JPH07175737A - Data transmitting device and method - Google Patents

Abstract

PURPOSE:To provide a data transmitting device/method which can recover the MODEM of the receiver side in a unidirectional data communication system where data are sent to a terminal equipment such as a display terminal from a host computer. CONSTITUTION:A 1st communication controller 50a included in a training signal adding device 10 receives the user data from a DTE 1a of a host computer and stores these data in a reception buffer 31. A timer 40 counts the timings to add the training signals and applies an interruption to a CPU 60. The CPU 60 sets the training signal data to a transmission buffer 32 when an interruption is received and otherwise sets the user data on the buffer 31 to the buffer 32 respectively. Then a 2nd communication controller 50b sends the data on the buffer 32 to a MODEM 2a in a data transmitting device/method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmitting apparatus used for data communication using a modem, and more particularly to a data transmitting apparatus capable of automatically recovering a receiving modem diverged in one-way communication. And its data transmission method.

[0002]

2. Description of the Related Art First, a conventional data communication apparatus using a modem will be described with reference to FIG. FIG. 3 is a configuration block diagram of a conventional data communication device. As shown in FIG. 3, a conventional data communication apparatus includes a data terminal equipment (Data Terminal Equipment: hereinafter referred to as DTE) 1a on a transmitting side and a line terminating equipment (Data Circuit Terminating).
Equipment: hereinafter referred to as DCE) 2a, DTE 1b on the receiving side, DCE 2b, and further DCE 2a and DC
It is composed of a communication line 3 capable of bidirectional communication for connecting to the E2b.

Next, the function of each part will be specifically described.
The DTEs 1a and 1b are terminal devices that transmit and receive data, and generally transmit information data from a host computer, which is the transmitting DTE 1a, and receive the DTE 1
It is often displayed on the display terminal device which is b.

DCE2a, 2b are DTE1a, 1
A device that connects a communication line in response to a request from b, confirms synchronization, and controls transmission / reception of data via the communication line 3. In a general communication line, an automatic synchronization function is provided. I'm supposed to use my own modem. The communication line 3 is a communication line capable of bidirectional communication.

Next, a data transmission method in the conventional data communication apparatus will be described. In a conventional data communication device, for example, when data is transmitted from DTE1a to DTE1b, when a transmission request is made from DTE1a to DCE2a, first the modem A of DCE2a sends the modem B of DCE2b to the direction A of communication line 3. Send a training signal using the line, perform a handshake that is an operation to check synchronization, and check the synchronization.
Start sending user data in the direction.

During the data communication, if the modem B becomes out of synchronization and a divergent state occurs in which the data transmitted from the modem A cannot be received normally, the modem B communicates with the modem A. A training signal resend request signal is sent out using the line B direction of the line 3 to notify that the modem B has diverged and request to resend the training signal in order to resynchronize.

Upon receiving the training signal resend request signal from the modem B, the modem A suspends the transmission of the user data, transmits the training signal, synchronizes again, and then resumes the transmission of the user data. Has become.

Next, in the conventional data communication apparatus, the DTE 1 on the transmitting side is the host computer and the DT on the receiving side is
FIG. 4 shows a case where E1b is a plurality of display terminal devices.
Use to explain. FIG. 4 is a configuration block diagram of a second conventional data communication device.

As shown in FIG. 4, the data communication apparatus of the second conventional example has one DTE 1 on the transmission side, DCE 2 connected to DTE 1, a unidirectional communication line 3 ', and a communication line 3 Signal distribution device 4 for distributing the data transmitted via the DCEs 2b to the plurality of DCEs 2b, and the plurality of reception side DCEs 2b
And a DTE 1b respectively connected to the plurality of DCEs 2b.

Next, the operation of each part of the data communication apparatus of FIG. 4 will be described in detail. DTE1 is a host computer which is a DTE on the transmission side, and DCE2 is a DTE1.
Is a modem A for transmitting data transmitted from the host computer to the communication line 3 ', and the communication line 3'is a communication line capable of unidirectional communication from the host computer to the terminal of the DTE 1b.

The signal distribution device 4 is a device for distributing the data transmitted from the host computer to the terminal devices of the plurality of DTEs 1b, and the DCE 2b.
Is a modem B that receives the data distributed by the signal distribution device 4, and DTE 1b is a terminal device that displays the data transmitted from the host computer.

In the data communication apparatus of the second conventional example, a plurality of DTs are connected from the host computer of DTE1.
Although it is good to transmit data in a 1: n configuration to the E1b terminal device, conversely, if an attempt is made to transmit a training signal resend request signal or the like from the terminal device to the host computer, an n: 1 configuration will result. Since the terminals may collide with each other, it is not possible to transmit a signal from the terminal device side to the host computer, and therefore, there is no choice but to perform unidirectional communication from the host computer to the display terminal device. is there.

