JPS6358504B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a store-and-forward data transmission system in which data transmission devices having a store-and-forward function are interconnected and data is transmitted between arbitrary data transmission devices.

Data transmission in a conventional store-and-forward data transmission system will be explained using a specific example. As shown in FIG. 1, data transmission devices ST1 to ST4 are interconnected. Each device also has terminals TM1 to TM.
8 are connected, and the transmission data shown in FIG. 2 is output from each terminal. This data consists of a destination address (ADD) indicating the destination terminal station and terminal, transmission information (DATA), and an error detection code (CHK) for detecting code errors.

The transmitter receives the transmitted data from the terminal,
When reception is completed, it is determined whether there is a code error or not.
If it is determined to be correct, it is transferred to the transmission device indicated by the address field; if it is determined to be incorrect, it is not transferred. Data transfer between each transmission device is performed by, for example, a packet switching method. In the packet switching method, when data is transferred from device ST1 to ST3 in Figure 1, a packet of a length that improves transmission efficiency or shortens transmission delay time is relayed through device ST2 or ST4. (Fig. 3, a to d) and transferred to the transmitting side.

The receiving station receives the sequentially transmitted packets, converts them back to the data format shown in FIG. 2 when all the packets are completed, and outputs the received data to the terminal. However, in such a system, the transmission to the destination device is started once the transmitter has completed receiving all the transmission data output from the terminal, so the transmission delay time is increased as shown in Figure 3. It has the disadvantage of being large.

SUMMARY OF THE INVENTION An object of the present invention is to provide a data transmission system that eliminates the above-mentioned drawbacks by starting transfer before completion of reception of transmission data from a terminal in a transmission section of a data transmission device.

Next, the present invention will be explained in detail with reference to the drawings.

In the following explanation, the present invention will be explained as shown in FIG. 1, in which data transmission devices ST1 to ST4 are interconnected to form a data exchange network, and terminals TM1 to TM8 connected to each device are connected to each other. A case suitable for a system that transmits data will be explained as an example.

Data in the format shown in FIG. 2 is input from the terminal to the terminal station.

In the transmitting units of the devices ST1 to ST4, the terminals TM1 to
While accumulating the data sent from TM8, the amount of data is counted. When this count reaches a certain value (N shown in Figure 4a), the stored data is divided into one or more pieces and transferred to the device indicated by the address field ADD (Figure 4b). . Thereafter, the sequentially accumulated data is transferred in the same manner as described above (FIG. 4c). When the reception of the transmission data from the terminal is completed, the presence or absence of a code error is determined, and the result is notified to the destination device along with a transmission data end notification.
In this way, in the transmission method of the present invention, data transmission delay time can be shortened by starting transfer to the destination device before all data is received.

FIG. 5 is a block diagram of a data transmission device used in the data transmission system of the present invention.

Transmission data A from the terminal TM is converted into a TTL level signal in the reception interface circuit 1, and then inputted to the transmission buffer circuit 5, and is also sent to the address detection circuit 4 for the destination device and the terminal connected to this destination device. address is detected. The transmission data amount detection circuit 6 counts the number of data accumulated in the transmission buffer circuit 5, and notifies the packet assembly circuit 7 when it reaches a certain value (N).
The packet assembling circuit 7, which has been notified of the accumulation of a certain amount of data, packetizes the data in the transmission buffer circuit 5, adds the address output from the address detection circuit 4 to the header part of the packet, and sends the packet to the packet exchange control circuit 8. input. Data end detection circuit 2
detects the end of the transmitted data, and notifies the packet assembly circuit 7 of this detection result and the presence or absence of a data error detected by the data error detection circuit 3. Upon receiving this notification, the packet assembling circuit 7 creates a data end notification packet P indicating the presence or absence of data errors. The packet switching control circuit 8 transfers the completion notification packet to the destination device according to the packet switching protocol.

On the other hand, in the receiving device, a received packet is decomposed by a packet decomposing circuit 9, a data portion is stored in a receiving buffer circuit 12, and an address portion is provided to an address storage circuit 11. When the packet disassembly circuit 9 receives the transmission data end notification, it checks whether there is a data error or not, and if there is a data error, it discards the data in the reception buffer circuit 12 and stops outputting it to the terminal.
If there is no data error, following the address in the address storage circuit 11, all the data in the reception buffer circuit 12 and the error detection code created by the error detection code creation circuit 10 are sent to the terminal via the selection circuit 13 and the transmission interface circuit 14. Output to.

As described above, in the present invention, data transfer to the destination device is started before the input of transmission data from the terminal is completed, so that the transmission delay time can be reduced.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the system configuration of the switched data transmission system, Figure 2 is a diagram showing the data input/output format with a terminal in the switched data transmission system, and Figures 3a to 3d are diagrams showing the conventional switched data transmission system. 4A to 4D are time charts for explaining an embodiment of the present invention, and FIG. 5 is a block diagram of a transmission device used in the present invention. In Fig. 1 and Fig. 5, ST1 to ST4...
...Data transmission device, TM1 to TM8...Terminal device, 1...Reception interface circuit, 2...Data end detection circuit, 3...Data error detection circuit, 4
... Address detection circuit, 5 ... Transmission buffer circuit, 6 ... Data amount detection circuit, 7 ... Packet assembly circuit, 8 ... Packet exchange control circuit, 9 ... Packet disassembly circuit, 10 ... Error detection code creation circuit, 11... address storage circuit, 12... reception buffer circuit, 13... selection circuit;

Claims (1)

[Claims] 1. In a store-and-forward data transmission system in which data transmission devices having a store-and-forward function and a transmitter and a receiver are connected to each other and data is transmitted between arbitrary data transmitters, the data transmitter as the source The transmitting unit monitors the amount of data to be transmitted supplied from the transmitting terminal, and when the amount of data reaches a certain value, starts transferring the data to the data transmission device of the destination, and transmits the data from the transmitting terminal. When the data ends, a data end packet indicating the presence or absence of an error in this data is transmitted, and when the receiving section of the destination data transmission device determines a data error in the data from the data end packet,
Abandoning the data existing in the destination data transmission device at that point, and stopping the transmission of the data from the transmission section of the destination data transmission device to the receiving terminal connected to this transmission section. A store-and-forward data transmission system characterized by: