JP2001251386A - Communication controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication controller that eliminates a harmful influence caused by a difference of transmission rates between a channel, which is installed between a facsimile terminal and the communication controller, and a digital channel so as to warrant quality of communication. SOLUTION: In the case of communication by a G3 facsimile terminal via digital channels 5 and 7, when a receiver side facsimile terminal 11 transmits a facsimile control signal DIS to the communication controller 8, the transmission rate of the digital channels 5 and 7 set between communication controllers 4 and 8 is compared with a maximum transmission rate of the receiver side facsimile terminal 11 described in the signal DIS, and when the transmission rate of the digital channels 5 and 7 is slower than the maximum transmission rate of the facsimile terminal 11, the contents of the signal DIS are rewritten and a transmission rate slower than the actual maximum transmission rate is reported to a transmitter side facsimile terminal 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art In recent years, communication via digital lines has been performed in communication terminal devices such as personal computers. At this time, a plurality of communications are simultaneously transmitted on a single digital line by using a communication control device that controls time-division multiplexing of a plurality of communications on a digital line.

[0003] Hereinafter, a conventional communication system using a digital line will be described with reference to the drawings. FIG. 12 is a system configuration diagram showing communication via a conventional digital line. In FIG. 12, reference numeral 201 denotes a communication terminal device (hereinafter, referred to as DTE) such as a personal computer. 20
Reference numeral 2 denotes a modem that converts digital data transmitted from the DTE 201 into analog data and modulates the data. An A / D converter 203 converts 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 loaded 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, digital data transmitted from the DTE 201 is transmitted to a modem 20 via a line such as RS-232C.
2 and converted into analog data by the modem 202 and modulated. The modulated analog data is transferred to the A / D converter 203, where it is converted into digital data. As a method used at that time, there is μ-LOW coding or the like, which is converted to a data rate of 64 Kbps. That is, the digital line 20
For a digital line having a data transmission rate of 1 Mbps as shown in FIG.
Is divided into 16 at the maximum, and data communication for 16 communication can be realized.

[0006]

However, in the above-described conventional configuration, the G3
In realizing the communication by the facsimile apparatus, there is a problem that an adverse effect occurs due to a transmission speed difference between the transmission speed of the line between the facsimile apparatus and the communication control device 204 and the transmission speed of the digital line.

That is, when the transmission speed of the line between the facsimile machine and the communication control device 204 is lower than the transmission speed of the digital line, the communication is interrupted due to the occurrence of an underflow state on the digital line network. The problem arises. On the other hand, if the transmission speed of the line between the facsimile machine and the communication control device 204 is higher than the transmission speed of the digital line, an overflow state occurs on the digital line network, thereby causing a communication disabled state. Problems arise.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems. In order 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 unit and the digital line It is an object of the present invention to provide a communication control device that can eliminate the adverse effects caused by the transmission speed difference from the transmission speed and can guarantee the communication quality.

[0009]

According to the present invention, in order to solve the above-mentioned problems, when communication is performed by a G3 facsimile apparatus via a digital line, a facsimile data transferred from the facsimile apparatus is temporarily demodulated in a communication control apparatus. In this configuration, analog data is converted into digital data, digitalized facsimile data is converted into a data form for data communication, and the data is transmitted over a digital line.

[0010] The present invention also provides a G
In performing communication by a three-facsimile apparatus, first, when converting a facsimile control signal into a data form for data communication, instead of performing data conversion processing after accumulating all data of the facsimile control signal, After a predetermined number of data of the facsimile control signal has been accumulated, it is sequentially converted and sent out to a digital line.

Further, according to the present invention, when communication is performed by a G3 facsimile apparatus via a digital line, if the transmission rate of the digital line is lower than the maximum transmission rate of the receiving facsimile apparatus, the communication control apparatus D
The content of the IS (facsimile control signal) is rewritten, and a transmission speed lower than the actual maximum transmission speed is transmitted to the transmission-side facsimile apparatus.

Third, the present invention has a configuration in which, when communication is performed by a G3 facsimile apparatus via a digital line, a specific transmission pattern is transmitted when an underflow occurs when image information is transmitted. It is a thing.

Fourthly, according to the present invention, when an underflow occurs at the time of transmitting image information during communication by a G3 facsimile apparatus via a digital line, a 0-fill is transmitted by a transmission-side communication control apparatus. The receiving-side communication control device has a configuration in which the zero fill is extracted in consideration of the minimum transmission time.

