JPH11177539A - Data communication control system, data communication method of data communication control system, and storage medium storing computer readable program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To warrant data quality even in the synchronization transmission system while utilizing data transmission by the synchronization transmission system so as to ensure a constant data rate. SOLUTION: On the occurrence of a non-response state in excess of a non- response period received from each destination in the data transmission processing between a data receiver 102 and a data transmitter 101, when the non-response state takes place in the data receiver 102, the receiver 102 requests data transmission to the data transmitter 101 or when the non-response state takes place in the data transmitter 101, the transmitter 101 sends data again to the data receiver 102.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data communication control system and a data communication control in which a data transmitting device and a data receiving device transmit predetermined transmission data based on the same period signal via a predetermined communication medium. The present invention relates to a data communication method of a system and a storage medium storing a computer-readable program.

[0002]

2. Description of the Related Art In recent years, with the digitization and multimedia of data, personal computers (PCs)
In addition to data, text, graphics, and still images, processing of real-time data such as audio and video has become possible.

[0003] Accordingly, the interface between the PC and the peripheral device also changes from the conventional transmission using an analog signal to the transmission using a digital signal. I can now plan.

As a result, all kinds of data can be transmitted on the same interface. However, in the data transmission, data having different properties such as real-time property and non-real-time property are mixedly transmitted.

For example, in the case of data that emphasizes real-time properties, such as audio and video, the value of the data is lost after a certain period of time. Since transmission of data is prioritized, a synchronous transmission mode is required in which a certain period is set and data is reliably transmitted within that period.

In the case of non-real-time data, the transmission quality of the data is more important than the time. Therefore, for data for which an error has been detected by error detection, the data is retransmitted and the reliability of the data is reduced. Asynchronous transmission mode that ensures the performance is required.

[0007] In this case, since real-time data is prioritized over non-real-time data, non-real-time data is transmitted in the idle time until the next synchronization timing after transmitting real-time data. Is transmitted.

[0008]

However, according to the above-mentioned prior art, synchronous transmission takes precedence over asynchronous transmission due to the temporal importance of transmitted media. Of these, asynchronous transmission is performed at the remaining transmission rate that secures the transmission rate used in synchronous transmission, and asynchronous transmission is greatly affected by the transmission rate of synchronous transmission.

Further, when the amount of data to be transmitted by the synchronous transmission is very large, the data transmission by the asynchronous transmission may be significantly reduced or may not be transmitted at all.

On the other hand, when the amount of data to be transmitted by the synchronous transmission is small, the transmission rate of the asynchronous transmission becomes high. Unable to receive data,
There is also a problem that the transmission side is in a waiting state, and the reception side performs useless transmission for transmitting busy, so that transmission efficiency is significantly reduced.

In the case of the synchronous transmission method, in order to give priority to time over data quality in synchronous transmission, if an error occurs in received data, no error is returned. Has not been done. In this case, the data may not be received at all due to an error in the header information of the data.

That is, in the case of synchronous transmission, although the data rate can be kept constant to some extent, since the data is not guaranteed, it is not suitable for a device requiring accurate data.

Here, in a serial printer or the like which does not have much memory, since the buffer capacity on the printer side is small and the timing of ink ejection from the print head is constant, a necessary data transmission method is required. Although it is better to transmit data accurately and at regular intervals as much as possible, both synchronous and asynchronous transmission have advantages and disadvantages as described above. there were.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a data receiving apparatus and a data transmitting apparatus which receive a non-response signal from each other in data transmission processing. If a non-response state that exceeds the period occurs, the data transmission device requests data transmission to the data transmission device, or the data transmission device retransmits data to the data reception device. By using the data transmission by the synchronous transmission method, it is possible to secure a constant data rate and to guarantee the data quality even in the synchronous transmission method, and to perform the data transmission between the data receiving device and the data transmitting device. Data communication control system capable of optimizing transmission processing, data communication method of data communication control system, and computer-readable To provide a storage medium storing a capability program.

[0015]

According to a first aspect of the present invention, a data transmitting apparatus and a data receiving apparatus transmit predetermined transmission data via a predetermined communication medium based on the same period signal. A data communication control system, comprising: first data holding means for holding the predetermined transmission data;
First registering means for registering a receiving-side no-response period notified from the data receiving device; and counting the receiving-side no-response period registered by the first registering means based on the same period signal. A first counting unit, wherein the type of a reply signal returned from the data receiving device during the counting of the non-response period of the receiving side by the first counting unit from the start of transmission of transmission data from the data transmitting device; First determining means for determining whether there is an abnormality;
A first retransmitting means for retransmitting the transmission data held in the first data holding means to the data receiving device when the determination means determines that the type of the reply signal is abnormal; A second determination is made as to whether or not a reply signal returned from the data receiving device has not been received from the start of transmission of transmission data from the device to the end of the non-response period of the receiving side by the first counting means. Determining means for transmitting the transmission data held in the first data holding means when the second determination means determines that the return signal returned from the data receiving apparatus has not been received; And second retransmission means for retransmitting the data.

A second invention according to the present invention is a data communication control system in which a data transmitting apparatus and a data receiving apparatus transmit predetermined transmission data based on the same period signal via a predetermined communication medium. A second data holding unit for receiving and holding the transmission data transmitted from the data transmission unit; a second registration unit for registering a transmission-side non-response period notified from the data transmission device; A second counting unit that counts the non-response period of the transmission side registered by the second registration unit based on the same period signal; and a second counting unit that starts receiving the transmission data from the data transmission device. Third determining means for determining whether the transmission data received from the data transmitting device is normal during counting of the transmission-side non-response period by the counting means, and the third determining means When the transmission data is determined to be normal, the first return means for returning the transmission data normal, and when the transmission data is determined to be abnormal by the third determination means, A second reply unit for discarding the transmission data held in the second data holding unit and returning a transmission data abnormality, and the transmission by the second counting unit from the start of reception of the transmission data from the data transmission device. A fourth determining unit that determines whether or not transmission data has been received from the data transmission device before the end of the no-response period; and a fourth determination unit that has not received transmission data from the data transmission device. A third return means for returning a request for retransmission of transmission data to the data transmission device when the determination is made.

In a third aspect of the present invention, the non-response period on the receiving side notified from the data receiving device is arbitrarily set by the data receiving device.

According to a fourth aspect of the present invention, the non-response period on the transmitting side notified from the data transmitting device is arbitrarily set by the data transmitting device.

