JPS62147844A - Data communication control system - Google Patents

Abstract

PURPOSE:To send a preamble in preceding over a transmission frame to attain the communication by sending a flag including a specific code pattern for a prescribed period repetitively in response to communication information. CONSTITUTION:A system control section 28 of a transmission station calls a reception station through a radio equipment 50 from an interface section 10, the reception station in response thereto returns a CED signal to the transmission station under the control of a communication control section 40 and returns a DIS signal in succession therewith. The DIS signal informs the function of the reception station to the transmission station and a flag pattern is sent for nearly 1sec single as the preamble. The communication control section 40 of the transmission station detects the CED and DIS signals, then sends the DCS signal in response thereto to apply the training of a modulator-demodulator 18 of the reception station and returns a CFR signal to the transmission station.

Description

[Detailed description of the invention] Technical field The present invention relates to a data communication control system.

Prior Art For example, in facsimile communication systems, high-level data link control procedures (r+wt<HnLc) are generally used.0 As is well known, CcI using HDLC control procedures
In the protocol based on the G3 facsimile standard of TT Recommendation T.30, control information such as a digital identification signal (Dis) is assembled into a frame and transmitted.

For example, in a noisy communication environment such as line communication, the information contained in the transmission frame is easily affected by foreign noise, and therefore control errors are likely to occur. When a transmission error occurs, the same frame must be sent by rlf, which increases the time for procedure control. Therefore, in wireless communications, a communication control system with better resistance to traffic congestion is desired.

[1] In view of such demands, an object of the present invention is to provide a data communication control system that improves the verbal nature of the transmission control protocol.

According to the present invention, in order to achieve the above object, information is assembled into a transmission frame, and a preamble is sent out in advance of the transmission frame to perform communication, and the preamble has a flag containing a specific code pattern. In a data communication system configured to occur repeatedly over a period of time, one piece of communication control information is transmitted by repeatedly sending out a flag containing a specific code pattern corresponding to the communication control information for a predetermined period of time. It is characterized by

Note that the term "data" in the present specification shall be interpreted in a broad sense, including not only digital data in a narrow sense, but also image information in an analog format such as facsimile information, audio information, and the like. Hereinafter, an embodiment of the present invention will be described.
Next, I will explain it in 34-dimensional terms.

CCIT using the HIILIC control procedure as is well known
In the protocol according to the G3 facsimile standard of Recommendation T.30, when a call arrives at a receiving station, a digital identification signal DIS is returned following a called station identification signal GED. This is to convey the function of the receiving station to the transmitting station, and the transmitting station notifies the receiving station of the communication function of the transmitting station using a digital command signal DO9. Such control information +V is included in a transmission frame as shown in FIG. 3, and is transmitted with a parameter indicating the function of the terminal device incorporated in a facsimile information field (PIF). The format for transmitting such a frame is shown in FIG.

In FIG. 3, the numbers in circles indicate the number of bits.

However, for example, in black wire facsimile communication, which uses radio waves as the communication medium, the transmitted signal is easily affected by foreign noise.
Therefore, such control information is no exception, and there is a relatively high probability that parameters indicating terminal functions will be erroneously communicated.

In this example, the method is almost based on such HDLC procedure,
Moreover, it provides a communication control procedure with excellent noise resistance. More specifically, a frame consists of a flag (
FLAG) followed by 0 In the normal system, this flag is a code pattern in which a specific binary number pattern, that is, a hexadecimal number (H) "7E" continues multiple times, as shown in FIG. The receiving station identifies this flag before analyzing the contents of the frame.

However, in this embodiment, the HDLC frame is not used to transmit control information, but by including control information in the flag pattern body, the communication control procedure signal is made to withstand noise F? Improved sex. In this embodiment, a flag pattern containing such control information is repeatedly transmitted for about one second or more, so that the probability of a reception error occurring at the receiving station is greatly reduced. As shown in FIG. 6, the codes that can be used as the flag pattern are L'Tfl, which is a combination of many hexadecimal numbers from roIHJ to rEFHJ.

However, in a normal facsimile, the types of parameters to be reported to the Be terminal are limited, and are usually about two types: the size of the document and the linear density.

The present example t is then: r 818181. ,,． 81J to A4 size, standard linear density (STD) r7E7E7E, 7EJ to 84 size, standard linear density (STD) r 8E8E8E, ,,,8EJ
A4 size, fine line density (DTL) r 717171. ,
,．． 71J to 84 size, like fine line density (DTL),
Code patterns are selected that do not overlap. This pattern is transmitted as a preamble flag shown in FIG.