As a result, before starting the transmission of the user data, the training signal is sent from the modem A to the modem B via the signal distribution device 4 to perform the handshake.
Although it is possible to start transmitting user data after confirming the synchronization, even if one of the modems B loses synchronization due to divergence during the data communication, the modem B transmits to the modem A. It was impossible to send the training signal resend request signal.

[0014]

Therefore, in the data communication apparatus of the second conventional example, there is no choice but to perform unidirectional communication from the host computer to the terminal apparatus such as the display terminal, and therefore the receiving modem. However, there is a problem in that the training signal resend request signal is sent from B to the modem A and the diverging reception side modem B cannot be recovered.

The present invention has been made in view of the above situation, and in unidirectional data communication from a host computer to a terminal device such as a display terminal, data transmission capable of recovering a divergent receiving modem. An object is to provide an apparatus and a data transmission method thereof.

[0016]

According to a first aspect of the present invention for solving the problems of the conventional example, a host computer for transmitting data and a modem for transmitting the data to a communication line for one-way communication are provided. In a data transmitting apparatus having: a reception buffer for accumulating data transmitted from the host computer, a transmission buffer for storing data to be transmitted to the modem, and a synchronization check between the host computer and the modem, A timer for counting the timing of adding a training signal to be interrupted, a first communication control controller for receiving the data transmitted from the host computer and accumulating it in the reception buffer, and accumulating in the reception buffer. Transferred data to the transmit buffer when there is no interrupt from the timer And a second communication controller that transmits the data set in the transmission buffer to the modem, and a main control unit that sets the data of the training signal in the transmission buffer when there is an interrupt from the timer. Is provided with a training signal adding device having

According to a second aspect of the present invention for solving the above-mentioned problems of the conventional example, in the data transmitting method of the data transmitting apparatus according to the first aspect, the data transmitted from the host computer by the first communication controller Received and stored in the receive buffer, the timer counts the timing of adding the training signal and interrupts the main control unit.When the main control unit receives an interrupt from the timer, the training signal data is set in the transmission buffer. Then
When there is no interruption from the timer, the accumulated data is transferred from the reception buffer to the transmission buffer and set, and the second communication control controller transmits the data set in the transmission buffer to the modem. There is.

[0018]

According to the first aspect of the present invention, the training signal adding device is provided between the host computer and the modem, and the first communication control controller inside the training signal adding device transmits data transmitted from the host computer. Received and stored in the receive buffer, the timer counts the timing of adding the training signal and interrupts the main control unit.When the main control unit receives an interrupt from the timer, the training signal data is set in the transmission buffer. However, when there is no interrupt from the timer, the data stored in the reception buffer is transferred to the transmission buffer and set, and the second communication control controller serves as a data transmission device that transmits the data set in the transmission buffer to the modem. Therefore, the first communication control controller receives and the main control unit A training signal is added and a training signal is mixed and transmitted at a constant interval between data transmitted from the host computer by performing each processing by a separate controller as if transmitted by the second communication control controller. Therefore, it is possible to send a training signal to the modem on the receiving side at regular intervals without minimizing the decrease in transfer rate and without causing data loss, and to use data that uses a unidirectional communication line. Even the transmitting device can prevent the modem on the receiving side from diverging.

According to the second aspect of the present invention, the first communication control controller receives the data transmitted from the host computer and stores the data in the reception buffer, and the timer counts the timing at which the training signal is added The control unit interrupts, the main control unit sets the training signal data in the transmission buffer when there is an interrupt from the timer, and transfers the data accumulated in the reception buffer to the transmission buffer when there is no interrupt from the timer The data transmission method of the data transmission device according to claim 1, wherein the second communication control controller transmits the data set in the transmission buffer to the modem.
Training signals can be mixed at regular intervals between the data sent from the host computer and sent to the receiving modem. Even if the data sending method uses a unidirectional communication line, the receiving modem It is possible to prevent divergence.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration block diagram of a data transmitting apparatus according to an embodiment of the present invention. It should be noted that parts having the same configuration as in FIG.

The configuration of the data transmitting apparatus of this embodiment is similar to that of the conventional data communication apparatus, and the DTE on the transmitting side is used.
(Data Terminal Equipment) 1a and a DCE (Data Circuit Terminating Equipmen) that sends data from the host computer to the communication line.
t) 2a, which is a modem A and a unidirectional communication line 3 ', and a DTE1
The training signal addition device 10 is provided between a and the DCE 2a.

This training signal adding device 10 is
An OM 20, a RAM 30 including a reception buffer 31, a transmission buffer 32, and a training signal area 33;
A timer 40 and two communication control controllers 50a,
50b and CPU60 are provided.

