JPH01190050A - Line interface selection system - Google Patents

Abstract

PURPOSE:To prevent selection mistake of a package by preparing one kind of package and connecting it to an interface desired to be used so as to apply changeover setting of interfaces by the hardware automatically. CONSTITUTION:A switching control section 7 is provided with a priority selection circuit, a signal representing the highest priority depending on a priority selection circuit (two inputs alpha and beta) is outputted from a signal line displaying the use of input and a selection signal (a) of the switching section 6 is commanded. The switching section 6 consists of a demultiplexer and a multiplexer and the input/output circuit is connected to the input/output circuit of the V.24 and X.21 via the demultiplexer and multiplexer by the control of the selection signal (a).

Description

[Detailed Description of the Invention] [Summary] Regarding a line interface selection method between a data terminal device and a line termination device in a public data network, analog transmission -
M/ that applies analog transmission interface V, 24
D and digital transmission-digital transmission interface X
, 21 to be automatically switched and selectively connected at the line control unit. 24 interface section and a switching section;
It consists of a line control section.

(Industrial Application Field) The present invention relates to a line interface selection method between a data terminal W (hereinafter referred to as DTE) and a line termination equipment (hereinafter referred to as DCE).

Currently, inter-system protocols are defined by CCITT recommendations, but recent rapid advances in microprocessor technology have significantly improved the processing speed of personal computers, and the rapid decline in memory prices has led to O3I, or open system interconnection, has been introduced to terminals such as

Generally, two types of interfaces, V.24 and X.21, are defined as interfaces between DTE and DCH in public data networks. 24 is applied to the analog transmission-analog transmission interface, and X, 21
has been applied to the digital transmission-to-digital transmission interface.

That is, V. 24 is an interface between DTE and DCH, which defines the functions of interconnection circuits used for transferring data, control signals, timing signals, etc., and 21 is a synchronous interface between DTE and DCE in the public data network. It defines its electrical characteristics, mechanical characteristics, functional characteristics of interconnection circuits, network control functions, etc.

In Figure 3, V. An example of connection of a public data network to which the 24, x, and 21 interfaces are applied is shown.

In the figure, when an analog telephone network is used for connection between line control devices, the interface with the modem is V. 2
4 is applied, and when a digital transmission network is used, the interface with the multiplexer is X, 21.

Therefore, depending on the connection between the line control device and the modem (M/D) or digital termination unit (DSU), the line interface is set to V. It is necessary to switch to 24 or X, 21 for use.

[Conventional technology]

A conventional method for selecting a line control unit and a line termination interface is shown in FIGS. 4(a) and 4(b).

Figure (a) shows one type of line termination section (M/D or DSt).
J) and a line control unit as a set are used as a window for each type of line termination unit, but this method has the drawback that it may lead to errors in selecting the package to be prepared.

Figure (b) shows a method for manually setting the line termination instructions in the package when there are n types of line terminations.

In the figure, 2 is a line control unit as a data terminal equipment f (DTE) connected to a processor 1, and an M/D or DSU is connected as a line terminating equipment (DCE).
is set to 3, the interface v, 24 with the M/D is set to 4, and the interface X, 21 with the DSU is set to 5.

In Figure (b), if the switching section is set to 6 and the selection instruction setting section is set to 8, the operation of the selection instruction setting section is performed by the operator's settings. It is easy to make a mistake in selecting the switching to connect.

[Problem that the invention seeks to solve]

In the conventional line interface selection method, switching between the line control unit and the line control unit is performed manually, making it easy to make mistakes in setting the connection interface.

The present invention aims to prevent mishandling by preparing one type of package and automatically selecting and setting it by hardware by connecting the line interface to be used.

[Means for solving problems]

That is, in the present invention, the line control section automatically identifies the interface actually used from the signals of each interface,
The present invention provides a method for automatically connecting the line termination section and the line control section.

FIG. 1 shows a diagram explaining the principle of the present invention. In the figure, 1 is a processor, 2 is a line control unit, and 3 is a line termination unit (M/D
or DSU), 4 is v, 24 interface for M/D connection, 5 is X, 21 interface for DSU connection,
Reference numeral 6 indicates a switching section, and 7 indicates a switching control section.

Note that the line control unit 2 is a data terminal equipment (DTE) connected to the processor, and the line termination unit 3 is a line termination unit (DC) connected to an analog telephone network or a digital telephone network.
E).

