Data communication system, data communication control unit, data communication control method, recording medium and program

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a data communication system, a data communication control device, a data communication control method, a recording medium and a program, and in particular, a plurality of electronic devices via a data communication bus capable of communicating by mixing control signals and data. It is suitable for use in a data communication system that connects so that communication is possible and performs data communication between each device.

【0002】

[Conventional technology]

Conventionally, a digital interface (hereinafter, "digital I / F") for connecting electronic devices so that data can be transmitted (transmitted and transmitted) between electronic devices (hereinafter, also referred to as "equipment"). There were various digital I / Fs. For example, a personal computer (hereinafter referred to as "PC") and a hard disk or printer frequently used in its peripheral devices are one of the typical digital I / Fs for general-purpose interfaces for small computers. Data communication was performed by connecting using SCSI (Small Computer System Interface).

【0003】

Further, for example, an image recording / playback device such as a digital camera or a digital video camera is also one of peripheral devices capable of transmitting data to a PC, and in recent years, an image taken by an image recording / playback device such as a digital camera ( Technology has been developed to capture still images and moving images) on a PC, store them on a hard disk, or edit them using a PC and then color print them using a printer. The number of users who save and edit the recorded images has also increased.

【0004】

As described above, when the captured image data is output from the PC to the hard disk or printer, data communication is performed between the PC and the hard disk or printer via the digital I / F such as SCSI. In order to send information with a large amount of data such as image data, a digital I / F with a high transfer data rate (transfer speed) and versatility was required. In response to such demands, a data communication bus (hereinafter referred to as "IEEE1394 serial bus") conforming to the IEEE1394 standard, which is a digital I / F capable of data transmission at a transfer data rate of up to 400 Mbits / sec, is available. It has been attracting attention.

【0005】

[Problems to be Solved by the Invention]

Here, in the data communication system using the IEEE1394 serial bus, the device number (node ID) is, for example, each device (node) connected via the bus such as a PC and a peripheral device (digital camera, etc.). Are assigned to each. In addition, according to the IEEE1394 standard, each device (node) can be connected to the bus with the power turned on (power is supplied), that is, the hot line can be inserted and removed, so that the IEEE1394 serial bus is , Has a bus initialization function called bus reset.

【0006】

Therefore, in a data communication system configured by using the IEEE1394 serial bus, for example, a certain device (node) is deleted from the network, or a certain device (node) is newly added to the network. When there is a change in the network configuration, by activating the bus reset, the network configuration up to that point is initialized and a new one is rebuilt.

【0007】

Specifically, in a data communication system configured with a network using the IEEE1394 serial bus, when bus reset is activated, first, in order to detect the connection status of the new network, the data communication system is directly connected. A parent-child relationship is declared between each device (node). When the parent-child relationship between all the devices (nodes) is determined, one device (node) to be the root is determined. This route is responsible for the bus management function in the data communication system. In addition, the device number (node ID) is assigned from the smallest number in the order of leaf branch root, and the device (node) that becomes the root is assigned the highest number.

【0008】

In this way, in the data communication system configured by using the IEEE1394 serial bus, when there is a change in the network configuration, the bus reset is automatically started, so that the network configuration at that time can be determined. Can be constantly set and recognized.

【0009】

However, in a data communication system configured with a network using the IEEE1394 serial bus, when a certain device (node) is inserted or removed from the network, whether or not data is being transmitted between other devices is determined. Regardless, a bus reset is triggered for the entire data communication system. Therefore, when data transmission is performed between other devices, the data transmission is interrupted. Then, after the network configuration is reconstructed, data transmission is restarted based on the newly set device number (node ID).

【0010】

Therefore, if the bus reset is frequently activated due to the insertion / removal of devices (nodes) in the data communication system, the data transmission between the devices is interrupted and the data transfer efficiency of the entire data communication system is lowered, and the entire data communication system There was a problem that the reliability of the data was lowered. For example, when a failure occurs in the root device (node) and it becomes inoperable, data transmission is performed between other devices (nodes) that operate normally without going through the root device (node). Even if this is the case, the bus reset is activated and the data transmission between the devices is interrupted, the data transfer efficiency of the entire data communication system is lowered, and the reliability of the entire data communication system is lowered.

【0011】

The present invention has been made to solve such a problem, and suppresses the activation of a bus reset during data transmission to continue data transmission and improve the reliability of the entire data communication system. With the goal.

