JPS63217736A - Data transmission system - Google Patents

Abstract

PURPOSE:To attain the normal transmission of all transmission data by one retransmission by dividing a sent data into plural partial data and providing a transmission check sum data at every partial data. CONSTITUTION:A computer 1 divides a transmission data to be sent into n-block to produce transmission check sum data 51-5n to each of partial data 41-4n. Thus, the data 41-4n added with the data 51-5n are sent in the lump to a terminal processor 2. The unit 2 uses a reception circuit 7 to receive them and produce the received check sum data 91-9n from the received partial data 81-8n and they are compared and collated with the sent data 51-5n. Thus, the discrimination between the partial data received normally in the received data in the equipment 2 and the partial data having transmission error is attained. Thus, so long as the transmission error is not caused in the same partial data at the retransmission request, the normal data transmission is attained by one retransmission.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to error detection and error recovery of transferred data in data transmission.

[Prior Art] Fig. 2 is a block diagram showing a conventional data transmission system disclosed in, for example, Japanese Patent Application Laid-Open No. 59-81940. 3 is a serial I10 line connecting this computer 1 and the terminal processing device 2, 4 is the transmission data sent by the computer 1, 5 is the transmission checksum data of this transmission data 4, and 6 is a serial 7 is a receiving circuit that receives information from serial I10 line 3; 8 is received data; 9 is received checksum data of the received data; 10 is the receiving circuit 7 and transmitting circuit 6; This is the control line that connects the

Next, the operation will be explained. Computer l is terminal processing device 2
In order to instruct the controller to operate, the transmitting circuit 6 transmits transmitting data 4 via the serial I10 line 3. At this time, in order to prevent transmission errors, the computer 1 generates transmission checksum data 5 from the transmission data 4, and
This is added to the transmission data 4 and transmitted. This transmission checksum data 5 is given as the value of the least significant word of the sum of all the words of the transmission data 4. The terminal processing device 2 receives these with the receiving circuit 7, generates received data 8 using the same method as the computer 1, and compares this with the transmitted data 5. Verify.

As a result, if the two match, the received data 8
Assuming that there is no error in the received data 8, the next terminal processing operation is started based on the contents of the received data 8. Further, if the two do not match as a result of the comparison, it is assumed that there is an error in the received data 8, and a retransmission request signal is sent from the receiving circuit 7 via the control line IO. The computer 1, which has received this retransmission request signal at the transmitting circuit 6, transmits the same transmitted data 4 and its transmitted index data 5 from the transmitting circuit 6 via the serial I10 line 3.

By performing such processing each time the computer I transmits the transmission data 4, the terminal processing device is prevented from malfunctioning due to an error in data transmission on the serial I10 line 3.

[Problems to be Solved by the Invention] Since the conventional data transmission system is configured as described above, when transmitting a large amount of transmission data 4 at one time, only one word of the transmission data 4 is transmitted. Since only transmission checksum data 5 is prepared, if data transmission errors are likely to occur in an electrical noise environment, it will be difficult to transmit all of the large amount of transmission data 4 without errors, and a retransmission request will be issued. There are problems such as an increase in the number of transmissions, or in extreme cases, data transmission becomes impossible, which hinders the operation of the terminal processing device 2.

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a data transmission method that can transmit a large amount of data even in an electrical environment where data transmission errors are likely to occur.

[Means for Solving the Problems] The data transmission method according to the present invention divides transmission data into a plurality of partial data, generates transmission checksum data for each partial data, and processes this transmission checksum data by dividing transmission data into a plurality of partial data. It is added to the transmission data and transmitted.

[Function] The data transmission method of the present invention divides the transmission data into a plurality of partial data and provides transmission exsum data for each partial data, so that the receiving side can successfully receive the 4-transmission data. It is possible to distinguish between partial data and partial data with a transmission error, and as long as a transmission error does not occur in the same partial data at the time of a retransmission request, normal transmission of all transmitted data is possible with one retransmission. .

