JPS62160835A - Data transmission system - Google Patents

Abstract

PURPOSE:To decrease the overhead and to make the processing efficient by managing a data block depending on a data length and applying transmission control by timeout. CONSTITUTION:When a data converter 6 receives a data 3 by one packet, a data block length 1, a status 2 and a block check data 4 are added and the result is sent to a PC 8. At the transmission, the transmission time interval between character units of data is specified as T1 or below. The PC 8 receives all data at a data interval T2 or below, a block data reception end notice is applied to a converter 6 within a set time T3. After the converter 6 completes the sending of a data block, when the converter 6 receives the data reception completion notice within a time T4, the transmission of next data block is started.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a character-oriented data transmission system for transmitting bit-oriented data blocks on a character-oriented transmission path.

[Conventional technology]

Conventionally, the character-oriented transmission method that transmits bit-oriented data using a character-oriented data transmission path is
The BSC (Binary Synchro) shown in the figure
Code-free data transmission was performed using special control characters, such as the transparent mode of nous communication (binary data synchronous communication). In FIG. 4, 9 and 11 are D L E (Data Link Escape;
Control characters such as Transmission Control Extensions (10) precede the text and are used to terminate headings, such as Start of Text (STX; beginning at text 13n), 12
is an end of text (ETXi text termination), which is a transmission control character that terminates text, and 3 is bit-oriented data.

The transparent mode of the conventional character-oriented transmission system is an extended mode of the I3SC as described above, and the BSC
This makes it possible to transmit only data as bit-oriented data while performing exactly the same operation as the procedure described in . In other words, if DLE is added to all BSC control codes and data is transmitted using this as a regular control code, the start-off character, which is a control character, is
It becomes possible to transmit data with the same bit pattern as 0 (5TX in FIG. 4). When data having the same pattern as the control character 11 appears in bit-oriented data, an extra control character 9 is added to represent the data.

[Problem that the invention seeks to solve]

The procedure of the conventional character-oriented transmission method described above requires that the content of all data to be transmitted be constantly monitored while controlling the transmission, and that it be checked whether it is DLE or not. In cases such as data transmission between two devices, there is a problem in that the dead time (dead time) becomes too large and processing efficiency decreases.

The present invention was made to solve the above-mentioned problems, and an object of the present invention is to obtain a data transmission method that allows data transmission with small overhead.

[Means for solving problems]

The data transmission method according to the present invention adds data with a data block length indicating the data length to a data block of bit-oriented data, and when receiving a transmission control, the data is based on the data with the data block length. The transmission of the bit-oriented data after the character-oriented data is transmitted is controlled based on the maximum reception time set.

[Effect]

The transmission control of the character-oriented transmission method in this invention treats a received packet as one data block, adds block data length data and transmission/reception status to the front of the data block, and adds block check data afterward, and sends out the character-oriented data. When receiving these data, the maximum value of the sending data interval and the maximum value of the time until receiving the reception completion notification from the data processing device after sending the data are specified, so that the overflow can be minimized. becomes possible.

[Embodiments of the invention]

An embodiment of the present invention will be described below. This embodiment converts data received from a bit-oriented data transmission path such as a captain's network or personal computer communication, and transmits data to a data processing device such as a personal computer. This is an embodiment in which the character-isomorphic data transmission method of the present invention is adopted for data transmission between a converter and a data processing device when bit-oriented data is transmitted using a channel.

FIG. 1 shows a transmission data block. In the figure, l is a data block length, 2 is a transmission/reception status having a fixed length, 3 is bit-oriented data, and 4 is block check data.

FIG. 2 is a configuration diagram of the above embodiment, and 5 is an HDLC (H
igh-Level DaLa Link Contr
6 is a data converter,
7 is an asynchronous transmission line, 8 is a personal computer (
(hereinafter referred to as Pc).

FIG. 3 shows the contents of timeout processing performed by the data converter side and the personal computer side, respectively.

