherein the data communication system includes an IEEE 1394 serial bus connecting a certain node to another node. In addition, a program code for control processing of a data communication system in which another IEEE 1394 serial bus is used as a bypass line to connect a certain node to the other node and form a loop with an original line and the bypass line And a code for executing a detecting step of detecting a data path in which the loop is formed, and one data path used for data communication among the detected data paths. Code for executing the selecting step. Computer-readable memory. 9. The code for performing the detecting step includes detecting, when any one of the nodes becomes incommunicable, a data path excluding a data path passing through the incommunicable node. 9. The computer readable memory of claim 8, wherein the memory is a computer readable memory. 10. A computer-readable memory storing a control processing program code of a data communication system having a network configuration in which a plurality of nodes are connected in a tree structure via an IEEE 1394 serial bus. A code for executing a step of detecting a state change of a partner node connected to the node, and a step of notifying the information of the state change to at least a node which is another node including a parent node and a route And a code for executing a holding step for holding the notified information.When the network is reconfigured, the code is already assigned to a newly connected node. A command for executing the step of setting the number from the number (ID) next to the device number (node ID) A computer-readable memory, characterized in that it comprises a de.