JPH11298509A - Data communication system, data communication method, data communication device and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a data transfer efficiency in a bus system from being deteriorated without raising the cost. SOLUTION: This system conducts communication between a source node 202 that sends information data and a destination node 204 that receives the information data by using a connection ID denoting logical connection between the nodes. A time interval required for reception processing of the destination node 204 is informed to the source node 202 to set a time interval between a time of sending i-th data ((i) is an optional integer) and a time of sending (i+1)-th data optimally and then efficient data communication is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for connecting a plurality of electronic devices (hereinafter referred to as "devices") by using a data communication bus capable of communicating control signals and data in a mixed manner. The present invention relates to a communication system.

[0002]

2. Description of the Related Art Among personal computer peripheral devices, hard disk drives and printers are most frequently used, and these peripheral devices are digital interfaces (hereinafter referred to as digital interfaces) which are typical general-purpose interfaces for small computers.
A connection is made between personal computers using SCSI (I / F) or the like, and data communication is performed.

A recording / reproducing device such as a digital camera or a digital video camera is also one of the peripheral devices used as an input means to a personal computer (hereinafter, referred to as a PC). The technology in the field of capturing video such as video to a PC and storing it on a hard disk or editing it on a PC and then color printing with a printer is advancing, and the number of users is increasing.

When the captured image data is output from a PC to a printer or a hard disk, data communication is performed via the above-described SCSI or the like. In such a case, the data amount is large as in the case of image data. In order to transmit information, these digital I / Fs must have high transfer data rates and versatility.

FIG. 6 shows a conventional digital camera,
FIG. 2 shows a block diagram when a PC and a printer are connected. 6, 101 is a digital camera, 102 is a personal computer (P
C) and 103 are printers. Further, 104 is a memory which is a recording unit of the digital camera, 105 is an image data decoding circuit, 106 is an image processing unit, 107 is a D / A converter, 108
Is the EVF, which is the display, and 109 is the digital
I / O section, 110 is digital I / O with PC digital camera
Reference numeral 111 denotes an operation unit such as a keyboard and a mouse.

Reference numeral 112 denotes an image data decoding circuit, 113 denotes a display, 114 denotes a hard disk drive, 115 denotes a memory such as a RAM, 116 denotes an MPU of an arithmetic processing unit, 117 denotes a PCI bus,
118 is a digital I / F SCSI interface (board),
119 is the SCSI interface of the printer connected to the PC with a SCSI cable, 120 is the memory, 121 is the printer head,
Reference numeral 122 denotes a printer controller of the printer control unit, and reference numeral 123 denotes a driver.

Next, an image picked up by the digital camera is
This section describes the procedure for importing to a PC and outputting from a PC to a printer. When the image data stored in the memory 104 of the digital camera 101 is read, one of the read image data is decoded by a decoding circuit 105,
Image processing for display by the image processing circuit 106 is performed,
It is displayed on the EVF 108 via the D / A converter 107. On the other hand, the digital signal is transmitted from the digital I / O unit 109 to the digital I / O unit 110 of the PC 102 via a cable for external output.

In the PC 102, the image data input from the digital I / O unit 110 is stored in the hard disk 114 when the image data input from the digital I / O unit 110 is stored by using the PCI bus 117 as a bus for mutual transmission.
In the case of displaying, after being decoded by the decoding circuit 112, it is stored as a display image in the memory 115 and
Displayed after being converted to analog signal by 3. PC 102
Operation input for editing on the PC is performed from the operation unit 111, and the PC 102
The entire processing is performed by the MPU 116.

When printing out an image, a PC 1
The image data is transmitted on the SCSI cable from the SCSI interface board 118 in the printer
The print image data received by the interface 119 is formed as a print image in the memory 120, and the print head 121 and the driver 123 operate under the control of the printer controller 122 to print the print image data read from the memory 120.

As described above, the conventional image data is taken into the PC,
Or the procedure up to printing. As described above, conventionally, each device is connected to a PC serving as a host, and image data captured by a recording / reproducing apparatus is printed via the PC.

Also, AV equipment such as a digital VTR, a TV, a tuner, and a personal computer (hereinafter, referred to as PC) are connected to each other using an IEEEP1394 serial bus (hereinafter, referred to as 1394). Communication systems for transmitting and receiving digital video signals, digital audio signals, and the like have been proposed.

In these systems, since it is important to transfer data in real time, so-called synchronous communication (hereinafter referred to as isochronous communication) is used.
Data communication is being performed.