According to the present invention, when communication is performed by a G3 facsimile apparatus via a digital line by the above-described configuration, the facsimile data is not directly converted into digital data by the communication control apparatus but is demodulated once.
Data volume does not increase. As a result, a larger number of communications can be transmitted in the same manner without increasing the number of existing digital lines.

Further, the present invention provides a G
In performing communication by the three facsimile apparatuses, first, when converting the facsimile control signal into a data form for data communication, the control signal transferred from the facsimile apparatus is
When the data amount for confirming the content of the control signal is accumulated, the data is sequentially converted into a data form for data communication and transmitted to a digital line. As a result, it is possible to prevent a delay in data transmitted to a digital line, as compared with the case where data conversion processing is performed after waiting for accumulation of all data of the facsimile control signal.

Further, according to the present invention, when communication is performed by a G3 facsimile apparatus via a digital line, second, a facsimile control signal DIS is transmitted from a receiving facsimile apparatus.
Is transmitted to the communication control device, the transmission speed of the digital line set between the communication control devices is compared with the maximum transmission speed of the receiving facsimile device described in the DIS, and the transmission of the digital line is performed. If the speed is lower, the contents of the DIS are rewritten, and a transmission speed lower than the actual maximum transmission speed is transmitted to the transmitting facsimile machine. As a result, it is possible to prevent a state in which communication is disabled during transmission of image information.

Still further, according to the present invention, when communication is performed by a G3 facsimile apparatus via a digital line,
When an underflow occurs when image information is transmitted to the printer, a special transmission pattern is transmitted as needed. As a result, it is possible to avoid a no-signal state on the digital line due to an underflow, and to guarantee continuation of communication.

Similarly, when an underflow occurs when image information is transmitted, the transmission-side communication control unit sends out a 0-fill, and the reception-side communication control unit removes the 0-fill. The processing of extracting the 0 fill is performed in consideration of the recording time. Thus, continuation of communication can be guaranteed without causing a delay in the recording time in the receiving facsimile machine.

[0019]

Embodiments 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 in one embodiment of the present invention. In FIG. 1, 1 facsimile apparatus, 2 is a private line for transferring analog data from the facsimile apparatus 1, and 3 is a private branch exchange that controls line concentrating from each communication terminal apparatus on the premises and connection control between each communication terminal apparatus and a digital line. It is. 4 converts analog data transmitted from the facsimile apparatus 1 into digital data, converts data used for facsimile communication into data used for data communication, converts a facsimile communication control procedure into a data communication control procedure, This is a communication control device that performs multiplexing processing. Reference numeral 5 denotes a digital line for simultaneously transmitting data of a plurality of communications time-division multiplexed by the communication control device 5, and 6 denotes a digital line network. 7 is the other party's digital line, 8 is the other party's communication control device, 9
Is the private branch exchange of the other party, 10 is the private line of the other party, 11
Is a facsimile machine of the other party.

FIG. 2 is a schematic block diagram showing the internal configuration of the communication control device 4 or 8. In FIG. 2, the same parts as those in FIG. Reference numeral 41 denotes a facsimile modem that demodulates analog data transmitted from the facsimile apparatus 1 and converts the data to digital data, converts data to the facsimile apparatus 1 into analog data, and modulates the data. 42 is the T.42 transferred from the modem 41. A DTE control unit that analyzes data according to a facsimile control procedure based on the rules of No. 30 and converts the data into a data format used for data communication such as EIA-578. An interface control unit 43 converts the parallel data input from the DTE control unit 42 into serial data and outputs the serial data. A multiplexing control unit 44 controls the multiplexing of the data from the plurality of private lines 2 input from the interface control unit 43 onto one digital line at a time interval. T.45 converts the data received from the digital line 5 from the data format used for data communication by EIA-578 or the like to T.45. This is a DCE control unit that performs control to convert the data into a data format of a facsimile control procedure based on the rules of No. 30 and output it to the modem 41.

The facsimile communication via a digital line using the communication control device configured as described above will be described below.

First, analog data modulated in the transmitting facsimile machine 1 is transferred to the private branch exchange 3 via the private 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 machine 1 at a transmission speed of 9600 bps, the facsimile modem 41 generates 9600 bits of digital data per second and outputs the data to the DTE control unit 42. As a result, analog data can be converted into digital data without greatly increasing the data amount and without impairing the information amount when converting the digital data into digital data. The contents of this digital data are 30
However, it is not possible to carry out communication by directly carrying the signal on the digital line 5.
Therefore, it is necessary to notify the other communication control device 8 of the data type via the digital switching network 6. As a technique, a data command according to EIA-578 or the like is added and communication is performed by synchronizing with each other. Is going. Subsequently, the digital data is input to the interface control unit 43 in parallel, sequentially stored in an internal buffer, and output to the multiplex control unit 44 in serial. In the multiplexing control unit 44, the digital data is divided and transmitted over one digital line 5 at a time interval. In the case of N-ISDN, the digital line 5 forms a single digital line by collecting digital lines having a transmission rate of 16 Kbps.
Data of 64 communications can be simultaneously transmitted on the same digital line 5 by one digital line.

