JP3419764B2 - Communication control device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication control device for realizing communication via a digital line between communication terminal devices such as a facsimile device which communicates by analog data.

[0002]

2. Description of the Related Art In recent years, communication terminals such as personal computers have been used for communication via digital lines. At that time, a plurality of communications are simultaneously transmitted on one digital line by using a communication control device that controls the time division multiplexing of the plurality of communications on the digital line.

A conventional communication system using digital lines will be described below with reference to the drawings. FIG. 12 is a system configuration diagram showing communication through a conventional digital line. In FIG. 12, 201 is a communication terminal device (hereinafter referred to as DTE) such as a personal computer. 20
Reference numeral 2 is a modem that converts digital data transmitted from the DTE 201 into analog data and modulates the analog data. Reference numeral 203 denotes an A / D conversion unit that converts the data modulated by the modem 202 into digital data. Reference numeral 204 denotes a communication control device that performs time division control when digital data is put on a digital line. 205 is a digital line, 1 Mb
It has a data transmission rate of ps.

The operation of the communication system via the digital line configured as described above will be described.

First, the digital data sent from the DTE 201 is transferred to the modem 20 via a line such as RS-232C.
2, and converted into analog data and modulated by the modem 202. The modulated analog data is transferred to the A / D conversion unit 203 and converted into digital data in the A / D conversion unit 203. A method used at that time is μ-LOW coding or the like, which is converted to a data rate of 64 Kbps. That is, the digital line 20
In the case of a digital line having a data transmission rate of 1 Mbps such as No. 5, the communication control device 204 is
Can be divided into 16 at maximum and data communication for 16 communication can be realized.

[0006]

However, in the above-mentioned configuration of the prior art, G3 is connected via the digital line 205.
In realizing communication by the facsimile device, a problem arises that a transmission speed difference between the transmission speed of the line between the facsimile device and the communication control device 204 and the transmission speed of the digital line causes a problem.

That is, when the transmission speed of the line between the facsimile device and the communication control device 204 is higher than the transmission speed of the digital line, an overflow condition occurs on the digital line, resulting in a communication disabled state. The problem arises.

The present invention is to solve the above-mentioned problems. To realize communication by the G3 facsimile apparatus via the digital line, the transmission speed of the line between the facsimile apparatus and the communication control device and the digital line It is an object of the present invention to provide a communication control device capable of eliminating the adverse effect caused by the difference in transmission rate from the transmission rate and guaranteeing the communication quality.

[0009]

The present invention SUMMARY OF THE INVENTION To solve the above problems, the invention according to claim 1, when performing communication by G3 facsimile device through the digital line, fax
The communication control device receives the fascimi control signal from the device.
Transfer to the communication control device,
Within the digital signal transmission speed and the fascimil control signal
The maximum transmission speed of the facsimile machine described in
In comparison, if the transmission speed of the digital line is slower,
Facsimile control signal contents are rewritten and actual maximum transmission is performed.
The transmission speed slower than the transmission speed is transmitted to the facsimile machine on the other side.
Get As a result, the state of communication failure during transmission of image information
It can be prevented from occurring.

The invention according to claim 2 is a digital circuit.
When communicating with a G3 facsimile machine via a line,
Fascimi control signal D from the facsimile machine on the receiving side
When the IS is transferred to the communication control device,
The transmission speed of the digital line set in
Fax machine described in the control signal DIS
Compared with the maximum transmission speed of the device, transmission of digital line
If the speed is slower, the facsimile control signal DIS
Rewrite the content of the transmission rate slower than the actual maximum transmission rate
To the facsimile machine on the other side. This allows you to
Preventing loss of communication while sending information
You can

[0011]

[0012]

[0013]

[0014]

[0015]

[0016]

[0017]

[0018]

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a system configuration diagram showing facsimile communication via a digital line according to an embodiment of the present invention. In FIG. 1, reference numeral 1 is a facsimile machine, 2 is a private branch line for transferring analog data from the facsimile machine 1, and 3 is a private branch exchange for controlling line concentrating from each communication terminal device in the premise and controlling connection between each communication terminal device and a digital line. Is. Reference numeral 4 converts the analog data sent from the facsimile apparatus 1 into digital data, converts the data used in the facsimile communication into the data used in the data communication, and also converts the facsimile communication control procedure into the data communication control procedure. It is a communication control device that is performing a multiplexing process. Reference numeral 5 is a digital line for simultaneously transmitting a plurality of pieces of communication data time-division multiplexed by the communication control device 5, and 6 is a digital line network. 7 is the other party's digital line, 8 is the other party's communication control device, 9
Is the other party's private branch exchange, 10 is the other party's private branch line, 11
Is a facsimile machine on the other side.