In this case, the real-time property of data transfer is guaranteed, but it is not guaranteed that communication is performed reliably. However, the problems of the digital interface mentioned in the above conventional example include a low transfer data rate for SCSI, a thick cable for parallel communication, a type and number of connected peripheral devices, and a connection method. There are limitations and many inconveniences have been pointed out.

Further, in the case of the conventional 1394 communication, since synchronous communication is performed, it is not guaranteed that the communication is reliably performed. Therefore, the conventional 1394 isochronous communication cannot be used in order to reliably transfer data.

In the conventional 1394 isochronous communication,
The total number of communications is also limited to 64, even if there is a vacancy in the communications band. For this reason, when it is desired to perform a large number of communications that do not require much communication bandwidth, the conventional 1394 isochrono
There was a problem that us communication could not be used.

In the conventional 1394 communication system, it is conceivable that the data transfer is interrupted due to a bus reset or an error during the data transfer. In this case, the conventional 1394
In the communication method, it is not possible to know what data content has been lost.

Therefore, in the conventional 1394 communication system, there is a problem that it is necessary to take a very complicated communication procedure in order to recover from the interruption of the data transfer. In order to solve the above problem, a connection ID representing a logical connection between a source node connected to a serial bus for transmitting arbitrary data and a destination node receiving the data. A protocol for logically connecting by number has been proposed.

[0018] In the protocol using the connection ID, a response from the destination node is transmitted even if a predetermined period or a timeout period or a response period is exceeded after the source node transfers data. If not, the source node is retransmitting data.

[0019]

However, in the above protocol, since the response cycle is a predetermined fixed value, a device serving as a destination node receives data and then transmits the data to a subsequent circuit. When the data transfer speed is low, the data retransmission frequently occurs. Therefore, there is a problem that the data transfer efficiency in the network or the bus system is significantly reduced.

In order to prevent this, if the data transfer speed inside the device connected to the network or the bus system is increased, there is a problem that the cost of the connected device is inevitably increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and it is possible to easily detect data lost due to interruption of data transfer, and to reliably recover from the interruption of data transfer. And can be performed easily, preventing the data transfer efficiency in the network or the bus system from being reduced, and reducing the data transfer speed in the device connected to the network or the bus system, thereby reducing costs. An object is to provide a device and a system that can be down.

[0022]

SUMMARY OF THE INVENTION A data communication system according to the present invention establishes communication between a source node transmitting information data and a destination node receiving the information data by a logical connection between the nodes. ID indicating the connection
In the data communication system using the method, the source node is notified of a time interval required for the receiving process of the destination node. Another feature of the data communication system of the present invention is that the time interval is determined by a time for reading out the information data from a storage unit for temporarily storing the received information data. . According to another feature of the data communication system of the present invention, the communication system further includes a control node that manages the connection ID, wherein the control node includes:
It is characterized in that a logical connection is set between a plurality of nodes performing communication. Another feature of the data communication system of the present invention is that the time interval is also notified to the control node. According to another feature of the data communication system of the present invention, the destination node ends the reception processing of the information data according to data indicating a transfer end included in the information data. I have. According to another feature of the data communication system of the present invention, the destination node releases a connection ID set with the source node based on the data indicating the end of the transfer. And Another feature of the data communication system of the present invention is that the control node ends the transfer of the information data in accordance with data indicating the transfer end included in the information data. In another feature of the data communication system of the present invention, the control node releases a connection ID set between the source node and the destination node based on the data indicating the end of the transfer. It is characterized by having Another feature of the data communication system of the present invention is that the information data is an IEEE
It is characterized by being transmitted using an asynchronous transfer system conforming to the 1394 standard. Another feature of the data communication system of the present invention is that the information data is broadcast to all nodes on the communication system. Other features of the data communication system of the present invention include:
The source node selects a maximum time interval from n time intervals required for reception processing of the n destination nodes. Other features of the data communication system of the present invention include:
The source node has a response period for receiving a response from the destination node that has received the information data, and detects a communication error when the response cannot be detected even after the response period. . Another feature of the data communication system of the present invention is that the response period is
It is characterized in that it is set based on the time interval. Another feature of the data communication system of the present invention is that a source node for transmitting information data, a destination node for receiving the information data, and communication between the source node and the destination node. In the data communication system including a control node that manages the time, a time interval required for the reception processing of the destination node is notified to the control node.