The configuration of the receiving side for receiving the transmission data transmitted from the data transmitting apparatus of this embodiment is the same as the conventional one, and if it is one-to-one communication, one pair as shown in FIG. D
If the communication is composed of TE and DCE and is one-to-many communication, FIG.
One signal distributor and multiple pairs of DTE and DCE
And any of them may be used in the present embodiment.

Next, the operation of each part of the data transmitting apparatus of this embodiment will be concretely described. The DTE 1a is a host computer that transmits user data as in the conventional case, and
CE2a is a modem A for transmitting the user data transmitted from the host computer and the training signal added by the training signal addition device 10 to the communication line 3 ', and the communication line 3'is a terminal such as a display terminal from the host computer. It is a communication line capable of unidirectional communication toward the device.

Next, the internal configuration of the training signal adding apparatus 10, which is a characteristic part of this embodiment, will be specifically described. The ROM 20 includes a control program for adding a training signal, training signal data to be added,
This is a read-only memory that stores an interval value to which a training signal is added.

The RAM 30 has a reception buffer 31, a transmission buffer 32, and a training signal area 3 inside.
3 is a writable memory, and the reception buffer 31 is a FIFO (First In First Out) buffer having a certain capacity, which is used for temporarily storing the user data transmitted from the host computer,
The transmission buffer 32 is a buffer for setting data to be transmitted via the DCE 2a.

The training signal area 33 is an area for storing training signal data to be added to the user data at regular intervals, and the training signal data stored in advance in the ROM 20 is used as the training signal adding device 1.
It is designed to copy when 0 is started.

The timer 40 is a timer used to count the timing of adding the training signal, and causes the CPU 60 to generate an interrupt at every training signal addition interval preset in the ROM 20 to output the training signal. It is designed to let you know when to add.

Next, the first communication controller 50a
Is a controller that receives the user data sent from the host computer of the DTE 1a and sequentially stores it in the FIFO reception buffer 31 in the RAM 30, and the second communication control controller 50b is set in the transmission buffer 32 in the RAM 30. It is a controller that sends the data to the modem A of the DCE 2a.

The CPU 60 is a main control section for controlling the inside of the training signal adding device 10. Specifically, the control program for adding the training signal stored in the ROM 20 operates to allow the receiving buffer 31 to operate. Transfer and set user data to the send buffer 32,
By setting the training signal data in the training signal area 33 in the transmission buffer 33 by interruption from the timer 40 which occurs at regular intervals, the training signal is added to the user data at regular intervals.

Next, a data transmitting method in the data transmitting apparatus of this embodiment will be described. The data transmitting method in the data transmitting apparatus of the present embodiment is such that the user data transmitted from the host computer is once taken into the training signal adding apparatus 10 and the training signal adding apparatus 1 is used.
Within 0, the training signal is mixed into the user data at regular intervals and transmitted to the unidirectional communication line 3'via the DCE 2a.

Specifically, first, the CPU 60 copies the training signal data stored in the ROM 20 to the training signal area 33 of the RAM 20 when the training signal adding device 10 is started up, starts the timer 40, and stores it in the ROM 20. The CPU 60 is set to generate an interrupt in accordance with the stored training signal addition interval, the control program stored in the ROM 20 is read, and the CPU 60 is activated.

On the other hand, the first communication controller 50a is
User data transmitted from the host computer of the DTE 1a is received and stored in the reception buffer 31 which is a FIFO buffer in the RAM 30 at any time.

Then, in the CPU 60, the control program operates to normally read the user data accumulated in the reception buffer 31 which is a FIFO buffer, transfer it to the transmission buffer 32 as it is, and set it. However, only when there is an interrupt from the timer 40, the training signal data copied in the training signal area 33 is transferred to the transmission buffer 32 and set.

Also, the second communication controller 50b
Sends the user data or training signal data transferred and set in the transmission buffer 32 to the DCE 2 and transmitted to a terminal device such as a display terminal via the communication line 3 '.

Next, the flow of processing of the control program in the data transmitting method of the data transmitting apparatus of this embodiment will be concretely described with reference to FIGS. 1 and 2. Figure 2
It is a flowchart figure which shows the flow of a process of the control program in the data transmission method of the data transmission apparatus of a present Example.

Training signal adding apparatus 10 of the present embodiment
It is stored in the internal ROM 20 and the CPU 60
The control program started up first determines whether there is an interrupt from the timer 40 (100), and if there is, sets the training signal data in the training signal area 33 to the transmission buffer 32 (200), Return to 100.

In process 100, if there is no interrupt,
Read user data from the receive buffer 31 (30
0), it is determined whether there is user data (30
1), if there is, send the user data to the transmission buffer 32
(310) and the process returns to the process 100. If there is no user data, the process returns to the process 100. The control program of this embodiment ends when the power is turned off.