FIG. 2 is a schematic block diagram showing the internal configuration of the communication control device 4 or 8. 2, the same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. Reference numeral 41 is a facsimile modem that demodulates analog data sent from the facsimile apparatus 1 and converts it into digital data, and also converts the data to the facsimile apparatus 1 into analog data and further modulates the data. 42 is a T.42 transmitted from the modem 41. It is a DTE control unit that analyzes data in accordance with the facsimile control procedure according to the standard of 30 and converts it into a data format used for data communication such as EIA-578. An interface control unit 43 converts parallel data input from the DTE control unit 42 into serial data and outputs the serial data. Reference numeral 44 denotes a multiplexing control unit that controls to multiplex the data input from the interface control unit 43 from the plurality of local lines 2 on one digital line at time intervals. 45 indicates data received from the digital line 5 from the data format used for data communication by EIA-578 or the like. It is a DCE control unit which controls to convert to a data format of a facsimile control procedure according to the protocol of 30 and output to the modem 41.

Facsimile communication via a digital line, which is carried out by using the communication control device configured as described above, will be described below.

First, the analog data modulated in the sending facsimile machine 1 is transferred to the private branch exchange 3 via the private branch line 2. The private branch exchange 3 controls connection with the communication control device 4 and transfers analog data to the communication control device 4. In the communication control device 4, analog data is not converted into digital data by sampling, but is first demodulated by the facsimile modem 41 and converted into digital data. That is, when data is transmitted from the facsimile device 1 at a transmission rate of 9600 bps, the facsimile modem 41 generates digital data of 9600 bits per second and outputs the data to the DTE control unit 42. As a result, when analog data is converted into digital data, the data amount can be converted into digital data without enormously increasing the data amount and without losing the information amount. The contents of this digital data are T. Thirty
Although the facsimile signal defined in 1) is shown, it cannot be placed on the digital line 5 as it is for communication.
Therefore, it is necessary to notify the communication control device 8 of the other party via the digital exchange network 6 of the type of data, and as a method thereof, a data command according to EIA-578 or the like is added to perform communication in synchronization with each other. Is going. Subsequently, the digital data is input to the interface control unit 43 in parallel, sequentially accumulated in the internal buffer, and serially output to the multiplexing control unit 44. In the multiplexing control unit 44, the digital data is divided and sent on one digital line 5 at time intervals. In the case of N-ISDN, the digital line 5 collects digital lines having a transmission rate of 16 Kbps to form one digital line, so that if the digital data is 9600 bps,
Data of 64 communications can be simultaneously transmitted on the same digital line 5 by one digital line.

As described above, when facsimile communication is executed through the digital line 5, the modulated analog data is not sampled and converted into digital data, but the modulated data is once demodulated and then digitally converted. Since the digital data is converted into a digital command and sent to the digital line 5 for communication by performing the process of converting into data, the digital command can be placed on the digital line 5 without increasing the number of digital lines. The effect that the number of communications can be increased can be obtained.

However, when the facsimile communication is realized through the digital line 5 as described above, since the transmission speed difference between the private line 2 and the digital line 5 is different, the sending side facsimile device 1 and the receiving side facsimile device A blank time occurs in the data transmission to and from 11. This causes a problem that communication is interrupted.

The above phenomenon will be described below with reference to FIG.
FIG. 3 is a sequence diagram showing a phenomenon caused by a difference in transmission speed between the private line and the digital line.

First, the communication control unit 4 to the communication control unit 8
AT + FRH = 3 is sent to and the HDLC protocol and the modulation method are designated to the receiving side (ST1). That is, here, V. 300bp by 21 modulation method
The reception side is designated to transmit data at the transmission rate of s. A response signal CONNECT is returned from the communication control device 8 to the communication control device 4 (ST2). The facsimile machine on the receiving side frames DIS (digital identification signal) by the HDLC system and sends it out (ST3). The communication control device 8 converts the DIS, which is a facsimile signal, into a data format for data communication and sends it to the digital line network 6 (ST4). Then, the data indicating the end of the data is transmitted (ST5). At this time, since the facsimile signal is transmitted at 300 bps on the private line 10,
It will take 26 ms for the bytes of data to be transmitted. On the other hand, since data is sent at the transmission rate of 16 Kbps on the digital line network 6 as described above,
The byte data will be transmitted in 0, 5 ms.
When considering sending only correct data to the partner communication control device 8, the communication control device 8 sequentially stores the framed DISs in an internal buffer and determines the presence or absence of a frame error by a frame check sequence. For,
Once all the frames (9 bytes worth) have been accumulated, a process of converting the data into a data format for data communication and sending it to the digital line network 6 is performed. Therefore, the time interval T1 from when the communication control device 8 receives the data from the partner facsimile machine 11 to when the data is sent to the digital line network 6
Will occur. Furthermore, in the communication control device 4, since it is necessary to convert the data form of the data communication to the data form of the facsimile communication again, it takes time or T2 from receiving the data to sending it (ST6). Finally, the receiving side facsimile machine 11 D
The time from when the IS is sent to when it reaches the facsimile apparatus 1 is significantly delayed as compared with normal facsimile communication.

