JPH09321754A - Data communication system, host-side data communication equipment and terminal-side data communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of a data communication error such as omission and ghost and the increase of data transmission by eliminating the generation of a charging pulse. SOLUTION: When a terminal-side data communication equipment 10 calls a host-side data communication equipment 20 to connect a public telephone line 40 to generate the charging pulse, a call-back request is transmitted to the host-side equipment 20. The host-side equipment 20 disconnects the line and calls the terminal side equipment 10 again to transmit/receive data through a general telephone line 30 which does not generate the charging pulse.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a public telephone line, etc.
The present invention relates to data communication performed using a telephone line in which a charge is collected when a charging pulse is generated.

[0002]

2. Description of the Related Art For example, in data transmission using a telephone line for public telephones, a charge pulse for fee collection may occur, resulting in missing or garbled communication data. It is necessary to retransmit the data in response to such missing communication data or garbled data. In that case, it has been considered that the transmission data is divided into a certain small size (block) and transferred for the purpose of minimizing the retransmission of the data.

Another control method is Japanese Patent Laid-Open No. 2-9.
As disclosed in Japanese Patent Publication No. 0865, it has been considered that the generation cycle of the charging pulse is acquired and the data transmission or the data reception is temporarily stopped at the generation timing of the charging pulse. As described above, conventionally, a data transfer method has been considered on the premise that a charging pulse is generated, and the main viewpoint is how to prevent the influence of the charging pulse.

[0004]

However, if the transmission data is divided into certain small blocks and transferred,
Since the total number of blocks to be transmitted increases, the burden required for blocking and the response processing required for each block also increase, resulting in a decrease in transfer efficiency. Also, if the method of acquiring the billing pulse generation period and temporarily stopping the data transmission / reception at the timing of the billing pulse generation is used, it takes an extra time to stop, especially for long-distance communication. Since the pulse is frequently generated, the transfer time is significantly increased.

The present invention has been made in order to solve the above-mentioned problems, and eliminates the generation of charging pulses and prevents the occurrence of data communication errors such as data loss and data corruption and the increase of data transfer time. The purpose is to

[0006]

Means for Solving the Problems and Effects of the Invention
The data communication system described in 1. connects the line with the terminal-side data communication device that may be connected to the telephone line where a charging pulse is generated when the line is processed and the line is connected. Then, in the data communication system for performing data communication with the host-side data communication device connected to the telephone line in which the charging pulse is not generated, the terminal-side data communication device has a charging pulse detection means for detecting the charging pulse. A call-back request for making a call-back call to the host-side data communication device when a charge pulse is detected by the charge-pulse detecting means when the host-side data communication device is called and a line is connected. Is transmitted, the line is disconnected, and a call from the host-side data communication device is awaited. When the return call request is received from the terminal side data communication device, the line is disconnected, and then the corresponding terminal side data communication device is called at a predetermined timing to perform data communication. It is characterized by being.

The data communication system is connected to a telephone line to which a public telephone, a so-called pink telephone, or the like is connected, that is, a telephone line in which a charging pulse is generated when the line is processed by calling to connect the line. It is connected to a telephone line that can connect a terminal-side data communication device that may be connected to a general telephone in the home, that is, a telephone line that does not generate a charging pulse even if the line is processed by calling to connect the line. Data communication is performed with the host side data communication device. In this case, when the host side data communication device calls the terminal side data communication device, there is no problem because the charging pulse does not occur.

However, when the data communication device on the terminal side calls the data communication device on the host side, a charging pulse may occur. To solve this problem, in the present invention, when the terminal side data communication device detects the occurrence of the charging pulse, the terminal side data communication device requests the host side data communication device to call back. As a result, the host-side data communication device connected to the telephone line where the charging pulse does not occur re-calls the terminal-side data communication device. by this,
Prevent the generation of billing pulses.

