JPH02202159A - Switching device for communication line - Google Patents

Abstract

PURPOSE:To immediately receive information sent via a public communication line with a first data terminal even when an operator is absent by automatically connecting the first data terminal to a modem by a control signal from the modem connected to the public communication line via first and third communication lines. CONSTITUTION:When the modem(M) 6 detects an incoming signal from the public communication line 7, the M6 sends a data channel reception carrier detecting signal(CD) and a data set ready signal(DR) to a switching device 1. A NAND gate circuit 11 receiving the signals CD and DR controls a relay circuit 12, and the relay circuit 12 separates the communication line 2 from the communication line 3, and connects it to the communication line 4. In such a way, the data terminal 8 can perform data communication with the data terminal on a call issuing side passing the switching device 1 and via the M6 and the public communication line 7.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a communication line switching device.

[Conventional technology]

For example, in a conventional communication line switching device, when a terminal device A is connected to a terminal device B via a communication line consisting of a data line and a plurality of control signal lines, an incoming signal from a public communication line is transferred to a modem. If detected, the communication line between terminal device A and terminal device B can be manually disconnected, and terminal device A and the modem can be manually connected.

[Problem to be solved by the invention]

The conventional communication line switching device described above is designed to manually switch the communication line between the main terminal equipment and between the modem and the terminal equipment connected to the public communication line, so the switching operation is not necessary. There is a drawback that if there is no worker to perform the work, information from the public communication line may not be received quickly.

[Means to solve the problem]

The communication line switching device of the present invention connects a first communication line connected to a first data terminal to a second communication line connected to a second data terminal, or It has a switching means that automatically determines whether to connect to a third communication line connected to a modem connected to a communication line using a control signal from the modem.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing an example of application of the embodiment of the present invention.

In FIG. 1, this application example shows a switching device 1 according to an embodiment of the present invention, and a modem device (hereinafter referred to as M) connected to a public communication line 7.
) 6 and data terminals 8 and 9, and the switching device 1 switches the communication line 2 connected to the data terminal 8 to the communication line 3 connected to the data terminal 9 or M6. A relay circuit 12 switches the connection to the connected communication line 4, and the relay circuit 12 receives a data channel reception carrier detection signal (hereinafter referred to as CD) and a data set ready signal (hereinafter referred to as DR) from M. The NAND gate circuit 11 is configured to include a NAND gate circuit 11 that controls when

Next, the operation of this application example will be explained.

In FIG. 1, normally, a relay circuit 1 of a switching device 1
2 is the illustrated state, where communication lines 8 and 9 are connected and data terminals 8 and 9 can communicate with each other.

Next, when M6 detects an incoming signal from public communication line 7, M6 sends a CD and DR double signal to switching device 1. C
A NAND gate circuit 11 that receives the D and DR double signals controls a relay circuit 12, which disconnects the communication circuit 2 from the communication circuit 3 and connects it to the communication line 4.

As a result, data terminal 8 passes through switching device 1 and M6.
Data communication can be performed with a data terminal (not shown) on the calling side via the public communication line 7.

When the data communication ends and the CD and DR multiplied signal NAND gate circuit 11 no longer receives data, the switching device 1 returns to the above-mentioned normal state.

〔Effect of the invention〕

As explained above, the present invention enables a first data terminal connected to a second data terminal via first and second communication lines to receive a control signal from a modem device connected to a public communication line. By making it possible to automatically connect to the modem device via the first and third communication lines, there is no need for a manual switching operation by the operator as in the past.
This has the effect of allowing the first data terminal to quickly receive information sent via a public communication line without the presence of an operator.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of application of the embodiment of the present invention. 1... switching device, 2.3, 4. ...communication line, 6.
...Modulator/demodulator (M>, 7...Public communication line, 8, 9
...Data terminal, 11...NAND gate circuit, 1
2...Relay circuit, 21,31.41...Signal bundle.

Claims (1)

[Claims] A first communication line connected to a first data terminal is connected to a second communication line connected to a second data terminal, or to a modem connected to a public communication line. A communication line switching device characterized in that it has a switching device that automatically determines whether to connect to a third communication line that is connected to a third communication line based on a control signal from the modulation/demodulation device.