JPS6059841A - Variable communication speed terminal equipment - Google Patents

Abstract

PURPOSE:To attain information transmission between terminal equipment different in communication speed by obtaining the maximum communication speed of an opposite side prior to the communication and allowing a terminal equipment having a higher communication speed to adjust the own communication speed so as to be matched to the maximum communication speed of the opposite side. CONSTITUTION:When a terminal equipment 2A dials to call a terminal equipment 2B, an exchange 1A identifies this dial signal and transmits an outgoing terminal number and an incoming terminal number to an exchange 1B via common line signal devices 7A, 7B and a line 7. The exchange 1B calls the exchange 2B from the incoming terminal number and the exchange 2B returns a response signal to the exchange 1A via the line 7. When the identification number of the mutual equipment is informed to the equipment 2A, 2B, the maximum communication speed of the opposite side is discriminated. The equipment having the higher communication speed than the opposite equipment frequency- divides a clock signal and adjusts the own communication speed so as to be matched to the communication speed of the opposite equipment, activates a transmission/reception circuit of the terminal equipment and transmits information via the exchanges 1A, 1B and a line 6.

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a variable communication speed terminal that enables communication between terminal devices having different communication speeds via a digital switching network.

Background of the Technology, Prior Art, and Problems When digital information such as data and voice is exchanged between terminal devices via an exchange, the terminal devices must use the same transmission control procedure, that is, the same protocol, and have the same communication speed. Conventionally, if the communication speeds between terminal devices are different, it is impossible to communicate between these terminal devices.

This is because these devices transmit and receive serial transmission information in synchronization, so if the communication speeds are different, synchronization cannot be achieved.

Recently, there has been an increase in the number of digital communications between terminal devices, but even if the protocol is the same, terminal device M has various communication speed limitations based on the performance constraints of the device. There is. In a case like B,
Instead of using complicated and expensive buffer processing equipment to adapt the communication speed or replacing the terminal device itself, you can use the relatively simple and inexpensive N route to connect any terminal device. However, there is a need for a variable communication speed terminal that allows information exchange.

OBJECTS OF THE INVENTION In order to solve the above-mentioned problems, the present invention generally provides a communication speed adjustment means in a terminal device, obtains the communication speed of the other party's terminal device prior to communication, and adjusts the communication speed of the other party's terminal device. Based on the idea that if the communication speed is lower than the own communication speed, communication will be performed by adapting to the lower communication speed of the other party.
The object of the present invention is to provide a variable communication speed terminal that enables information transmission between terminal devices having the same transmission control procedure but different communication speeds.

Structure of the Invention In the present invention, in a digital switching network in which communication between terminal devices having the same transmission control procedure is performed via an exchange, at least the number of the other terminal device to be communicated with is obtained prior to the communication. and means for mutually learning the maximum communication speed of the other party, and means for the terminal device of the higher maximum communication speed to adjust its own communication speed to match the maximum communication speed of the other party, There is provided a variable communication speed terminal, characterized in that an exchange system with a high communication speed operates at the adjusted communication speed to allow communication between the terminal devices having arbitrary communication speeds. Ru.

Embodiment of the Invention An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a schematic configuration of a digital switching network having variable communication speed terminals according to the present invention. In FIG. 1, IA indicates an exchange to which a terminal device 2A and a line termination device 3A are connected. In addition, the opposite exchange IB via the line 6 includes a line termination device 3B and a terminal device 2.
B is connected. The exchanges IA and IB each operate under a control device (ec) +4A I 4 B, and common line signaling devices 7A and 7B are connected between the exchanges. Here, the line 6 is used for data communication between the terminals 2A and 2B, and the line 7 is used for transmitting and receiving control signals necessary for switching functions between exchanges via a common line signaling device.

FIG. 2 illustrates the circuit configuration of two terminal devices or 2B (hereinafter collectively referred to as 2). In FIG. 2, the terminal device 2 includes a level conversion circuit 21, a clock control circuit 22, and a transmitting circuit 2.
3. It has a receiving circuit 24 and a terminal control device 25, and is connected to a line termination device 3 (indicated by either 3A or 3B). The level conversion circuit 21 adjusts the signal level of the line termination device 3 side and the circuits 42 to 45, and performs conversion to TTL level or inverse conversion. Transmission circuit 23 and reception circuit 2
4 performs transmission and reception at a predetermined communication speed based on the clock signal elk. It also performs parallel-to-serial conversion with 23.24U25. The terminal control device 25 controls keyboard processing, printer output, and other processing provided in the terminal device 2.