Next, the operation will be explained. Data transmission is done by data converter 6
However, when the data converter 6 receives one packet worth of data 3 from the transmission path 5, it converts the data block length 1, status 2, block check data 4 as shown in FIG. is added and the data is sent to the PC 8 via the transmission line 7. At this time, data block length l
is the length from status 2 to block check data 4. When transmitting data from the data converter 6 to the PCB, the transmission time interval between data characters is T,
It stipulates that the following shall be done. The PC 8 constantly measures the data reception interval, and if all data can be received with the data interval less than T2, the time Tel (
Block data reception completion notification is given within time 3 calculated from data block length 1. This is done in the same data block format as in FIG. 1, but in this case, status 2 mainly has completion information, and data 3 may not be present. When the data converter 6 receives a data reception completion notification within time T4 after data block transmission is completed, it assumes that data transmission has been completed normally and starts transmitting the next data block. However, Tt and T in the above
z, 'r, , 'r4 are Tt < Tt, T3
<T4 is preset.

Here, during data transmission from the data converter 6 to βC 8, if the PCB cannot receive data for more than time T2, or if an abnormality in the received data block is detected by the block check data 4, the PCB The data block is invalidated, a data reception failure notification is clearly indicated on status 2 to the data converter 6, and the first
All of the data blocks shown in times or data block length 1. Status 2. Block check data 4
Send out. Moreover, the data converter 6 clearly indicates data retransmission on status 2 and sends the same program again to the PCB.

Also, the data converter 6 sends a data reception completion notification at time T4.
If the block cannot be received even after waiting longer than that, the same block is sent out with a clear indication of re-sending on status 2.

In the above embodiment, the data block length is 1 and the status is 2. Data 3. Although the total length of block check data 4 is shown, the length of only data 3, the total length of data 3 and block check data 4, or the total length of status 2 and data 3 is also shown. Good too,
Furthermore, if the status 2 is made to indicate the status length, the status 2 can have a variable length.

Further, in the above embodiment, although the transmission line 5 is HDLC in the above embodiment, it may be any other bit-oriented data transmission format, and furthermore, although the transmission line 7 is a start-stop synchronization, this transmission method may also be used. A character-oriented data transmission format may also be used.

Although the personal computer 8 is used in the above embodiment, any computer may be used as long as it has a character-oriented data transmission/reception function.

Further, the method of the present invention may be used for communication between data processing devices.

[Effects of the Invention] As described above, according to the present invention, data blocks are managed by data length and transmission control is performed by timeout, so there is no need to monitor all received data, and special control is not required. Since it is no longer necessary to define data, there is an effect that over-rad is reduced and processing efficiency is improved.

[Brief explanation of drawings]

FIG. 1 is a data format diagram of a character-oriented data transmission system according to an embodiment of the present invention, and FIG. 2 is a configuration diagram of a system in which the data blocks of FIG. 1 are transmitted.
FIG. 3 is a conceptual diagram of timeout in FIG. 2, and FIG. 4 is a format diagram showing the transparent mode of the BSC in the conventional character-oriented transmission system. 1 is data block length data, 2 is transmission/reception status, 3 is bit-oriented data, 4 is block check data, 5 is bit-oriented data retransmission, 6 is a data converter, 7 is character-oriented data retransmission, 8 is a personal computer, 9°11 is a control code, IO is a start of text, and 12 is an end of text. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] In a data transmission method for transmitting and receiving data blocks of bit-oriented data between two devices connected to a character-oriented data transmission path, each of the devices transmits and receives data blocks of bit-oriented data, Transmission/reception status, block check data, and data block length indicating the length of the data block or transmission signal status or block check data are added and transmitted, and when received, the length indicated by the data block length is A data transmission method characterized in that a maximum reception time is set based on the maximum reception time, and if the data of the data block is not received within the maximum reception time and a timeout occurs, reception is determined to be poor.