According to a fifth aspect of the present invention, there is provided a data communication control system in which a data transmitting apparatus and a data receiving apparatus transmit predetermined transmission data based on the same period signal via a predetermined communication medium. A communication method, wherein a first registration step of registering a non-response period of a receiving side notified from the data receiving device in a memory resource, and the non-response period of the receiving side registered in the first registration step is performed by A first counting step of counting based on the same period signal; and a step of counting from the start of transmission of transmission data from the data transmitting apparatus to the receiving side non-response period in the first counting step. A first determination step of determining whether the type of a reply signal returned from
A first retransmission step of retransmitting held transmission data to the data receiving apparatus when the first determination step determines that the type of the return signal is abnormal; and transmitting data from the data transmission apparatus. A second determination step of determining whether or not a response signal returned from the data receiving apparatus has not been received from the start of transmission to the end of the receiving-side non-response period in the first counting step; A second retransmitting step of retransmitting the held transmission data to the data receiving apparatus when the second determining step determines that a reply signal returned from the data receiving apparatus has not been received. is there.

According to a sixth aspect of the present invention, there is provided a data communication control system in which a data transmitting apparatus and a data receiving apparatus transmit predetermined transmission data based on the same period signal via a predetermined communication medium. A communication method, wherein a second registration step of registering a transmission-side non-response period notified from the data transmission device in a memory resource, and the transmission-side non-response period registered in the second registration step is performed by A second counting step of counting based on the same period signal, and a step of counting the transmission-side non-response period by the second counting means from the start of reception of transmission data from the data transmission device; A third determining step of determining whether the transmission data received from the server is normal, and transmitting the data if the transmission data is determined to be normal by the third determining step. A first return step of returning normal data, and a second return step of discarding the held transmission data and returning an abnormal transmission data when the third determination step determines that the transmission data is not normal. Determining whether or not transmission data has been received from the data transmission device between the start of reception of transmission data from the data transmission device and the end of the non-response period on the transmission side by the second counting process. A fourth determining step, and a third returning step of returning a transmission data retransmission request to the data transmitting apparatus when the fourth determining step determines that transmission data has not been received from the data transmitting apparatus. And

According to a seventh aspect of the present invention, there is provided a data communication control system in which a data transmitting apparatus and a data receiving apparatus transmit predetermined transmission data based on the same period signal via a predetermined communication medium. A storage medium storing a computer-readable program to be executed, the first registration step of registering a non-response period of a receiving side notified from the data receiving apparatus in a memory resource, and the first registration step A first counting step of counting the received non-response period based on the same period signal, and the receiving side non-response period from the start of transmission of transmission data from the data transmission device by the first counting step. A first determination step of determining whether a type of a return signal returned from the data receiving apparatus is abnormal during the response period counting;
A first retransmission step of retransmitting held transmission data to the data receiving apparatus when the first determination step determines that the type of the return signal is abnormal; and transmitting data from the data transmission apparatus. A second determination step of determining whether or not a response signal returned from the data receiving apparatus has not been received from the start of transmission to the end of the receiving-side non-response period in the first counting step; A second retransmitting step of retransmitting the held transmission data to the data receiving apparatus when the second determining step determines that the reply signal returned from the data receiving apparatus is not received. A readable program is stored in a storage medium.

An eighth invention according to the present invention controls a data communication control system in which a data transmitting device and a data receiving device transmit and process predetermined transmission data based on the same period signal via a predetermined communication medium. A storage medium storing a computer-readable program to be transmitted, wherein the second registration step registers a transmission-side non-response period notified from the data transmission device in a memory resource, and the second registration step A second counting step of counting the transmission-side non-response period based on the same period signal, and the transmission-side non-response by the second counting means from the start of reception of transmission data from the data transmission device. A third determining step of determining whether the transmission data received from the data transmitting apparatus is normal during the response period counting, and When the transmission data is determined to be normal, the first return step of returning the transmission data normal, and when the transmission data is determined to be abnormal by the third determination step, is held. A second return step of discarding the transmission data and returning a transmission data abnormality, and from the start of reception of the transmission data from the data transmission apparatus to the end of the transmission-side non-response period by the second counting step, A fourth determining step of determining whether or not transmission data has been received from the data transmitting apparatus; and determining that the transmitting data has not been received from the data transmitting apparatus in the fourth determining step. And a third return step of returning a transmission data retransmission request to a storage medium.

[0023]

FIG. 1 is a block diagram showing an example of a printing system to which a data communication control system according to an embodiment of the present invention can be applied. This corresponds to a case where the data receiving apparatus 102 that receives transmission data from the apparatus 101 is configured to be communicable via a predetermined interface.

In the data transmission apparatus 101, reference numeral 103 denotes an overall control unit which controls the overall control of the data transmission apparatus, and is constituted by, for example, a CPU. Reference numeral 104 denotes a storage unit including a RAM or the like, which stores programs, data, and the like necessary for the overall control unit 103 to perform processing.

Reference numeral 105 denotes an input unit for inputting image data or the like like a scanner or a camera. An operation unit 106 is input by an operator to control the data transmission device 101. A display unit 107 includes, for example, a CRT, an LCD, and an FLC, and displays image data such as graphics and text generated by the overall processing unit on a screen.

Reference numeral 108 denotes a synchronization counter which counts synchronization intervals of synchronous transmission. Reference numeral 109 denotes a timer, and the overall control unit 103 monitors the timer. Reference numeral 110 denotes a header generation unit that generates a header of transmission data for synchronous data transmission. 11
Reference numeral 1 denotes an error check bit generation unit that generates and processes an error check bit (for example, a CRC) of the data.

Reference numeral 112 denotes a buffer for temporarily storing transmission data. A buffer 113 temporarily stores the received data. A transmission / reception buffer 114 temporarily stores data during asynchronous transmission.

Reference numeral 115 denotes a synchronization control unit which controls data transmission / reception processing during synchronous transmission. An asynchronous control unit 116 controls data transmission / reception processing during asynchronous transmission. An interface unit (I / F unit) 117 transmits and receives data that satisfies the electrical and physical conditions of the interface.

The data receiving device 102 (in this embodiment,
In a printer device, a control unit 118 includes a CPU and the like, and controls the entire data receiving apparatus 102. Reference numeral 119 denotes a storage unit including a RAM or the like, which stores programs, data, and the like necessary for the control unit 118 to perform processing.

