JP2000286891A - Data transmitter, data transmission method, data communication system and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a data transmission system where traffic with a transmitter on a communication channel can be reduced, and to provide a data transmission method, a recording medium and a data transmitter. SOLUTION: A data size management section 50 of this data transmitter refers to a size of data in a received data storage section 40 to calculate a receptible data size. A data time management section 60 transfers received data to a communication opposite party via a channel accommodation section 30 and calculates a receptible time interval on the basis of channel transfer rate information, and the data size in the received data storage section 40. A control section 10 transmits the information of the data size and the receptible time interval to a terminal via the terminal housing section 20. The terminal transmits transmission data to this data transmitter on the basis of the data size and the receptible time interval information.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a data transmission apparatus for receiving data from a transmission apparatus and transmitting the data to a reception apparatus, a data transmission method and a recording medium, and a data communication system.

[0002]

2. Description of the Related Art Conventionally, as an embodiment for carrying out data communication between a transmitting terminal and a receiving terminal, there is a type of data transfer (serial transfer) by handshake.

In the data transfer by the handshake, flow control is performed by transmitting and receiving a handshake packet. For example, the transmitting terminal always transmits data (data transmission request) and responds to the handshake packet from the receiving terminal, for example, an acknowledgment (ACK).
Alternatively, by receiving a negative acknowledgment (NAK), it is determined whether data transmission is possible or impossible.

As a serial transfer interface, there is a USB (Universal Serial Bus). In this USB, a plurality of USB devices such as a mouse, a keyboard, and a modem can be connected to a host such as a single personal computer using a single USB cable.

[0005] Further, as a transfer method by USB, there are methods such as bulk transfer and isochronous transfer.

A data transmission device is disclosed in
No. 1-270952 (hereinafter referred to as gazette 1),
Japanese Patent Application Publication No. 168017 (hereinafter referred to as Publication 2) and Japanese Patent Application Laid-Open No. 9-319672 (hereinafter referred to as Publication 3) are known.

[0007] In the device described in the above publication 1, the second transmission unit for receiving data and transmitting the data to another transmission unit includes the type and number of data and the reception or transmission state of the second transmission unit. Correspondingly, data transmission is performed by switching between the handshake method and the one-way data transmission method.

In the device described in the above publication 2, the transmitting device predicts the transfer frequency by referring to the data type and the data amount, and also stores the data amount and the predicted transfer frequency in the past. Determine the transfer mode suitable for the transfer of the data according to the request with reference to the history of data transmission,
Data is transmitted to the ATM network according to the transfer mode.

Further, in the device described in the above publication 3, the data transmission completion time predicting means of the data receiving device predicts the end time of the data transmission of the preceding data transmitting device. The other data transmitting apparatus is notified of the end time, and the other data transmitting apparatus is transmitting data at the notified end time.

[0010]

As described above, in the conventional data transfer by handshake, the flow control is performed by transmitting and receiving a handshake packet. By receiving a packet (ACK signal or NAK signal), it is necessary to determine whether data can be transmitted.

That is, the transmitting terminal cannot know that the transmission destination (receiving terminal) cannot receive the data unless the transmitting terminal always waits for the return of the handshake from the receiving terminal.

In the case where the transmitting terminal is made to wait for a NAK (negative acknowledgment) packet until data transmission can be performed, as in the case of the above USB, the terminal serving as the USB host uses the NAK ( (Negative acknowledgment) The transmission process of the packet must be performed, and the USB host is overloaded. Further, it was a factor that made the whole system unstable.

For example, when data is transferred by the USB bulk transfer method, the receiving terminal must transmit a NAK handshake packet to the USB bus, that is, the transmitting terminal in order to make the data reception wait.

Since the NAK indicates a retransmission request from the receiving terminal to the transmitting terminal, the transmitting terminal transmits the transmission data to the US in order to retransmit the same transmission data as the previous transmission data.
Must be transmitted on the B bus. As described above, the transmission of the transmission data and the NAK data is repeated, and the traffic on the USB bus is increased.