The receiving side facsimile device 11 sends a response signal to the DIS within a predetermined time to the transmitting side facsimile device 1.
If it is not returned from ST, the DIS is sent again to the private line 10 in accordance with the facsimile communication procedure (ST7).
The communication control device 8 again converts the DIS into the data format for data communication and sends the data to the digital line network 6 after T3 (ST8). On the other hand, the sending facsimile machine is DIS
Is received, and DCS (digital command signal) is transmitted as a response (ST9). Therefore, when the delays are overlapped on the line, the DC from the sending facsimile machine 1
A phenomenon occurs in which S and the DIS from the receiving side facsimile apparatus 11 collide. Since the signal disappears due to the collision, the DCS does not arrive at the facsimile apparatus on the receiving side, and after a lapse of a predetermined time, it times out and the line is disconnected. That is, a phenomenon occurs in which communication is interrupted.

Therefore, in the present invention, the communication control device 8 does not store all the 9 bytes of frame data, but upon receipt of facsimile data, creates a data format for data communication as needed and sends it to the digital line network 6. By sending data, the delay time is shortened.

The details will be described below with reference to FIG. Figure 4
Is a flow chart showing control when the communication control device 4 or 8 converts to a data format.

First, the DISC framed by the receiving side facsimile apparatus 11 to the communication control apparatus 8 is converted into an HDLC frame.
Is sent. The communication control device 8 first determines whether or not the opening flag of the frame data is detected (ST1). When the opening flag is detected and data is subsequently received (ST2), the data is accumulated in the internal buffer byte by byte (ST3). Next, it is determined whether or not data of n bytes or more has been accumulated in the buffer (ST4). That is, in the communication control device 8, the T. In order to interpret the 30 communication procedure, it is necessary to analyze the framed facsimile data and determine what the meaning is. Since information for determining what kind of control signal is contained in the facsimile control field (hereinafter referred to as FCF) corresponding to the 3rd byte of the frame data, 3 bytes of data are stored in the buffer. Then, T. Three
0 It becomes possible to judge which data in the communication procedure. Therefore, when data of 3 bytes or more is accumulated in the buffer, 1 byte of data is sent to the digital line network 6 (ST5). In this way, the frame data is not converted after waiting for all 9 bytes of data to be accumulated in the buffer, but the data is converted at the predetermined byte and the data is transmitted. Can be reduced.

After transmitting the data, it is judged whether or not the closing flag is detected (ST6). When the closing flag is not detected, the data is subsequently received (ST2). When the closing flag is detected, the frame checking sequence (hereinafter referred to as FCS) is operated and the operation result is held (ST
7) Go to step 8.

In step 8, it is judged whether or not the data accumulated in the buffer has been transmitted, and if there is data in the buffer, the data is transmitted (ST9). When the data transmission is completed, based on the calculation result, if the frame data is a normal frame,
Indicates the end of data and that the data is normal <D
LE><ETX> is transmitted (ST11). If the frame data is an error frame, it indicates the end of the data and that the data is an error frame <D
LE><ESC> is transmitted (ST12). In this way, by changing the type of data indicating the end of the data, the communication control device 4 is notified of whether the transmission data is normal or an error. Therefore, which type of data was received by the partner communication control device 4? Thus, it is possible to reliably reproduce the frame data in a normal state or an error state.
The frame reproduction process of the partner communication control device 4 will be described below with reference to FIG. FIG. 5 is a flowchart showing the processing on the receiving side.

First, the communication control device 4 is connected to the digital line network 6
More data is received (ST1). Next, it is determined whether or not the received data is of the type <DLE><***> (ST2). If the received data is not <DLE><***>, the received data is stored in the FIFO memory (ST3). Then, the received data is sent to the facsimile device 1.
It is stored in the transmission buffer in the DCE control unit 45 in order to be sent to. When an empty area is formed in the sending buffer (ST4), the received data is sequentially fetched from the FIFO memory and stored in the sending buffer (ST5).