【0012】

[Means for solving problems]

The data communication system of the present invention serves as a first data communication control device for controlling data communication using the data communication bus by connecting a plurality of communication devices capable of transmitting and receiving data signals via a data communication bus. A data communication system in which any communication device of the plurality of communication devices functions, and one communication device among the plurality of communication devices is used as the data communication bus in place of the first data communication control device. It is characterized by including a setting means set in the second data communication control device for controlling the data communication used.

【0013】

Another feature of the data communication system of the present invention is that the second data communication control device is based on the second data communication control device and a communication device connected below the second data communication control device. It is characterized in that data communication can be controlled. Another feature of the data communication system of the present invention is a state detecting means for detecting the operating state of the first data communication control device and an inoperable state of the first data communication control device by the state detecting means. It is characterized in that it further includes a processing means for performing a predetermined process when is detected.

【0014】

Another feature of the data communication system of the present invention is that when the processing means is performing data communication using the data communication bus, the state detection means causes the first data communication control device to be inoperable. When it is detected, it is characterized by providing a bus reset suppressing means for suppressing the activation of the bus reset that initializes the data communication system. Another feature of the data communication system of the present invention is that the bus reset suppressing means suppresses the activation of the bus reset according to the communication path of the data communication performed using the data communication bus. To do.

【0015】

Another feature of the data communication system of the present invention is that the processing means provides information on the second data communication control device when the state detection means detects that the first data communication control device is restarted. Further, the information notification means for notifying the first data communication control device of information about the communication device connected to the lower level of the second data communication control device is further provided. Another feature of the data communication system of the present invention is that the information about the second data communication control device and the communication device is identification information for identifying each of the above communication devices on the data communication bus. And.

【0016】

Another feature of the data communication system of the present invention is that the data communication bus is a data communication bus compliant with the IEEE1394 standard.

【0017】

The data communication control device of the present invention is a data communication control device for controlling data communication using a data communication bus by a plurality of communication devices capable of transmitting and receiving data signals, and is one of the plurality of communication devices. It is characterized by comprising a setting means for setting one communication device as an alternative data communication control device for controlling data communication using the data communication bus in place of the data communication control device.

【0018】

Another feature of the data communication control device of the present invention is that it further includes a comparison means for comparing the number of communication devices connected below the communication device, and the setting means is based on the comparison result by the comparison means. It is characterized in that one communication device is set as an alternative data communication control device.

【0019】

Another feature of the data communication control device of the present invention is that when the main data communication control device is in an inoperable state, data communication using a data communication bus by a plurality of communication devices capable of transmitting and receiving data signals is performed. A data communication control device for control, when a state detecting means for detecting the operating state of the main data communication control device and an inoperable state of the main data communication control device are detected by the state detecting means. When data communication is performed using the data communication bus, the data communication bus is characterized by being provided with a bus reset suppressing means for suppressing the activation of the bus reset that initializes the configuration of the data communication bus by the plurality of communication devices. And.

【0020】

Another feature of the data communication control device of the present invention is that when the state detection means detects the restart of the main data communication control device, it is connected to the data communication control device and the lower level of the data communication control device. It is further provided with an information notification means for notifying the main data communication control device of information about the communication device.

【0021】

The data communication control method of the present invention is a data communication control method in which a plurality of communication devices capable of transmitting and receiving data signals are connected via a data communication bus to control a data communication system controlled by the first data communication control device. It is characterized in that one communication device among the plurality of communication devices is set as a second data communication control device that controls the data communication system in place of the first data communication control device. And.

【0022】

Another feature of the data communication control method of the present invention is that the second data communication control device detects the operating state of the first data communication control device, and the first data communication control device cannot operate. When data communication is performed using the data communication bus when the state is detected, it is characterized by suppressing the activation of the bus reset that initializes the data communication system.

【0023】

Another feature of the data communication control method of the present invention is that when the inoperability state of the first data communication control device is detected and then the restart of the first data communication control device is detected, the first It is characterized in that the information about the data communication control device 2 and the information about the communication device connected to the lower level of the second data communication control device are notified to the first data communication control device.

【0024】

In the program of the present invention, a plurality of communication devices capable of transmitting and receiving data signals are connected via a data communication bus, and the plurality of communication devices are used as a first data communication control device for controlling data communication using the data communication bus. In a data communication system in which any communication device of the above communication device functions, data using one communication device among the plurality of communication devices using the above data communication bus in place of the first data communication control device. It is characterized in that a computer functions as a setting means set in a second data communication control device for controlling communication.