According to the data communication method of the present invention, a communication between a source node transmitting information data and a destination node receiving the information data uses a connection ID indicating a logical connection between the nodes. In the data communication method applicable to the data communication system, the time interval required for the reception processing of the destination node is notified to the source node. Another feature of the data communication method of the present invention is that a source node that transmits information data, a destination node that receives the information data, and a communication between the source node and the destination node. In a data communication method applicable to a communication system including a control node that manages a time period, a time interval required for reception processing of the destination node is notified to the control node.

A data communication device of the present invention is required for a reception process of the destination node in a data communication device for managing communication with a source node transmitting information data and a destination node receiving the information data. It is characterized by comprising receiving means for receiving a time interval, and transmitting means for transmitting the time interval to the source node.

[0025] The storage medium of the present invention is characterized in that the steps constituting the data communication method are stored so as to be readable by a computer. Another feature of the storage medium of the present invention is that a program for causing a computer to function as each of the above means is stored.

[0026]

Since the present invention has the above technical means, the source node detects the time interval of data reception of the destination node when making a logical connection, and the source node uses the detection result to detect the time interval. The time interval between the time of transmitting the i-th data (i is an arbitrary integer) and the time of transmitting the (i + 1) -th data is set.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. In Figure 1, 10 is computer
Where 12 is the arithmetic processing unit (MPU) and 14 is the first 13
94 interface, 16 is a first operation unit such as a keyboard, 18 is a first decoder, 20 is a display device such as a CRT display, 22 is a hard disk, and 24 is a first memory, which is a computer 10 according to the present embodiment. Internal memory 26 is a computer internal bus such as a PCI bus.

Reference numeral 28 denotes a VCR, reference numeral 30 denotes an image pickup optical system,
32 is an analog-to-digital (A / D) converter, 34 is a video processing unit, 36 is a compression / expansion circuit, 38 is a first memory, 4
0 is the second memory, 42 is the first data selector, 44
Is the second 1394 interface, 46 is the first memory control circuit, 48 is the second memory control circuit, 50 is the system controller, 52 is the second operation unit, 54 is the finder, 56 is the D / A converter, 58 is a recording unit.

Reference numeral 60 denotes a printer, 62 denotes a third 1394 interface, 64 denotes a second data selector, 66 denotes a third operation unit, 68 denotes a printer controller, 70 denotes a second decoder, and 72 denotes a second decoder. Three memories, 74
Denotes an image processing unit, 76 denotes a driver, and 78 denotes a printer head.

Computer 10, VCR 28, and printer 6
0 means the first to third 1394 interface 14, 4
4, 62 constitute a 1394 serial bus node, and the first to third 1394 interfaces 14,
They are connected to each other via 44 and 62, and can exchange data and control by commands.

In the present embodiment, for example, the computer 10
Operates as a controller for transmitting and receiving image signals on the 1394 serial bus. Comput according to the present embodiment
In the er 10, for example, the MPU 12 and internal devices such as a 1394 interface 14, a keyboard 16, a decoder 18, a CRT display 20, a hard disk 22, and an internal memory 24 are connected by a computer internal bus 26 such as a PCI bus. Interconnected.

The MPU 12 executes software recorded on the hard disk 22 and moves various data to the internal memory 24. MPU12 is a PCI bus
The arbitration operation of each device connected by 26 is also performed.

The 1394 interface 14 receives an image signal transferred on the 1394 serial bus,
The image signal recorded on the hard disk 22 and the image signal stored in the internal memory 24 are transmitted.

The 1394 interface 14 is a 1394 interface.
It sends command data to other devices connected on the serial bus. 1394 interface 14
Transfers a signal transferred on the 1394 serial bus to another 1394 node.

The operator causes the MPU 12 to execute software recorded on the hard disk 22 through an operation unit such as the keyboard 16. Information such as the software is presented to the operator by a display device 20 such as a CRT display.

The decoder 18 decodes an image signal received from the 1394 serial bus through the above software. The decoded image signal is also presented to the operator by a display device 20, such as a CRT display.

In the present embodiment, for example, the VCR 28 operates as an image signal input device. The luminance signal (Y) and color difference signal (C) of the video input from the imaging optical system 30 are A /
The data is converted to digital data by the D converter 32.

The digital data is sent to the video processing unit 3
4 is multiplexed. Thereafter, the data amount of the image information is compressed by the compression / expansion circuit 36. In general, the compression processing circuit is provided independently for YC. Here, for simplification of description, an example of compression processing in YC time division will be described.