Next, the operation will be described in detail. First, the terminal side data communication device calls the host side data communication device and connects the line. At this time, a charging pulse may occur in the connected line. Then, if the charging pulse is not detected by the charging pulse detection means, normal data communication is performed, but if the charging pulse is detected, the terminal side data communication device causes the host side data communication device to re-call. A call-back request for sending to the host-side data communication device. The call back request includes information for the host-side data communication device to call back the terminal-side data communication device that has transmitted the request, for example, the telephone number of the terminal-side data communication device. When the terminal-side data communication device requests a call back from the host-side data communication device by transmitting a call-back request, the terminal-side data communication device performs line disconnection processing, such as on-hook, to perform processing from the host-side data communication device. Wait for a call.

On the other hand, when the host side data communication device receives the call back request sent by the terminal side data communication device, the host side data communication device disconnects the line by performing, for example, on-hook, and then the terminal side sending the call back call request. Call the data communication device and connect the line. Then, data communication is performed with the terminal side data communication device.

This makes it possible to prevent data loss and data corruption. In addition, in order to keep the data resend request to a minimum, it is not necessary to divide the transfer data into small pieces or to perform processing for avoiding the charging pulse such as stopping data transmission / reception at the charging pulse. There is no reduction in speed.

The "predetermined timing" described in claim 1 may be immediately after the host side terminal device receives the call back request and disconnects the line, or claim 2
Alternatively, it may be performed after performing a predetermined process as shown in FIGS. By the way, both the terminal-side data communication device and the host-side data communication device perform the line disconnection process such as on-hook, but either data communication device may perform the line disconnection process first. As a result, the communication line is disconnected by the data communication device that has previously performed the line disconnection process.

The line usage charge in the data communication system having such a configuration is such that when the terminal side data communication device calls the host side data communication device for data communication, the terminal side data communication device side uses the line. It is usual to pay the fee. However, in the data communication system of the present invention, in order to eliminate the generation of the charging pulse as described above, the data communication device on the host side calls the data communication device on the terminal side again. Therefore, the line usage fee will be charged to the host-side data communication device that normally does not have to pay, but the host-side data communication device must collect the line usage fee using, for example, a videotex system. Is possible.

Considering the present situation in which the usage fee of the public line connected to the pink telephone or the like is higher than the usage fee of the ordinary line connected to the home telephone or the like, the telephone line is connected to the ordinary line. Calling the data communication device on the terminal side from the data communication device on the host side to perform data communication means that the data communication device on the host side collects the line usage fee but pays the usage fee. Currently, it is considered to be advantageous to the side.

By the way, as such a data communication system, for example, a system in which a plurality of terminal side data communication devices are provided for one host side data communication device is conceivable. For example, a situation is conceivable in which the host-side data communication device serves as a place for sharing information and is accessed by a plurality of terminal-side data communication devices. In such a system, immediately after the host-side data communication device receives a call back request from the terminal-side data communication device, the terminal-side data communication device that has sent the call-back request is called to perform data communication. When configured,
A situation may occur in which another terminal side data communication device cannot access until the end of the data communication.

In order to solve such a situation, claim 2
The configuration shown in is effective. That is, the host-side data communication device further includes a call request storage unit that stores the received call return request and another call return request storage unit that stores a call return request request when the call return request is stored in the call request request storage unit. And a calling presence / absence judging means for judging presence / absence of a calling from the terminal side data communication device, and when the calling presence / absence judging means judges that there is a calling from another terminal side data communication device, If a line is connected between another terminal side data communication device and the calling presence / absence determining means determines that there is no call from another terminal side data communication device,
In the call back request stored in the call request storage means, the call to the corresponding terminal-side data communication device is not made, and the terminal corresponding to the call back request stored at the oldest time point. The configuration is such that the data communication device on the side is called to perform data communication.

In this case, the host side data communication device stores the return call request transmitted from the terminal side data communication device in the call request storage means. When the return call request is stored in the call request storage means at the time of disconnecting the line, the call presence / absence determining means always determines the presence / absence of a call from another terminal side data communication device. Here, when there is a call from another terminal side data communication device, data communication is performed with the other terminal side data communication device in response to the other terminal side data communication device first. .
When the other terminal side data communication device further transmits a call back request, this call back request is also stored in the call request storage means and the line is disconnected. At this time, if the call presence / absence determining means determines that there is a call from a terminal side data communication device other than the above two terminal side data communication devices, the terminal side data communication device is further determined. Data communication with.