Reference numeral 120 denotes an input / output unit (I / O unit) which connects to the functions of each unit of the data receiving apparatus 102 to perform matching. 121 is a panel part (indicator & key sense)
And a display unit and a key input unit. Reference numeral 122 denotes an LF motor which carries the paper in the paper feed direction of the printer. A CR motor 123 drives a header to be printed on paper.

Reference numeral 124 denotes a head for discharging ink droplets based on raster image data onto a recording medium based on print data input via the I / O unit 120.

Reference numeral 125 denotes a header analysis unit which analyzes the header of the received data for synchronous transmission. Reference numeral 126 denotes an error check unit which detects the presence or absence of a data error by using an error check bit added to the received data.

Reference numeral 127 denotes a buffer for temporarily storing received data. A buffer 128 temporarily stores transmission data at the time of synchronous transmission. A buffer 129 temporarily stores transmission data at the time of asynchronous transmission. Reference numeral 130 denotes a synchronization control unit which controls data transmission / reception processing during synchronous transmission. 131 is an asynchronous control unit.
Controls data transmission / reception processing during asynchronous transmission.

Reference numeral 132 denotes an interface unit (I / F unit)
Then, transmission and reception of data satisfying the electrical and physical conditions are performed.
Reference numeral 133 denotes a period counter, which counts up by a signal indicating a certain period generated by the synchronization control unit 130 or extracted from another device via an I / F unit. Reference numeral 134 denotes a period number counter, which counts up with a signal indicating a certain period generated by the synchronization control unit 115 or extracted via an I / F unit from another device.

[Asynchronous Transmission Processing] First, when data is received by the asynchronous transmission processing, an error check of data and a handshake of data are performed by the asynchronous control unit, and correct data is stored in the buffer. The content of the received data is guaranteed.

On the other hand, when data is transmitted, it is guaranteed that the data stored in the buffer is reliably transmitted to the data receiving device.

However, since the data is transmitted while confirming that the data has been transmitted correctly, the data transmission time is not guaranteed. Therefore, the data transmission rate fluctuates considerably.

[Synchronous transmission processing] On the other hand, in the synchronous transmission processing, unlike asynchronous transmission, time is given priority, so that the transmission rate is guaranteed, but the data contents cannot be guaranteed.

Therefore, by adding an error correction bit or the like, it is possible to cope with some errors, but if an error occurs that cannot be corrected, it cannot be corrected. There is no guarantee.

For this reason, usually, even if an error is detected, there is not enough time to perform retransmission or the like, so that an error check can be performed on the receiving side, but retransmission of erroneous data is not performed.

However, in the present embodiment, the data transmission is synchronized with the data transmission in both directions, that is, the downlink data transmission from the data transmitting apparatus 101 to the data receiving apparatus 102 and the uplink data transmission from the data receiving apparatus 102 to the data transmitting apparatus 101. The data transmission method of the formula is adopted, the time interval of a fixed period (for example, a frame period) used in the synchronous data transmission is counted and the time is monitored, and the received data transmitted by the downlink data transmission in the above uplink data transfer. By transmitting the error information, it is possible to reliably transmit data while securing a certain data rate.

On the other hand, the transmitting side transmits the synchronous transmission data with an error check bit added thereto, and the receiving side detects the presence or absence of a data error based on the error check bit.

If an error is detected, the data receiving apparatus 102 transmits a refresh request for retransmitting data to the data transmitting apparatus 101, and starts transmitting data again from the data in which the error has occurred. As a result, while ensuring the transmission rate, the data contents can also be guaranteed, and efficient transmission is possible with a device having a small buffer capacity such as a serial printer.

As another method, starting from data transmission, the data receiving apparatus 102 transmits the data to the data transmitting apparatus 101.
To the data transmission device 10
On the one hand, the process of determining the next data to be transmitted on the basis of the result and transmitting the data is performed in synchronization with the synchronization timing, thereby facilitating time management easily and reliably and enabling efficient transmission. .

Hereinafter, the characteristic configuration of this embodiment will be described with reference to FIG.

The data transmitting apparatus and the data receiving apparatus transmit predetermined transmission data based on the same period signal via the predetermined communication medium (predetermined bidirectional interface, network) configured as described above. A data communication control system, comprising: first data holding means (buffer 128) for holding the predetermined transmission data; and first registration means (Registering a receiving-side no-response period notified from the data receiving device) The control unit 118 executes a control program stored in a ROM (not shown) or a memory resource (not shown) and performs registration processing in the storage unit 119).
First counting means (number-of-periods counter 133) for counting the non-response period of the receiving side registered by the registering means based on the same period signal, from the start of transmission of transmission data from the data transmitting apparatus. A first determination unit (the synchronization control unit 130 performs a determination process) to determine whether a type of a reply signal returned from the data receiving device is abnormal during the counting of the receiving-side non-response period by the first counting unit; And a first retransmission for retransmitting the transmission data held in the first data holding unit to the data receiving device when the first determination unit determines that the type of the return signal is abnormal. Means (the synchronization control unit 130 reads out from the buffer 128 and performs retransmission processing) and the first counting means from the start of transmission of transmission data from the data transmitting apparatus. Second determining means (determining by the synchronization control unit 130) whether or not a reply signal returned from the data receiving device has not been received by the end of the non-response period on the receiving side; When the determining means determines that the reply signal returned from the data receiving device has not been received, the transmission data held in the first data holding means is retransmitted to the data receiving device.
(The synchronization control unit 130 reads out from the buffer 128 and performs retransmission processing), so that during the synchronous communication processing with the data receiving apparatus, the receiving side that is notified from the data receiving apparatus that should receive the transmission data has no Even if the reply from the data receiving device does not exceed the predetermined time during the elapse of the response period, or even if an abnormal reply is notified, retransmission of the transmission data can be determined on the data transmitting side, which is an advantage of synchronous communication. If a transmission error occurs while ensuring communication at a constant data rate, the transmission data can be retransmitted without fail, so that the quality of the transmission data can be guaranteed.

