JPH02276332A - Data communication system - Google Patents

Abstract

PURPOSE:To enable data terminal equipment to be connected to another data line terminating device in tandem by comprising a data communication system of the data terminal equipment and a data line terminating device incorporating a bit buffer being operated synchronizing with a clock from the data terminal equipment positioned at an intermediate part. CONSTITUTION:The data line terminating device 1, after absorbing the jitter of a transmission clock ST1 from the data terminal equipment 2 by a built-in bit buffer, sends it to a data line. The data line terminating device 4 sends the clock RT extracted from reception data to the data terminating device 5 as the clock ST1 of a data terminal. The data terminating device 5, after absorbing the jitter of the clock ST1 of the data terminal by the built-in bit buffer, sends it to an opposite data line terminating device 3. Meanwhile, as for a data flow from the data terminal equipment 6 to the data terminal equipment 2, data is sent to the data line terminating device 5 synchronizing with a clock ST2 extracted from the reception data that is equivalent to the reception clock RT.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to synchronous data transmission, and particularly to a data communication system for realizing multi-stage interconnection of data line termination devices.

[Conventional technology]

An example of a conventional synchronous data communication system is shown in FIG. 2 and will be described.

In the figure, 11 is a data terminal device, 12 is a data line termination device that performs data transmission in synchronization with the transmission clock 5TIK of this data terminal device 11, and 13 is data communication in synchronization with clock ST2 extracted from the received data of the data line. 14 is a data terminal device. RT indicates a reception clock.

In the data communication system configured in this way, the data flow K from the data terminal device 14 to the data terminal device 11 is because the data line termination device 13 operates in synchronization with the clock extracted from the received data. , the transmission data from the data line termination device 13 is sent to the data line termination device 12 in synchronization with the clock ST2, which is the same as the reception clock RT.

The data line termination device 12 then sends and receives data to and from the data terminal device 11 in synchronization with the clock extracted from the received data.

[Problem to be solved by the invention]

In the conventional synchronous data communication system described above, when one data line terminating device uses the clock supplied from the data terminal device as the transmission clock, the opposing data line terminating device uses the clock extracted from the received data. There was no reason for it to work in sync.

As a result, there has been a problem in that it is impossible to connect tandemly to other data line terminating devices on the data terminal device side of a data line terminating device that operates in synchronization with a clock extracted from received data.

[Means to solve the problem]

The data communication system of the present invention includes a first synchronous data line termination device that includes a built-in bit buffer and transmits data using a clock supplied from a data terminal device as a transmission clock, and a first synchronous data line termination device that extracts a clock from received data on the data line. and a second synchronous data line termination device that performs data transmission in synchronization with the extracted clock, and the first and second
A tandem-connected 2n (n a natural number) system with a built-in pit halafah located in the middle of the synchronous data line terminal equipment, which transmits data in synchronization with the clock from the data terminal equipment. It consists of multiple data line termination devices.

[Effect]

In the present invention, the data line termination device sends and receives data to and from the data terminal device in synchronization with the clock extracted from the received data.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 is a block diagram showing an embodiment of a data communication system according to the present invention.

In the figure, 1 has a built-in bit buffer and transmits the clock supplied from the data terminal device 2 as a transmission clock 8T.
3. Synchronous data line termination device that performs data transmission as
4.5 is a synchronous data line termination device that extracts a clock from received data on a data line and transmits data in synchronization with the nine clocks; 4.5 is an intermediate between the above two types of synchronous data line termination devices 1.3. It has a built-in bit buffer and is equipped with a tandem-connected 2n (n
: natural number) is a data line terminal device.

6 is a data terminal device.

Next, the operation of the embodiment shown in FIG. 1 will be explained.

First, the data line termination device 1 performs data transmission in synchronization with the transmission clock 8T11C of the data terminal device 2. Next, the data line terminating device 3 extracts data from the received data on the data line and performs data communication in synchronization with sT2.

Furthermore, the 1-data line termination devices 4 and 5 perform data transmission in synchronization with the clock from the data terminal device. The data line termination devices 4 and 5 are tandemly connected to each other on the data terminal ink 7ace side.

On the other hand, data line termination equipment*1. S has a built-in bit buffer for absorbing clock jitter supplied from the terminal side interface.

Now, the data sent out by the data terminal device 2 is synchronized with the transmission clock ST of the data terminal device 2. Then, the data line termination device 1 absorbs the jitter of the transmission clock ST1 from the data terminal device 2 using a built-in bit buffer, and then transmits it to the data line.

Then, the data line terminating device 4, which is opposite to the data line terminating device 1, receives the clock R extracted from the received data.
T is sent to the data line termination device 5 as the data terminal clock ST. This data line termination device 5 uses a built-in bit buffer to provide the data terminal clock signal ST! After absorbing the jitter, the signal is sent to the opposing data line termination device 3.

On the other hand, regarding the data flow K from the data terminal device 6 to the data terminal device 2, since the data line terminating device 3 operates in synchronization with the clock extracted from the received data, the transmission from the data line terminating device 3 is The data is sent to the data line termination device 5 in synchronization with a clock 8TzK extracted from the received data, which is the same as the received clock RT.

The data line terminating device 5 then supplies the clock (receiving clock) RT extracted from the received data to the data line terminating device 4. This data line termination device 4 uses the reception clock RT from the data line termination device 5 as a transmission clock, and sends data to the data line termination device 1.

Finally, the data line termination device 1 sends and receives data to and from the data terminal device 2 in synchronization with the clock extracted from the received data.

〔Effect of the invention〕

As explained above, the present invention provides a data line terminating device with a built-in bit buffer that operates in synchronization with a data terminal equipment clock, a data line terminating device that extracts received data and operates in synchronization with nine clocks, and the data line terminating device that operates in synchronization with nine clocks extracted from received data. If a data communication system is configured with a data line termination device located in the middle that has a built-in bit buffer that operates in synchronization with the clock from the data terminal device, it will be possible to connect to other data line termination devices in tandem. There is an effect that can be done.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a data communication system according to the present invention, and FIG. 2 is a block diagram showing an example of a conventional synchronous data communication system. 1...Data line termination device, 2...-data terminal device, 3-5...Data line termination device, 6...
Data terminal equipment.

Claims (1)

[Claims] A first synchronous data line termination device that has a built-in bit buffer and performs data transmission using the clock supplied from the data terminal device as a transmission clock; It is located between a second synchronous data line terminating device that performs data transmission, and the first and second synchronous data line terminating devices, and has a built-in bit buffer and is connected to the clock from the data terminal device. 1. A data communication system comprising tandem-connected data line termination devices with 2n (n: natural number) that perform data transmission synchronously.