When data is retransmitted by handshake, it is necessary to perform a NAK (unreceivable) handshake between the transmitting terminal and the USB host. It is necessary to perform monitoring of the USB host, so that a load is applied to the USB host.

[0016] In the apparatus described in the above publication 1,
According to the type, the number of data, and the reception or transmission state of the second transmission unit, data is transmitted by switching between the handshake method and the unidirectional data transmission method. No consideration is given to the data storage state of the data transmission device (for example, how much data size data can be received).

Also, in the device described in the above publication 2, a transfer suitable for data transfer is performed based on data transmission information related to the transmitting device, for example, a transfer frequency, a data amount, and a history of past data transmission. The mode is determined and data is transmitted, and no consideration is given to the data storage state of, for example, a data transmission device that receives the data.

Further, also in the device described in the above publication 3, the other data transmission device transmits data at the end time notified by the data transmission completion time prediction means of the data reception device. No consideration is given to the receivable state of the data transmission device that receives the data, for example.

As described above, in the devices described in the above publications, since the data storage state of the data transmission device that receives data from the transmission device, for example, is not considered at all, the amount of data that can be stored exceeds When data is transmitted to the data transmission device, a data transmission error occurs. For this reason, transmission data is retransmitted, which causes an increase in traffic on the communication line.

An object of the present invention is to provide a data transmission device, a data transmission method, a recording medium, and a data communication system that can reduce traffic on a communication line with a transmission device.

[0021]

In order to achieve the above object, a data transmission device according to a first aspect of the present invention is connected to a transmission device and a reception device via a communication line, respectively. A data transmission device for receiving data and transmitting the data to the receiving device, wherein the receiving device receives data from the transmitting device, a storage device for storing the data received by the receiving device, and A first transmitting unit that reads data and transmits the data to the receiving device; a unit that determines a size of a free area of the storage device based on a data amount of data stored in the storage device; A transmission timing at which the transmitting device should transmit data next time, based on preset communication speed information of the communication line between Timing determining means for determining a second to transmit the information indicating the determined timing by the information and the timing determining means for indicating the amount of free space obtained by the obtaining unit to the transmitting device
And transmission means.

In the above data transmission device, the size of the free area (ie, the amount of data that can be transmitted by the transmitting device) is determined by the obtaining unit based on the amount of data stored in the storage unit. The determining means determines, based on the communication speed information of the communication line with the receiving device and the size of the free area, the timing at which the transmitting device should transmit data next time (this is because the data transmitting device transmits data next time). (Which is also the receivable timing). Then, the information indicating the size of the empty area and the information indicating the timing are transmitted to the transmitting device by the second transmitting means.

Therefore, the transmitting apparatus can know the amount of data that can be transmitted and the timing at which data should be transmitted next (the time when data can be transmitted) before data transmission.
The data to be transmitted next time can be transmitted to the receiving device via the data transmission device based on the timing (time at which transmission becomes possible).

That is, when the data transmission device is in a receivable state, the transmission device transmits data of a data size that can be reliably transmitted to the data transmission device (eventually, the reception device).
Can be sent to

[0025] In the data transmission apparatus according to the first aspect, after receiving the inquiry about the information about the data transmission from the transmission apparatus, the receiving means may receive the information indicating the size of the empty area and the information indicating the timing. Means for receiving data transmitted from the transmitting device based on the data.

In this case, since the data transmission device receives data from the transmission device when the device itself is in a receivable state, no data reception error occurs. It is not necessary to execute a process such as returning a negative response to the transmitting device.

In other words, the transmission device can transmit data of a data size that can be transmitted reliably to the data transmission device (eventually, the reception device) when the data transmission device is in a receivable state. it can.

[0028] Further, the means for obtaining includes the rated storage capacity of the storage means, the data amount of data stored in the storage means, and the data amount of data read by the first transmission means. Calculating means for calculating the size of the free area of the storage means based on the information.

In this case, the means for obtaining is based on the data amount of the data to be received and stored, the data amount of the transmitted data, and the rated storage capacity,
That is, the amount of data that can be transmitted by the transmitting device is determined.