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
In the figure, 1 is a computer, 2 is a terminal processing device, 3 is a serial I10 line, 6 is a transmitting circuit, 7 is a receiving circuit, 1
0 is a connecting control line, and these are the same as or equivalent to the conventional ones, which are given the same reference numerals in FIG.
Detailed explanation will be omitted. Further, 4I to 4n are partial data obtained by dividing the transmission data of the computer 1 into n blocks, 5I to 5n are transmission checksum data of each of the partial data 41 to 4n, and 8. ~8n is partial data received by the terminal processing device 2; 9. ~9n is each partial data 8
．． This is the received checksum data of ~8n.

Next, the operation will be explained. Computer l is terminal processing device 2
In order to instruct the controller to operate, the transmission circuit 6 transmits transmission data via the serial I10 line 3. At this time, the computer 1 divides the transmission data to be transmitted into n blocks, and generates transmission checksum data 51 to 5n for each of the partial data 41 to 4n. These transmission checksum data 5I to 5n are each partial data 4. ~4n
It is given as the value of the least significant word of the sum of all words for each case. The partial data 41 to 4n to which the transmission checksum data 51 to 5n have been added in this way are transmitted to the terminal processing device 2 all at once. Terminal processing device 2
is received by the receiving circuit 7, and the received partial data 8
1 to 8n, receive checksum data 9. using the same method as computer 1. .about.9n are generated and compared with the sent transmission checksum data 5I.about.5n. As a result, if the two match across all blocks, it is assumed that there was no error in the received data.
The next terminal processing operation is started based on the content of this received data.

Here, as a result of this comparison and verification, for example, if the two do not match in the m-th block (l≦m≦n), the terminal processing device 2 determines that there is an error in the received data and sends the message to the computer 1. A retransmission request signal is sent from the control line 10 via the receiving circuit 7. The computer I that received this retransmission request signal at the transmitting circuit 6 transmits the same partial data 41 to 41.
Transmission test data 5I to 5n are added to 4n and transmitted again. In the terminal processing device 2, this retransmitted partial data 4. ~4n and transmission checksum data 51~5n
When receiving , partial data 8m of only the m-th block where a mismatch was detected last time and transmission checksum data 9m are received.
and discard other blocks that have been successfully received. Next, received data 9m is generated from the captured partial data 8m, and this is compared with the transmitted data 5m that has been sent.

The above process is repeated for all blocks until the results of the comparison between the received checksum data and the transmitted checksum data match.

Here, if data transmission errors occur randomly, the probability that a transmission error will occur two or more times in a row in a particular block is low; Even if the frequency is extremely high, if you increase the number of block divisions and reduce the number of words per block, the probability of occurrence of transmission errors for each block will be lowered. Therefore, the probability that a transmission error will occur two or more times in a row is low.

Therefore, normally, by retransmitting the transmission data one or more times, all the transmission data is transmitted to the terminal processing device 2 without error. When the terminal processing device 2 receives the received data without error, it starts the next terminal processing operation based on the contents of the received data.

=8- [Effects of the Invention] As described above, according to the present invention, a large amount of transmission data is divided into a plurality of blocks, and the data is added to each block and transmitted. Even if the transmission line is used in an environment where transmission errors are likely to occur, it is possible to transmit error-free transmission data with a small number of retransmission processes. This has the effect of providing a high data transmission method.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a data transmission system according to an embodiment of the present invention, and FIG. 2 is a block diagram showing a conventional data transmission system. l is the sending side (computer), 2 is the receiving side (terminal processing device),
4 is transmission data; 4. ~4n is partial data, 5,51~
5n is the transmitting exsum data, 8 is the receiving data, 8.
~8n is partial data, 9°9, ~9n is received checksum data. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. (2 others)

Claims (1)

[Claims] The transmitting side generates transmission checksum data from the transmission data, adds it to the transmission data, and transmits it to the reception side, and the reception side generates reception checksum data from the reception data and transmits it. In the data transmission method, the transmission checksum data is compared with the transmitted checksum data that has been received, and if an error is detected in the received data, a retransmission request is made to the transmitting side. A data transmission method characterized in that the data is divided into partial data, transmission checksum data is generated for each of the partial data, and this data is added to the transmission data and transmitted to the receiving side.