Next, a shuffling process is performed for the purpose of making the image data resistant to transmission path errors. The purpose of this processing is to convert a burst error, which is a continuous code error, into a random error, which is a discrete error that can be easily corrected and interpolated.

In addition, in the case where importance is placed on the purpose of equalizing the unevenness of the amount of information due to the density of the image within the screen, if this processing step is brought before the compression processing, the run length and the like can be changed. This is convenient when a long code is used.

In response to this, data identification (ID) information for restoring data shuffling is added. The ID added by the ID adding operation is used as auxiliary information together with the mode information of the system recorded at the same time in the decompression processing (information amount expansion processing) at the time of reproduction. Error correction (ECC) information is added in order to reduce errors in reproducing these data. Processing up to the addition of such a redundant signal is performed for each independent recording area corresponding to each information such as video and audio.

As described above, the image signal to which the ID information and the ECC information are added is recorded on a recording medium such as a magnetic tape by the recording section 58, and is also recorded in a first memory 3 described later.
8 is temporarily stored.

On the other hand, the image data multiplexed by the video processing section 34 is converted into a digital signal by the D / A converter 56.
It is converted into an analog signal and observed by the operator on the electronic viewfinder 54.

Further, the operator sends various operation information to the system controller 50 via the second operation section 52, and the system controller 50 controls the whole VCR based on the operation information. .

The image data multiplexed by the video processing unit 34 is output to the second memory 40 and is temporarily stored. The first memory 38 mentioned above and the second memory
The operations of 40 are controlled by a system controller 50 via a first memory control circuit 46 and a second memory control circuit 48, respectively.

The first data selector 42 selects data from the first memory 38 and the second memory 40 described above and transfers the data to the second 1394 interface 44 or the second 1394 interface 44 And passes it to either the first memory 38 or the second memory 40.

By the above operation, the second 13 in the VCR 28
From the interface 44, compressed image data and uncompressed image data can be selected and output by the operator.

The second 1394 interface 44 is a 1394 interface.
Command data for controlling the VCR 28 is received via the serial bus. The received command data is input to the system controller 50 through the first data selector 42.

The stem controller 50 creates response data to the above-mentioned command data, and sends the data to the 1394 serial bus via the first data selector 42 and the second 1394 interface 44.

In this embodiment, for example, the printer 60
Operates as an image printout device. The third 1394 interface 62 transmits an image signal transferred on the 1394 serial bus and the printer 6 through the 1394 serial bus.
Command data for controlling 0 is received. Further, the third 1394 interface 62 transmits response data to the command.

The received image data is input to the second decoder 70 through the second data selector 64. The second decoder 70 decodes the image data and outputs it to the image processing unit 74. The image processing section 74 temporarily stores the decoded image data in the third memory 72.

On the other hand, the received command data is passed through the second data selector 64 to the printer controller.
Entered in 68. The printer controller 68 controls the paper feed by the driver 76 according to the command data,
Various printing controls such as the position control of the printer head 78 are performed.

The printer controller 68 transmits the image data temporarily stored in the third memory 72 as print data to the printer head 78 to perform a printing operation.

As described above, the first to third 1394 interfaces 14, 44, 62 according to the present embodiment are:
Each constitutes a 1394 serial bus node. first
The 1394 interface 14 operates as a control node or a controller, the second 1394 interface 44 operates as a source node of image data, and the third 1394 interface 44 operates as a destination node.

The operation of each node according to the present embodiment will be described below with reference to FIG. In FIG. 2, 200 is a controller, 202 is a source node, 204 is a destination node, 206 is a subunit inside the source node, 2
08 is an object such as image data, 210 is the first memory space inside the destination node, 212 is the first connection, 214 is the nth memory space of the destination,
216 is an n-th connection.

The controller 200 is a node that manages a connection ID for establishing a connection between the source node 202 and the destination node 204 that perform data transfer, and a memory space address to be described later.

The controller 200 includes a source node 202,
And, the node may be independent of the destination node 204, or the source node or the destination node and the controller may be the same. In the latter case, no transaction is required between the controller and the source or destination node, which is the same node as the controller.

In this embodiment, the controller 200 includes the source node 202 and the destination node 204
An example in the case where it exists in a different node from that shown in FIG. In the communication device according to the present embodiment, it is possible to establish a plurality of connections.

The source node 202 is an internal subunit
The object 208 such as image data is written from the 206 to the first memory space 210 inside the destination node through the first connection 212, for example. Further, the transmission and reception of data by the above-described connection is performed, for example, by using asynch
This is performed using a ronous broadcast packet.