In step 2, <DLE><**
When the data of type *〉 is received, the FIFO
It is determined whether or not the data transfer from the memory to the transmission buffer is completed (ST6). If the data transfer is not completed, the received data is transferred (ST8) depending on the state of the transmission buffer (ST7).

When the data transfer is completed in step 6, <DLE><***> becomes <DLE>.
Judge whether <ETX> or <DLE><ESC> (ST
9), if <DLE><ETX>, frame data including normal FCS is generated and transmitted to the facsimile apparatus 1 (ST10), and if <DLE><ESC>, frame including FCS that causes an error is generated. Data is generated and transmitted to the facsimile machine 1 (ST11).

As described above, according to the present invention, when the communication by the G3 facsimile apparatus is realized using the digital line, when the receiving side communication control device 8 receives the data of a predetermined byte or more, the receiving side stores all the frame data. Without waiting for
Since the data is sequentially sent out on the digital line, the delay of data transmission due to the line transmission speed can be reduced. Further, by determining the type of data indicating the end of the received data on the transmitting side, the frame data to be sent to the facsimile device can be reliably reproduced by the transmitting side communication control device 4.

In the present embodiment, the type of data indicating the end of the data transmitted on the digital line is changed.
The end data may be the same data, and invalid data may be added in the case of error frame data.
In this case, unlike the above case, the facsimile device 1 or 11 judges the invalidity of the data.

The above description is for the case where the transmission speed of the private line 2 or 5 is slower than the transmission speed of the digital line network 6, but in the opposite case, that is, the transmission speed of the digital line network 6 is the transmission of the private line 2 or 5. If the speed is lower than the speed, an overflow condition will occur on the digital network 6, resulting in a communication disabled condition.

Therefore, according to the present invention, when the transmission speed of the digital line network 6 is slower than the maximum transmission speed of the receiving side facsimile apparatus 11, the contents of the DIS sent from the receiving side facsimile apparatus 11 are rewritten and the transmitting side facsimile apparatus is rewritten. 1 is controlled so that the maximum transmission speed of the receiving side facsimile device 11 is notified slower than the actual transmission speed.

A description will be given below with reference to FIGS. 6 and 7. FIG. 6 is a flow chart showing the control of the DTE control unit 42 in the communication control device 4, and FIG. 7 is a frame configuration diagram showing the configuration of the facsimile information field (hereinafter referred to as FIF) in the DIS signal of the present embodiment. Is.

First, the facsimile apparatus 11 on the receiving side receives a DI
When S is sent, the receiving communication control device 8
Is converted into a data format for data communication and sent to the digital line network 6. When the transmission-side communication control device 4 receives the data, the DTE control unit 42 internally stores the data in the memory (ST1). It is judged which type of facsimile control signal the stored data is (S).
T2). If it is DIS, proceed to step 3 and DT
If it is C (digital transmission command signal), the same step 3
Go to. If it is DIS, the transmission speed of the digital line network 6 is checked (ST3), the maximum transmission speed of the receiving side facsimile apparatus 11 is checked from the FIF of DIS, and both are compared (ST4). The transmission speed of the digital line network 6 is preset in the communication control device. When the transmission speed of the digital line network 6 is slower, for example, when the transmission speed of the digital line network 6 is 8 Kbps and the maximum transmission speed of the receiving side facsimile device 11 is 14 and 4 Kbps, the contents of the DIS FIF are shown in FIG. As shown by 14,
V. indicating 4 Kbps V. 17 showing 7200 bps from the display. 27 ter + V. A rewriting process to display 29 is performed (ST5). When the FIF rewriting process of the DIS is completed, the DTE control unit 42 transfers the data to the modem 41 (ST6). As described above, even when the transmission speed of the digital line network 6 is slower than the maximum transmission speed of the receiving side facsimile apparatus 11, the content of the DIS sent from the receiving side facsimile apparatus 11 is rewritten to be slower than the actual transmission rate, so that the transmission is performed. Since the side facsimile machine 1 specifies a transmission rate lower than the actual maximum transmission rate, it is possible to prevent the occurrence of an overflow state on the digital line network 6 and continue the communication.

