JPS62123851A - Data transmission system - Google Patents

Abstract

PURPOSE:To improve the operability by sending a control signal when a format sent from one digital line termination equipment to an opposite line termination equipment is all logic 1 for a prescribed time together with an identification bit and a data when not. CONSTITUTION:When its own termination equipment (DEC)1 detects that a data from a terminal equipment (DTE)1 to be sent to an opposite DCE2 is all '1' for a prescribed time, a bit string BA11 comprised of bit string 0, S0, S1, S2 is sent to the opposite DCE2. Since the head identification bit is 0, the DCE2 keeps the data to the DTE2 to logic 1, receives the next bits S0, S2 as a control signal and sends it to the DTE2. When the data from the DET1 to the DCE2 is other than all '1', the identification bit is changed into '1' and sent to the DCE2, which recognizes that the next bit string is a data. The transmission from the DCE2 to the DCE1 is executed similarly. Thus, even during data communication, the control signal is sent to the opposite DCE so as to improve the operability.

Description

[Detailed Description of the Invention] [Summary] If the formant transmitted from one digital line terminating device to the other line terminating device is "1" at a certain time, a control signal is sent, and if not, data is identified. It was designed to be sent with a bit attached.

[Industrial Application Field] The present invention improves operability by changing the transmission format when a digital terminal is connected to a switching network via a digital line termination device and data is transmitted from the line termination device to another digital terminal. Regarding data transmission methods.

[Prior Art] A digital transmission system has a basic configuration shown in FIG. In FIG. 4, reference numeral 1 denotes a digital exchange which connects a plurality of data transmission lines 2-1, 2-2-. A digital line termination device 3- is installed at the front end of each transmission line.
1.3-2 (DCE), each corresponding digital terminal 4-1.4-2-...-(DTE) is connected. Digital terminal 4-1.4-2-... (DTE
) When transmitting data between each other, control bits SO and SL are added to the 6-bit data Do-D5 sent from one terminal at the digital line termination equipment (DCE) as shown in the formant shown in Figure 5. Then, it is sent as a total of 8 bits of data to the other party's line termination device DCE via exchange 1 (PBX). At this time, the transmission speed is made 4/3 times faster than in the case of only data Do-D5. The received line terminal device DCE removes the control bits So and SL and uses the remaining Do-D5 as regular data to send to the terminal device D.
Send to TE. Explain how to use the control beeps) So and SL. When the terminal DTE communicates with each other as an extension terminal,
An R3 signal (transmission request signal) is carried as SO, and the other party's line terminating device 1DCE sends the received R3 signal to the DTE as a CD signal.

In addition, as Sl, the RS signal is returned and the C8 signal (
From this signal, the original line terminating device DCE knows that the R3 signal has arrived at the other line terminating device DCE.

Furthermore, in the case of data transmission using the PCM24B communication system, a bit steal system is adopted, so for example, 81 bits (corresponding to LSB) are used once every 6 frames as a call signal and a call termination signal.

Therefore, 81 bits cannot be used for data transmission, and currently only SO can be used as a control signal.

[Problems to be Solved by the Invention] There is a desire to receive and pass a larger amount of control information during data transmission than during voice transmission, but in reality, it is only possible to use SO bits and it is not possible to increase the amount of control information. In particular, once data transmission has started, when it becomes necessary to send control information to the other party's line terminating device, it cannot be carried out quickly. - The object of the present invention is to improve the above-mentioned drawbacks, to distinguish between data transmission and control signal transmission using formant identification bits, to transmit a large amount of control information between line termination devices, and to improve operability. The purpose is to provide a data transmission method.

[Means for Solving the Problems] FIG. 1A is a diagram showing a transmission format during transmission of a control signal sent from a line termination device according to the present invention, and FIG. 1B is a diagram showing a format during data transmission.

In Figure 1A, the first bit "0" is an identification bit indicating that the following bit is a control signal, and in Figure 1B
When the identification bit is set to "1", the continuation bit indicates data.
The line terminating device DCEI is the other line terminating device DC.
Set as an identification bit indicating that a control signal is to be sent to E2. (Alternatively, after this set, when it becomes necessary to transmit control information again after starting data transmission using the means and actions described later, the data bit string is kept in the "1" state for a predetermined period of time, so that it can be detected. (The first bit is set to "0" and the control information is placed on the following bit string and transmitted.) The control information is transferred to the predetermined control line according to the order of control for the own line termination device 1DcE1 and the other party's line termination device 1DcE1. For example, it transmits control information such as a terminal transmission ready signal ER to SO, a transmission request signal R3 to Sl, and 81-bit information from the other party's line terminal device to S2. A communication method that conforms to the 100 series interface of CCITT Recommendation V24 will be explained below with reference to FIG. In Figure 2, DCEl is its own line termination device,
DCE2 is the other party's line terminating device, PBX is a digital exchange, DTEl is a terminal corresponding to the line terminating device DC'EI, and DTE2 is a terminal corresponding to the line terminating device DCE2. The V24-100 dotted line indicates that the interface conditions at that location satisfy the 100 series of CCITT Recommendation V24. The own line terminating device DCE 1 keeps the data from the terminal DTE 1 to be sent to the other party's line terminating device DCE 2 as all “1” for a predetermined period of time.
When detected, 0. Bit string BAL of So, Sl, S2
L is transmitted toward the other party's line terminal device DCE2.