A data communication control system in which a data transmitting device and a data receiving device transmit predetermined transmission data based on the same period signal via a predetermined communication medium (a predetermined bidirectional interface or network). A second data holding unit (a buffer 11) for receiving and holding the transmission data transmitted from the data transmission unit.
3), a second registration unit for registering the transmission-side non-response period notified from the data transmission device (registered in the storage unit 104 by the overall control unit 103), and the second registration unit A second counting unit (a period counter 134) for counting the transmission-side non-response period based on the same period signal, and a second counting unit that starts receiving transmission data from the data transmitting device. A third determining unit that determines whether the transmission data received from the data transmitting device is normal during the transmission-side non-response period counting (the synchronization control unit 115 performs a determination process); When it is determined that the transmission data is normal, the first response means for returning normal transmission data (the synchronization control unit 115 performs a response process (reply of ACK)), and If the transmission means determines that the transmission data is not normal, the transmission data held in the second data holding means is discarded, and a second reply means (synchronization control unit 115 transmits a transmission data abnormality) is returned. Reply processing (reply of NAK)) and receiving transmission data from the data transmission device from the start of reception of transmission data from the data transmission device to the end of the transmission-side non-response period by the second counting means. The fourth to determine whether
And a request for retransmission of transmission data to the data transmission device when the fourth determination device determines that transmission data has not been received from the data transmission device. (A synchronization control unit 115 performs a reply process (reply of a retransmission request packet)), so that the data transmission device to transmit the transmission data during the synchronous communication process with the data transmission device is provided. Even if the data transmission from the data transmitting device during the elapse of the non-response period of the receiving side notified from the user does not exceed the predetermined time, the data receiving side can request the retransmission of the transmission data, which is an advantage of synchronous communication. If a transmission error occurs while ensuring communication at the data rate, the transmission data can be retransmitted without fail, so the quality of the transmission data can be guaranteed. .

Further, the non-response period of the receiving side notified from the data receiving apparatus 101 is the same as that of the data receiving apparatus 10.
Since 1 is arbitrarily set, it is possible to monitor the response state of the data receiving device during an optimal non-response period depending on the data processing speed of the data receiving device, for example, the print processing speed.

The transmission-side non-response period notified from the data transmitting apparatus 102 is the same as that of the data transmitting apparatus 102.
Can be arbitrarily set, so that the data transmission state of the data transmission device can be monitored in an optimal non-response period depending on the data communication of the data transmission device.

Next, data transmission processing in the data transmitting apparatus 101 and the data receiving apparatus 102 shown in FIG. 1 will be described with reference to flowcharts shown in FIGS.

FIGS. 2 and 3 are flowcharts showing an example of a first data processing procedure in the data communication control system according to the present invention. The data transmitting apparatus 1 shown in FIG.
01 corresponds to the data communication process. In addition, (1)-
(26) shows each step.

First, it is determined whether or not the data transmission apparatus 102 starts data transmission (1). If it is determined that the data transmission is to be started, a notification of the number of non-response periods of the transmission apparatus is sent to the data reception apparatus 102. It is determined whether or not it is not (2), and if it is determined that the notification is to be made, a non-response period number notification is transmitted to the data receiving apparatus 102 (3), and the process proceeds to step (4).

On the other hand, if it is determined in step (2) that notification is not to be made, it is determined whether or not a packet has been transmitted (4). If it is determined that a packet has been transmitted, the transmission data is determined. The data is transferred from the storage unit 119 to the read buffer 128 (5), a header of the transmission data is generated (6), and transmitted as a transmission data packet to the data receiving apparatus 102 (7). The count value of the number-of-periods counter 133 for monitoring the response to this data is set to "0" and the count-up is started (8).

Next, it is determined whether or not data has been received from the data receiving apparatus 102 (12). If it is determined that there is received data, the number of non-response periods of the receiving apparatus notified from the data receiving apparatus 102 is determined. It is determined whether or not the number is the number of non-response periods of the receiving device (25).
6), the process proceeds to step (13). On the other hand, if it is determined that the number is not the number of non-response periods of the receiving device, the process proceeds to step (13).
Move to

Next, the count value of the number of periods of the period number counter 133 is set to "0", and counting is started (1).
3) It is determined whether or not the received data is an acknowledgment (ACK) packet (14). If it is determined that the received data is an ACK packet, a transmission corresponding to the acknowledgment (ACK) packet is transmitted from the transmission buffer 128. The data is deleted (15), and the process proceeds to step (4) shown in FIG.

On the other hand, if it is determined in step (14) that the received data is not an ACK packet,
It is determined whether or not the received packet is a K packet (16). If it is determined that a negative acknowledgment (NAK) packet has been received, the process proceeds to step (20). It is determined whether or not the packet is a retransmission request packet (17). If it is determined that the reproduction request packet has been received, the process proceeds to step (20). If it is determined that the retransmission request packet has not been received, another packet is received. The process is executed (18), and the process proceeds to step (24).

On the other hand, if it is determined in step (12) that no packet has been received, the data receiving apparatus 1
01 and the number of periods of the receiving device non-response period stored in the storage unit 119 and the number of periods (the period counter 133
(8) to determine whether the number of non-response periods of the receiving device is equal to or greater than the number of periods, and determine that the number of periods is equal to or less than the number of non-response periods of the receiving device. If it is determined that the period count is greater than the receiving device non-response period number, the data transmitted immediately before to the data receiving device 102 is read from the transmitting buffer 128 as retransmission data (step (12)). 20), generate header data (21), transmit the retransmission data packet to the data receiving apparatus 102 (22),
The count value of the number of periods of the period counter 133 is set to "0" to start counting up (23), and it is determined whether or not the data transmission has been completed (24). Go to step (4) shown in 2
If it is determined that the data transmission has ended, the data communication process ends.

On the other hand, if it is determined in step (4) that there is no packet transmission, the period number count (the period count value of the period number counter 133) is compared with the transmission device response period number. Is determined to be equal to or greater than the number of periods (9). If it is determined that the number of periods is equal to or less than the number of non-response periods of the transmitting device, the process proceeds to step (4), and If it is determined that the number is greater than the number of periods, error processing is performed (1
0), thereby determining whether or not to recover (11),
If it is determined to recover, the process proceeds to step (24), and if it is determined that recovery does not occur, the data communication ends.

FIGS. 4 and 5 are flow charts showing an example of the second data processing procedure in the data communication control system according to the present invention. The data receiving apparatus 1 shown in FIG.
It corresponds to the data communication process on the 02 side. In addition, (1)-
(24) shows each step.