On the other hand, only when there is no call from another terminal side data communication device, the terminal side data communication device that has transmitted the return call request based on the return call request stored in the call request storage means. Is reissued from the host-side data communication device to perform data communication. If a plurality of call-back call requests are stored, the host-side data communication device stores the oldest call-back call request sent by the terminal-side data communication devices that have not yet made call-back calls. The call-back request. That is,
A call is made from the data communication device on the host side, and the data communication device on the terminal side, which has been waiting for the call from the data communication device on the host side for the longest time, is called. As described above, when a plurality of requests for call back are stored, the terminal-side data communication device is called in the order in which the requests are stored. At the time when the data communication with the terminal side data communication device is completed and the line is disconnected, the calling presence / absence judging means judges whether or not there is a call from another terminal side data communication device and repeats the above processing.

As described above, when a line with a data communication device on a terminal side is disconnected, a call from another data communication device on another terminal side is detected every time, so that a plurality of data communication devices on the terminal side can transmit data on the host side. The opportunity to access the communication device can be increased. Further, as described in claim 1, since the transfer efficiency is not deteriorated by the charging pulse, the time for one terminal side data communication device to occupy the host side data communication device is shortened. Therefore, in a system where the host-side data communication device is frequently accessed, for example,
This is desirable because it is possible to increase the number of terminal-side data communication devices that can perform data communication during the day, and also to increase the opportunity to access the host-side data communication device from the terminal-side data communication device.

By the way, in the above-mentioned structure of the present invention, when a data communication device on one terminal side transmits a call back request, another data communication device on another terminal continues to make a call. It is possible that the host side data communication device does not make a return call.

Therefore, the data communication system according to claim 3 is intended to solve such a situation. That is, in the data communication system, even when the call presence / absence determining unit determines that there is a call from another terminal side data communication device, the call to the corresponding terminal side data communication device is not made. If the predetermined time has elapsed from the time when the oldest call back request was stored among the call back call requests that have not been made, the terminal-side data communication device that transmitted the call back call request is called. It is characterized in that it is configured to perform data communication.

In this case, the host-side data communication device, even when the call presence / absence determining means determines that there is a call from another terminal-side data communication device, transmits the return call request for a predetermined time. When there is a terminal side data communication device waiting for a call from the host side data communication device, the terminal side data communication device is called to perform data communication.

As a result, even when a call from another terminal-side data communication device continues, the terminal-side data communication device that has transmitted the call-back request is always sent from the host-side data communication device within a predetermined time. , And data communication can be performed. Further, a host-side data communication device which is effective in a data communication system as described above is provided by claim 4.
As shown in FIG. 5, in the host side data communication device connected to the telephone line where the charging pulse is not generated when the line connection is performed by the calling process, the call back call for making the call back call to the host side data communication device Data communication is possible with a terminal side data communication device capable of transmitting a request, and when the return call request is received from the terminal side data communication device, the line is disconnected once and then at a predetermined timing. It is characterized in that it is configured to perform data communication by calling a corresponding terminal side data communication device.

The operation of the data communication device on the host side has been described in the above description of the operation of the data communication system, and will not be repeated here. Further, also in such a host side apparatus, as described in claim 5, further, the call-back request storage means for storing the received call-back call request and the call-back request request are stored in the call-request storage means. When the line is disconnected, it is provided with a call presence / absence determining means for determining presence / absence of a call from another terminal side data communication device, and the call presence / absence determining means makes a call from another terminal side data communication device. If it is determined that there is a call, the line is connected to the data communication device on the other terminal side, while the call presence / absence determining means determines that there is no call from the data communication device on the other terminal side. In the case where the call-back request storage means stores a call-back request, the call to the corresponding terminal-side data communication device has not been made,
The data communication device corresponding to the return call request stored at the earliest time is configured to perform data communication by calling the data communication device on the terminal side. The opportunity for the device to access the host-side data communication device can be increased.

