JPS62190955A - Connection control system for data communication circuit - Google Patents

Abstract

PURPOSE:To confirm the connection of a circuit and to securely instruct that a communication is ready by transmitting and receiving a fixed pattern signal between connected data terminal interface devices, and switching transmission lines in the data terminal interface devices. CONSTITUTION:When data terminal interfaces 1b and 1c detect the 1st fixed pattern signal for confirmation through a connected circuit by monitoring circuits 14, their pattern signal generating circuits 12 generate and send out the 2nd fixed patterns to the circuit side. The data terminal interface devices 1b and 1c at the time of detecting the 2nd fixed pattern signals by the monitoring circuits 14 perform switching by origination-side switching circuits 13 and termination-side switching circuits 16 so that the fixed pattern signals from the sending data terminal interface devices 1b or 1c is sent out to the opposite data terminal interface device 1c or 1b. Consequently, the instruction of the communication ready state is sent to a data terminal device 2 at the same time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to data communication in a communication network using digital transmission, and particularly to a data communication line connection control system for data communication via a plurality of cables.

〔overview〕

The present invention provides a data communication line connection control system that includes a data terminal device and a data terminal interface device that is connected to the data terminal device and controls the data terminal device. In the respective data terminal interface devices on the receiving side and the receiving side, a third fixed pattern signal is given to each data terminal device, which instructs the data terminal device to wait for communication. ) to confirm the line connection, the line connection is confirmed by detecting the first fixed pattern signal sent in the same way from the receiving side, and then the above data A second fixed pattern signal that instructs the terminal device to enable communication is sent to each destination data terminal interface, the second fixed pattern signal is detected, and it is applied to the data terminal device to enable communication. By providing a means for doing so, it is possible to confirm the connection of the line and then simultaneously send and receive data, thereby ensuring reliable data communication.

[Conventional technology]

FIG. 6 is a block diagram showing the main points of the configuration of a conventional data communication system. Multiple data terminal equipment (DTE)
2 are each data terminal ink face equipment (DCE)
Time division switch (TDSW) 3 in exchange 6 via 1
The connection is controlled by the iB controller (CG) 4 on the central processing side.

Conventionally, in these data communications, when the data terminal interface device 1 indicates that the line connection to the data terminal device 2 is completed, that is, the communication is possible, the exchange 6 selectively connects the line and waits for a response from the called terminal. For example, the data terminal interface device 1 was controlled to issue an instruction to the data terminal device 2 to complete line connection.

[Problems that the invention attempts to solve]

In the conventional data communication line connection control method described above, the sixth
In the case of data communication within one exchange as shown in the figure, there is only one exchange 6 that controls the line and controls the data terminal interface device 1, so the data terminal devices 2 that are trying to communicate with each other are , instructions to complete the line connection are issued almost at the same time, and data communication can be started without any problems.

However, when data communication is performed through a plurality of exchanges 6 as shown in FIG. 2, the exchanges 6 that control each line and data terminal interface device are different. Therefore, instructions to complete the line connection cannot be given to the data terminal devices 2 on the calling and receiving sides at the same time. When the data terminal device 2 starts data communication immediately upon receiving an instruction to complete the line connection, there is no guarantee that the line will be connected at the exchange 6 located in the middle. Since there is no guarantee that the completion instruction has been issued and the data communication preparation state has been reached, there is a drawback that normal data communication cannot be performed in such a case.

It is an object of the present invention to provide a data communication line connection control method that eliminates the above-mentioned drawbacks and simultaneously sends out an instruction signal indicating that communication is possible after confirming the line connection, thereby ensuring reliable data communication. Our goal is to provide the following.

[Means for solving problems]

The present invention provides a data communication line connection control method that includes a data terminal interface device that is connected to a data terminal device and controls the data terminal device. a first pattern signal generating means for generating a second fixed pattern signal that allows communication to be given; a multiplexed signal in which the transmission data from the data terminal device and the control 'a signal are multiplexed; and the first pattern signal generating means. a second pattern signal generating means for generating a third fixed pattern signal for instructing the data terminal device to wait for communication; and the third fixed pattern. a means for switching between the signal and a multiplexed signal received from a connection destination and outputting the same to the data terminal device; and a monitoring means for detecting reception of the received multiplexed signal and the first and second fixed pattern signals. It is characterized by

[Effect]

In the present invention, when there is a call from a data terminal device on the sending side, the data terminal interface devices on both the sending side and the receiving side first receive a second pattern signal from the second pattern signal generating means that puts the data terminal device on communication standby. Three fixed pattern signals are provided to each data terminal device. At the same time, the first fixed pattern signal from the first pattern signal generation means for confirming the connection of the line is sent to each connected data terminal interface device and detected by each monitoring means. At the same time when the first fixed pattern is detected by the monitoring means, a second fixed pattern signal from the first pattern signal generation means for instructing the data terminal device to enable communication is sent to each connected data terminal interface device. Send.