【0025】

Another feature of the program of the present invention is a data communication system in which a plurality of communication devices capable of transmitting and receiving data signals are connected via a data communication bus and controlled by a first data communication control device. To have a computer execute a process of setting one of the plurality of communication devices to a second data communication control device that controls the data communication system in place of the first data communication control device. It is characterized by. The computer-readable recording medium of the present invention is characterized in that the above-mentioned program is recorded.

【0026】

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following, a data communication system configured by using an IEEE1394 serial bus to which the data communication system according to the embodiment of the present invention is applied will be described. FIG. 1 is a block diagram showing a configuration example of a communication unit 100 included in each of the devices constituting the data communication system according to the present embodiment. In the following description, the "device" is referred to as a "node", and the "device number" is referred to as a "node ID".

【0027】

In FIG. 1, 101 is an external input unit, and supplies signals (control signals and data) input via the IEEE1394 serial bus to the communication control unit 103. Further, 102 is an external output unit, which outputs a signal supplied from the communication control unit 103 to the IEEE1394 serial bus.

【0028】

The communication control unit 103 includes a bus reset control unit 104 and a bus state detection unit 105, and controls each functional unit of the communication unit 100. The communication control unit 103 controls, for example, data input / output to the IEEE1394 serial bus of the node including the communication unit 100, that is, data communication.

【0029】

The bus reset control unit 104 is for controlling whether or not to output a bus reset signal on the IEEE1394 serial bus when a change in the network configuration due to addition, deletion, etc. of a node is detected. The bus state detection unit 105 is for detecting the state of the IEEE1394 serial bus. The bus state detection unit 105, for example, detects a change in the network configuration, detects whether or not data transmission is being performed, and detects whether or not the network configuration has been reconstructed.

【0030】

Reference numeral 106 denotes an internal input unit, which supplies data or the like input from an information processing unit (not shown) of the node including the communication unit 100 to the communication control unit 103. Further, 107 is an internal output unit, and outputs the data supplied from the communication control unit 103 to an information processing unit or the like (not shown).

【0031】

Reference numeral 108 denotes a storage unit, which includes a node type storage unit 109 and an ID storage unit 110. The node type storage unit 109 stores a flag indicating whether the node including the communication unit 100 is a root, a branch, or a leaf. Further, when the node is set as the second route, the node type storage unit 109 stores setting information (flag, etc.) indicating that the node is the second route. The ID storage unit 110 stores the node ID set for the node.

【0032】

Reference numeral 111 is an arbitration processing unit, and when the node including the communication unit 100 is the root (including the case where the branch which is the second route functions as the root), the external input unit 101 and the communication control unit are connected from the IEEE1394 serial bus. Arbitration processing (arbitration) of the request supplied via 103 is performed. Here, the requests supplied via the IEEE1394 serial bus include a node ID setting request at the time of building a network configuration and a bus right request at the time of normal operation.

【0033】

Reference numeral 112 denotes an ID setting unit, which sets a node ID to each node constituting the data communication system according to the arbitration processing result of the arbitration processing unit 111. Reference numeral 113 denotes a unit for detecting the number of connected nodes, and the direction of the lower side of the network (the direction of root branch leaf is the lower direction. Similarly, the direction of leaf branch root) with respect to the node including the communication unit 100. Detects the number of nodes connected in the upper direction.

【0034】

Reference numeral 114 denotes a second route setting unit, which is configured to have a connection node number comparison unit 115, and sets a node to be the second route when the node including the communication unit 100 is the route. The second route setting unit 114 compares the number of connection nodes detected by the connection node number detection unit 113 of the node directly connected to the node by the connection node number comparison unit 115. Based on the above comparison result, the second route setting unit 114 sets a node to be the second route.

【0035】

Next, a general bus reset operation and a node ID setting operation in a data communication system configured by a network using the IEEE1394 serial bus according to the present embodiment will be described with reference to FIGS. 2 to 5. FIG. 2 is a diagram showing a connection mode of a data communication system configured by a network using an IEEE1394 serial bus.

【0036】

In FIG. 2, device A201 is a node called a root (hereinafter referred to as "root node"), and device B202, device C203 and device D204 are nodes called branches (hereinafter referred to as "branch node"). is there. Further, the device E205, the device F206, the device G207, and the device H208 are nodes called leaves (hereinafter, referred to as "leaf nodes"). A node ID is set for each node. Examples of the devices 201 to 208 include a personal computer, a hard disk, a printer, an image recording / playback device (digital camera, etc.), and the like.