Further, as described in claim 6, even when the calling presence / absence judging means judges that there is a calling from another terminal side data communication apparatus, the corresponding terminal side data communication apparatus is called. If a predetermined time has elapsed from the time when the oldest call-back request was stored, the terminal-side data communication device that sent the call-back request By making a configuration for making a call from the host side data communication device, even if a call from another terminal side data communication device continues, a call back request is sent and a call is made from the host side data communication device. The terminal side data communication device waiting for the call can be called from the host side data communication device within a predetermined time.

A terminal-side data communication device which is effective in the above-mentioned data communication system is, as described in claim 7,
A terminal side data communication device that may be connected to a telephone line where a charging pulse is generated when a line is connected after calling processing is performed, and the terminal side data communication device receives the transmitted call back request. Data communication is possible with a host-side data communication device capable of making a call, and a charging pulse detection means for detecting a charging pulse is provided, and the host-side data communication device is called and a line is connected. Upon connection, when a billing pulse is detected by the billing pulse detecting means, a return call request for returning a call to the host side data communication device is transmitted, the line is disconnected and the host side data communication device is disconnected. It is characterized in that it is configured to wait for a call from.

The operation of the data communication device on the terminal side has been described in the above description of the operation of the data communication system, and will not be repeated here.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of a data communication system 1 of this embodiment. The data communication system 1 includes a terminal-side data communication device 10 as a “terminal-side data communication device” and a host-side data communication device 20 as a “host-side data communication device”.
It is composed of The terminal side data communication device 10 is
It is possible to connect to either a telephone line that generates a charging pulse or a telephone line that does not generate a charging pulse. When the host-side data communication device 20 is called, the connection is established via either the public telephone line 40 in which the charging pulse is generated or the general telephone line 30 in which the charging pulse is not generated. On the other hand, the host-side data communication device 20 does not generate the charging pulse when the line is connected after the call processing is performed and the general telephone line 3
Connect to a telephone line that can be connected with 0.

It is assumed that the host side data communication device 20 is alternately accessed by a plurality of terminal side data communication devices 10 as described later. Next, the configurations of the terminal-side data communication device 10 and the host-side data communication device 20 will be described. The terminal-side data communication device 10 and the host-side data communication device 20 have similar configurations.

Therefore, first, the components common to the terminal side data communication apparatus 10 and the host side data communication apparatus 20 will be described. As common constituent elements, a CPU 11 (21) as a control means, a RAM 12 (22) as a temporary storage means for a work area and the like, a ROM 13 (23) as a program storage means, and data modulation and demodulation. Connect the line between the modem 14 (24) and the network
NCU (Network Control Un) that disconnects and dials
It: network controller 15 (25). Here, the numbers written in parentheses () are symbols attached to the components of the host-side data communication device 20. The CPU 21 of the host-side data communication device 20 corresponds to "calling presence / absence determining means".

Next, different components of the terminal side data communication device 10 and the host side data communication device 20 will be described. First, the terminal-side data communication device 10 is provided with a charging pulse detection circuit 16 as "billing pulse detection means" for detecting the presence or absence of a charging pulse. On the other hand, the host-side data communication device 20 includes a memory device 26 as a "calling request storage means" for storing a "callback request" sent from the terminal-side data communication device.

Here, the operation of the data communication system 1 of this embodiment will be described with reference to the flow charts of FIGS. 2, 3 and 4. FIG. 2 is a flowchart showing the operation of the terminal-side data communication device 10. The present invention is intended to prevent data communication in which a charging pulse is generated when a call is made from the terminal side data communication device 10,
The terminal side data communication device 10 is the host side data communication device 2
Consider the case of calling 0.

First, in step S100, off-hook is performed to prepare for connection of a line. Next, S11
At 0, the host-side data communication device 20 is dialed, the host-side data communication device 20 is called, and the line is connected. When the line connection is completed, in S120, a flag K for substituting the detection result of the charging pulse in preparation for detection of the charging pulse.
Is initialized to 0. Next, in S130, the interrupt process is permitted. Only when the interrupt processing is permitted, the interrupt processing is performed by the signal from the charging pulse detection circuit.