Therefore, the transmission data from the transmitting device is stored in the data transmitting device and then transmitted to the receiving device. Therefore, it is necessary for the transmitting device to perform processing such as a data transmission error and retransmission of data. Disappears.

Further, the timing determining means divides a value indicating the data amount of the predetermined data to be stored in the free area determined by the determining means by a value indicated by the preset communication speed information. Calculating means for calculating a time required for the second transmitting means to transmit all of the predetermined data to the receiving device; and calculating the time required by the transmitting device for exceeding the data amount of the predetermined data. The timing at which the data is to be transmitted includes determining means for determining a point in time when all of the predetermined data has been transmitted by the second transmitting means and the time calculated by the calculating means has elapsed. good.

In this case, the calculating means calculates the data amount of the predetermined data (for example, 8 Kbytes) / communication speed information (for example, 64 Kbps / 8 bits) = 1 sec, and the determining means transmits the data exceeding the data amount. The timing to be performed is that 8 Kbytes of data is transmitted and 1
It is determined that the time has elapsed. Information indicating 1 sec is transmitted to the transmitting device as information indicating this timing.

In the transmitting apparatus, when the data amount of transmission data to be transmitted (for example, 10 Kbytes) exceeds a predetermined data amount (for example, 8 Kbytes),
For data having a data amount exceeding this data amount (2 Kbytes), 8 Kbytes of data is transmitted and 1s
At the time when ec has elapsed, the transmission may be performed.

In order to achieve the above object, a data transmission method according to a second aspect of the present invention is connected to a transmitting device and a receiving device via a communication line, and receives data from the transmitting device. A data transmission method in a data transmission device for transmitting data to the receiving device, wherein a receiving step of receiving data from the transmitting device, a storing step of storing data received in the receiving step, A first transmitting step of reading data stored by the storage device and transmitting the data to the receiving device; a step of obtaining a size of a free area based on a data amount of the data stored by the storing step; Based on the communication speed information set in advance for the communication line between the communication line and the size of the free area obtained by the obtaining means. A timing determining step of determining a timing at which the transmitting device should transmit data next time; information indicating a size of a free area determined by the determining means; and information indicating a timing determined by the timing determining means. And a second transmitting step of transmitting to the transmitting device.

In order to achieve the above object, a computer-readable recording medium according to a third aspect of the present invention includes a receiving step for receiving data from a transmitting device, and a method for receiving data received by the receiving step. A storage step of storing, a first transmission step of reading out the data stored in the storage step and transmitting the data to a receiving device, and a size of an empty area based on a data amount of the data stored in the storage step And the communication speed information set in advance of the communication line for transmitting data to the receiving device, based on the size of the free area determined by the obtaining step,
A timing determining step of determining a timing at which the transmitting device should transmit data next time; and information indicating the size of the free area determined by the determining unit and information indicating the timing determined by the timing determining step. A second transmission step for transmitting to the transmission device is recorded.

Further, in order to achieve the above object, a data communication system according to a fourth aspect of the present invention comprises:
A data communication system comprising: a receiving device, a data transmission device connected to each of the devices via a communication line, and receiving transmission data from the transmitting device and transmitting the data to the receiving device. A transmission unit that receives transmission data from the transmission device, a storage unit that stores the transmission data received by the reception unit, and a first unit that reads data from the storage unit and transmits the data to the reception device. Transmitting means, means for determining the size of an empty area of the storage means based on the amount of data stored in the storage means, and a preset communication speed of a communication line between the receiving apparatus A timing determination unit that determines a timing at which the transmitting apparatus should transmit data next time based on the information and the size of the empty area obtained by the obtaining unit. Means for transmitting, to the transmitting apparatus, information indicating the size of the vacant area determined by the determining means and information indicating the timing determined by the timing determining means. The apparatus comprises: means for receiving information indicating the size of the empty area and information indicating the timing from the second transmitting means; and transmitting data to the data transmitting apparatus based on the reception information received by the receiving means. And means for transmitting

[0037]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram illustrating a configuration of a data transmission device according to an embodiment of the present invention. As shown in FIG. 1, the data transmission device 1 includes a control unit 10, a terminal accommodation unit 20, a line accommodation unit 30, a reception data storage unit 40, a data size management unit 50, a data time management unit 60, , Is provided.

