JP2619652B2 - Data transmission equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a data transmission device, and more particularly to a data transmission device that facilitates data monitoring and the like when performing data communication with another device via a modem. It is.

(Prior Art) When a data terminal device such as a computer transmits data via a communication line or the like, modulation and demodulation for converting a signal form output from the terminal device into a signal conforming to a use condition of a transmission line. A device (hereinafter, referred to as a modem) and a network controller (hereinafter, referred to as an NCU) for connecting the modem to a transmission line such as a telephone line are used. Things were common.

FIG. 4 is a diagram showing a conventional connection method between a transmission line and a terminal device or the like, wherein telephone lines L ₁ and L ₂ are connected to NCU ₁ ;
The output end of NCU 1 is connected to modem 2. Furthermore, modem 2
Between the signal transmission terminal SD ₁ and the signal receiving end RD ₁ of the switching circuit 3
One of the switches SW ₁ and the terminal device including a computer or the like via the SW ₂ (hereinafter, referred to as terminals) 4 of the signal receiving end
RD ₂ and the signal transmitting end SD ₂ are connected to each other.

Further, a controller 5 is provided in addition to the NCU and the modem, and the controller 5 controls the NCU and the modem by a command signal from a terminal.

The transmitting / receiving terminals SD ₂ and RD ₂ of the terminal 4 are connected to the NCU via the modem, and the switches SW ₁ and SW of the switching circuit 3
₂ is connected to the signal transmitting / receiving terminals SD ₃ and RD _{3 of the} controller 5.

In the data transmission device configured as described above, when transmitting a signal from the terminal 4 to the telephone line, first, the changeover switch is switched to the terminal b by a command signal from the terminal, and the signal from the terminal is transmitted to the controller. 5 is controlled.

After controlling the modem 2 and NCU1 in accordance with a command signal from the controller 5, the terminal 4, the signal transmission end SD ₃
A signal to the effect that the initial state setting has been completed is sent to the terminal via the terminal.

Upon receiving this signal, the terminal 4 controls the changeover switch 3 via the controller 5 and switches SW ₁ , SW ₂
Is switched to a, and the required data is transmitted to the telephone lines L ₁ and L ₂ via the modem 2.

As is well known, the modem 2 converts the digital signal from the terminal 4 into a signal format allowed by the telephone lines L ₁ and L ₂ , for example, the digital code “1” “0” corresponds to an analog signal such as a different tone signal. And output it.

In the conventional data transmission device, as described above, the signal input / output terminal of the data terminal is switched to either the modem or the controller by using the changeover switch. This makes it impossible to transmit a command to the device, and cannot perform forced interruption or other signal monitoring during data transmission or reception.

Conventionally, in order to solve this drawback, for example, as shown in FIG.
The transmission / reception circuit is always duplexed so that the transmission / reception signal can be monitored at all times.However, to achieve this, it is not enough to duplicate only the transmission line at the end. A similar transmission / reception device had to be added to the input / output signals. For this reason, there have been the drawbacks that the apparatus configuration becomes very complicated and that the apparatus becomes large and expensive.

(Objects of the Invention) The present invention has been made in view of the above, and has been made without complicating the configuration, and monitors data or control signals of a modem or the like and controls interrupts and the like when performing data communication using a modem. It is an object of the present invention to provide a data transmission device that can arbitrarily perform the data transmission.

(Summary of the Invention) In order to achieve the above object, in a data communication apparatus according to the present invention, a control signal from a data terminal (terminal) to a controller is transmitted via a modem (modem), and the controller and the modem are transmitted. In this case, a signal is always supplied from the terminal. That is, the data transmission device of the present invention includes a modulation / demodulation device that modulates / demodulates data from the communication line or to the communication line, and a controller that controls the modulation / demodulation device based on a signal from the data terminal device. Among the transmission data and the control signal output by the data terminal device, a leak component circulating from the transmission side to the reception side at the inside or the input / output end of the modem is input, and the modem is controlled based on the leak component. It is characterized by the following.

(Embodiment) Hereinafter, an embodiment of the data transmission device of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing an embodiment of a data transmission device according to the present invention, wherein L ₁ and L ₂ are telephone lines, NCU 7 is a network control device, reference numeral 9 is a controller, and 10 is a terminal including a computer ( In this embodiment, a signal output SD from the terminal 10 is output to the modem 8 and an input signal to the terminal 10 is output from the controller 9. Further, the NCU 7 and the modem are transmitted from the telephone line. 8 are all inputted to the controller 9,
Part of it is sent to terminal 10.

The NCU 7 and the modem 8 are both controlled by a control signal from a controller 9, and the controller 9 is controlled by an echoed-back signal from a terminal 10 received via the modem.

As in this embodiment, if all the contents of communication performed via the modem are input to the controller 9 and a part of the communication is fed back to the terminal, control of the controller is always performed regardless of the data transmission / reception mode. Since the communication can be performed and the communication contents can be monitored, interruption and monitoring become extremely easy.