[Effect]

The switching control section 7 monitors the signals α and β indicating that the usable state is available in each of the interface sections 4 and 5, and gives an instruction to the switching section 6 using the selection signal a to switch to the interface side displaying the usable state.

Monitoring of the following signals can be considered to detect whether each interface unit is usable. That is, V. 24 interface,
Data cent ready signal (CCITT circuit number 107)
When is on, the data set (M/D) is available. In addition, in the case of the X, 21 interface, when the display signal I according to the CCITT recommendation is on, the
U) is available.

〔Example〕

FIGS. 2(a) and 2(b) show an embodiment of the switching control section for v, 24 and x, 21, and FIG. 2(c) shows a circuit diagram of the switching section. The entire system is as shown in FIG.

V in figure (a). 24 interface, the data set ready circuit with interconnection circuit number 107
The logical connection conditions from E to DTE are shown, and the electrical standard conditions are V.E to DTE. The conditions set out in Article 28 shall apply. This brings the threshold voltage to +3V by a threshold control circuit connected to the receiver, so that the logic judgment is turned off when the input is open. In other words, the logic judgment level is that when the voltage to ground at the interconnection point V = h < 3V, the output α is turned off,
When the ground voltage y, , >+3y, the output α is turned on. Therefore, when Dataset Ready is on, the interface is available for use.

In the case of the X, 21 interface in figure (b), it is an interconnection circuit! is a circuit that displays the signal element timing from DCE to DTE, and the electrical standard conditions are V. 11 shall apply. In other words, the logical judgment level is A,
If the ground voltages of the B line are Va and Vm, when the differential significance level of the receiver is V, -VB<-0.3V, the output β of the receiver is turned off.

-v, >+9.3v, the receiver output β is turned off. Therefore, when I (No. 8) is on, the interface becomes usable.The termination resistor circuit is of a bleeder type as shown in the dotted line in the figure, so that the logic judgment is turned off when the input is open.

Therefore, as shown in 11(c), a priority selection circuit is provided in the switching control unit 7, and the priority selection circuit (in this example, two manual inputs α and β) among the signal lines indicating that they are available for input.
It outputs a signal indicating the highest priority determined by , and instructs it to the selection signal a of the switching section 6 . The switching unit 6 is composed of a demultiplexer and a multiplexer, and under the control of the selection signal a, connects the input/output circuits to the input/output circuits of the respective v, 24 and X, 21 interfaces via the demultiplexer and the multiplexer.

〔Effect of the invention〕

Conventionally, the selection signal a of this switching section was operated by a manual switch, but in the present invention, it is automatically operated by an instruction from an interface, and troubles such as erroneous connections due to manual operation can be prevented. Moreover, by preparing one type of package and connecting it to the desired interface, it is possible to automatically switch settings using hardware, making it easy to use O8L as an inter-system protocol for terminals such as personal computers. It can be introduced.

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining the principle of the present invention, and FIG. 2(a). (b) and (c) are examples of the switching control unit and the circuit diagram of the switching unit, Fig. 3 is an example of connection with a public data network, and Fig. 4 <a
> and (b) show the configuration diagram of a conventional example. In the figure, 1 is a processor, 2 is a line control unit, 3 is a line termination unit (M/D or SU from t), and 4 is a V. 24 interface, 5 is X, 21 interface, 6 is a switching section, 7 is a switching control section, and 8 is a selection instruction setting section. Diagram for explaining the principle of the present invention. Figure 1. Connection example of public data network. Figure 3. (a) Example of V, 24 interface switching control unit (b)
) X, 21 Interface Switching Control Unit Embodiment Example Interface Switching Control Unit 7 (C) Switching Unit Circuit Diagram Embodiment

Claims (1)

[Claims] In a line interface selection method between a data terminal device and a line termination device in a public data network, a processor (
1) and the line control unit (2) connected to M/D or D
A line termination section (3) consisting of SU, the above line control section and M
/D, which defines the interface between V. X.24 interface (4) and the X.24 interface (4) defining the interface between the DSU and the X.24 interface (4). 21 interface (5) and switching unit (6
) and a switching control unit (7), the switching control unit (7) monitors the signals indicating availability at each interface unit (4) and (5), and the interface side where the availability display is displayed is monitored by the switching control unit (7). A line interface selection method characterized in that the switching unit (6) is instructed to switch and connect the line control unit (2) to the line interface.