The detailed circuit of the clock control circuit 22 in FIG.
As shown in the figure. The clock control circuit 22 receives a signal 825, which will be described later, from the counter 221, the counter preset circuit 222, the decoder 223, and the terminal control device 25, and generates a latch clock L. It consists of a register 224 latched by K.

A clock signal CLK of a predetermined period applied to the terminal device M2 is inputted to the counter 221, and the clock signal CLK is applied to the terminal device M2.
LK can be frequency-divided into a clock signal elk with a predetermined period by a signal 825 from the terminal control device 25. For example, suppose the line clock CLK is 48 bits/second, and the signal S25 is 2-bit data (00 to 11).
This data is stored in register 224 and decoder 22
3 and setting a preset value in the counter preset circuit 222, the clock CLK is divided to generate the following clock signal cllc.

00 1/1 48 bits/second 01 115 9.6 10 1/10 4.8 11 1/20 2.4 The transmitter circuit 23 and the receiver circuit 24 operate according to the clock signal clk frequency-divided in this way. do.

The operation of the device according to the invention illustrated in FIGS. 1 to 3 will now be described with reference to FIG. M4.

Fig. 4 shows the operation sequence. Fig. 4 (A) shows the timing, and Fig. 4 (B) shows the signals TD and C (see Figure 2), Figure 4 (C) is the line termination device 3A.
The signals RD and C (see FIG. 2), FIG. 4 (D) and M4 (E) received from the exchange IA via
shows.

Figure 4 follows the communication rules based on the recommendations of the Consultative Committee on International Telegraph and Telephones (CCITT). In FIG. 4, the shaded area indicates that data is being communicated.

We will discuss the case where data is exchanged between two terminal devices and the terminal bag ff2B, but the maximum communication speed between the two terminal devices is 48
An example will be described in which the maximum communication speed of the terminal device 2B is approximately 9.6 bits/second.

A case will be described in which two terminal devices make a call and the call is received at the terminal device 2B. First, after making a call on two terminal devices (the fourth
Figure (A) Timing jl + Figure 4 (B) C: 0FF
-+ON), dialable signal from exchange IA (Fig. 4 (
C) Receive RD; SYN, SYN, +, 10) (timing 11) and dial Ay to call the terminal device 2B.
(Figure 4 (B) TD; SYN, SYN.

DIAL). Exchange] A receives this dial signal and identifies that the call is to the terminal device 2B accommodated in the exchange IB, and then transmits the [calling terminal number (terminal device 2A) and the called terminal number (terminal device 2B)" are transmitted to the exchange IB (timing ts).

The exchange IB sends an incoming signal from the "terminating terminal number" to the terminal device 2B to call the terminal device 2B, and if the terminal device 2B responds, the response signal is sent to the common line signaling device 7B.
and returns it to the exchange IA via the line 7 (timing t4 + FIG. 4(D)C: OFF→ON).

In addition, after the terminal device 2B responds to the incoming call, the exchange IB notifies the terminal device 2B of the numbers (partner identification signals) IDs of the two terminal devices (the fourth
Figure (E) RD). When the number of the terminal device of the other party is known in this way, the maximum communication speed of the other party can be determined. The maximum value of the communication speed of the other party is stored in advance in the terminal control device 25. Alternatively, if the exchange adds terminal identification (communication speed, transmission control procedure, fixed/variable communication speed) identification information to the other party identification signal and transmits it to the terminal, the terminals can identify each other's communication speed.

In this way, when the maximum communication speed of the other party's terminal device is known, in this example, as mentioned above, the terminal device 2A side
K bits/sec, and the terminal device 2B side has a pit of 9.6 seconds and a pit of 7 seconds.If the communication speed of the terminal device is higher than that of the other device, the clock system (M1 circuit 22 At this time, the frequency of the lock signal elk is divided to suit the communication speed of the other party.In other words, the clock signal CLK (48K-Iz) of the two terminal devices is
is set to IA by the clock control circuit 22, and the transmitting circuit and receiving circuit of the multi-terminal device 2A are operated by the clock signal CLLC set to 17MO. On the other hand, the clock signal on the terminal device 2B side is not divided and its maximum clock frequency ('9.6
kHz) in the transmitting and receiving circuits.