The above is the facsimile communication procedure phase B.
The means for solving the problem caused by the difference in data transmission speed between the local line 2 and the digital line network 6 has been described. However, when the image information is actually transmitted as long as the transmission speed difference exists,
That is, the transmission speed difference also has an effect in the phase C of the facsimile communication procedure. That is, since the transmission speed of the normal digital line network 6 is faster than the transmission speed of the local line 2, the data sent to the digital line network 6 when the image information is transmitted is not in time, an underflow occurs, and the communication is interrupted. The problem arises. Therefore, in the present invention, when an underflow occurs, a specific transmission pattern <DLE><NULL> is transmitted to prevent the occurrence of a no-signal state on the line.

The processing of the communication control device when an underflow occurs will be described below with reference to FIGS. 8 and 9. FIG. 8 is a sequence diagram showing a state of transmitting image information in the phase C of the facsimile communication procedure. Figure 8
In, PIX indicates image information. RTC is 1
This is a control signal indicating the end of transmission of image information for a page, and is converted into a data format for data communication on a digital line. <DLE><ETX> after RTC is the end of one unit of data and indicates that the data is normal.

As shown in FIG. 8, when <DLE><ETX> is added after image information is transmitted to indicate the presence or absence of an error in the transmission image data, the meaning of the image data is shown in the transmission image data. <DLE><ETX> and <DLE><ESC> may appear as data. That is, <DLE><ETX> and <DLE><ES
C> is merely information that has been agreed in advance between the communication control devices 4 and 8 to indicate whether or not there is an error. <DLE> is an ASCII code <10>, and the usage mode is specified. Since it is not data, it can naturally appear in the transmitted image data. Therefore, in the communication control device 8, <DLE><ET in the transmission image data
X> may be erroneously recognized as data indicating the end of transmission of image data, and if erroneously recognized, there is a problem that reception of image data is interrupted in the middle, but this is well known in the present embodiment. It is solved by using the transparent processing of.

FIG. 9 is a flow chart showing the processing when the communication control device sends a specific transparent pattern. In FIG. 9, the image information transferred from the facsimile device 1 is <11><DL in the communication control device 4.
The description will be made assuming that E><0><DLE><DLE> are converted in this order and transmitted to the digital line network 6.

First, when the communication control device 4 converts facsimile image information and sends <11>, it is determined whether the NULL sending flag is set (ST1) or the DLE sending flag is set (ST2). . Since <11> is the first data, both flags are not set and ST3
Go to. In ST3, it is determined whether or not the buffer inside the interface control unit 43 has a free space. If there is a space, it means that the data transfer from the facsimile apparatus 1 is delayed and an underrun occurs. However, since <11> has already been stored in the buffer, ST
Go to 4. In ST4, it is determined whether the final transmission data is DLE. Since there is no data before <11> here, the final transmission data is not DLE, and the process proceeds to ST5 and transmits <11> to the digital line. The final transmission data is set to <11> and the processing is finished (ST6).

Next, the process of transmitting the next data <DLE> is performed. In this case, the above determination is repeated again. That is, ST1 → ST2 → ST3 → ST4. ST
4, the final transmission data is <11>, so S
Proceed to T5 to send out <DLE>. The final transmission data is set to <DLE>, and the process ends (ST6).

Next, the process of transmitting <0> is performed. In this case, ST1 → ST2 → ST3 → ST4. ST4
Since the final transmission data is <DLE>, the process proceeds to ST7. In ST7, since the data in the buffer is <0> and not <DLE>, the process proceeds to ST8 and <DLE> is sent out instead of <0>. The final transmission data is converted from <DLE> to <SUB>, and the process ends (ST9). In ST9, the final transmission data <DL
Since E> may be changed to another symbol, a symbol other than <SUB> may be used.

Next, since <0> has not been transmitted yet, the process proceeds to ST1 → ST2 → ST3 → ST4 → ST5,
<0> is transmitted. The final transmission data is changed from <SUB> to <0>, and the process ends (ST6).

Next, it is assumed that the data transfer from the facsimile apparatus 1 to the communication control apparatus 4 is not in time and an underrun occurs. In this case, ST1 → ST2 → ST3.
In ST3, an underrun occurs, and there is an empty buffer in the interface control unit 43.
Go to ST10. In ST10, it is determined whether or not the transmission of the transmission image data is completed. Since the image information is being transmitted here, the process proceeds to ST11. In ST11, since the final transmission data is <0> instead of <DLE>, the process proceeds to ST12 and <DLE> is transmitted. NULL
The transmission flag is set and the process ends (ST13).

Return to ST1 again. In ST1, NU
Since the LL transmission flag is set, the process proceeds to ST14 <N
ULUL> is transmitted and the NULL transmission flag is turned off (ST15). That is, here, <DLE><NULL> is transmitted in byte units due to occurrence of underrun.