First, the data receiving apparatus 102 determines whether or not to start data transmission (1). If it is determined that data transmission is not started, the process proceeds to step (1). If it is determined, it is determined whether to notify the number of non-response periods of the receiving device (2),
If it is determined that the number of non-response periods is to be notified, a notification of the number of non-response periods is transmitted to the data transmitting apparatus 101 (3), and the process proceeds to step (4).

On the other hand, if it is determined in step (2) that the number of the receiving device non-response periods is not notified, it is determined whether or not a packet has been received from the data transmitting device 102 (4). If it is determined that it has been received,
It is determined whether or not the data is data (5). If it is determined that the data is not data, it is determined whether or not the number of transmission device non-response periods notified from the data transmission device 102 is satisfied (6). If it is determined that the number of periods has been received, it is stored in the storage unit 104 and registered (7), and the process proceeds to step (32) shown in FIG. , Processing other than the data and the number of non-response periods of the transmission device is performed (8), and the process proceeds to step (32) in FIG.

On the other hand, if it is determined in step (5) that the received packet is data, the received data is stored in the buffer 113 (9), and the number of periods of the period counter 134 for counting the number of periods is stored. The count value is set to "0" and count-up is started (10).

Next, the result of the error check of the received data is determined (11). If it is determined that the data is abnormal (NG), the received data is stored in the buffer 11
Discard from step 3 (17) and proceed to step (28) and subsequent steps.
NAK packet data is generated, header data is generated by the header generation unit 110 (29), and the number of periods is compared with the number of non-response periods of the receiving device. Judge (30),
If it is determined that the period count is equal to or less than the receiving device non-response period, a NAK packet is transmitted to the data transmitting device (31), and the process proceeds to step (25). If it is determined that the value is larger, the process proceeds to step (26).

On the other hand, if it is determined in step (11) that the data is normal (OK), the header of the received data is analyzed and the received data No. Is recognized and stored in the storage unit 104 (12).

Next, the data No. It is determined whether or not the received data is retransmitted data (13). If it is determined that the received data is retransmitted data, it is determined whether or not the retransmitted data is already stored (14). If it is determined that the data is stored, the received retransmission data is discarded from the reception buffer 113 (15).
Move to step (21).

On the other hand, if it is determined in step (13) that the data is not retransmitted data, or if it is determined in step (14) that the data is not stored, it is recognized that the next new data has been received, and the received new data is received. The transferred data is transferred to the storage unit 104 (16), and ACK packet data is generated (2).
1), header data is generated by the header generation unit 110 (22), and the number of periods is compared with the number of non-response periods of the receiving device to determine whether or not the number of non-response periods of the receiving device is equal to or greater than the number of periods. 23) If the number of periods is equal to or less than the number of non-response periods of the receiving device, an ACK packet is transmitted to the data transmitting device 101 (24);
The count value of the number of periods of 4 is set to "0", counting is started (25), and it is determined whether or not to end the data transmission (32). If it is determined that the data transmission is not ended, The process proceeds to step (2), and if it is determined that the data transmission is to be terminated, the process is terminated.

On the other hand, if it is determined in step (23) that the period number count is larger than the receiving device non-response period number,
For example, if the period count exceeds either the number of non-response periods of the receiving device or the number of non-response periods of the transmitting device and an error occurs, the process proceeds to step (26) and error recovery processing for the error is performed. The process is executed to determine whether or not recovery has been made (27). If it is determined that recovery has been made, the process proceeds to step (32). If it is determined that recovery has not been made, the process ends.

On the other hand, if it is determined in step (4) that no packet has been received, the number of periods is compared with the number of non-response periods of the transmission device to determine whether the number of non-response periods of the transmission device is greater than or equal to the number of periods. (18), when it is determined that the period count is equal to or less than the transmission device non-response period number, the process proceeds to step (4), and it is determined that the period number count is greater than the transmission device non-response period number. In this case, it is determined whether or not to send a retransmission request (19). If it is determined that there is no retransmission request, the process proceeds to step (26). If it is determined that there is a retransmission request, the retransmission request is sent. The packet is transmitted (20), and the process proceeds to step (4).

Hereinafter, the characteristic structure of the present invention will be described with reference to FIGS.
This will be described with reference to FIG.

The data transmitting apparatus 102 and the data receiving apparatus 101 transmit predetermined transmission data based on the same period signal via the predetermined communication medium (predetermined bidirectional interface) configured as described above. A data communication method of a data communication control system, or controlling a data communication control system in which a data transmitting device and a data receiving device transmit and process predetermined transmission data based on the same period signal via a predetermined communication medium. A first storage step (not shown) of registering a non-response period of the receiving side notified from the data receiving apparatus in a memory resource, the storage medium storing a computer-readable program to be read by the computer; A first count for counting the non-response period of the receiving side registered in the registration step based on the same period signal. Degree (step of FIG. 2 (8),
(13), (23)) and a reply signal returned from the data receiving device during the counting of the non-response period of the receiving side in the first counting step from the start of transmission of transmission data from the data transmitting device. The first determination step (step (16) in FIG. 3) for determining whether the type of the return signal is abnormal, and is retained when the first determination step determines that the type of the return signal is abnormal. A first retransmission step of retransmitting transmission data to the data receiving apparatus (step (2) in FIG. 3)
0)) and a state in which a reply signal returned from the data receiving device is not received from the start of transmission of transmission data from the data transmitting device to the end of the receiving-side non-response period in the first counting step. The second to determine whether
(Step (19) in FIG. 3), and when the second determining step determines that the reply signal returned from the data receiving device has not been received, Since there is a second retransmission step (step (20) in FIG. 3) for retransmitting to the receiving apparatus, during the synchronous communication processing with the data receiving apparatus, the receiving side notified from the data receiving apparatus to receive the transmission data Even if the reply from the data receiving device does not exceed the predetermined time during the elapse of the no-response period, or even if an abnormal reply is notified, the data transmission side can determine the retransmission of the transmission data. If a transmission error occurs while ensuring communication at a certain data rate, the transmission data can be retransmitted without fail, ensuring the quality of the transmission data. .

