JPS59169269A - Data transmission system - Google Patents

Abstract

PURPOSE:To attain the transmission of data with no complicated control by setting the ineffective data consisting of dummy bits between the intermittent effective transmission data to divide the transmission data into blocks and adding a validity identification code to each block. CONSTITUTION:The character data supplied to a facsimile transmitter is stored in a buffer memory 1. When the memory 1 is congested and synchronous with the transmission timing of the block data, the contents of the memory 1 are sent to a frame generating part 2 for each block data with addition of an effective code from a coder 3. No effective data to be transmitted is obtained while the memory 11 is storing the character data, and therefore an ineffective code is added from the coder 3. Then the contents of the part 2 are converted 4 serially in accordance with the transmission timing of the block data in the form of dummy bits. The converted contents of the part 2 are transmitted after modulation 5. The receiving part extracts 8 the transmission data and identifies 9 the validity or invalidity of the data. Thus only effective data can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a data transmission system for transmitting data while keeping a transmission line closed.

[Technical background of the invention and its problems]

Originally, facsimile machines were used to transmit image information, but in recent years, facsimile machines have been used as office automation equipment (O
It came to be used for data transmission such as characters so that it could be used for networking of A device).

For example, can character information generated in a word processor or office computer be transmitted over the phone to a facsimile machine? A network is constructed in which the information is transmitted to another facsimile machine via # and inputted into a peripheral word processor or office computer.

Therefore, the character information stored in the memory of one device is sent to the buffer memory in the facsimile machine and transmitted sequentially, but it is necessary to transmit the character information separately from the image information. After performing some processing, it must be sent to the buffer memory.

The processing speed required for this processing is slower than the transmission speed of the line, so after the contents of the buffer memory in the facsimile machine are transmitted via the line, the buffer memory is transferred to
It took a while for it to go into a secret state.

Therefore, after transmitting the contents of the buffer memory, control is required to disconnect the line twice, wait for the buffer memory to become stable, restore the line, and resume transmission. The problem was that it took a lot of time and effort.

,: The problem is that a buffer memory with a huge capacity is provided, all the character information to be transmitted is processed, it is stored in the buffer memory inside the facsimile machine, and then this processed character information is transmitted all at once. It's resolved. However, there are cases where the amount of information to be transmitted is small, and it is uneconomical to provide a backup memory with a huge capacity in case a large amount of information is to be transmitted.

Also, since the line is disconnected and connected every time the data is transmitted, a method of transmitting a standby command to the receiving side after transmitting data and transmitting data while maintaining the circuit 161 closed is also considered. However, this method has the problem of complicated control such as sending out standby commands.

[Purpose of the invention]

An object of the present invention is to provide a data transmission method that can transmit data that is generated intermittently without complicating control.

[Outline of the invention]

The above object of the present invention is to interpose invalid data consisting of dummy bits between valid takes to be transmitted that are generated intermittently, to divide fixed transmission data into blocks, and to check the validity of the data in each block for each block. This is achieved by adding a code to identify the data and transmitting data while keeping the transmission path closed.

[Embodiments of the invention]

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

FIG. 1 is a block diagram showing a facsimile transmitter (σ) according to an embodiment of the present invention, and FIG. 2 is a block diagram showing a facsimile receiver according to an embodiment of the present invention.

Character data input from another OA device connected to the facsimile transmitter is stored in a buffer memory l of the facsimile machine. (If the storage capacity of the sofa memory 1 is set to the standard size, it can store 4 pages worth of character information.) buffer memory l
When the character data becomes stuck in the character data and synchronizes with the timing of block data transmission under the control of a control unit (not shown), the contents of the buffer memory 1 are changed for each block data of a predetermined fixed length (in the normal format). At this time, the encoder 3 sends to the frame generator 2 a valid code indicating that the data is valid. The frame generation unit 2 adds the valid code of the process to the block data consisting of character data,
Generate block data for l frames. The contents of the frame generator 2 are subjected to parallel-to-serial conversion in a parallel-to-serial converter 4 according to the timing of block data transmission, and then transmitted via a modulator 5. Since valid data to be transmitted is not processed while the buffer memory l is storing character data, the contents of the frame generation unit 2 to which the invalid code from the encoder 3 indicating that the data is invalid are added are dummy. It is used as a bit for the timing of block data transmission, is converted from parallel to serial by the parallel-to-serial converter 4, and is transmitted via the modulator 5. Note that the transfer of the contents of each section, the decoding transmission to the encoder 30, and the block data transmission are performed by a control section (not shown).

FIG. 3 shows the structure of a frame that conveys block data in this manner. A flag indicating the start and end of the Fk frame, a valid or invalid code indicating the validity of the A1 frame, and B are data. Mani, fu.

hs if valid data exists in part of the lock data
A code indicating the effective data σ) address within the block data is entered in code 4.

Next, on the receiving side, the transmitted data is demodulated in the demodulation section 7 and sent to the transmission data extraction section 8. The data identification unit 9 identifies whether the data is valid or invalid by referring to the code (A) in the frame;
Only valid data, i.e. character data, can be obtained.

According to this embodiment, data can be transmitted while the transmission path is kept closed, and there is no need for complicated controls for disconnecting and connecting the transmission path.

Furthermore, when there is no data to be transmitted, invalid data with an invalid code added is transmitted as transmission data, so data transmission appears to be continuous. Therefore, since it is not necessary to send a predetermined standby signal to interrupt transmission, control can be further simplified.

Although the above embodiment has been described with respect to the transmission of U-character data, even if it is applied to the case of intermittently transmitting 1Ill image data, etc., the same 0. ) Effect 2 can be obtained.

'f, and as another embodiment of the present invention, the transmitting side equipment e
) Even when data to be transmitted becomes invalid due to an abnormality or the like, an invalid code may be added to the data to inform the receiving side that the data is invalid.

〔Effect of the invention〕

According to the present invention, when data is transmitted intermittently, it is possible to transmit data with easy control, which would otherwise require complicated control.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a facsimile transmitter applied to an embodiment of the invention, FIG. 2 is a block diagram showing a facsimile receiver applied to an embodiment of the invention, and FIG. 3 is a block diagram showing a facsimile receiver applied to an embodiment of the invention. FIG. 2 is a diagram showing the structure of a frame of transmission data according to an embodiment. l@e...Processing section, 2a...-Buffer memory, 3...
... Frame generation unit, 4 ... Encoder, 5 @ @
11 @Parallel-serial converter, 6...Modulator,
7... Demodulation section, 8... Data extraction section, 9...
・Data identification section

Claims (1)

[Claims] Transmission data is divided into blocks consisting of valid data and invalid data made up of dummy bits, and a code is added to each block to identify the validity of the data within the block, keeping the transmission path closed. A take transmission method characterized by continuous data transmission in the state.