Next, the process of transmitting <DLE> is performed.
In this case, ST1 → ST2 → ST3 → ST4. ST
In step 4, since the final transmission data is <0>, ST
Go to step 5 and send <DLE>. The final transmission data is changed from <0> to <DLE>, and the process ends.

Next, assume that an underrun occurs again.
In this case, ST1 → ST2 → ST3. Since an underrun has occurred in ST3, the process proceeds to ST10. In ST10, image data is being transmitted, so the process proceeds to ST11. Since the final transmission data is <DLE> in ST11, the process proceeds to ST16. ST16
At <STEP>, <NULL> is sent, the DLE flag is set, and the process is terminated (ST17). That is, <DLE><NULL> is transmitted due to the occurrence of underrun.

Next, since <DLE> as the original data is added with <NULL> and transmitted, the receiving side communication control device 8 recognizes that it is data indicating an underrun. Therefore, the process returns to ST1 and proceeds to ST2. Since the DLE transmission flag is set in ST2, the process proceeds to ST18. In ST18, <DLE> is transmitted, the DLE transmission flag is lowered, and the process ends (ST19). That is, the data is <DLE> → <NU
Since it has been transmitted as LL> → <DLE>, the receiving communication control device recognizes <DLE><NULL> as data meaning underrun, and <DLE> as meaningful data in the image data. Therefore, erroneous recognition does not occur in the reception side communication control device 8.

Next, the process of transmitting <DLE> is performed.
In this case, ST1 → ST2 → ST3 → ST4.
Since the final transmission data is <DLE> in ST4, the process proceeds to ST7. In ST7, since the data in the buffer is <DLE>, the process proceeds to ST20, <SUB>
Is transmitted (ST20). The data in the buffer is advanced by 1 byte (ST21), the final transmission data is changed from <DLE> to <SUB>, and the process is terminated (ST9). That is, since <DLE><DLE> and transmission data <DLE> are repeated twice, the data is converted to <DLE><SUB> and transmitted to the digital line.

As a result, <11><DLE> [DL
E] <0> [DLE] [NULL] <DLE> [NUL
The data is transmitted in the order of L] [DLE] <SUB>, and the data transmission process of the transmission side communication control device ends. The data in [] is the data added for the transparent processing and the underrun processing.

A process in which the data converted by the transparent process as described above is reproduced in the reception side communication control device 8 will be described with reference to FIG. Specifically, <11><DL
E><DLE><0><DLE><NULL><DL
A case where data is received in the order of E><NULL><DLE><SUB> will be described. FIG. 10 is a flowchart showing a process in which the reception-side communication control device 8 reproduces the transparent-processed data.

First, the received data is fetched in the register a (ST1). That is, <11> is taken into a and the process proceeds to ST2. In ST2, it is determined whether the DLE flag is set. Since the DLE flag is not set, ST
Go to 3. In ST3, since a is <11> instead of <DLE>, <11> is stored in the reception data buffer inside the interface control unit 43 in the communication control device 8 (ST4) and the process is terminated.

Next, <DLE> is taken into a (ST
1). Since the DLE flag is not set in ST2, the process proceeds to ST3. In ST3, since a is <DLE>, the DLE flag is set (ST5) and the process is terminated. That is, <DLE> is discarded without being stored in the reception data buffer of the interface control unit.

Returning to ST1 again, the next data <DLE>
To a and proceed to ST2. In ST2, DLE
Since the flag is set, the process proceeds to ST6. In ST6, it is determined whether or not the data taken in by a is <NULL>. <DL> instead of <NULL>
Since E> has been captured, the process proceeds to ST7. In ST7, it is determined whether or not the data contained in a is <DLE>. Since a is <DLE>, <DLE> is stored in the reception data buffer of the interface control unit 43 (ST8). The DLE flag is lowered and the process ends (ST9).

Next, <0> is received. In this case, <0> is taken into a (ST1), and it is determined whether the DLE flag is set (ST2). Since the DLE flag is not set, the process proceeds to ST3. In ST3, since a is <0>, the process proceeds to ST4 and <0> is stored in the reception data buffer of the interface control unit 43.

Next, <DLE> is received. In this case, a
<DLE> is taken in (ST1), and since the DLE flag is not set (ST2), the process proceeds to ST3. In ST3, since a is <DLE>, the process proceeds to ST5, sets the DLE flag, and ends the process. That is, <DLE> is discarded without being stored in the reception data buffer of the interface control unit 43.