Referring to FIG. 1, there is shown an embodiment in which the data communication control system based on unissued IJJ is applied to a facsimile machine. However, the radio device 50 may be, for example, an MCA communication system line where there is a time limit on the use of radio waves, and the input/output line 1 of the interface section IG.
6 is connected to a modem 18. The modulator/demodulator 18 is connected to a coder/demodulator (CODEC) 22 . The modulator/demodulator 18 is a modulator/demodulator that modulates a facsimile signal to be transmitted using a predetermined modulation method and also demodulates a received facsimile signal.

The encoding/decoding 'Jji 22 is the facsimile 4r to be transmitted.
This is an encoding/decoding circuit that frames No. 5 and performs run-length compression encoding according to a predetermined encoding method, and also deframes a received facsimile signal and decodes and reproduces it using the encoding method. At that time, for example, CRC
The normality of the received signal is also checked, such as a (cyclic code check) check.

In this embodiment, an encoding method, a W clock conversion method, a modulation method, and a demodulation method conforming to the CCITT Recommendation G3 standard are advantageously applied to the modulator/demodulator 18 and the encoder/decoder 22.

The facsimile data received by the radio device 50 is demodulated by the modem 18, and stored in the line buffer 24 in units of sub-scanning lines through the encoder/decoder 22. this is,
The data is sequentially read out from the line buffer 24 to the Mfi2B, and recorded as a hard copy on a recording medium by the recording unit 28. Of course, the recording unit 28 may include an image information display device such as a CRT that generates a soft copy.

The facsimile data to be transmitted is sequentially read from the original by the photoelectric conversion element of the reading section 30 by rask scanning, converted into a z-value signal, and stored in the line/transfer buffer 24 in units of sub-scanning lines. This is sequentially read out from the line buffer 24 to the encoding decoder 22, and the encoding decoder 2
2, f'41 regulator 18 and interface i'%lO
It is transmitted from the radio 50 through.

The atF- and operations of these various parts within this apparatus are unified and controlled by the system control section 2B. In this embodiment, the system control section 28 is advantageously constituted by a processing system such as a microprocessor.This device also includes a communication procedure control section 40 for controlling communication procedures, and a communication system 4i1 section for carrying out communication control. 0 communication procedure control unit 40 having 42 executes exchange of procedure and control signals with the other station via the modem 18.
4 parts 28, 40 and 42 c, the control program is configured to perform communication VT control through wireless communication using the line machine 50.

By the way, as shown in FIG.
Facsimile communication proceeds in a manner that substantially follows the protocol according to the G3 facsimile standard of CI TT Recommendation T, 30. In the figure, the hatched portion indicates the signal of the high-speed modem.

The device is applicable to both transmitting and receiving stations. The system control unit 28 of the transmitting station calls the receiving station from the interface unit 10 through the radio 50. In response, the receiving station transmits the CHD under the control of the communication procedure control unit 40.
(called station identification) signal back to the transmitting station, followed by an IS (digital identification) signal.

This DIS signal notifies the transmitting station of one manufacturer of receiving station equipment, and the flag pattern described above is used as the preamble (fourth
In this embodiment, the frame is not configured to be transmitted following this flag pattern, but it is formally configured to transmit the frame successively. The communication procedure control of the transmitting station may be configured as f! 140 detects the CED and IS signals and analyzes the communication control parameters included in the flag pattern according to the flow shown in FIG. 818181. ,,． 81J
If so, the document size is A4 and the linear density is standard (ST).
D). Therefore, the system control unit 28 sets the reading unit 30 to such a document size and linear density.

The communication order control fi40 of the transmitting station is controlled by CED and
When a signal is detected, an OCS (digital command) signal is sent out in response. This DC9 signal notifies the receiving station of the a capability of the five communication stations, and the aforementioned flag pattern is also transmitted as a preamble for about one second. Note that the same may apply to the case of the digital transmission command signal qDTc; the communication of the receiving station; the L order control unit 40
When the signal is received, the communication control parameters included in this flag pattern are analyzed according to the flow shown in FIG.

Thereafter, the communication procedure control fi40 of the transmitting station is carried out in the same way as in the normal facsimile transmission side mp+*t.
A training pattern signal is transmitted to the receiving station to train the modulator/demodulator 18 of the receiving station. When the receiving station completes the training, its communication f order control unit 40 transmits a C:FR (receiving readiness confirmation) signal. Return it to the transmitting station.