The control section 10 controls the entire apparatus.

The terminal accommodating section 20 provides an interface with the terminal (that is, controls the transmission and reception of data).

The line accommodating unit 30 provides an interface with a communication partner (that is, controls transmission and reception of data).

The reception data storage section 40 is set to a rated storage capacity (size) of 8 Kbytes, and receives and stores data from the terminal.

The data size management unit 50 manages the size of data. The data size management unit 50 counts the size of data stored in the reception data storage unit 40 at the time of data reception. Then, the size of the data read from is counted, and the size of the current data stored in the reception data storage unit 40 is calculated based on these count values.

The data time management section 60 transfers the data stored in the reception data storage section 40 to the communication partner via the line accommodating section 30 and, at the same time, the communication line (connection) A receivable time interval (reception timing) is calculated based on the line speed information of the line (line) and the data size in the reception data storage unit 40.

FIG. 2 is a block diagram showing in detail the configuration of the data size management unit 50 and the data time management unit 60 in the data transmission device 1.

In FIG. 2, the data size management unit 50
Includes a reception write pointer 51, a transmission read pointer 52, and a remaining data number storage unit 53.

The reception write pointer 51 stores the number of data (data amount) at the time of reception by a pointer.

The transmission read pointer 52 is stored in the control unit 10.
Reads the data from the reception data storage unit 40 and, when transmitting the data to the communication partner via the line accommodating unit 30, points to the number of data (data amount) read from the reception data storage unit 40. Remember by

The remaining data number storage unit 53 stores the pointer value of the reception write pointer 51 and the transmission read pointer 52
And the amount of data (the number of remaining data) stored in the reception data storage unit 40 is calculated based on the difference value and the rated storage capacity of the reception data storage unit 40. This calculation result (accumulated data number information)
Is stored.

The data time management unit 60 includes a transmission data storage unit 61, a line speed storage unit 62, a speed matching unit 63,
A reception data interval calculation unit 64.

The transmission data storage section 61 temporarily stores the data read from the reception data storage section 40 by the control section 10 for transmission to the line accommodating section 30.

The line speed storage unit 62 stores line speed (data transmission speed) data of a communication line.

The speed matching unit 63 includes a transmission data storage unit 61
, And sends the read data to the line accommodating unit 30 in accordance with the line speed data stored in the line speed storage unit 62.

The reception data interval calculation section 64 is based on the line speed data stored in the line speed storage section 62 and the stored data number information stored in the remaining data number storage section 53. In addition to calculating the receivable (ie, storable) data size of the received data 40, the received data storage unit 40
Predict how much the stored data will exceed the rated storage capacity.

FIG. 3 shows a configuration example of a data communication system having the data transmission device 1 having the above configuration.

As shown in FIG. 3, in the data communication system, the terminal accommodating unit 20 of the data transmission device 1 and the transmission terminal (communication source) 2 are connected via the USB interface 3. Line accommodating unit 30 and ISDN
(Comprehensive service digital network) The configuration is such that the line 4 is connected. The data transmission device 1 has an ISDN line 4
Is connected to a receiving terminal (communication partner) 5 via the PC and transmits and receives data. The line speed (data transmission speed) of the ISDN line 4 is 64 Kbps.

In this embodiment, data transfer is realized by a USB protocol which is one of terminal interfaces for performing handshake.

That is, the control unit 10 of the data transmission device 1
Performs a handshake of data transmission with the transmitting terminal 2 by bulk transfer.

The control unit 10 notifies the receivable data size and the receivable data interval using the logical pipe of the endpoint 0.