Next, the operation of each of the controller 200, the source node 202, and the destination node 204 will be described with reference to FIG. The controller negotiates to establish a connection between the source node selected by the user and the destination node. For the negotiation, a packet for making a connection is used.

The packet is, for example, an asynchronous broadcast packet. In the payload of the packet, a connection ID indicating a connection number and an interval time allowed by the destination are written. Each node identifies a connection by the connection ID.

The interval at which the source node performs data transfer is determined by the interval time. The source node receiving the above negotiation packet from the controller waits for a transmission command packet from the controller. On the other hand, the destination node receiving the negotiation packet waits for the asynchronous broadcast packet of the inquiry from the source node.

When the above negotiation is completed, the controller transmits a command packet for data transmission to the source node. The source node that has received the command packet transmits an asynchronous broadcast packet for inquiry to the destination node. The connection ID is written in the inquiry packet.

Upon receiving the inquiry packet, the destination node checks the connection ID written in the inquiry packet against the connection ID obtained by the negotiation, and determines whether the inquiry packet is transmitted from the source node of the same connection. Determine if it is a packet.

When the inquiry packet has the same connection, the destination node transmits a response packet in which the same connection ID as the inquiry packet, the capacity of the buffer for receiving data, and the node offset of the destination node are written. asyn
Sent by chronous broadcast.

As described above, at the time of data transfer, the source node performs a write transaction with respect to the node offset of the destination node specified in the response packet from the destination node specified by the controller. . The write transaction is performed using an asynchronous broadcast packet.

The source node segments the data to be transmitted and transmits the data. The divided data is called segment data. Transmission of segment data is performed in one broadcast transaction. The data amount of the segment data is determined, for example, by the capacity of a FIFO memory (not shown) of the node that receives the data.

The source node converts the above segment data into as
Transmit using an asynchronous broadcast packet. Asynchronous broadcast packets containing one segment data are called segment packets. segmen
t The packet includes the connection ID described above and the segmen
A sequence number indicating the order of t data is written.

The destination node receiving the packet compares the connection ID written in the segment packet with the connection ID previously notified by the controller.

If the connection ID written in the segment packet matches the connection ID previously notified by the controller, the destination node receives the packet, and receives the same connection ID as the packet. A response packet in which the sequence number in the data is written is transmitted using asynchronous broadcast. The source node identifies the packet to the own node by the connection ID of the received packet.

The above-described response operation is performed for one segment.
This will occur with the transfer of data. As previously mentioned,
Prior to data exchange, an inquiry packet is transmitted from the source node to the destination node. The destination node notifies the buffer size of the buffer owned by the destination node using a response packet to the inquiry.

In the above-described example, the transmission of the response packet occurs once with the transmission of the segment data. However, after the buffer of the destination node is filled with the segment data, the destination node transmits the response packet. May transmit a response packet. In the case of this configuration, the number of response operations performed by the destination node can be reduced, so that there is an effect that the destination node can be simplified.

The sequence number of the i-th received segment packet is compared with the sequence number of the (i + 1) -th received segment packet, and data inconsistency is monitored. When a mismatch is detected in the sequence numbers, the destination node can request the source node for segment data again by transmitting a response packet indicating a retransmission request.

The response packet indicating the retransmission request can specify the sequence number at which the retransmission request has occurred. On the other hand, after transmitting the segment packet, the source node waits for a response from the destination node.

As described above, the response packet in which the connection ID and the sequence number are written is transmitted from the destination node as an asynchronous broadcast packet. The connection ID is written in a response packet transmitted as a broadcast packet.

When this value matches the connection ID indicating the connection with the target destination node, the packet is a response packet. Upon receiving the response packet, the source node increments the sequence number and transmits the next segment packet in the same manner.

By repeating the above procedure, the source node performs data transfer. The time during which the source node waits for a response from the destination node is determined by the above-described interval time, and this cycle is called a response cycle.

After transmitting the ith segment packet,
If a response cannot be received even if the response period is exceeded, the source node resends the same segment packet as the i-th segment packet.

Further, when receiving the retransmission request response from the destination node as described above, the source node transmits a segment packet having the sequence number specified in the response packet.

In the present embodiment, the above procedure has an effect that the data transfer can be easily restored even when the data transfer is interrupted due to the occurrence of a bus reset or some error. When the data transfer is completed by transmitting all segment packets, the source node sends out a broadcast packet indicating segment end.