At timing t in FIG. 4(A), the two terminal devices receive and analyze the other party's identification number, and then determine the speed of their own terminals. When exchanges IA and B set up the bus between 2A and 2B, a communication enable signal is sent to each terminal (see Figure 4).
C) and (E) ノI; OFF'→ON). From this point on, communication is carried out as shown in the figure on the toll line where communication is possible.

FIGS. 5(A) to 5(D) show signal characteristic diagrams for two terminal devices, where the clock signal elk is the clock signal CLK.
It is shown that in response to this clock signal cllc, a reception signal RD transmitted from the partner terminal device 2B and a transmission signal TD transmitted from the two own terminal devices are generated. Details of these signals are shown in FIG.

On the other hand, line termination equipment? ! Since ¥3A operates at the original communication speed, the same data is repeated five times in the transmission and reception data passing through the line. In order to synchronize the communication speed of the terminal device 2B, which has a low communication speed, the exchange IA of the two terminal devices samples the received data from the two terminal devices once every five times and sends it to the other party's exchange IB. On the other hand, the same data received from the other party's exchange IB is transmitted five times in a row to two terminal devices.

The exchange IB and the terminal device 2B operate based on the original communication speed.

When the required communication is completed as described above, each terminal device resets to its original communication speed, that is, the communication speed registered with the exchange.

In carrying out the present invention, extreme variations from those described above may be adopted. For example, clock signal CL
The frequency division ratio for dividing K into the clock signal elk can be set to an arbitrary percentage. Further, the circuit diagram in FIG. 3 which details the clock control circuit 22 in FIG. 2 is not limited to this, and various other frequency dividing circuits may be used.

Furthermore, it goes without saying that if the terminal devices each have iJ different communication speeds, communication will be performed at the lower maximum communication speed.

In the above embodiments, data communication was exemplified, but the present invention can be similarly applied to communication of digital information such as voice.

Further, in principle, the variable communication speed circuit can also be provided in a line termination device or the like.

Effects of the Invention As described above, according to the present invention, as long as the transmission control procedure is the same between terminal devices, even if the communication speeds are different, the terminal device with the higher communication speed will control the maximum communication of the terminal device with the lower communication speed. This has the effect of being able to perform actions that match the speed and mutually exchange information.

Further, this adaptation operation is performed automatically without requiring any intervention from the user, and has the advantage of not imposing any burden on the user. Furthermore, the above effects can be obtained with a relatively simple circuit configuration without requiring any complicated intermediate devices.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a switching network as an embodiment of the present invention, FIG. 2 is a circuit diagram of a terminal device in FIG. 1, and FIG. 3 is an M
A circuit diagram of the clock control circuit in FIG. 2, FIG. 4 is an example of an operation sequence for the exchange in a terminal device, and FIG. 5 is a signal waveform diagram in the terminal device shown in FIG. 3.
It is. (Explanation of symbols) IA, IB...Switchboard, 2A, 2B...Terminal device, 3A, 3B...Line termination device, 7A, 7B...Common line signal device, 21...Level conversion circuit , 22... Clock control circuit, 23... Transmission circuit, 24... Receiving circuit, 25... Terminal control device, 221... Counter, 222... Counter preset circuit, 223...・Decoder, 224...Register. Figure 1 Figure 2

Claims (1)

[Claims] 1. In a digital switching network in which communication between terminal devices having the same transmission control procedure is carried out via a switch, at least the number of the other party's terminal device to be communicated with is obtained prior to the communication, and the number of the other party's maximum An exchange system with a high communication speed, comprising means for mutually learning communication speeds, and means for a terminal device on the side with a higher maximum communication speed to adjust its own communication speed to match the maximum communication speed on the other side. A variable communication speed terminal, characterized in that the terminal operates at the adjusted communication speed and allows communication between the terminal devices having arbitrary communication speeds.