Further, between the control unit 10 and the transmission terminal 2, transmission data from the transmission terminal 2 (data transmitted from the transmission terminal 2) is exchanged at the endpoint 1, and the control unit 1
The transmission data from 0 (that is, the data received by the transmission terminal 2) is transmitted and received by the endpoint 2. Note that a packet having a maximum packet length of 64 bytes is used for exchanging data with the endpoint.

Here, the end point means a uniquely identifiable portion of the USB device in the communication flow between the host (for example, the control unit 10) and the USB device (for example, the transmitting terminal 2). Therefore, the above-mentioned end points are assigned to the transmitting terminal 2.

The data transmission processing of the data communication system having such a configuration will be described.

In this case, the data transmission device 1 uses the ISDN
4 (transmission rate 64 Kbps) is completed, and data communication with the receiving terminal (communication partner) 5 is possible.

The transmission terminal 2 scans at a fixed cycle, and sends a signal to the endpoint 0 on the USB bus.
An information request for receivable data size and receivable data interval information is issued.

The control unit 10 receiving this information request via the terminal accommodating unit 20 requests the data time management unit 60 to calculate the receivable data size and the receivable data interval.

In the data transmission device 1, the transmitting terminal 2
In a state where data is not exchanged with the receiving terminal 5, the pointer value of the reception write pointer 51 indicates “0”, and the control unit 10 does not perform transmission to the line side. The pointer value of the pointer 52 also indicates “0”.

The remaining data number storage unit 53 recognizes that the difference between the two pointers is the value “0”,
Based on this difference value, it is determined that the number of remaining data is a value “0”.

Based on the remaining data number “0” stored in the remaining data number storage unit 53, the reception data interval calculation unit 64 determines that the receivable data size is 8K bytes (8K bytes−8K bytes).
0), the 8K bytes and the line speed data (64
Kbps), the next receivable data interval is calculated.

That is, the receivable data interval is 8
Since this means the time during which K bytes can be transmitted to the line side (ISDN4) at 64 Kbps, the reception data interval calculation unit 64 calculates 8 Kbyte / (64 Kbit / 8 bit),
1Sec is obtained.

The receivable data interval information of 1Sec indicates that when the data to be transmitted from the transmitting terminal 2 is 8 Kbytes, the transmitting terminal 2 can transmit data at any time. Means.

When the data to be transmitted from the transmitting terminal 2 has a size of, for example, 10 Kbytes, the transmitting terminal 2 can transmit data up to 8 Kbytes at any time. , For 2K bytes of data exceeding 8K bytes, it means that the data transmission can be performed after the transmission of the 8K bytes of data has been completed and after 1 sec has elapsed. I have.

As described above, the receivable data interval information indicates the timing at which the transmitting terminal 2 can transmit data.

The control unit 10 includes a reception data interval calculation unit 60
With reference to the information on the receivable data size and the receivable data interval calculated by the above, the information is notified to the transmitting terminal 2 through the terminal accommodating unit 20. That is, the control unit 10 notifies the receivable data size and the receivable data interval information to the USB endpoint 0.

The transmitting terminal 2 notified of the receivable data size “8 Kbps” and the receivable data interval information “1Sec” from the control unit 10 of the data transmission apparatus 1, if the data to be transmitted is 8 Kbytes or less. All the data is transmitted, while if the data amount is larger than 8 Kbytes, data of up to 8 Kbytes is transmitted, and then the remaining data is transmitted after the next 1 sec.

Next, data transmission between the transmission terminal 2 and the data transmission device 1 will be described with reference to the sequence diagram shown in FIG. Here, a data transmission process when the transmitting terminal 2 transmits 2 Kbytes of data to the receiving terminal 5 will be described.

In the data transmission device 1, when data is not received, the reception write pointer 51
And the transmission read pointer 52 both indicate a pointer value “0”.

The transmission terminal 2 scans at a fixed cycle, and thereby, with respect to the endpoint 0 on the USB bus,
An information request for receivable data size and receivable data interval information is issued (S101).