When each data terminal interface device detects the second fixed pattern signal by its monitoring means, it switches the third fixed pattern signal to each data terminal device and provides the second fixed pattern signal to enable communication. state.

In this way, it becomes possible to transmit and receive data at the data terminal device simultaneously after confirming the connection of the line.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a data terminal interface device according to an embodiment of the present invention. FIG. 2 is a block diagram showing the system configuration.

In this embodiment, a data terminal interface device (DCE) is connected to a data terminal device (DTE) 2 and controls it.
In the data communication line connection control system including La, the data terminal interface device 1a sends a first fixed pattern signal for confirming the connection of the line 7 and a second fixed pattern to enable communication to be given to the data terminal device 2. A first pattern signal generation circuit 12 that generates a signal, a multiplexed signal in which transmission data and control signals from the data terminal device 2 are multiplexed, and the output of the pattern signal generation circuit 12 are switched and sent to a connection destination. A switching circuit 13 as a means, and a second pattern signal generation circuit 1 that generates a third fixed pattern signal that instructs the data terminal device 2 to wait for communication.
5, a switching circuit 16 serving as a means for transmitting the third fixed pattern signal and the multiplexed signal received from the connection destination to the switching data terminal device 2, and a switching circuit 16 serving as a means for transmitting the third fixed pattern signal and the multiplexed signal received from the connection destination to the switching data terminal device 2; The monitor circuit 14 includes a monitoring circuit 14 that detects reception of a pattern signal. In FIG. 1, 11 is a multiplex circuit, and 17 is a separation circuit.

The feature of the present invention is that pattern signal generation circuits 12 and 15, switching circuits 13 and 16, and monitoring circuit 14 are provided in FIG.

Next, the operation of this embodiment will be explained. In order to make the explanation more concrete, the International Telegraph and Telephone Advisory Committee (CCITT)
) Consider the case of a data terminal device having an interface of Recommendations X and 21. FIG. 3 is an explanatory diagram showing the sequence of outgoing and incoming calls on the Recommendation X/21 interface until four communications are possible.

The data terminal device 2 changes the transmission data T from "1" to "0".
At the same time, the control signal C is changed from "off" to "on" to start transmission. After that, when receiving a selection signal transmission cylinder and a signal character as reception data R from the data terminal interface device 1a, the other party data terminal device 2
The selected number is sent as a character in the transmission data T. When the receiving side receives a character indicating an incoming call in the received data R, it changes the control signal C from "off" to "on" as a response to the incoming call.
Make it.

When each data terminal interface device 1a confirms that the line is connected, it changes the display signal ■ from "off" to "on" to indicate that the line connection is complete, that is, communication is possible, to each data terminal interface device 1a.
give to Here, communication re-instructions using the respective display signals I must be performed simultaneously. Therefore, in order to provide simultaneity, first, the first
In the multiplexing circuit 11 shown in the figure, the control signal C and the transmission data T are multiplexed in the configuration shown in FIG. 4 and transmitted together as 8-bit data. On the receiving side, the separation circuit 17 separates the control signal C as a display signal (2), the transmission data as reception data, and sends it to the data terminal device 2. In this embodiment, such a data transmission method is adopted.

Next, the signal path between the data terminal interface device 1b on the originating side and the data terminal interface device 1c on the destination side will be explained in detail with reference to FIGS. 5+8) to 5(C).

When the data terminal device 2 on the originating side makes a call and an instruction to wait for a subscriber response is given from the network side (for example, an exchange) to the data terminal interface device 1b according to the sequence shown in FIG. The pattern signal generation circuit 15 generates a third fixed pattern signal in which the character indicating waiting for a subscriber response and the display signal ■ are turned off, and the signal is sent to the data terminal device 2 via the separation circuit 17. . At this time, the switching circuit 16 receives the signal from the pattern signal generation circuit 1 rather than the signal from the connected partner.
It has been switched so that the signal comes from 5.

Simultaneously with the above operations, the data terminal interface device lb causes the pattern signal generation circuit 12 to generate a first fixed pattern signal for confirming the connection of the line to the data terminal interface device IC of the connection partner (receiving side). and send it. At this time as well, the switching circuit 13 switches the signal from the pattern signal generation circuit 12 instead of the signal from the data terminal device 2 on the transmitting side.

When the data terminal interface device 1c on the receiving side detects that the control signal C changes from "off" to "on" as a response to the incoming call from the data terminal device 2 on the receiving side, it instructs the data terminal device 2 to receive the call. A synchronization character is sent instead of the indicated character. At this time, the display signal I to the data terminal device 2 has a pattern that is "off".