【0037】

In the data communication system shown in Fig. 2 above, when there is a change in the network configuration due to, for example, an increase or decrease in the number of nodes due to node insertion / removal or power ON / OFF, and it is necessary to recognize a new network configuration, the network configuration Each node that detects a change (increase / decrease in the number of nodes, etc.) transmits (outputs) a bus reset signal on the IEEE1394 serial bus. As a result, the data communication system is in an operating state for recognizing the new network configuration. Here, the change in the network configuration is detected by detecting the change in the bias voltage on the IEEE1394 interface board board included in each node.

【0038】

After invoking the bus reset and initializing the network configuration as described above, the data communication system is in an operating state in which a node ID is set for each node in order to construct a new network configuration.

【0039】

The operation from bus reset activation to node ID setting will be described below with reference to FIG. FIG. 3 is a flowchart showing the operation from bus reset activation to node ID setting in the data communication system as shown in FIG.

【0040】

In FIG. 3, the nodes (devices A201 to H208) shown in FIG. 2 transmit a bus reset signal on the IEEE1394 serial bus when they detect a change in the network configuration. When nodes 201 to 208 each detect that a bus reset has been activated in the network based on the bus reset signal (step S301), in the data communication system, the network configuration is initialized and the network is renewed. A parent-child relationship is declared on all of the directly connected (one-to-one) nodes 201 to 208 in order to detect the connection status (step S302).

【0041】

Then, when the parent-child relationship is determined in all of the nodes 201 to 208 by the declaration of the parent-child relationship in step S302 (step S303), one node that becomes the root node responsible for the bus management function in the data communication system becomes one node. Determine (step S304). Until the parent-child relationship is determined for all of the nodes 201 to 208, the declaration of the parent-child relationship in step S302 is repeated, and the root node is not determined either.

【0042】

When the root node is determined in step S304, the data communication system performs ID setting processing for assigning node IDs to nodes 201 to 208 according to the new network configuration (step S305). In step S305, when the node IDs are assigned to all the nodes 201 to 208 in a predetermined node order (step S306), the new network configuration in the data communication system is recognized, and the data can be transmitted. Becomes (step S307).

【0043】

As described above, when the new network configuration of the data communication system is recognized and the data can be transmitted, the nodes 201 to 208 are in the state of detecting the activation of the bus reset again. Then, when the activation of the bus reset is detected by the nodes 201 to 208, the above-described processes from step S301 to step S306 are executed.

【0044】

Next, based on FIGS. 4 and 5, the operation from the bus reset activation to the root node determination and the operation from the root node determination to the end of the node ID setting shown in FIG. 3 will be described in detail.

【0045】

FIG. 4 is a flowchart showing an operation (START to root node determination (step S304) shown in FIG. 3 above) from bus reset activation to root node determination in the data communication system. In FIG. 4, when the bus state detection unit 105 detects a change in the network configuration, the nodes 201 to 208 transmit a bus reset signal from the bus reset control unit 104 to the IEEE1394 serial bus via the external output unit 102. When the nodes 201 to 208 each detect that the bus reset has been activated based on the bus reset signal (step S401), the network configuration in the data communication system is initialized.

【0046】

As a first step for re-recognizing the connection status of the initialized network, the nodes 201 to 208 each set a flag indicating that the node type storage unit 109 in the storage unit 108 is a leaf node (step). S402).

【0047】

Next, each node 201 to 208 checks the number of ports connected to other nodes, that is, how many ports among the ports provided by the nodes 201 to 208 themselves are connected to other nodes (step S403). ). Further, the nodes 201 to 208 check the number of ports whose parent-child relationship has not been determined (hereinafter referred to as "undefined port") in order to declare the parent-child relationship according to the result of the number of ports (step). S404). Immediately after initialization by bus reset, "number of ports" = "number of undefined ports", but as the parent-child relationship is declared and the parent-child relationship is determined, the undefined ports detected in step S404 The number of is changing (decreasing).

【0048】

Here, immediately after the initialization by the bus reset, the parent-child relationship can be declared first only for the node that becomes the leaf node. The node that becomes the leaf node can be known by checking that the number of ports (number of undefined ports) = 1 in the confirmation of the number of ports in step S403 (step S404). For example, in the data communication system shown in FIG. 2, the nodes are 205 to 208. Then, the node that becomes the leaf node declares "I am a child and the other party is a parent" to the node connected to itself and ends the operation (step S405).