Here, based on the flowchart of FIG.
An interrupt process performed when the charging pulse detection circuit 16 of the terminal side data communication device 10 detects a charging pulse will be described. This interrupt processing is executed by the CPU 11 of the terminal side data communication device 10 in response to a signal from the charging pulse detection circuit 16.

In the first step S500, the flag K of the charging pulse detection result is set to 1 (indicating that the charging pulse has been detected). Then, once the charging pulse is detected, the interrupt process is prohibited in S510 so that the interrupt process does not occur, and the process ends. Next, returning to the description of FIG.
Data is transmitted and received in the processing of S140 to S160. S
At 140, data transmission / reception is performed in block units (units of a plurality of bytes). Then, in S160, the completion of data transmission / reception is determined. If the completion of data transmission / reception is not determined in S160 (S160: NO), the process proceeds to S140 and the next data block is transmitted / received.

In S150, it is determined whether or not the flag K = 1 (whether the billing pulse is detected) every time data in block units is transmitted or received in the data transmission / reception process of S140. When K = 1 is not satisfied (S150: NO), that is, when the charging pulse is not detected, the process proceeds to S160 and data transmission / reception is continued. When flag K = 1 (S
150: YES), that is, when the charging pulse is detected, the data transmission / reception process of S140 to S160 is interrupted and the process proceeds to S190.

When the charging pulse is not detected (K = 0 in S150 at all times) and the completion of data transmission / reception is determined in S160 (S160: YES), the process proceeds to S170, the interrupt process is prohibited, and the on-hook operation is performed in S180. And disconnect the line. In this case, the processing is the same as the conventional data transmission / reception.

When the charging pulse is detected, the terminal side data communication device 10 transmits a return call request to the host side data communication device 20 in S190. And S20
On-hook at 0 and disconnect the line. Next, S2
At 10, it is determined whether or not there is a call back request from the host-side data communication device 20 in response to the transmitted call back request. If there is a return call from the host-side data communication device 20 (S210: YES), the process proceeds to S220. When the return call is not made from the host side data communication device (S210: NO), the determination of S210 is repeated until the return call is made from the host side data communication device.

When the return call is made from the host-side data communication device 20, the off-hook operation is performed in S220, and the line is connected to the return call from the host-side data communication device 20. After that, the processing of S230 and S240 is repeated to transmit and receive data. In S230, data is transmitted or received in block units, and in S240, the completion of data transmission / reception is determined. When the data transmission / reception is not completed (S240: NO), the process proceeds to S230 again,
Send or receive the next block of data. When data transmission / reception is completed (S240: YES), on-hook is performed in S250 to disconnect the line and end the process.

Next, the main processing of the host-side data communication device 20 will be described based on the flowcharts of FIGS. 3 and 4. The main process is a process performed in response to a call from the terminal side data communication device 10 described based on the flowchart of FIG.

First, in the first step S310, it is determined whether or not there is a call from the terminal side data communication device 10.
When there is no call from the terminal side data communication device 10 (S3
10: NO) continues this process until it is determined that there is a call from the terminal side data communication device 10. Figure 2 here
When a call is made from the terminal side data communication device 10 by the processing of S100 and S110 in the above (S310: YE
In S) and S320, the off-hook is performed, and the line is connected to the call originated from the terminal side data communication device 10.

After the line is connected, data is transmitted and received in S330 to S350. This processing is a data transmission / reception processing performed corresponding to the data transmission / reception processing of S140 to S160 of the terminal side data communication device 10 in FIG. S330
In, data is transmitted and received in a predetermined block unit. Then, in S340, it is determined for each data transmission / reception in block units whether or not the return call request transmitted from the terminal side data communication device 10 by the processing of S190 in FIG. 2 is received. When the return call request is received (S340: YES), the process proceeds to S360 and the received return call request is stored in the memory device 26 shown in FIG.
On-hook is performed in S370, and the line is disconnected once during data transmission / reception. When the return call request is not received (S340: NO), the data transmission / reception (S330) is continued until the data transmission / reception is completed (S350: NO). Then, when it is determined in S350 that the data transmission / reception is completed (S350: YES), on-hook is performed in S370 to disconnect the line. If it is determined that the data transmission / reception has been completed (S350: YES),
This is the case where the charging pulse is not detected by the terminal-side data communication device 10, which means that the same processing as the conventional data communication is performed.