The controller receiving this packet releases the connection ID and the node offset, and the data transfer ends. In the present embodiment, the segmen
The controller that has received the “t end” explicitly releases the connection ID and the node offset.

However, since the packet indicating the segment end is a broadcast packet, the segment
The destination node can detect the end of the data transfer by the ent end packet. For this reason, the destination node may release the connection ID and the node offset.

In order to transfer data reliably, it is desirable that the data transfer be promptly restarted even if the data transfer is interrupted due to the occurrence of a bus reset or some error. As described above, in the present invention,
The problem is solved by providing a retransmission request procedure.

Next, the procedure of the retransmission request will be described with reference to FIG. For example, if the data transfer is interrupted when the sequence number is i, each node first reconstructs the bus according to the procedure defined by the standard. After the bus rebuild is complete, the destination node
Retransmission request packet (resendrequest) in which ion_offset, connection ID, and sequence number i are written
Is transmitted in a broadcast packet. If data transfer can be resumed, the source node returns an ack response.

Thereafter, the source node collates the connection ID of the received packet, collates the node offset, and successively broadcasts data subsequent to the requested sequence number, that is, data of a data sequence starting with the sequence number (i + 1). Send in packets.

According to the above-described procedure, the source node, the destination node, and the controller node can stop the data transfer without considering the node ID.
Subsequent data transfer can be easily and reliably restarted. As described above, in the present embodiment,
Even when the data transfer is interrupted, the control procedure of the controller can be simplified.

Next, with reference to FIG. 4, details of data transfer performed between the source node and the destination node according to the present invention will be described. In FIG. 4, 250 is the source node, 252 is the communication data buffer inside the destination node, 254 is the next stage circuit inside the destination node, 256 is the ith data transfer, 258 is the ith response, and 260 is (i +1) th data transfer, 262
Is the (i + 1) th response, 264 is the response period, 2
66 is data movement inside the destination node, 268
Is a delay due to data movement inside the destination node.

Data is transferred from the source node 250 by the i-th data transfer 256. The transferred data is stored in the communication data buffer 252 inside the destination.
Is temporarily stored, and then the data is stored in the next circuit 2
Go to 54.

When the movement of the data is completed, response data in which the data movement is written is created in the communication buffer 252 and transmitted to the source node 250 (the i-th response
258). As described above, the delay 268 is caused by the data movement 266 inside the destination node.

The delay time 268 has been transmitted to the source node 250 as an interval time during the above negotiation. The source node 250 determines the response cycle 264 from the interval time.

[0091] As shown in FIG.
64 is usually set as a cycle longer than the above-mentioned interval time. The (i + 1) th data transfer 260 and (i + 1) th response 258 from the source node 250 are also the ith data transfer 256 and ith response 2 described above.
Same as 58. Further, by repeating this operation, all data is transferred.

With the above configuration, in the present embodiment, the response period can be dynamically set at the time of connection based on the performance of the destination node. In addition, it is possible to prevent the occurrence of retransmission packets.

In the present embodiment, the response cycle can be set shorter when the performance of the destination node is high, and longer when the performance of the destination node is low. In addition, there is an effect that operability can be improved.

Next, referring to FIG. 5, the above asynchronous
The packet will be described. Asynchronous according to the present invention
The packet is, for example, a data packet in units of 4 bytes (32 bits, hereinafter referred to as a quadlet).

In the asynchronous packet, the first 16
bits is a destination_ID field, which indicates the node ID of the destination. When broadcasting is performed as in the present embodiment, the value of this field is FFFF (hexadecimal).

The next 6 bits field is a transaction label (tl) field, and is a tag unique to each transaction. The next 2 bits field is a retry (rt) code, which specifies whether the packet will try to retry.

The next 4 bits field is a transaction code (tcode). tcode specifies the format of the packet and the type of transaction that must be performed. In the present embodiment, for example, this value is 0001 _2, using the transaction write request data block.

The next 4 bits field is a priority (pri) field, and specifies the priority. In this embodiment, because of the use of asynchronous packet, the value of this field is 0000 _2. Next 16 b
its is the source_ID field, the node ID of the sender
Is shown. The next 48 bits are a destination_offset field, which is the lower 48 bits of the packet destination node address.
bits are specified by this field.

In the present invention, for example, the destinatio
The value of n_offset is determined by the value of a connection_ID field described later. The next 16 bits are data_length
This field indicates the length of a data field described later in bytes.