Next, <NULL> is received. in this case,
<NULL> is taken into a (ST1), and since the DLE flag is set (ST2), the process proceeds to ST6. In ST6, since a is <NULL>, the DLE flag is lowered (ST9), and the process is terminated. That is,
<NULL> is discarded without being stored in the reception data buffer of the interface control unit 43.

Next, <DLE> is received. In this case, S
The process proceeds from T1 → ST2 → ST3 → ST5, and the DLE flag is set to complete the process. That is, <DLE> is discarded without being stored in the reception data buffer of the interface control unit 43.

Next, <NULL> is received. in this case,
The process proceeds to ST1 → ST2 → ST6 → ST9 and ends. That is, <NULL> is discarded without being stored in the reception data buffer of the interface control unit 43.

Next, <DLE> is received. In this case, S
The process proceeds from T1 → ST2 → ST3 → ST5, and the DLE flag is set to complete the process. That is, <DLE> is discarded without being stored in the reception data buffer of the interface control unit 43.

Next, <SUB> is received. In this case, a
<SUB> is taken in (ST1), and the process proceeds to ST2. ST
In 2, the DLE flag is set, so the process proceeds to ST6. Since a is <SUB>, ST6 → ST7 → S
Go to T10. In ST10, since a is <SUB>, the process proceeds to ST11, and <SUB> is replaced with two <DL>.
E> Data is stored in the reception data buffer of the interface control unit 43. Turn down the DLE flag (S
T9) The process ends. In ST10, if a is other than <SUB>, that is, <ET
If it is X> or <ESC>, the process proceeds to ST12.

At ST12, the receiving side communication control device 8
Is <DLE><ETX> or <DLE><ESC>
Since the reception of one page of data is completed, <DLE><ETX> or <DLE><ES
The processing according to C> is executed.

In this way, the SI in the communication control device on the receiving side is
<11><DLE><0> in the O receive data buffer
Since <DLE><DLE> is stored, it can be seen that the transmission data is correctly reproduced.

With the above processing, if an underrun occurs due to the difference in transmission speed between the private line 2 and the digital line network 6, the transmission side communication control device 4 sends specific data <DLE><NULL>. Since it is a process of inserting and removing <DLE><NULL> in the receiving side communication control device 8, C
It is possible to prevent a signalless state on the digital line network 6 without increasing the load on the PU. When an underrun occurs, 0 fill may be sent to the digital line network 6 until the data on the next line is transferred from the transmitting side facsimile apparatus 1. In this case, the receiving side communication control device 8 performs the process of removing the 0 fill, but instead of removing all the 0 fills, the 0 fill is extracted to the receiving side facsimile device 11 in consideration of the minimum transmission time. I have to transfer. That is, since the 0 fill is inserted between the lines, the recording time of the receiving side facsimile apparatus is delayed by that amount. Therefore, it is necessary to remove the 0 fill in consideration of the minimum transmission time in order to prevent the delay of the recording time. The process of removing the 0 fill is performed in the transparent pattern <DLE><NU.
Unlike the case where LL> is extracted, since the same data as the 0 fill inserted in consideration of the minimum transmission time, the CPU load increases accordingly.

The process by which the receiving side communication control device 8 removes the 0 fill will be described below with reference to FIG. FIG. 11 is a flowchart showing a process in which the communication control device 8 removes 0 fill. It is assumed that one line of the data sent by the transmission side communication control device starts with EOL.

First, the data in the interface controller 43 is fetched into the register a for each byte (ST1), and the counter value is incremented (ST2). It is determined whether the count value of the counter is equal to or longer than the minimum transmission time (ST3). If not exceeded, the process proceeds to ST7, the data contained in a is transferred to the modem 41, and the process ends.

Next, the next 1 byte of data is put into a (ST1), and the process proceeds from ST2 to ST3. At ST3,
Until the count value of the counter exceeds the minimum transmission time,
The processes of ST1 → ST2 → ST3 → ST7 are repeated.

In ST3, when the count value of the counter becomes equal to or longer than the minimum transmission time, it means that the data amount equal to or longer than the minimum transmission time has been transferred to the modem 41. Therefore, if the 0 fill is inserted, the removal processing is performed. Will be done.
That is, the process proceeds to ST4. In ST4, it is judged whether or not the 1-byte data taken in by a is 8 consecutive 0s. If it is not 8 consecutive 0s, it is judged that it is meaningful data, not the 0 fill inserted at the time of underrun, and the data contained in a is transferred to the modem 41 and the process is terminated (ST7).