Also, in the same way as on the originating side, a first fixed pattern signal for confirming the connection of the line (+1!) is sent to the data terminal interface device 1b on the originating side. Figure 5 shows the signal flow so far. (a).

Next, mutual data terminal interfaces 1b and 1c
However, when the monitoring circuit 14 detects the first fixed pattern signal for confirmation through the connected line, a second fixed pattern signal different from the first fixed pattern signal for confirmation, in this case the fourth fixed pattern signal is detected. The C/I bit shown in the figure is “off”,
The data (T/R) bit is the data terminal device 2 on the receiving side.
Each pattern signal generating circuit 12 generates a pattern in which all the signals are "1" and sends it to the line side.

When the monitoring circuit 14 of each data terminal interface device 1b and IC detects this second fixed pattern signal, the switching circuit 13 on the originating side and the switching circuit 16 on the receiving side detect the second fixed pattern signal in the data terminal interface devices 1b and lc. The fixed pattern signal generated by the data terminal interface device 1b or lc is not sent out, but the fixed pattern signal from the own data terminal interface device 1b or lc is sent out to the other party's data terminal interface device 1c or tb.

At this time, since it is impossible for the calling side and the receiving side to switch at the same time, they are shifted in time, for example, as shown in Fig. 5(b).
As shown in FIG. 3, the data terminal interface device 1b is temporarily in a delayed state. However, the data terminal device 2 connected to the data terminal interface device 1c that was switched first receives the second fixed pattern signal, that is,
Display signal I “off” and reception data R “1” are sent,
At this point, it is not yet ready for communication. Conversely, the "on" control signal C of the data terminal device 2 is sent to the other party's data terminal interface device 1b, but in the data terminal interface device 1b, the signal has not yet been switched in the switching circuits 13 and 16, so the data terminal A pattern in which the display signal I generated within the data terminal interface device lb is "off" is sent to the data terminal device 2 connected to the interface device 1b, and communication is also possible on the data terminal interface device lb side. It's not a state.

Next, it is not until the switching circuit 13.16 of the data terminal interface device 1b operates after a delay that it enters the state shown in FIG. The display signal I is sent to the display signal I, and the communication becomes possible.

After confirming the connection of the line using the first fixed pattern signal, the operation of the switching circuit is controlled by detecting the special second fixed pattern signal, and finally the switching circuit on one side is Depending on the operation, an instruction to enable communication can be given to the data terminal device 2 at the same time.

〔Effect of the invention〕

As explained above, the present invention transmits and receives fixed pattern signals between connected data terminal interface devices,
By switching the transmission path within the data terminal interface device, it is possible to confirm the connection of the line, and at the same time, it is possible to give a reliable instruction to enable communication to the data terminal device.

Therefore, according to the present invention, it is possible to obtain a data communication line connection control method that transmits a communication enable instruction signal after confirming the line connection and performs control to ensure reliable data communication. It's large.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a data terminal interface device according to an embodiment of the present invention. FIG. 2 is a block diagram showing the system configuration of this embodiment. FIG. 3 is an explanatory diagram of the sequence of CCITT Recommendations X and 21 used in this embodiment. FIG. 4 is a multiplex configuration diagram of control signals and data used in this embodiment. Figures 5 (al to C) are explanatory diagrams showing the signal flow of this embodiment. Figure 6 is a block diagram showing the system configuration of the conventional example. L la, lb, IC... data terminal interface device ( DCE), 2...Data terminal equipment (DTE)
), 3... Time division switch (TDgW), 4... Central processing control unit (CC), 5... Interface trunk (TRK), 6... Exchange, 7... Line,
11... Multiplex circuit, 12.15... Pattern signal generation circuit, 13.16... Switching circuit, 14... Monitoring circuit, 17... Separation circuit, C... Control signal, ■.・・・
Display signal, R...reception data, T...transmission data.

Claims (1)

[Claims] (1) In a data communication line connection control system that includes a data terminal interface device that is connected to a data terminal device and controls it, a first fixed pattern signal for confirming connection of the line and a communication enable signal given to the data terminal device. a first pattern signal generating means (1) for generating a second fixed pattern signal of
2); means (13) for switching between a multiplexed signal in which transmission data and control signals from the data terminal device are multiplexed and the output of the first pattern signal generating means and transmitting the same to a connection destination; a second pattern signal generating means (15) for generating a third fixed pattern signal that instructs the device to wait for communication, and switching between the third fixed pattern signal and the multiplexed signal received from the connection destination; A means of outputting to a terminal device (
16); and monitoring means (14) for detecting reception of the received multiplexed signal and the first and second fixed pattern signals.