This is a specific hexadecimal flag pattern r7E?, as shown in Figure 2. E7E, ,, .

7EJ is used, and is also transmitted as a preamble for approximately 1 second each time the cap is opened. For train failure signal FTT, r
818181. ,,． 81J is sent in the same manner.

At the transmitting station, when the communication procedure control unit 40 detects a CFR signal, the system control unit 28 controls the reading unit 26 to
Reading of the original image information is started at the previously set linear density. The image information, that is, the message read from the original by the photoelectric conversion element is compressed and encoded via the line buffer 24, encoder/decoder 22, and modem 18, assembled into a transmission frame, modulated, and sent to the interface section IO. and is transmitted from the black line machine 50.

At the receiving station, this message is received by the black line a50, demodulated by the modem 18, deframed by the encoder/decoder 22, and reproduced in code. Output as a copy.

In this embodiment, when there is no 0-order transmission document in which the image information message for l rti, that is, one page in this embodiment is transmitted from the transmitting station, the communication procedure control unit of the transmitting station 40 is EOP (end in order) in end processing
Send a signal. In this EOP signal, a specific flag pattern is also transmitted as a preamble every time the plug is opened for about 1 second. In this embodiment, as shown in FIG. 2, the EOP signal is a hexadecimal flag pattern r7E7E7E, ,
, 7EJ is used, and also about 1 as the preamble.
Sent in seconds. Note that in the case of a multi-page signal MPS in which the next page of the transmission document exists, r818181.
,,． 81J is sent in a similar manner.

In response, the communication procedure control unit 40 of the receiving station returns the MCF signal. The communication f order control unit 40 of the transmitting station is an MCF
When the signal is detected, it sends a DCN (disconnection command) signal ( ) back to the receiving station to restore the connection.

In this embodiment, the transmission frame in HDICp order is not used as a carrier of communication control information, but information about the terminals 4'l tE of the receiving station and the transmitting station is used as a flag in the preamble when transmitting the transmission frame. It is configured to be transmitted as a pattern to the other station. This preamble flag pattern continues and repeatedly occurs for a predetermined period of time, for example, about one second. Therefore, the probability that this acquisition will fail at the other station is very low.Therefore, there are few communication control errors even in communications in a communication environment with relatively high foreign noise such as wireless communication, and even if an error occurs, HDLCf order There is no increase in control time due to frame retransmission, and therefore noise resistance performance is improved.

It goes without saying that the present invention can be effectively applied to data transmission as well as facsimile communication.

Effects According to the present invention, transmission frames in HDLCf order are not used for transmitting control information, and the control information of the receiving station and the transmitting station is carried in the preamble when transmitting the transmission frame to be transmitted to the other station. I'm trying to convey it. Since this preamble is continuously and repeatedly sent out for a predetermined period of time, there is a low probability that the other station will fail in its identification.Therefore, even if there is a relatively large amount of foreign interference 1"f, there will be fewer communication control errors, and even if an error occurs, Even if this occurs, there is no increase in the required control time due to it.

Therefore, the noise resistance performance is improved and the reliability of the transmission control protocol is improved. Further, even in the case of a wireless facsimile central line procedure flow, a protocol time comparable to the G3 standard can be achieved.

[Brief explanation of drawings]

FIG. 1 is a functional flowchart showing an embodiment in which the data communication control method according to the present invention is applied to a facsimile machine, and FIG. Figure 3 is an explanatory diagram showing the structure of an HDLC transmission frame. FIG. 5 is an explanatory diagram showing the format for transmitting the transmission frame in this embodiment.
FIG. 6 is an explanatory diagram showing a normal flag pattern transmitted in the preamble shown in FIG. 754, and FIG. The explanatory diagram shown in FIG. 7 is a flow diagram showing an example of the operation flow of the communication procedure control unit for classifying the flag patterns shown in FIG. 7ITJ6. Description of codes for main parts IJ1 10, Interface unit 18, Modulator/demodulator 28, System control unit 40, Communication procedure control unit 42, Communication control unit 50, % Line equipment 2 Kogo 3123 爲4Figure 4-Puri 7 Nople (1*t)◆ Abusive 5TZI Tamero 7

Claims (1)

[Claims] Data communication in which information is assembled into a transmission frame, and a preamble is transmitted in advance of the transmission frame to perform communication, and the preamble is constituted by a flag containing a specific code pattern repeatedly occurring for a predetermined period of time. A data communication control method, characterized in that communication control information is transmitted by repeatedly sending out a flag containing a specific code pattern corresponding to the communication control information for a predetermined period of time.