A data communication control system in which the data transmitting apparatus 101 and the data receiving apparatus 102 transmit predetermined transmission data based on the same period signal via a predetermined communication medium (a predetermined bidirectional interface). A data communication method, or a computer that controls a data communication control system in which a data transmission device and a data reception device transmit predetermined transmission data based on the same period signal via a predetermined communication medium are readable. A second registration step (step (7) in FIG. 4) for registering a transmission-side non-response period notified from the data transmission apparatus in a memory resource, A second counting step of counting the transmission-side non-response period registered in the registration step based on the same period signal (FIG. 4) Step (10), and (25)),
A third determination for determining whether the transmission data received from the data transmission device is normal during the counting of the non-response period of the transmission side by the second counting means from the start of reception of the transmission data from the data transmission device; A step (step (11) in FIG. 4) and a first reply step (step (FIG. 5) in which the transmission data is returned normally when the transmission data is determined to be normal by the third determination step. 24))
And a second return step of discarding the held transmission data and returning a transmission data abnormality when the transmission data is determined to be abnormal in the third determination step (step (31) in FIG. 5). A) determining whether or not transmission data has been received from the data transmission device from the start of reception of transmission data from the data transmission device to the end of the transmission-side non-response period in the second counting step. (Step (18) in FIG. 4), and when it is determined in the fourth determination step that transmission data has not been received from the data transmission device, a request for retransmission of transmission data is sent to the data transmission device. Since there is a third reply process (step (18) in FIG. 4) for replying, during the synchronous communication process with the data transmitting device, the data transmitting device to which the transmission data is to be transmitted is notified. Even if the data transmission from the data transmitting device during the elapse of the non-response period of the receiving side does not exceed the predetermined time, the data receiving side can request the retransmission of the transmission data at a constant data rate which is an advantage of synchronous communication. In the case where a transmission error occurs while ensuring the above communication, the transmission data can be reliably retransmitted, so that the quality of the transmission data can be guaranteed.

The configuration of a data processing program readable by a printing system to which the data communication control device according to the present invention can be applied will be described below with reference to a memory map shown in FIG.

FIG. 6 is a diagram for explaining a memory map of a storage medium storing various data processing programs that can be read by a printing system to which the data communication control system according to the present invention can be applied.

Although not shown, information for managing a group of programs stored in the storage medium, for example, version information, a creator, etc. are also stored, and information dependent on the OS or the like on the program reading side, for example, a program is stored in the storage medium. An icon or the like for identification display may also be stored.

Further, data dependent on various programs is also managed in the directory. In addition, a program for installing various programs on a computer or a program for decompressing a program to be installed when the program to be installed is compressed may be stored.

The functions shown in FIG. 2, FIG. 3, FIG. 4, and FIG. 5 in this embodiment may be executed by a host computer by a program installed from the outside. In this case, the present invention is applied even when a group of information including a program is supplied to the output device from a storage medium such as a CD-ROM, a flash memory, or an FD, or from an external storage medium via a network. Things.

As described above, the storage medium storing the program codes of the software for realizing the functions of the above-described embodiments is supplied to the system or the apparatus, and the computer (or CPU or MP) of the system or the apparatus is provided.
It goes without saying that the object of the present invention is also achieved when U) reads and executes the program code stored in the storage medium.

In this case, the program code itself read from the storage medium realizes the novel function of the present invention, and the storage medium storing the program code constitutes the present invention.

As a storage medium for supplying the program code, for example, a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, C
DR, magnetic tape, nonvolatile memory card, RO
M, EEPROM and the like can be used.

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

Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, based on the instruction of the program code, The CPU provided in the function expansion board or function expansion unit performs part or all of the actual processing,
It goes without saying that a case where the function of the above-described embodiment is realized by the processing is also included.

According to the above embodiment, when the receiving apparatus is constituted by, for example, a serial printer or the like, if the data transmission rate is adjusted to the output speed of the printer, the throughput is reduced even if the receiving buffer is reduced in capacity. The cost performance is improved.

Further, since the capacity of the reception buffer is reduced and the throughput adjustment is not required, the cost can be reduced by simplifying the frame control.

Further, since only the count of the number of synchronization periods is used and a timer is not used, timer monitoring by software becomes unnecessary, or in the case of synchronizing with a synchronization signal from a partner device, Since the synchronization signal generator and the timer generator are not required, the cost can be reduced accordingly.

Further, since the timing of an arbitrary fixed period of the synchronous transmission system is used, the system can be further optimized by synchronizing the management of the processing time in the apparatus with this timing.

Further, since the number of non-response periods is variable and can be set remotely by notifying the partner device, it is easy to set the number of non-response periods to a large value even if there is a device with a slow response. Therefore, the system can be flexibly configured.

[0087]

As described above, the first embodiment according to the present invention is described.
According to the invention, a data communication control system in which a data transmitting device and a data receiving device transmit predetermined transmission data based on the same period signal via a predetermined communication medium, wherein the predetermined transmission data A first data holding unit for storing a receiving-side no-response period notified from the data receiving device; a receiving-side non-response period registered by the first registering unit. First counting means for counting the data based on the same period signal, and from the start of transmission of transmission data from the data transmitting apparatus, during the counting of the non-response period of the receiving side by the first counting means. First determining means for determining whether the type of the reply signal returned from the receiving device is abnormal, and when the first determining means determines that the type of the reply signal is abnormal A first retransmitting means for retransmitting the transmission data held in the first data holding means to the data receiving apparatus, and a first retransmission means for transmitting the transmission data from the data transmitting apparatus, A second determining means for determining whether or not a reply signal returned from the data receiving device has not been received by the end of the receiving-side non-response period; and the second determining means returning a response signal from the data receiving device. And a second retransmitting means for retransmitting the transmission data held in the first data holding means to the data receiving device when it is determined that a reply signal has not been received. During the synchronous communication process, when the reply from the data receiving device during the elapse of the receiving side non-response period notified from the data receiving device that should receive the transmission data does not exceed a predetermined time In the event that a transmission error occurs while ensuring communication at a constant data rate, which is an advantage of synchronous communication, the data transmission side can determine retransmission of transmission data even if an abnormal reply is notified. Since the transmission data can be reliably retransmitted, the quality of the transmission data can be guaranteed.