【0049】

Also, in checking the number of ports in step S403 immediately after initialization by bus reset, a node with a plurality of ports (number of undefined ports> 1) is recognized as a branch node (step S404). ). For example, in the data communication system shown in FIG. 2, the nodes are 201 to 204.

【0050】

The node recognized as a branch node first sets a flag indicating that it is a branch node in the node type storage unit 109 (step S406), and accepts the "parent" by declaring the parent-child relationship from the leaf node. Wait for (step S407). Here, accepting a "parent" means that the leaf node declares "I am a child and the other party is a parent".

【0051】

Then, the leaf node declares the parent-child relationship, and the branch node that receives the parent-child relationship declaration from the leaf node in step S407 confirms the number of undefined ports in step S404 as appropriate. As a result of the above confirmation, the branch node in which the number of undefined ports = 1 declares "I am a child and the other party is a parent" to the nodes connected to the remaining undefined ports. It becomes possible to declare a parent-child relationship.

【0052】

On the other hand, as a result of checking the number of undefined ports in step S404 above, the branch node having 2 or more undefined ports is again in step S407 a leaf node or another branch node (branch with 1 undefined port). Wait to accept the "parent" from the node).

【0053】

By repeating the above operation, when any one of the branch nodes finally becomes the number of undefined ports = 0 (zero) in the confirmation of the undefined ports in the above step S404, the entire data communication system This means that the declaration of the parent-child relationship has been completed. Then, in the confirmation of the undefined ports in the above step S404, the branch node in which the number of undefined ports = 0 (zero) sets a flag in the node type storage unit 109 indicating that it is the root node (step S408). ), It is recognized as a root node (step S409). In exceptional cases, a node that should be a leaf node may become a root node because it did not operate promptly even though it could declare a child.

【0054】

As described above, the operation from the start of the bus reset in the data communication system to the declaration of the parent-child relationship between the connected nodes and the determination of the root node is completed.

【0055】

FIG. 5 is a flowchart showing the operation from the determination of the root node to the end of the node ID setting in the data communication system (from the determination of the root node (step S304) to the end of the node ID setting (step S306) shown in FIG. 3 above).

【0056】

In FIG. 5, by the operation shown in FIG. 4 described above, flags indicating that the nodes are leaf nodes, branch nodes, or root nodes are set in the node type storage units 109 of the nodes 201 to 208, respectively. , Each node 201-208 is classified into a leaf node, a branch node, or a root node based on the flag (step S501).

【0057】

When allocating a node ID to each node 201 to 208 (in the node ID setting process), the node ID can be set by the ID setting unit 112 of the root node from the leaf node. In the node ID setting process, the node IDs are set in the nodes 201 to 208 from the smallest number (node ID = 0) in the order of leaf node branch node root node.

【0058】

First, the number N of leaf nodes existing in the data communication system (N is a natural number) is set (step S502). Next, each leaf node 205 to 208 requests the root node 201 to allocate a node ID (node ID setting request) (step S503).

【0059】

Here, when there are a plurality of the above-mentioned node ID setting requests, the arbitration processing unit 111 of the root node 201 performs arbitration (the work of arbitrating to one) of the node ID setting requests (step S504). The ID setting unit 112 of the root node 201 assigns a node ID to one leaf node that has won the arbitration (selected as a result of the arbitration process), and notifies the losing leaf node of the result of the failure (step S505). .. The node ID assigned from the root node 201 is stored in the ID storage unit 110 in the storage unit 108 of the leaf node.

【0060】

The leaf node that has failed to acquire the node ID outputs the node ID setting request to the root node 201 again. Then, the operations of steps S503 to S505 described above are repeated (step S506).

【0061】

The leaf node to which the node ID is assigned from the root node 201 transfers the node ID information of the node by broadcasting to all the nodes in the data communication system (step S507). When the broadcast of one node ID information ends, the number of remaining leaf nodes N is decremented by one (step S508). Here, when the number of remaining leaf nodes N is 1 or more (step S509), the operation from the output of the node ID setting request in step S503 is repeated. Finally, when all the leaf nodes broadcast the node ID information and the number of remaining leaf nodes N = 0, the next step is the node ID setting process of the branch node.

【0062】

The node ID setting process of the branch node is also performed in the same manner as the node ID setting process of the leaf node described above. First, the number M (M is a natural number) of branch nodes existing in the data communication system is set (step S510). Next, each branch node 202 to 204 requests the root node 201 to allocate a node ID (node ID setting request) (step S511).