The next 16 bits are an extended_tcode field, and this value is 0000 ₁₆ in a data block write request transaction used in the present embodiment.

The next 32 bits are a header_CRC field, and extend from the destination_ID field described above.
Up to the ed_tcode field is called a packet header,
Used for error detection of the packet header.

The next 16 bits are the connection ID described above.
(connection_ID) field, which identifies the connection by the data. With the connection ID, it is possible to establish a connection of (2 16) × (the number of nodes). Therefore, in the present invention, the number of connections can be increased until the total amount of bandwidth used by each connection reaches the capacity of the bus.

The next 8 bits are the protocol type (protoco
l_type) field, which indicates a procedure of data transfer using the header information. The procedure of exchanging this embodiment, for example, 01 ₁₆ values are used. next
8 bits are a control flag (control_flags) field in which control data is written.

The most significant bit of the control flag field is, for example, a retransmission request (resend_request) flag. When the value of this bit is 1, it indicates that a data retransmission request has occurred.

The next 16 bits are the sequence number (sequence number).
nce_number) field. As described above, the sequence number field contains a specific connection ID.
A continuous value is used for the data packet transmitted and received by the.

The destination node monitors the continuity of significant data by using the sequence number field, and when a mismatch occurs, sends a retransmission request to the source node.

The next 16 bits are the confirmation response number (reconfirm
ation_number) field. This field is meaningful only when the value of the above-mentioned retransmission request flag is 1.

When the value of the retransmission request flag is 1, this field indicates the sequence number of the start packet for which a retransmission request has occurred. The next 16 bits are a buffer size (buffer_size) field. In this field, the buffer size of the destination node is written.

The next 48 bits are an offset address (off
set_address) field. In this field, the offset address of the destination node is written.

[0110] The next 32 bits are a destination interval (destination_interval) field.
The destination node notifies the source node and the control node of the above-mentioned interval time by using this field.

The next field is a variable-length data field, and this data field is called the payload of the packet. In the present embodiment, if the data field is not a multiple of a quadlet, bits less than the quadlet are filled with zeros.

The next 32 bits field is a data_CRC field, and is used for detecting an error between the header information and the data field, similarly to the header_CRC field. It is needless to say that the data_CRC field may be added only to the data field.

According to the above-described operation, in the present embodiment, it is possible to prevent the data transfer efficiency in the network or the bus system from being reduced, and to reduce the data transfer speed in the connected destination node. .

Although the above embodiment shows a case where there is only one destination node, it goes without saying that the same method can be applied to a case where there are a plurality of destination nodes.

When there are a plurality of destination nodes, a maximum value may be set as the above-mentioned response cycle, or a plurality of each may be individually set for each destination node.

(Other Embodiments of the Present Invention) The present invention is applied to a system composed of a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), but is also applicable to a device composed of one device. You may.

Further, in order to realize the functions of the above-described embodiments, a device connected to the above-mentioned various devices or a computer in a system is operated so as to operate various devices so as to realize the functions of the above-described embodiments. The present invention also includes programs implemented by supplying the program code of the software described above and operating the various devices according to programs stored in a computer (CPU or MPU) of the system or apparatus.

In this case, the program code itself of the software realizes the functions of the above-described embodiment, and the program code itself and means for supplying the program code to the computer,
For example, a storage medium storing such a program code constitutes the present invention. As a storage medium for storing such a program code, for example, a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM,
A magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.

When the computer executes the supplied program code, not only the functions of the above-described embodiment are realized, but also the OS (operating system) or other operating system running on the computer. Needless to say, the program code is also included in the embodiment of the present invention when the functions of the above-described embodiment are realized in cooperation with application software or the like.

Further, 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 function expansion board or the function expansion unit is specified based on the instruction of the program code. It is needless to say that the present invention also includes a case where a CPU or the like provided in the first embodiment performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

[0121]

As described above, according to the present invention, it is possible to prevent the data transfer efficiency in the network or the bus system from being lowered and to reduce the data in the device connected to the network or the bus system. There is an effect that it is possible to provide a device capable of reducing the transfer speed and reducing the cost.

According to the present invention, when a communication band is not used much, a large number of communications can be performed simultaneously, and data lost due to interruption of data transfer can be easily detected. There is an effect that the recovery from the interruption of the data transfer can be performed reliably and easily.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing the operation of each node according to the present invention.

FIG. 3 is a diagram showing a diagram of transmission and reception of commands and data between nodes according to the present invention.