According to the second invention, there is provided a data communication control system in which a data transmitting apparatus and a data receiving apparatus transmit predetermined transmission data based on the same period signal via a predetermined communication medium, A second data holding unit that receives and holds the transmission data transmitted from the data transmission unit, a second registration unit that registers a transmission-side non-response period notified from the data transmission device, Second counting means for counting the transmission-side non-response period registered by the registration means based on the same period signal, and the second counting means from the start of reception of transmission data from the data transmission device. A third determining unit that determines whether the transmission data received from the data transmitting device is normal during the counting of the transmission-side non-response period by the third determining unit; A first return unit that returns normal transmission data when the transmission data is determined to be normal; and a second return unit that determines that the transmission data is not normal by the third determination unit. A second reply unit that discards the transmission data held in the data holding unit and returns a transmission data abnormality, and the transmission unit that starts the reception of the transmission data from the data transmission device by the second counting unit. Fourth determining means for determining whether or not transmission data has been received from the data transmitting apparatus before the end of the no-response period, and determining that the fourth determining means has not received transmission data from the data transmitting apparatus. In this case, there is provided a third return means for returning a retransmission request of the transmission data to the data transmission apparatus, so that the transmission data should be transmitted during the synchronous communication processing with the data transmission apparatus. Even if data transmission from the data transmission device during the elapse of the non-response period on the reception side notified by the data transmission device does not exceed a predetermined time, retransmission of transmission data can be requested on the data reception side, which is an advantage of synchronous communication. When a transmission error occurs while ensuring communication at a certain data rate, the transmission data can be retransmitted without fail, so that the quality of the transmission data can be guaranteed.

According to the third aspect, the non-response period on the receiving side notified from the data receiving device is arbitrarily set by the data receiving device, so that the data processing speed of the data receiving device, for example, the print processing speed, is reduced. It is possible to monitor the response state on the data receiving device side during the optimum non-response period that depends on it.

According to the fourth aspect, the transmission-side non-response period notified from the data transmission device is arbitrarily set by the data transmission device. The data transmission state of the data transmission device can be monitored during the period.

According to the fifth and seventh aspects of the present invention, there is provided a data communication control system in which a data transmitting apparatus and a data receiving apparatus transmit predetermined transmission data via a predetermined communication medium based on the same period signal. A data communication method, or a computer that controls a data communication control system in which a data transmission device and a data reception device transmit predetermined transmission data based on the same period signal via a predetermined communication medium are readable. Registering a non-response period of the receiving side notified from the data receiving device in a memory resource, wherein
A first counting unit that counts the non-response period of the receiving side registered in the first registration step based on the same period signal;
During the counting step and during the receiving-side non-response period counting by the first counting step from the start of transmission of transmission data from the data transmitting apparatus, whether the type of the reply signal returned from the data receiving apparatus is abnormal. The first to determine whether
And a first retransmission step of retransmitting the held transmission data to the data receiving device when the first determination step determines that the type of the return signal is abnormal,
It is determined whether or not a response signal returned from the data receiving device has not been received from the start of transmission of transmission data from the data transmitting device to the end of the non-response period of the receiving side in the first counting step. A second determining step of retransmitting the held transmission data to the data receiving apparatus when the second determining step determines that the return signal returned from the data receiving apparatus has not been received; During the synchronous communication process with the data receiving device, the reply from the data receiving device during the elapse of the receiving-side non-response period notified from the data receiving device that should receive the transmission data takes a predetermined time. Retransmission of transmission data can be determined by the data transmission side even if it does not exceed or when an abnormal reply is notified, and certain data which is an advantage of synchronous communication While ensuring communication over bets, when the transmission error can guarantee the quality of the transmitted data since it is possible to retransmit reliably transmit data.

According to the sixth and eighth aspects of the present invention, there is provided a data communication control system in which a data transmitting device and a data receiving device transmit predetermined transmission data via a predetermined communication medium based on the same period signal. A data communication method, or a computer that controls a data communication control system in which a data transmission device and a data reception device transmit predetermined transmission data based on the same period signal via a predetermined communication medium are readable. A second storage step of storing a transmission-side non-response period notified from the data transmission device in a memory resource.
A second counter that counts the transmission-side non-response period registered in the second registration step based on the same period signal.
Determining whether the transmission data received from the data transmission device is normal during the counting of the non-response period of the transmission side by the second counting means from the start of reception of the transmission data from the data transmission device. A third determining step of determining whether the transmission data is normal by the third determining step, a first returning step of returning normal transmission data, and the third determining step When it is determined that the transmission data is not normal, the second transmission step of discarding the transmission data held and returning an abnormal transmission data; and A fourth determining step of determining whether or not transmission data has been received from the data transmitting apparatus by the end of the transmitting-side no-response period by the counting step;
A third return step of returning a transmission data retransmission request to the data transmission apparatus when the fourth determination step determines that transmission data has not been received from the data transmission apparatus. During the synchronous communication process with the device, retransmission of the transmission data even if the data transmission from the data transmission device during the elapse of the non-response period of the receiving side notified from the data transmission device to which the transmission data is to be transmitted does not exceed a predetermined time. Can be requested on the data receiving side, and if a transmission error occurs while ensuring communication at a constant data rate, which is an advantage of synchronous communication, transmission data can be retransmitted without fail. Quality can be guaranteed.

Therefore, by utilizing the data transmission by the synchronous transmission method, it is possible to guarantee the data quality even in the synchronous transmission method while securing a constant data rate.
It is possible to optimize the data transmission process between the data receiving device and the data transmitting device.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an example of a printing system to which a data communication control system according to an embodiment of the present invention can be applied.

FIG. 2 is a flowchart illustrating an example of a first data processing procedure in the data communication control system according to the present invention.

FIG. 3 is a flowchart illustrating an example of a first data processing procedure in the data communication control system according to the present invention.

FIG. 4 is a flowchart showing an example of a second data processing procedure in the data communication control system according to the present invention.

FIG. 5 is a flowchart illustrating an example of a second data processing procedure in the data communication control system according to the present invention.

FIG. 6 is a diagram illustrating a memory map of a storage medium that stores various data processing programs that can be read by a printing system to which the data communication control device according to the present invention can be applied.