Data transmission device 1 responding to this information request
, The control unit 10 controls the reception data interval calculation unit 60
Receivable data size (8 Kbytes) calculated by the above and receivable data interval information (8 Kbytes / (64 Kbit
/ 8 bit) = 1Sec), and notifies these information to the transmitting terminal 2 through the terminal accommodating unit 20 (S102).
That is, the receivable data size and the receivable data interval information for the information request are transmitted toward the endpoint 0.

The transmitting terminal 2 obtains a receivable data size of 8 Kbp by performing a periodic scan for the endpoint 0.
s and the receivable data interval 1Sec are notified,
2K bytes of data are transmitted to endpoint 1 on the USB bus.

In this case, the 2K-byte data is divided into a predetermined number, set to a packet having a maximum packet length of 64 bytes, and transmitted to the data transmission apparatus 1 (S10).
3). The data transmission device 1 that has received this packet returns an ACK (acknowledge) when it is normally received (S104).

In the same manner, the above processing operation is repeated until all 2 Kbytes of data are transmitted to the data transmission device 1 (S105 to S108).

In the data transmission apparatus 1 which has received all 2 Kbytes of data from the transmission terminal 2 in this manner, the data is stored in the reception data storage section 40 through the terminal accommodating section 20.
K bytes are accumulated, and upon reception, a pointer value “2K” indicating 2 Kbytes is stored in the reception write pointer 51 of the data size management unit 50.

Since the data stored in the reception data storage unit 40 has not yet been transmitted from the data transmission device 1 to the ISDN 4, the transmission read pointer 52 stores the pointer value “0”. The remaining data number storage unit 53 stores data “2” indicating the remaining data number “2 Kbytes”.
K ”is stored.

The data transmission apparatus 1 in such a state
Then, when an information request from the transmitting terminal 2 is input to the terminal accommodating unit 20 (S109), the control unit 10
Data interval calculation unit 64 in response to the information request from
Requesting data for returning to the transmitting terminal 2 (response information to the information request).

Then, the reception data interval calculation unit 64 stores the line speed data “64 Kbps” from the line speed storage unit 62.
And the number of stored data “2K” is obtained from the remaining data number storage unit 53, and the receivable data size is 6 Kbytes (8 kbyte−2) based on the stored data number “2K”.
kbyte = 6kbyte).

The reception data interval calculation section 64 sets the receivable data interval to 750 mSec (6 kbyte / (64 kbps) based on the acquired line speed data “64 Kbps” and the calculated receivable data size “6 Kbyte”.
bit / 8bit) = 750ms).

Further, the reception data interval calculation section 64 returns the calculated receivable data size and receivable data interval data to the control section 10.

The control unit 10 sets the receivable data size “6
K bytes "and receivable data interval" 750 mSe
"c" to the transmitting terminal 2 through the terminal accommodating unit 20 (S110).

In the transmitting terminal 2 which has input the return information in response to the information request, up to 6 Kbytes of data, it is determined that the data may be transmitted to the data transmission device 1 immediately, and all the data is transmitted. If the data to be transmitted exceeds 6K bytes, the data for 6K bytes is transmitted immediately, and the data exceeding 6K bytes is transmitted after 750msec. In this case, the transmission data is transmitted to the endpoint 1 on the UBS bus.

In the data transmission apparatus 1 which has received the transmission data from the transmission terminal 2, when the terminal accommodating section 20 receives the data transmitted toward the endpoint 1, the control section 10 transmits the data from the reception data storage section 40. The data is read, and the data is written to the transmission data storage unit 61.

At the same time, the transmission read pointer 52 counts the number of data read by the control unit 10 as needed, and when the control unit 10 reads all 2 Kbytes of data, “2K” indicating 2 Kbytes is read. Is stored.

A value equal to “2K” is stored in both the reception write pointer 51 and the transmission read pointer 52, and a value “0” obtained by calculating the difference is stored in the remaining data number storage unit 53. Is done.

The data stored in the transmission data storage unit 61 is transmitted to the receiving terminal 5 at a line speed of 64 Kbps through the speed matching unit 63 and the line accommodating unit 30 under the control of the control unit 10.