The other party's line termination device DCE2 receives the bit string BALL. Since the identification focus is "0", the data to the terminal DTE2 is held at 1', SO receives it as a data set ready signal DR, and Sl receives it as a carrier detection signal CD, and sends it to the terminal DTE2. In addition, the line termination device DCE
When the data from the terminal DTE2 to be sent to the terminal DTE2 is detected to be all "1" for a predetermined period of time, the bit string BA21 of the control'a signal is sent to the line terminating device DCE1. That is, the terminal transmission ready signal ER is placed on the identification bit "O" with M<so, the transmission request signal R3 is placed on Sl, and the received carrier detection signal CD is placed on G2.

The line termination device DCEI receives the bit string BA21,
Since the identification bit is “0”, the data to DTEI is 1”.
, and receives SO as a data set ready signal DR, SL as a carrier detection signal CD, and G2 as a transmittable signal CS.

If the data call from the terminal DTE1 is other than "1", the line terminating device DCEI changes it to the identification billatra "1",
Send the bit string shown in FIG. 1B.

The other party's line terminal device DCE2 looks at the identification bit and knows that the next bit string is data. The same applies when data is sent from the other party's line terminating device DCE2 to the line terminating device DCE1.

Note that the idea of bit stealing can be applied to bit string 86 or D6, so it is normally left empty so that it can be used when necessary.

[Operations] In the present invention, we focused on a pattern of all "1"s during data transmission, and sent control data during that time. This makes it possible to increase the amount of control data transferred, and to reduce bits on the exchange side. It has no effect on steel.

[Embodiment] FIG. 3 shows a configuration diagram of a circuit provided in the line termination device DCE as an embodiment of the present invention. In Figure 3, 1
1.12 is Orgate (Gl) (G2), 21,22
, 23.24 is a shift register (SRI) (SR2
) (SR3) (SR4), 30 is the selector (S
EL), 31, 32.33 are registers (REGI) (
REG2) (REG3), 40 is a flip-flop (FF), and 50 is an all "1" detection circuit.

Data from terminal DTE is sent to line terminating device DCE via SD line.
and serially connected by shift register 21 (SRI).
It is converted into parallel data and held in register 31 (REGI). When the parallel-converted data is all "1", the all-1" detection circuit 50 outputs "0", and the output of the selector 30 is connected to the B line. 1st bit of B “
0'' is an identification bit, the second bit SO is the terminal device ready signal ER, and the third bit S1 is the transmission request signal R.
3, the fourth pin 32 carries a 31-bit return signal from the destination line termination device DCE, and those four bits are converted from parallel to serial in the register 22 (SR2) and sent to the destination line termination device. Sent to DCE. The signal from the other party's line terminal device DcE is sent to the register 23 (SR
3), is serial-to-parallel converted, and is stored in register 3.
2 (REG2). Since the first bit (identification bit) is "O", the OR gate 12 (G2) is closed through the flip-flop 40, the terminal RD is fixed at 1", and the OR gate 11 (Gl) is opened.

As a result, the second to fourth bits are taken into the register 33 (REG3) by the clock CLK, and become the data set ready signal DR, carrier detection signal CD, and transmittable signal CS, respectively. The CD signal then enters the selector 30 (SEL) at the same time and becomes 82. Fourth
Bin) G2 sends back the CD signal received by the line terminating device. Upon receiving it, it enters the register 32 (REG2) and obtains a send enable signal CS.

When the output of the register 31 (REGI) is not all "1", the output of the detection circuit 50 becomes "1", and the selector 3
The output of 0 (SEL) is connected to the line A, the first bit "1" is an identification bit, and the data on the signal line SD is sent out.

If the identification bit from the other party is “1”, register 31
The first bit of (REGI) becomes "1", closing the OR gate 11 (Gl), opening the OR gate 12 (G2) through the flip-flop 40, and outputting the data of the shift register 24 (SR4) to the terminal RD. .

[Effects of the Invention] Thus, according to the present invention, even during data communication, if data continues to be "1" for a certain predetermined period of time, control information can be transmitted to the other party's line terminal device (for example, (If one bit of start-stop data is sampled at multiple points at 12 or more points, control information can be sent as long as even one bit is "1".) This improves operability and improves communication efficiency. It also improves.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a transmission format sent to the other party's line termination device according to the present invention, FIG. 2 is an explanatory diagram of a state in which the transmission format of FIG. 1 is transmitted to each other, and FIG. FIG. 4 is a diagram showing the configuration of a circuit provided in a terminal device, FIG. 4 is a diagram showing the configuration of a digital data transmission system, and FIG. 5 is a diagram showing a conventional transmission format. 1.-Digital exchange PBX

Claims (1)

[Claims] In a data transmission method between digital line termination devices housed in a digital exchange based on digital signals from a digital terminal, the transmission format for transmission from one line termination device to the other is determined by the data from the terminal. When it is detected that all "1"s are set for a predetermined period of time, the identification bit for control signal transmission and a control signal to the line termination device are transmitted in the next frame, and if the data from the terminal is any other value, the transmission signal is data. The receiving side looks at the identification bit and sets the transmission data to the terminal as “1” if it is a control signal.
A data transmission method characterized in that the bit string is held as data, and if the identification bit indicates data, the subsequent bit string is sent to the terminal as data.