【0063】

The root node 201 performs arbitration (arbitration) in response to the node ID setting request (step S512), and the ID setting unit 112 of the root node 201 arbitrates the node ID from the next smaller number that has been assigned to the leaf node. Allocate to the branch nodes that have won. The root node 201 outputs the node ID information or the failure result notification to the branch node that outputs the node ID setting request (step S513). The node ID assigned from the root node 201 is stored in the ID storage unit 110 in the storage unit 108 of the branch node.

【0064】

The branch node that has failed to acquire the node ID outputs the node ID setting request to the root node 201 again. Then, the operations of steps S511 to S513 described above are repeated (step S514).

【0065】

The branch node to which the node ID is assigned from the root node 201 transfers the node ID information of the node by broadcasting to all the nodes in the data communication system (step S515). When the broadcast of one node ID information ends, the number of remaining branch nodes M is decremented by one (step S516).

【0066】

Here, when the number of remaining branch nodes M is 1 or more (step S517), the operation from the output of the node ID setting request in step S511 is repeated. Then, it is finally performed until all the branch nodes broadcast the node ID information, and when the node ID information is allocated to all the branch nodes and the number of remaining branch nodes becomes M = 0, the node ID setting process of the branch node is performed. Is finished.

【0067】

By the above operation, the node for which the node ID information has not been acquired is finally only the root node 201. Therefore, the smallest number among the unallocated node IDs is set in the ID storage unit 111 as its own node ID. (Step S518). Then, the root node 201 broadcasts the node ID information of the root node (step S519). In this way, a general bus reset operation and a node ID setting operation are performed.

【0068】

Next, the data communication system in which the node serving as the second route according to the present embodiment is set will be described with reference to FIGS. 6 to 9.

【0069】

FIG. 6 is a diagram showing another configuration example of a data communication system configured by a network using an IEEE1394 serial bus. In FIG. 6, device A601 is a root node, device B602 and device D604 are branch nodes, and device C603, device E605 and device F606 are leaf nodes.

【0070】

In the data communication system shown in FIG. 6, the operation when the bus reset is activated and the network configuration is constructed will be described with reference to the flowchart shown in FIG. In FIG. 7, when the bus reset is activated in the data communication system (step S701), the parent-child relationship is declared between the connected nodes 601 to 608 in the same manner as in step S302 shown in FIG. 3 described above. (Step S702), the root node is sequentially determined from the leaf node.

【0071】

Then, in step S702, when the parent-child relationship is declared between each node 601 to 608 and the parent-child relationship is determined among all the nodes 601 to 608, the root node in the data communication system (data communication shown in FIG. 6 above). In the example system, device A601) determines (step S703). Next, in the data communication system, node IDs corresponding to the constructed network configuration are set in each node 601 to 608 in the same manner as in steps S305 and S306 shown in FIG. 3 described above (step S704).

【0072】

Next, in the data communication system, the number of nodes (leaf node and branch node) connected to the lower side of the network is compared with the branch node directly connected to the root node, and the second route is determined based on the comparison result. To do.

【0073】

In the example of the data communication system shown in FIG. 6, the root node 601 detects the number of connected nodes of the branch nodes 602 (device B) and 604 (device D) directly connected to the root node node 601 (device A). The number of connected nodes connected to the lower side detected by the unit 113 is compared by the connected node number comparison unit 115 in the second route setting unit 114 (step S705).

【0074】

In the data communication system shown in FIG. 6, since one leaf node 603 is connected to the branch node 602 and two leaf nodes are connected to the branch node 604, the second route setting unit in the root node 601 is connected. 114 selects and configures branch node 604 (device D) as the second route (step S706). Here, if the number of nodes connected to the lower side of the branch node 602 (device B) is large, the second leaf becomes the branch node 602 (step S707).

【0075】

As described above, after the network configuration of the data communication system is constructed, data transfer is performed between the nodes 601 to 606. The operation of data transfer between nodes is the same as the operation of data transfer on a general IEEE1394 serial bus, so the description thereof will be omitted.

【0076】

For example, it is assumed that data is transferred from the leaf node 604 (device E) to the leaf node 606 (device F) by relaying the second route node 604 (device D). At this time, in the data communication system, the processing operation when the root node 601 becomes inoperable due to hang-up, power off, insertion / removal from the network, etc., and a change occurs in the network configuration is shown in FIGS. 8 and 9. It will be explained based on. In FIG. 8, the same blocks as those shown in FIG. 6 are designated by the same reference numerals.