In ST4, if the 1-byte data is 8 consecutive 0s, it is possible that the 0-fill was inserted at the time of underrun, so the process proceeds to ST5. In ST5,
It is determined whether or not the data before a is 11 consecutive 0s. That is, in the MH encoding system, data in which 0s are consecutively 10 or more cannot be other than EOL (000000000001), so 1 is preceded by 8 consecutives currently in a.
It can be seen that there is a 0 fill when there are 1 consecutive 0s. Therefore, in ST5, if 11 consecutive 0s precede a, 8 consecutive 0 data are not transferred to the modem transmitting section (ST6). When the line changes, the count value is reset to 0.

As a result, in the transmission side communication control device 4, the inserted 0 fill can be removed in the reception side communication control device 8 in consideration of the minimum transmission time.

As described above, according to the present invention, when the communication by the G3 facsimile apparatus is realized through the digital line,
While the number of digital lines remains the same, more communication can be transmitted simultaneously, and at the same time disconnection of lines is prevented by preventing adverse effects due to the difference in transmission speed between the local line and digital line. It is possible to obtain the effect that the facsimile communication can be surely continued without inviting.

[0079]

As is apparent from the above description, according to the present invention, the transmission speed of the digital line is the receiving side facsimile apparatus.
If the transmission speed is slower than the maximum transmission rate held by
The actual maximum transmission speed of DIS sent from the millimeter device
Send to the sending facsimile machine at a speed lower than the maximum transmission speed.
Since it is informing process, send the fraction information.
Minimizes the difference in transmission speed between the digital line and the local line
Can avoid the communication loss
It

[0080]

[0081]

[0082]

[0083]

[Brief description of drawings]

FIG. 1 is a system configuration diagram showing facsimile communication via a digital line according to an embodiment of the present invention.

FIG. 2 is a schematic block diagram showing an internal configuration of a communication control device of the present invention.

FIG. 3 is a sequence diagram showing a phenomenon caused by a transmission speed difference between a private line and a digital line.

FIG. 4 is a flowchart showing a data format conversion process in the communication control device of the present invention.

FIG. 5 is a flowchart showing a frame generation process of a communication control device on the receiving side.

FIG. 6 is a flowchart showing control of a DTE control unit in the communication control device.

FIG. 7 is a frame configuration diagram showing a configuration of a facsimile information field in a DIS signal according to the present embodiment.

FIG. 8 is a sequence diagram showing a state of transmitting image information in phase C of a facsimile communication procedure.

FIG. 9 is a flowchart showing a process of transmitting a specific transparent pattern in the communication control device.

FIG. 10 is a flowchart showing a process in which the communication control device on the receiving side reproduces the transparent processed data.

FIG. 11 is a flowchart showing processing when the communication control device removes the 0 fill on the receiving side.

FIG. 12 is a system configuration diagram showing communication via a conventional digital line.

[Explanation of symbols]

1 Facsimile machine 2 premises lines 4 Communication control device 5 digital lines 41 modem 42 DTE control unit 43 Interface control unit 44 Multiplexing control unit 45 DCE controller

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Go Shida 2-3-8 Shimomeguro, Meguro-ku, Tokyo Matsushita Transmission System Co., Ltd. (72) Inventor Dai Shiken 2-3, Shimomeguro, Meguro-ku, Tokyo No. 8 in Matsushita Electric Transmission System Co., Ltd. (56) Reference JP-A-4-21237 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H04L 29/08 H04N 1/00 107

Claims (2)

(57) [Claims] 1. A modem for analyzing a facsimile control signal transferred from a facsimile terminal device, and a maximum transmission speed held by the facsimile terminal device and a transmission speed of a digital line are compared on the basis of the analysis result, and the digital transmission speed is compared. the case towards the line transmission speed of slow facsimile
The maximum transmission speed in the control signal is the transmission speed of the digital line
Rewriting later than once, converting means for converting the facsimile control signal into a data format used for data communication, and a transmitting section for transmitting the converted data to the digital line,
A communication control device comprising: 2. The data is transferred from the receiving side facsimile terminal device.
A modem for analyzing the received facsimile control signal DIS,
Based on the analysis result, the receiving side facsimile terminal device
The maximum transmission speed of the device and the transmission speed of the digital line
If the transmission speed of the digital line is slower,
The maximum transmission speed in the facsimile control signal DIS
Rewrite slower than the transmission speed of the digital line,
The dummy control signal DIS is used for data communication.
Conversion means for converting the converted data into a data form and the conversion data
And a transmitter for transmitting to a digital circuit.
A communication control device to.