Subsequent processing moves to S380 shown in FIG. In S380, it is determined whether or not the return call request is stored in the memory device 26 shown in FIG. Memory device 2
When the call back request is not stored in 6 (S38)
0: NO), the process from S310 of FIG. 3 is repeated. On the other hand, when the call back request is stored in the memory device 26 (S380: YES), the process proceeds to S390.

In S390, the host side data communication device 2 among the call back request stored in the memory device 26 is executed.
Data communication device 10 on the terminal side where 0 is not calling back
It is determined whether or not there is a call-back request sent from the terminal for which a predetermined time has passed. For example, in the present embodiment, the predetermined time is 1 hour. In this case, S3
At 90, there is a call back request sent from a certain terminal-side data communication device 10 and stored, and a call back request for which one hour has passed after being stored in the call back request not yet issued. To judge. When there is a call back request of an uncalled one hour after storing (S3
90: YES), and moves to S410. If there is no call back request for an uncalled one hour that has been stored (S390: NO), the process proceeds to S400.

In S400, it is determined whether or not there is a call from another terminal side data communication device 10 other than the terminal side data device 10 which transmitted the call back request. At this time, if there is a call from another terminal side data communication device 10 (S4
00: YES), the process proceeds to S320 in FIG. 3 and data communication is performed with the other terminal side data communication device 10.
If there is no call from another terminal side data communication device 10 (S400: NO), the process proceeds to S410.

In step S410, the off-hook operation is performed, and the terminal-side data communication device 10 that has transmitted the call back request is prepared to call back. At this time, if an affirmative judgment is made in S390, there is a possibility that a call is made from another terminal side data communication device 10, and in that case the dial operation cannot be performed. Therefore, in S412, it is determined whether a dial tone has been detected. When the dial tone is not detected (S412: NO), that is, when there is a call from another terminal side data communication device 10, the process proceeds to S414 to perform on-hook, and waits for 2 seconds in S416 and then S410. Repeat the process from. On the other hand, if a dial tone is detected (S412: YES), that is, if there is no call from another terminal side data communication device 10, S
Move to 420. In subsequent S420, the memory device 26
The terminal-side data communication device 10 that has transmitted the call-back call request stored at the oldest time among the call-back call requests that have not been called and is stored in (1) is called. At this time, the terminal-side data communication device 10 that has transmitted the call back request disconnects the line (S200 in FIG. 2), and the host-side data communication device 2
Waiting for a return call from 0 (S21 in FIG. 2)
0). Therefore, when the host-side data communication device 20 makes a call, the terminal-side data communication device 10 goes off-hook (S220 in FIG. 2). As a result, the line is connected to the call (S420) of the host-side data communication device 20.

In S430 and S440, data is transmitted and received. This data transmission / reception process corresponds to the data transmission / reception process of the terminal side data communication device 10 of S230 and S240 in FIG. In S430, data transmission / reception in block units is performed, and in S440, it is determined whether the data transmission / reception is completed. If data transmission / reception has not been completed (S440:
If NO, the process proceeds to S430 and the data transmission / reception in S430 and S440 is repeated. If data transmission / reception is completed (S440: YES), the process from S380 is repeated after on-hooking and disconnecting the line in S450.

As described above, when the terminal-side data communication device 10 calls the host-side data communication device 20 and connects the line to generate the charging pulse, the terminal-side data communication device 10 makes a call back request. Host-side data communication device 2
0 (S190 in FIG. 2), and waits for a call back from the host-side data communication device (S21 in FIG. 2).
0). On the other hand, when the host side data communication device 20 receives the return call request, the host side data communication device 20 stores it in the memory device 26 (S360 in FIG. 3) and issues the terminal side data communication device 10 corresponding to the stored return call request. A call is made (S420 in FIG. 3) to perform data transmission / reception. At this time, as described above, the host-side data communication device 20 is connected to the telephone line that does not generate the charging pulse even if the call processing is performed and the line is connected. When the side data communication device 10 is called back and the line is connected, the connection is always made through the general telephone line 30 in which the charging pulse is not generated. As a result, it is possible to prevent the charging pulse from being generated, and it is possible to prevent data loss and data corruption. Further, the processing for avoiding the charging pulse, which has been conventionally considered, for example, to divide the transfer data into small pieces in order to minimize the data retransmission request, and to stop the data transmission / reception in synchronization with the charging pulse. Since it is not necessary to perform any special processing, the transfer speed does not decrease.