As described above, the data transmission apparatus 1 sequentially updates the pointer, calculates the difference, and estimates the data reception interval, and performs the communication processing. Causes the transmitting terminal 2 to transmit data.

As described above, according to this embodiment, in data communication using handshake,
Since the data transmission apparatus 1 notifies the transmitting terminal 2 of the receivable data size and the receivable data interval information in advance, the handshake packet (for example, the NAC packet) that causes the transmitting terminal 2 to wait for data transmission. ) Need not be sent. Therefore, traffic on the connection line (USB interface) with the transmission terminal can be reduced.

In this embodiment, the data transmission device 1
Is transmitted from the transmitting terminal 2 when the self-device is in a receivable state. Therefore, when the USB bus is used for bulk transfer, the NAK is used to make the terminal wait for data transmission. It is not necessary to transmit the (negative acknowledgment) handshake packet to the USB bus (that is, the transmitting terminal 2).

Therefore, the NA for making data transmission wait.
Since transmission of K is eliminated, transfer of transmission data (transmission data for retransmission) and NAK packets on the USB bus is reduced, and thus traffic on the USB bus can be reduced.

Further, the transmitting terminal 2 does not need to accumulate retransmission data when retransmitting data by handshake and monitor the handshake in real time.
This is the NAK between the transmitting terminal 2 and the data transmission device 1.
Since there is no (reception impossible) handshake, an optimum performance operation is possible in the system, which means that software processing can be simplified.

Next, an application example of this embodiment will be described. In the above embodiment, the communication line is IS
Although the DN is used, the present invention is not limited to this. By changing the line speed storage unit 62, the speed matching unit 63, and the line accommodating unit 30, a dedicated line, a local area network (LAN) can be used as a communication line. Can be a line. In addition, a partner terminal can be directly connected for file transfer or the like.

In the above-described embodiment, the USB interface is adopted as the terminal-side accommodation form. However, the present invention is not limited to this, and an RS-232C which is a serial interface may be used. In this case, even in the case of data communication in which a handshake is performed by a protocol, it can be realized by preparing local information transfer.

In this embodiment, a program for realizing each function of the data transmission apparatus 1 and executing each procedure of the above processing is a program such as a floppy disk,
The program may be stored and distributed on a computer-readable recording medium such as a D-ROM and an MO.

The program may be stored in, for example, a ROM, and the ROM may be arranged so that the control unit 10 can access the program. The control unit 10 may read the program from the ROM and execute the program.

Further, in the data transmission apparatus 1, the above program created by the transmission terminal 2 is transferred to the USB 3
And the program created by the receiving terminal 5 by downloading through the terminal accommodating unit 20 or by the ISDN
4 and via the line accommodating unit 30, or
The above program created by, for example, a computer connected to the ISDN 4 is transferred to the ISDN 4 and the line accommodation unit 3.
0, and the control unit 10 may execute this program.

[0103]

As described above, according to the present invention,
When the data transmission device is in a receivable state, the transmission device can transmit data corresponding to the amount of data that can be transmitted reliably to the data transmission device (eventually, the reception device),
The traffic on the communication line between the transmission device and the data transmission device can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a data transmission device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a detailed configuration of the data transmission device shown in FIG.

FIG. 3 is a diagram illustrating a configuration example of a data transmission system having a data transmission device.

FIG. 4 is a sequence diagram showing a data transmission processing operation between a terminal and a data transmission device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 data transmission device 2 transmission terminal 3 USB (universal serial bus) 4 ISDN (integrated service digital network) 5 reception terminal 10 control unit 20 terminal accommodation unit 30 line accommodation unit 40 reception data storage unit 50 data size management unit 51 reception write pointer 52 Transmission read pointer 53 Remaining data number storage unit 60 Data time management unit 61 Transmission data storage unit 62 Line speed storage unit 63 Speed matching unit 64 Received data interval calculation unit

Claims (7)