[Explanation of symbols]

 Reference Signs List 101 data transmission device 102 data reception device 103 overall control unit 104 storage unit 112 buffer 113 buffer 115 synchronization control unit 117 interface unit 118 control unit 127 buffer 128 buffer 130 synchronization control unit 132 interface unit 133 period counter 134 period counter 134

Claims (8)

[Claims] 1. A data communication control system in which a data transmitting device and a data receiving device perform transmission processing of predetermined transmission data based on a same period signal via a predetermined communication medium, wherein the predetermined transmission data is A first data holding unit for holding, a first registration unit for registering a non-response period of the receiving side notified from the data receiving apparatus, and a non-response period registered by the first registration unit. A first counting based on the same period signal;
And counting means for determining whether the type of a reply signal returned from the data receiving device is abnormal during the counting of the non-response period of the receiving side by the first counting device from the start of transmission of transmission data from the data transmitting device. First determining means for determining whether or not the type of the return signal is abnormal when the first determining means determines that the type of the return signal is abnormal; First retransmitting means for retransmitting the data to a device, and a reply signal returned from the data receiving device from the start of transmission of transmission data from the data transmitting device to the end of the non-response period of the receiving side by the first counting means. A second determining means for determining whether or not the data has not been received; and the second determining means determining that a reply signal returned from the data receiving device has not been received. And a second retransmitting means for retransmitting the transmission data held in the first data holding means to the data receiving device when the data communication control system receives the data. 2. A data communication control system in which a data transmitting device and a data receiving device transmit predetermined transmission data based on the same period signal via a predetermined communication medium, wherein the data transmission device transmits the predetermined transmission data. A second data holding unit that receives and holds the received transmission data, a second registration unit that registers a transmission-side non-response period notified from the data transmission device, and a second registration unit that is registered by the second registration unit. A second period in which the transmission-side non-response period is counted based on the same period signal.
Counting means for determining whether or not the transmission data received from the data transmission device is normal during the counting of the transmission-side non-response period by the second counting device from the start of reception of transmission data from the data transmission device. Third determining means for performing, when the third determining means determines that the transmission data is normal, first returning means for returning normal transmission data; and When it is determined that the transmission data is not normal, second transmission means for discarding the transmission data held in the second data holding means and returning a transmission data abnormality, and transmission data from the data transmission device. A fourth determination is made as to whether or not transmission data has been received from the data transmission device between the start of reception of the data and the end of the non-response period of the transmission side by the second counting means. Determining means; and third returning means for returning a transmission data retransmission request to the data transmitting apparatus when the fourth determining means determines that transmission data has not been received from the data transmitting apparatus. A data communication control system, comprising: 3. The data communication control system according to claim 1, wherein the non-response period on the receiving side notified from the data receiving device is arbitrarily set by the data receiving device. 4. The data communication control system according to claim 1, wherein the non-response period on the transmission side notified from the data transmission device is arbitrarily set by the data transmission device. 5. A data communication method of a data communication control system in which a data transmitting apparatus and a data receiving apparatus transmit and process predetermined transmission data based on a same period signal via a predetermined communication medium, wherein A first registration step of registering a reception-side non-response period notified from a reception device in a memory resource; and counting the reception-side non-response period registered in the first registration step based on the same period signal. First
During the counting of the receiving-side non-response period by the first counting step from the start of transmission of transmission data from the data transmitting apparatus, and whether the type of a reply signal returned from the data receiving apparatus is abnormal. A first determination step of determining whether the type of the return signal is abnormal, and a first retransmission of retransmitting the held transmission data to the data receiving apparatus when the first determination step determines that the type of the return signal is abnormal. And whether or not a reply signal returned from the data receiving device has not been received from the start of transmission of transmission data from the data transmitting device to the end of the receiving-side non-response period by the first counting process. A second determining step of determining whether or not a response signal transmitted from the data receiving apparatus has not been received; And a second retransmission step of retransmitting data to the data receiving apparatus. 6. A data communication method for a data communication control system in which a data transmitting device and a data receiving device transmit predetermined transmission data based on a same period signal via a predetermined communication medium, the data transmission method comprising: A second registration step of registering a transmission-side non-response period notified from the transmission device in a memory resource; and counting the transmission-side non-response period registered in the second registration step based on the same period signal. Second
And determining whether the transmission data received from the data transmission device is normal during the counting of the transmission-side non-response period by the second counting means from the start of reception of transmission data from the data transmission device. A third determining step of performing, when the transmission data is determined to be normal by the third determining step, a first returning step of returning transmission data normal; and If it is determined that the transmission data is not normal, discard the retained transmission data,
A second replying step for returning a transmission data abnormality, and from the start of reception of the transmission data from the data transmission apparatus to the end of the transmission-side non-response period in the second counting step, the transmission data from the data transmission apparatus. A fourth determination step of determining whether or not a transmission data has been received, and a request to retransmit the transmission data to the data transmission apparatus when it is determined in the fourth determination step that the transmission data has not been received from the data transmission apparatus. And a third replying step of replying the following. 7. A computer-readable program for controlling a data communication control system in which a data transmitting apparatus and a data receiving apparatus transmit predetermined transmission data based on the same period signal via a predetermined communication medium. A first storage step of registering, in a memory resource, a non-response period of a receiving side notified from the data receiving apparatus; and a non-response period of the receiving side registered in the first registration step. Is counted based on the same period signal.
During the counting of the receiving-side non-response period by the first counting step from the start of transmission of transmission data from the data transmitting apparatus, and whether the type of a reply signal returned from the data receiving apparatus is abnormal. A first determination step of determining whether the type of the return signal is abnormal, and a first retransmission of retransmitting the held transmission data to the data receiving apparatus when the first determination step determines that the type of the return signal is abnormal. And whether or not a reply signal returned from the data receiving device has not been received from the start of transmission of transmission data from the data transmitting device to the end of the receiving-side non-response period by the first counting process. A second determining step of determining whether or not a response signal transmitted from the data receiving apparatus has not been received; And a second retransmission step of retransmitting the data to the data receiving apparatus. 8. A computer readable program for controlling a data communication control system in which a data transmitting device and a data receiving device transmit predetermined transmission data based on the same period signal via a predetermined communication medium. A second registration step of registering a transmission-side non-response period notified from the data transmission device in a memory resource, and the transmission-side non-response period registered in the second registration step. Is counted based on the same period signal.
And determining whether the transmission data received from the data transmission device is normal during the counting of the transmission-side non-response period by the second counting means from the start of reception of transmission data from the data transmission device. A third determining step of performing, when the transmission data is determined to be normal by the third determining step, a first returning step of returning transmission data normal; and If it is determined that the transmission data is not normal, discard the retained transmission data,
A second replying step for returning a transmission data abnormality, and from the start of reception of the transmission data from the data transmission apparatus to the end of the transmission-side non-response period in the second counting step, the transmission data from the data transmission apparatus. A fourth determination step of determining whether or not a transmission data has been received, and a request to retransmit the transmission data to the data transmission apparatus when it is determined in the fourth determination step that the transmission data has not been received from the data transmission apparatus. And a third replying step of replying the following. A storage medium storing a computer readable program.