In the data communication system 1 of the present invention, in order to eliminate the generation of the charging pulse as described above, the host side data communication device 20 is changed to the terminal side data communication device 1.
I try to call back 0 again. for that reason,
A line usage fee is charged to the host-side data communication device 20 side, which normally does not need to pay, but the host-side data communication device 20 must collect the line usage fee using, for example, a videotex system. Is possible.
In addition, the usage fee of the public telephone line 40 connected when calling from a pink telephone or the like is higher than the usage fee of the general telephone line 30 connected when calling from a home telephone or the like. Considering that, when the calling process is performed, the host side data communication device 20 connected to the general telephone line 30 calls the terminal side data communication device 10 to perform data communication. Although the usage fee is collected, it is considered to be advantageous at present for the terminal side data communication device 10 side who pays the usage fee.

By the way, the data communication system 1 of the present embodiment is premised on that one terminal side data communication device 20 is accessed by a plurality of terminal side data communication devices 10. Therefore, in the host-side data communication device 20 of the present embodiment, S390 and S4 shown in FIG.
In the processing of 00, a plurality of terminal side data communication devices 10
The following measures have been taken for access from.

In the data communication system 1 as described above, when the host side data communication device 20 is occupied by one terminal side data communication device 10, another terminal side data communication device 10 cannot easily access. The situation can occur. Therefore, in the host-side data communication device 20 of this embodiment, a certain terminal-side data communication device 1
The return call request from 0 is stored in the memory device 26 (S360), and it is determined whether there is a call from another terminal side data communication device 10 (S400). Then, when there is a call from another terminal side data communication device 10, a line is connected to the other terminal side data communication device 10 to perform data communication. As a result, another terminal-side data communication device 10 is transferred to the host-side data communication device 20.
Can increase the opportunities to access.

When the call from another terminal side data communication device 10 continues, a return call request is transmitted (S190 in FIG. 2) and the host side data communication device 20 waits for a call. (S210 in FIG. 2) A situation is conceivable in which the terminal side data communication device 10 does not call back forever.

Therefore, in the host-side data communication device 20 of the present embodiment, there is an uncall back call request even if one hour has elapsed in the call back request stored in the memory device 26. If so, it is judged (S39
0), prioritizing a response to another terminal-side data communication device 10, calls back the terminal-side data communication device 10 corresponding to the call-back request. As a result, even if calls are continuously made from another terminal-side data communication device 10, the terminal-side data communication device 10 that has transmitted the call-back request is not delayed by at least one hour. The host side data communication device 20 is always called back, and data communication can be performed. As described above, the present invention is not limited to such an embodiment at all, and can be implemented in various forms without departing from the gist of the present invention.

For example, in the above embodiment, the data communication system 1 including the host-side data communication device 20 that is frequently accessed by the plurality of terminal-side data communication devices 10 is considered. Data communication device 1
In the host-side data communication device 20 in which access from 0 is not frequently performed, it is not necessary to perform the above determination process.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a data communication system.

FIG. 2 is a flowchart showing main processing in a terminal side data communication device.

FIG. 3 is a flowchart showing a first half of a main process in the host-side data communication device.

FIG. 4 is a flowchart showing the latter half of the main processing in the host-side data communication device.

FIG. 5 is a flowchart showing an interrupt process accompanying detection of a charging pulse in the terminal-side data communication device.