[Claims] 1. A data transmission device connected to a transmission device and a reception device via a communication line, receiving data from the transmission device, and transmitting the data to the reception device, comprising: Receiving means for receiving the data, storing means for storing data received by the receiving means, first transmitting means for reading data from the storing means and transmitting the data to the receiving device, and stored in the storing means. Means for determining the size of an empty area of the storage means based on the data amount of data; communication speed information preset for a communication line with the receiving device; Timing determining means for determining a timing at which the transmitting device should transmit data next time, based on the size, and a size of an empty area determined by the determining means. Data transmission apparatus, characterized in that it comprises a second transmission means for transmitting to the transmitting device and information indicating the determined timing by the information and the timing determining means to indicate. 2. The method according to claim 1, wherein the receiving unit is configured to transmit, from the transmitting device, information based on information indicating a size of the empty area and information indicating the timing after receiving an inquiry about data transmission from the transmitting device. The data transmission device according to claim 1, further comprising: a unit that receives data. 3. The method according to claim 1, wherein the determining means determines a rated storage capacity of the storage means, a data amount of data stored in the storage means, and a data amount of data read by the first transmission means. The data transmission device according to claim 1, further comprising: a calculation unit that calculates a size of a free area of the storage unit based on the data. 4. The timing determining means divides a value indicating a data amount of predetermined data to be stored in a free area determined by the determining means by a value indicated by the preset communication speed information. Calculating means for calculating a time required for the second transmitting means to transmit all of the predetermined data to the receiving device; and The timing at which the data is to be transmitted includes: a determination unit that determines when all of the predetermined data has been transmitted by the second transmission unit and the time calculated by the calculation unit has elapsed. The data transmission device according to claim 1, wherein 5. A data transmission method in a data transmission device which is connected to a transmission device and a reception device via a communication line, receives data from the transmission device, and transmits the data to the reception device. A receiving step of receiving data from the device; a storing step of storing the data received by the receiving step; a first transmitting step of reading out the data stored by the storing step and transmitting the data to the receiving device; Determining a size of a free area based on a data amount of data stored in the storage step; predetermined communication speed information of a communication line with the receiving device; Based on the size of the vacant area thus determined and a timing for determining when the transmitting apparatus should transmit data next time. And a second transmitting step of transmitting to the transmitting device information indicating the size of the empty area obtained by the obtaining means and information indicating the timing determined by the timing determining means. A data transmission method characterized by the above-mentioned. 6. A receiving step of receiving data from a transmitting device, a storing step of storing the data received in the receiving step, and a step of reading out the data stored in the storing step and transmitting the data to the receiving device. 1) a step of determining the size of a free area based on the amount of data stored in the storage step; and a preset communication speed of a communication line for transmitting data to the receiving device. A timing determining step of determining a timing at which the transmitting device should transmit data next time, based on the information and the size of the free area obtained by the obtaining step; and a size of the free area obtained by the obtaining means. And information indicating the timing determined by the timing determining step A computer-readable recording medium characterized by recording a program for executing a second transmission step of transmitting to the transmitting device. 7. A transmitting device, a receiving device, and a data transmitting device connected to each of the devices via a communication line, receiving transmission data from the transmitting device and transmitting the data to the receiving device. In the data communication system, the data transmission device includes: a reception unit that receives transmission data from the transmission device; a storage unit that stores the transmission data received by the reception unit; and reads data from the storage unit. A first transmitting unit that transmits the data to the receiving device based on a data amount of data stored in the storing device, a unit that determines a size of an empty area of the storing device, On the basis of the communication speed information set in advance on the communication line and the size of the free area obtained by the obtaining means, the time at which the transmitting apparatus should transmit data next time is determined. Timing determining means for determining the timing, a second transmitting means for transmitting to the transmitting device information indicating the size of the empty area determined by the determining means and information indicating the timing determined by the timing determining means, The transmitting device comprises: a unit for receiving information indicating the size of the empty area and information indicating the timing from the second transmitting unit; and based on the reception information received by the receiving unit, A data communication system, comprising: means for transmitting transmission data to a data transmission device.