【0077】

Here, when a change occurs in the network configuration in the data communication system, the bus reset is conventionally activated for the entire data communication system. Therefore, the data transfer from the leaf node 605 to the leaf node 606 at that time via the node 604 is interrupted. Then, since the root node 601 does not start, a data communication system newly configured by a network is configured by nodes 604 to 606 (device D, device E, and device F), and a new node ID is set to each node 604 to 606. After that, data transfer from leaf node 605 to leaf node 606 via node 604 is resumed.

【0078】

That is, in a conventional data communication system, after a change in network configuration occurs due to an abnormality in root node 601 to interruption of data transfer, activation of bus reset, resetting of node ID, and restart of data transfer. It will take time.

【0079】

On the other hand, in the data communication system of the present embodiment, as shown in FIG. 9, the root node 601 hangs up during data transfer from the leaf node 605 to the leaf node 606 via the node 604 (step S901). It becomes inoperable due to the above, and a change occurs in the network configuration (step S902). At this time, in the data communication system according to the present embodiment, different processing is performed depending on whether or not the second route is set in advance (step S903).

【0080】

In the data communication system, if the node that is the second route is not set (No in step S903), the data transfer is interrupted (step S904) in the same manner as before, and the entire data communication system is To activate the bus reset (step S905). Then, after rebuilding the network configuration of the data communication system and resetting the node ID to each node (step S906), the data transfer is restarted (step S907).

【0081】

On the other hand, in the data communication system, if the node that is the second route (node 604 in the example shown in FIG. 8) is set (Yes in step S903), the node 604 that is the second route is the root node. Detects 601 changes (inoperable state). When node 604 confirms that the detected change in root node 601 does not affect the data transfer currently being performed (leaf node 606 via node 604 from leaf node 605), the bus reset control unit 104 Suppresses the activation of bus reset by (step S908). Therefore, data transfer from leaf node 605 to leaf node 606 via node 604 is continued (step S909).

【0082】

Further, when the second route node 604 detects that the root node 601 has restarted after the data transfer is completed (step S910), the node 604 is connected to its own lower side (leaf node 605). , 606) is notified to the node 601 which has become the root node again (step S911). As a result, the network configuration of the entire data communication system is completed, and normal operation can be continued again.

【0083】

As described in detail above, according to the present embodiment, in a data communication system configured by using an IEEE1394 serial bus, among the nodes directly connected to the root node that manages the IEEE1394 serial bus. When the root node becomes inoperable, select the node that manages the bus and set it as the second route.

【0084】

As a result, even if the root node becomes inoperable during data transmission, the second route node can manage the IEEE1394 serial bus, improving the reliability of the entire data communication system. Can be done.

【0085】

Further, a bus state detection unit 105 is provided in the communication unit 100 to detect the state of the IEEE1394 serial bus, and when a change in the network configuration is detected, a predetermined process is performed according to the detected bus state. As a result, even if the root node becomes inoperable during data transmission, for example, depending on the data transmission path, if the root node is not involved in data transmission, the node that is the second route is in the bus state. Appropriate processing can be performed on behalf of the root node according to the above, and the reliability of the entire data communication system can be improved.

【0086】

In addition, a bus reset control means 104 is provided in the communication unit 100 to control whether or not to output a bus reset signal on the bus according to the state of the IEEE1394 serial bus. Therefore, the root node during data transmission. Even if the bus becomes inoperable, if the root node is not involved in data transmission, the second route node can suppress the activation of the bus reset and continue the data transmission. Therefore, it is possible to suppress a decrease in data transfer efficiency in the entire data communication system and improve the reliability of the entire data communication system.

【0087】

In addition, when the node that is the second route suppresses the activation of the bus reset and continues data transmission with respect to the inoperable state of the detected root node, and then detects the restart of the root node, The node that is the second route notifies the node that has become the root node by restarting information such as the node ID of the node including itself connected to the lower level of the network. As a result, the network configuration of the entire data communication system can be easily completed, and the reliability of the entire data communication system can be improved.

【0088】

(Other Embodiments of the Present Invention) The functions of the above-described embodiments are provided to a device connected to the various devices or a computer in the system so as to operate various devices in order to realize the functions of the above-described embodiments. The scope of the present invention also includes those carried out by supplying a program code of software for realizing the system or operating the above-mentioned various devices according to a program stored in a computer (CPU or MPU) of the system or device.

【0089】

Further, in this case, the program code itself of the software realizes the function of the above-described embodiment, and stores the program code itself and means for supplying the program code to the computer, for example, such a program code. The recording medium constitutes the present invention. As a recording medium for storing such a program code, for example, a flexible disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a magnetic tape, a non-volatile memory card, a ROM, or the like can be used.