[Explanation of symbols]

1 ... Data communication system 10 ... Terminal side data communication 20 ... Host side data communication system 11,21 ... CP
U 12,22 ... RAM 13,23 ... RO
M 14,24 ... Modem 15,25 ... NC
U 16 ... Charge pulse detection circuit 26 ... Memory device 30 ... General telephone line 40 ... Public telephone line

Claims (7)

[Claims] 1. A charging pulse is generated when a call processing is performed and a line is connected, and a terminal side data communication device that may be connected to a telephone line that generates a charging pulse is connected. In a data communication system for performing data communication with a host-side data communication device connected to a telephone line, in which the terminal-side data communication device includes a charging pulse detection unit for detecting a charging pulse, When a billing pulse is detected by the billing pulse detection means when the host side data communication device is called and a line is connected, a call back request for sending back a call to the host side data communication device is transmitted. , And disconnects the line to wait for a call from the data communication device on the host side, while the data communication device on the host side is connected to the terminal side. When the return call request is received from the data communication device, the line is disconnected, and then the corresponding data communication device on the terminal side is called at a predetermined timing to perform data communication. Characteristic data communication system. 2. The data communication system according to claim 1, wherein the host-side data communication device further includes a call request storage unit that stores the received call back request, and a call request storage unit. When the return call request is stored, a call presence / absence determining unit for determining presence / absence of a call from another terminal side data communication device when the line is disconnected is provided, and the call presence / absence determining unit determines another If it is determined that there is a call from the terminal-side data communication device, a line is connected to the other terminal-side data communication device, while the call-presence / absence determining means determines another terminal-side data communication. If it is determined that there is no call from the device, in the call back request stored in the call request storage means, the call to the corresponding terminal-side data communication device has not been made, and Oldest Data communication system, characterized in that by calling the terminal side data communication apparatus satisfying stored folded call request at point is configured to perform data communication. 3. The data communication system according to claim 2, wherein the host-side data communication device determines that there is a call from another terminal-side data communication device by the call presence / absence determining unit. Even if there is a call to the corresponding terminal-side data communication device, if the predetermined time has elapsed from the time when the oldest call back call request was stored among the call back call requests that were not made, A data communication system configured to call a terminal-side data communication device that has transmitted a call back request and perform data communication. 4. A host-side data communication device connected to a telephone line in which a charging pulse is not generated when a line is connected by performing a calling process, and a return call for causing the host-side data communication device to return a call. Data communication is possible with a terminal-side data communication device capable of transmitting a request, and when the return call request is received from the terminal-side data communication device, the line is disconnected once and then at a predetermined timing. A host-side data communication device, which is configured to make a data communication by calling a corresponding terminal-side data communication device. 5. The host-side data communication device according to claim 4, further comprising a call request storage unit that stores the received call return request, and the call request storage unit that stores the call return request. If stored, the terminal includes a calling presence / absence judging means for judging whether or not there is a calling from another terminal side data communication device when the line is disconnected, and the calling existence / non-existence judging means allows the terminal side data communication device to If it is determined that there is a call from the other terminal side data communication device, a line is connected to the other terminal side data communication device, while the call presence / absence determining means determines that a call from another terminal side data communication device is made. If it is determined that there is no call, the call-back request stored in the call-request storage means has not been called to the corresponding data communication device on the terminal side, and is stored at the oldest time. Back from departure The host-side data communication apparatus, characterized in that by calling the terminal side data communication apparatus satisfying the request is configured to perform data communication. 6. The host-side data communication device according to claim 5, which is applicable even when the call presence / absence determining unit determines that there is a call from another terminal-side data communication device. If a predetermined time has elapsed from the time when the oldest call-back call request was stored without calling to the terminal-side data communication device, the call-back call request is sent. And a host-side data communication device configured to make a data communication by calling the terminal-side data communication device. 7. A data communication device on the terminal side, which may be connected to a telephone line where a charging pulse is generated when a call processing is performed and the line is connected, receives the transmitted call-back request and receives the call-back request. Data communication is possible with a host-side data communication device capable of calling the terminal-side data communication device, and a charging pulse detection means for detecting a charging pulse is provided, and the host-side data communication device is When a charging pulse is detected by the charging pulse detecting means when a call is made and the line is connected, a return call request for making a return call to the host side data communication device is transmitted, the line is disconnected and A terminal-side data communication device, which is configured to wait for a call from the host-side data communication device.