Next, a specific method of echoing back a signal from the modem to the controller will be described with reference to an actual example.

First, in FIG. ₁ , received signals from the lines L ₁ and L ₂ are input to the controller 9 via the modem 8 and further transmitted to the terminal 10, so that monitoring of the received signals is easy.

However, since the purpose of the signal SD from the terminal 10 is to be sent to the NCU 7 via the modem 8, the signal from the terminal 10 input to the modem 8 is fed back to the controller 9 in the embodiment shown in FIG. It is necessary to add a means to do this.

As a means for this feedback, for example, when transmitting a signal from the terminal 10 to the NCU, a leakage component between transmission lines indicated by a broken line in the modem is demodulated by the modem, and wraps around to the controller as indicated by a dashed line. In some cases, however, this wraparound is actively utilized in the present embodiment.

That is, a circuit for preventing the sneaking into the terminal is conventionally inserted into the modem. In this embodiment, the sneaking is positively used. In other words, if the wraparound level is appropriate, the SD signal output from the terminal reaches the NCU via the modem, but a part of the signal leaks and is input from the modem to the controller.

Therefore, the controller can monitor the data transmitted from the terminal, so that data insertion such as a long space can be performed relatively easily.

In the above embodiment, the case where a leak component of a signal between lines that is originally undesirable is used is shown. However, as shown in FIG. 2, the signal transmitted by the terminal is transmitted to the NC through the modem as shown in FIG.
U and the transmission signal from the terminal may be branched and transmitted directly to the controller via a modem.

FIG. 3 is a block diagram showing a modified embodiment of the present invention, in which the transmission output terminal SD of the terminal 10 is connected to the transmission signal input terminal SD of the modem 11, and the reception signal output terminal RD of the modem 11 is connected to the controller 12. In addition to the controller at the reception signal input terminal RD
Twelve transmission signal output terminals SD are connected by an RS232C interface to input to the reception signal input terminal RD of the terminal 10.

On the other hand, the telephone lines L ₁ and L ₂ are connected to the input / output terminals L ₁ and L _{2 of the} modem 11 and the NCU dial circuit 14 via the changeover switch 13, and the NCU dial line 14 is controlled by the output of the controller 12. It is configured to:

 The operation of the above configuration will be described.

First, when a dial command signal is output from the terminal 10 via the RS232C interface, the dial command signal is input to the SD terminal of the modem 11 via the SD terminal and is output to the b terminal of the changeover switch 13 and at the same time, a part of the signal is output. The content is sent from the RD terminal of the modem 11 to the RD of the controller 12, and the contents thereof are read.

A part of the dial command signal input to the controller 12 is also distributed to the NCU dial circuit 14, and the dial signal generated based on this signal is changed by the changeover switch 13
Are transmitted to the telephone lines L ₁ and L ₂ via the terminal a, and a communication partner is selected.

In this state, since the changeover switch 13 is connected to the terminal a, the signal from the modem is not output to the telephone line. Therefore, even if various control signals are output from the terminal 10, there is another problem. , The modem and the controller can be controlled.

When the line connection with the communication partner is completed, the changeover switch 13 is connected to the terminal b by the controller, and the terminal 10 is connected.
Is output to the telephone line via a similar route.

Also in this case, the data transmitted from the terminal 10 to the communication partner is transmitted to the controller 12, which monitors the data and sends necessary signals to the terminal 10 via the SD terminal.

Conversely, the data sent from the communication partner is
Is once sent to the controller 12 via the RD terminal, and is monitored by the controller 12 and output to the terminal 10 via the SD terminal.

In this way, data is sent and received,
In any case, since the data and the control signal pass through the controller 12, their monitoring is easy, and control such as a control interrupt can be arbitrarily performed.

(Effects of the Invention) As described above, the present invention is configured to input a leakage component between transmission lines in a modem to a controller, so that monitoring of data or control signals when data communication is performed using the modem is not required. This is always possible, and interrupts, interruptions, data modifications, and the like can be arbitrarily performed as needed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention. FIG. 2 is a partial block diagram showing a modified embodiment of the present invention. FIG. 3 is a block diagram showing another modified embodiment of the present invention. FIG. 4 and FIG. 5 are block diagrams for explaining the prior art. 7 NCU (network control circuit) 8, 11 Modem 9, 12 Controller 10 Terminal 13 Changeover switch 14 NCU dial circuit

Claims (1)

(57) [Claims] 1. A data transmission device used when a data terminal device performs data transmission with another data terminal device via a communication line, the modem device modulating and demodulating data from or to the communication line. A controller that controls the modem based on a signal from the data terminal device, wherein the controller is configured to transmit data and control signals output by the data terminal device, inside or at an input / output end of the modem device. A data transmission device, comprising: a leakage component circulating from a transmission side to a reception side; and controlling the modulation / demodulation device based on the input.