【0090】

Further, by executing the program code supplied by the computer, not only the functions of the above-described embodiments are realized, but also the OS (operating system) or other application software in which the program code is running in the computer, etc. Needless to say, such a program code is included in the embodiment of the present invention even when the function of the above-described embodiment is realized in collaboration with the above-mentioned embodiment.

【0091】

Furthermore, after the supplied program code is stored in the memory provided in the function expansion board of the computer or the function expansion unit connected to the computer, the CPU provided in the function expansion board or function expansion unit is based on the instruction of the program code. It goes without saying that the present invention also includes a case where a part or all of the actual processing is performed by the processing and the functions of the above-described embodiment are realized by the processing.

【0092】

For example, the node including the communication unit 100 shown in FIG. 1 has a computer function 1000 as shown in FIG. 10, and the operation according to the present embodiment is performed by the CPU 1001.

【0093】

As shown in FIG. 10, the computer function 1000 includes a CPU 1001, a ROM 1002, a RAM 1003, a keyboard controller (KBC) 1005 for a keyboard (KB) 1009, and a CRT controller for a CRT display (CRT) 1010 as a display unit. CRTC) 1006, disk controller (DKC) 1007 of hard disk (HD) 1011 and flexible disk (FD) 1012, and network interface card (NIC) 1008 are connected to each other via system bus 1004 so that they can communicate with each other. It is said.

【0094】

The CPU 1001 comprehensively controls each component connected to the system bus 1004 by executing the software stored in the ROM 1002 or the HD 1011 or the software supplied from the FD 1012. That is, the CPU 1001 controls to realize the operation in the present embodiment by reading and executing the processing program for performing the above-described operation from the ROM 1002, HD1011, or FD1012.

【0095】

RAM1003 functions as the main memory or work area of CPU1001. The KBC1005 controls instruction input from the KB1009, a pointing device (not shown), and the like. CRTC1006 controls the display of CRT1010. The DKC1007 controls access to the HD1011 and FD1012 that store boot programs, various applications, user files, network management programs, and the above processing programs in this embodiment. NIC1008 exchanges data bidirectionally with other devices on network 1013.

【0096】

[Effect of the invention]

As described above, according to the present invention, any communication device of the plurality of communication devices is used as a first data communication control device for controlling data communication between a plurality of communication devices using a data communication bus. In the data communication system in which the above functions, the second data communication control device for controlling the data communication using the data communication bus instead of the first data communication control device is included in the plurality of communication devices. Set up one of the communication devices.

【0097】

As a result, even if the root node becomes inoperable during data transmission, the node that is the second route can manage the data communication bus, suppress the activation of the bus reset, and continue the data transmission. Therefore, it is possible to suppress a decrease in data transfer efficiency in the entire data communication system and improve the reliability of the entire data communication system.

[Simple explanation of drawings]

[Figure 1]

It is a block diagram which shows the configuration example of the communication part 100 provided in the apparatus which comprises the data communication system by this embodiment.

[Figure 2]

It is a figure which shows the connection form of the data communication system configured in a network.

[Fig. 3]

It is a flowchart which shows the operation from the bus reset start to the node ID setting in the data communication system shown in FIG.

[Fig. 4]

It is a flowchart which shows the operation from the bus reset start to the root node determination in the data communication system shown in FIG.

[Fig. 5]

It is a flowchart which shows the operation from the root node determination to the end of node ID setting in the data communication system shown in FIG.

[Fig. 6]

It is a figure which shows the other configuration example of the data communication system which is network-configured.

[Fig. 7]

FIG. 5 is a flowchart showing an operation of constructing a network configuration after a bus reset is activated in the data communication system shown in FIG.

[Fig. 8]

It is a figure which shows the other configuration example of the data communication system which is network-configured.

[Fig. 9]

It is a flowchart which shows the operation when the network configuration changes during the data transmission in the data communication system shown in FIG.

[Fig. 10]

It is a figure for demonstrating an example of the computer function 1000 which a node has.

[Explanation of symbols]

101 External input section 102 External output 103 Communication control unit 104 Bus reset control unit 105 Bus status detector 106 Internal input section 107 Internal output 108 Memory 109 Node type storage 110 ID storage 111 Mediation processing department 112 ID setting section 113 Connection node number detector 114 Second route setting section 115 Connection node number comparison unit 601 root node 602 branch node 603, 605, 606 leaf nodes 604 Branch node (second route)