JPS58195347A - Automatic switching system of line transmission speed - Google Patents

Abstract

PURPOSE:To attain the ease of use of plural transmission speeds, by switching the transmission speed at the other station automatically while one station repeats retrials, when the transmission speeds are different in the communication of plural transmission speeds and the synchronizing signals are not received correctly. CONSTITUTION:A modulation and demodulation device 12 at the center side switches the transmission speed with a signal from an electronic computer 11. The transmission speeds at terminals 16-18 are 600, 1,200 and 2,400 bit/s. When the electronic computer 11 detects a calling from a terminal station, the communication is started at 600 bit/s at first. When the terminal is assumed as a station having the transmission speed of 2,400 bit/s, both stations make no response. Next, the terminal station makes retrial at 2,400 bit/s, the center station switches the transmission speed to 1,200 bit/s for the communication. In this case, however, no response is obtained. When the center station switches the speed to 2,400 bit/s, the response is repeated for both stations.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a data communication system, and more particularly to a system for automatically switching transmission speeds in a communication section that allows selection of two or more types of transmission speeds.

(2) Prior art and problems When using two or more types of transmission speeds in the conventional system, ■' The operator switches in advance to the transmission speed to be used.

(2) Prepare as many L-s as the number of types of transmission speeds to be used, and decide the transmission speeds to be used for each motherboard.

There are two methods: (1) It requires human intervention to switch the blind transmission speed, so it has the disadvantage that unattended operation is not possible, and (2) requires the same number of times as the type of transmission speed to be used. Therefore, there were 105 disadvantages that it cost a lot of money.

Immediate and automatic sacrifice, 411e, 4! The objective is to provide a system that makes it possible to easily utilize transmission speeds such as I.

(4) Structure of destination - The purpose of this is to transmit 11ft-1[d between two stations in a system that uses 4i[, and when the transmission speeds are different and the same lA polarization cannot be received correctly, the -station can retry. - During the return, the other station changes the transmission speed so that the transmission fs speed tL'fl
The present invention will be explained using an example of 4JLI1 of Ming Dynasty (91). .

FIG. 1 is a block diagram of a data communication system showing an embodiment of the present invention.
1 story exchange network, 15 is an acoustic coupler, 16 is a terminal, LF is layer end B, 18 is a wire C119 is MIIMA (12QO
blt/8), lwork0 is MDMB (2400bit/
Figure 3 is a system configuration diagram of another embodiment of the present invention. In the figure, 31 is a switching circuit, and 32 is a 1-1 exchange cable. □ By the way, this book @Ming takes advantage of the fact that synchronization signals cannot be received correctly when the transmission speeds of the two N6s (the center side and the terminal @) are different, so that while one layer repeats retries, the other layer This allows stations to match their transmission speeds one after another.

The data transmission speed of the center-side converter 12 can be changed by a signal from the computer 11.

Subscription telephone line network14. In this case, many terminal stations to be connected to the center station are connected in Mk, and the transmission speed of the terminal stations is f#i.
600 btt/1! , 1200 bit/s and 2
There are three types of 400 btt/g. A terminal station can connect to the center station at any transmission speed.

This shows a state in which when a station is called, an interrupt occurs in the computer 11 of the center station. The terminal station calls the central office in the same way that a regular telephone user dials the other party's telephone number.

When the center station call computer 0 learns that it has been called by the terminal station by an interrupt, it first sends a 600 call.
)b1t/s communication is started.

In FIG. 2, the terminal station is assumed to have a transmission rate of 2400 bit/a. a o o btt/s and 2400 b
With tt/a, it is not possible to receive the synchronization decoding completely correctly, so there is no response from either the local station.0 This is the state of (sha).

Next, the terminal station tries again with 2400 bit7s, and the center station switches to l200 blt/- and tries to communicate. However, in this case as well, since the transmission speeds do not match, there is no response. This is the state (2).

Next, when the center station switches to 2400 btt/s, the transmission rate matches that of the terminal station, so the synchronization signal is received and a response is returned to both stations. In the example, both stations use 5 encl ( Since the transmission starts from [transmission], a collision response is returned.And, as a collision response is returned,
The slave station @ (terminal station in the embodiment) receives Receive (Receive 1
The switching data is transferred at the same time. This is ■.

FIG. 3 shows another embodiment of the present invention, in which the transmission rate is switched not by a modulator/demodulator but by a switching circuit 31. The switching circuit 31 operates according to a control signal from the electronic computer 11. In this example, the change dl! - Can be used even if the device does not have a transmission speed switching function.

(6) As described in detail, according to the present invention, it is possible to dynamically switch the transmission speed of the line, and it is possible to use several transmission speeds on the line, allowing one communication partner to can communicate without worrying about the transmission speed of its own station,
Able to create efficient and economical data communication systems□

[Brief explanation of drawings]

FIG. 1 is a block diagram of a data communication system showing an embodiment of the present invention. FIG. 2 shows the transmission rate switching procedure 11! according to an embodiment of the present invention. FIG. 3, which is a clear diagram, is a diagram showing the system configuration of another embodiment of the present invention. Explanation of the symbols: 11 is the tiK device, 12 is the MDM (variable*g device), 13 is the N0TT (network control device), 14 is the subscriber telephone switching network, lδ is the acoustic coupler, 16 is the terminal A 117 is the terminal 8118 is the terminal 0 .19 is M D M & (120
0blt/a), 110 is MDMB (2400btt
/s). Sender rules--Hatoki Ikoku sender example jlilh Mii-machi interrupting half-'s □Prime water and thatch? Mistake! -Figure 3

Claims (1)

[Claims] In a system where communication between two stations is carried out at a transmission speed of 1 it - Australia, if the transmission speeds are different and the synchronization signal cannot be received correctly, - while the station repeats retries, the other station changes the transmission speed and the transmission speed increases. A method for automatically switching line transmission speeds to match f to 4Mt.