FIG. 4 is a diagram showing details of data exchange performed between a source node and a destination node according to the present invention.

FIG. 5 is a diagram showing an asynchronous packet according to the present invention.

FIG. 6 is a block diagram showing a conventional example.

[Explanation of symbols]

10 computer 12 Processing unit (MPU) 14 First 1394 interface 16 First operation unit such as keyboard 18 First decoder 20 Display device such as CRT display 22 Hard disk 24 First memory 26 Internal bus of computer such as PCI bus 28 VCR 30 Imaging optical system 32 A / D converter 34 Video processing unit 36 Compression / expansion circuit 38 Second memory 40 Third memory 42 First data selector 44 Second 1394 interface 46 First memory control circuit 48 Second memory control circuit 50 System controller 52 Second operation unit 54 Electronic viewfinder 56 D / A converter 58 Recording unit 60 Printer 62 Third 1394 interface 64 Second data selector 66 Third operation unit 68 Printer Controller 70 Second decoder 72 Fourth memory 74 Image processing unit 76 Driver 78 Printer head 200 Control node 202 Source node 20 4 Destination node 206 Subunit inside source node 208 Object such as image data 210 First memory space inside destination node 212 First connection 214 nth memory space inside destination node 216 nth connection 250 Source node 252 Communication data buffer inside destination node 254 Next stage circuit inside destination node 256 i-th data transfer 258 i-th response 260 (i + 1) -th data transfer 262 (i + 1) -th response 264 Response period 266 Data movement inside the destination node 268 Delay due to data movement inside the destination node

Claims (19)

[Claims] 1. A source node for transmitting information data,
In a data communication system in which communication with a destination node receiving the information data is performed using a connection ID indicating a logical connection between the nodes, a time interval required for reception processing of the destination node Communication to the source node. 2. The data communication system according to claim 1, wherein the time interval is determined by a time for reading out the information data from a storage unit for temporarily storing the received information data. 3. The communication system further includes a control node for managing the connection ID, wherein the control node sets a logical connection between a plurality of nodes that perform communication. Item 3. The data communication system according to item 1 or 2. 4. The data communication system according to claim 3, wherein the time interval is also notified to the control node. 5. The information processing apparatus according to claim 1, wherein the destination node terminates the reception processing of the information data in accordance with data indicating a transfer end included in the information data. A data communication system as described. 6. The data communication system according to claim 5, wherein the destination node releases a connection ID set with the source node based on the data indicating the end of the transfer. 7. The data communication system according to claim 3, wherein the control node terminates the transfer of the information data according to data indicating a transfer end included in the information data. 8. The connection set between the source node and the destination node based on the data indicating the end of the transfer.
The data communication system according to claim 7, wherein the ID is released. 9. The data communication system according to claim 1, wherein the information data is transmitted by using an asynchronous transfer method conforming to the IEEE 1394 standard. 10. The data communication system according to claim 1, wherein the information data is broadcast to all nodes on the communication system. 11. The apparatus according to claim 1, wherein the source node selects a maximum time interval from n time intervals required for reception processing of the n destination nodes. 2. The data communication system according to claim 1. 12. The source node has a response period for receiving a response from the destination node that has received the information data, and detects a communication error if the response cannot be detected even if the response period is exceeded. The method according to claim 1, wherein:
A data communication system according to item 9. 13. The data communication system according to claim 12, wherein the response period is set based on the time interval. 14. A data communication system including a source node transmitting information data, a destination node receiving the information data, and a control node managing communication between the source node and the destination node. A data communication method for notifying the control node of a time interval required for reception processing of the destination node. 15. A data communication system for performing communication between a source node transmitting information data and a destination node receiving the information data using a connection ID indicating a logical connection between the nodes. An applicable data communication method, wherein a time interval required for reception processing of the destination node is notified to the source node. 16. Applicable to a communication system including a source node transmitting information data, a destination node receiving the information data, and a control node managing communication between the source node and the destination node. A possible data communication method, wherein the control node is notified of a time interval required for reception processing of the destination node. 17. A source node for transmitting information data,
In a data communication device that manages communication with a destination node that receives the information data, receiving means for receiving a time interval required for reception processing of the destination node, and transmitting the time interval to the source node A data communication device, comprising: a transmission unit. 18. A storage medium wherein the steps constituting the data communication method according to claim 15 or 16 are stored so as to be readable by a computer. 19. A storage medium storing a program for causing a computer to function as each means according to claim 17.