According to the data transmitter of this embodiment, the DT
The reception buffer 31 that temporarily stores the user data transmitted from the host computer of E1a is a FIFO buffer having a relatively large capacity, and the first communication control controller 50a performs the process of receiving the user data from the host computer. Since the CPU 60 and the control program perform the processing of mixing the training signal into the data, and the second communication control controller 50b performs the processing of transmitting the data to the modem A of the DCE 2a, the respective controllers distribute the processing. As a result, it is possible to minimize the decrease in the transfer rate as a whole, and do not worry about missing data when mixing the training signal, and perform data transmission with the training signal mixed regularly. Data transmission using unidirectional communication line An apparatus is effective can prevent divergence of the receiving modem also.

Further, according to the data transmitting method of the data transmitting apparatus of this embodiment, the user data transmitted from the host computer is temporarily stored in the receiving buffer 31 in the training signal adding apparatus 10, and the user data is transmitted at regular intervals. Since the training signal is mixed in and transmitted from the transmission buffer 32, the modem on the receiving side can regularly receive the training signal and resynchronize, and as a result, the unidirectional communication line can be obtained. Even with the data transmission method using, there is an effect that the divergence of the modem on the receiving side can be prevented.

[0041]

According to the first aspect of the present invention, a training signal addition device is provided between the host computer and the modem, and the first communication control controller inside the training signal addition device is transmitted from the host computer. Data is received and accumulated in the receive buffer, the timer counts the timing at which the training signal is added, and interrupts the main controller.When the main controller receives an interrupt from the timer, the training signal data is sent to the buffer. And a data transmission device that transfers the data accumulated in the reception buffer to the transmission buffer and sets it when there is no interruption from the timer, and the second communication control controller transmits the data set in the transmission buffer to the modem. Therefore, the first communication control controller receives the The training signal is added by the control unit, and the processing is performed by a separate controller so that the second communication control controller transmits the training signal, so that the training signal is mixed at a constant interval between the data transmitted from the host computer. Since it is transmitted, the training signal can be periodically transmitted to the modem on the receiving side with a minimum decrease in transfer speed and without causing data loss, etc., and a unidirectional communication line can be established. Even the used data transmission device has an effect of preventing divergence of the receiving modem.

According to the second aspect of the present invention, the first communication control controller receives the data transmitted from the host computer and accumulates it in the reception buffer, and the timer counts the timing of adding the training signal to the main communication controller. The control unit interrupts, the main control unit sets the training signal data in the transmission buffer when there is an interrupt from the timer, and transfers the data accumulated in the reception buffer to the transmission buffer when there is no interrupt from the timer The data transmission method of the data transmission device according to claim 1, wherein the second communication control controller transmits the data set in the transmission buffer to the modem.
Training signals can be mixed at regular intervals between the data sent from the host computer and sent to the receiving modem. Even if the data sending method uses a unidirectional communication line, the receiving modem It has the effect of preventing divergence.

[Brief description of drawings]

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

FIG. 2 is a flowchart showing the flow of processing of a control program in the data transmission method of the data transmission device of this embodiment.

FIG. 3 is a configuration block diagram of a conventional data communication device.

FIG. 4 is a configuration block diagram of a data communication device of a second conventional example.

[Explanation of symbols]

1a, 1b ... DTE, 2a, 2b ... DCE, 3,
3 '... communication line, 4 ... signal distribution device, 10 ... training signal addition device, 20 ... ROM, 30 ... RA
M, 31 ... Receive buffer, 32 ... Transmit buffer,
33 ... Training signal area, 40 ... Timer,
50a, 50b ... Communication control controller, 60 ... CPU

Claims (2)

[Claims] 1. A data transmission device comprising a host computer for transmitting data and a modem for transmitting the data to a communication line for one-way communication, wherein the data is transmitted from the host computer between the host computer and the modem. A buffer for storing data to be transmitted, a transmission buffer for storing data to be sent to the modem,
A timer that counts the timing of adding a training signal used for synchronization confirmation and interrupts; a first communication control controller that receives the data transmitted from the host computer and accumulates it in the reception buffer; A main control unit that transfers the data accumulated in the buffer to the transmission buffer when there is no interrupt from the timer and sets the data, and sets the training signal data to the transmission buffer when there is an interrupt from the timer; A data transmission device, comprising: a training signal addition device having a second communication controller for transmitting the data set in the transmission buffer to the modem. 2. A first communication control controller receives data transmitted from a host computer and accumulates the data in a reception buffer, and a timer counts the timing at which a training signal is added and interrupts the main control unit. The control unit sets the data of the training signal to the transmission buffer when there is an interrupt from the timer, and transfers and sets the accumulated data from the reception buffer to the transmission buffer when there is no interrupt from the timer,
2. The data transmitting method of the data transmitting apparatus according to claim 1, wherein the second communication control controller transmits the data set in the transmission buffer to the modem.