As described above, when performing facsimile communication via the digital line 5, instead of sampling the modulated analog data and converting it to digital data, the modulated data is once demodulated and then demodulated. By performing a process of converting the data into data, the digital data is converted into a digital command and transmitted to the digital line 5 for communication. Therefore, the digital command is put on the digital line 5 without increasing the number of digital lines. The effect that the number of communication can be increased can be obtained.

However, when facsimile communication is realized through the digital line 5 as described above, the transmission facsimile apparatus 1 and the reception facsimile apparatus 1 have different transmission speeds between the private line 2 and the digital line 5. A blank time occurs in the data transmission between the first and second data. 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 one phenomenon caused by a transmission speed difference between a private line and a digital line.

First, from the communication control device 4 to the communication control device 8
AT + FRH = 3 is sent to the receiving side to specify the HDLC protocol and the modulation method (ST1). That is, in this case, CC. 300 bp by 21 modulation methods
This means that the receiving side is instructed to transmit data at the transmission speed of s. CONNECT, which is a response signal, is returned from communication control device 8 to communication control device 4 (ST2). The receiving-side facsimile machine forms a frame of the DIS (digital identification signal) by the HDLC method and transmits the frame (ST3). The communication control device 8 converts the DIS, which is a facsimile signal, into a data form for data communication and sends it to the digital network 6 (ST4). Subsequently, 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, 1
It takes 26 ms for the byte data to be transmitted. On the other hand, since data is transmitted at a transmission rate of 16 Kbps on the digital circuit network 6 as described above,
The byte data is transmitted in 0 and 5 ms.
When it is considered that only correct data is transmitted to the other communication control device 8, the communication control device 8 sequentially stores the framed DIS in an internal buffer, and determines whether there is a frame error in a frame check sequence. For,
Once all frames (9 bytes) have been stored, the data is converted into a data format for data communication and sent to the digital network 6. Therefore, the time interval T1 from when the communication control device 8 receives data from the other party's facsimile device 11 to when the communication control device 8 sends data to the digital line network 6
Will occur. Further, 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 transmitting it (ST6). Finally, the receiving facsimile machine 11
The time from sending the IS to arriving at the facsimile apparatus 1 is greatly delayed as compared with normal facsimile communication.

The reception-side facsimile apparatus 11 sends a response signal to the DIS within a predetermined time.
If it is not returned, the DIS is transmitted again on the private line 10 according to the facsimile communication procedure (ST7).
The communication control device 8 converts the DIS into the data form of the data communication again, and sends the data to the digital network 6 after T3 (ST8). On the other hand, the sending facsimile machine is DIS
And a DCS (Digital Command Signal) is sent out as a response (ST9). Therefore, if the delays overlap on the line, the DC from the transmitting facsimile machine 1
A phenomenon occurs in which S and DIS from the receiving facsimile machine 11 collide. Since the signal disappears due to the collision, the DCS does not arrive at the receiving facsimile machine, and after a predetermined time elapses, a timeout occurs and the line is disconnected. That is, a phenomenon that communication is interrupted occurs.

Therefore, in the present invention, the communication control unit 8 does not accumulate all 9 bytes of frame data, but generates a data form for data communication at any time as soon as facsimile data is received. By sending data, the delay time is reduced.

The details will be described below with reference to FIG. FIG.
Is a flowchart showing the control when the communication control device 4 or 8 converts the data into the data form.

First, the receiving facsimile apparatus 11 sends the HDC framed DIS to the communication control apparatus 8.
Is sent. The communication control device 8 first determines whether or not the opening flag of the frame data has been detected (ST1). When the opening flag is detected and the data is subsequently received (ST2), the data is stored byte by byte in the internal buffer (ST3). Next, it is determined whether or not data of n bytes or more has been stored in the buffer (ST4). That is, in the communication control device 8, In order to interpret the 30 communication procedure, it is necessary to analyze framed facsimile data and determine what meaning the data has. Since a facsimile control field (hereinafter, referred to as FCF) corresponding to the third byte of the frame data contains information for determining what kind of control signal is used, three bytes of data are stored in the buffer. If T. Three
0 It is possible to determine which data in the communication procedure. Then, when data of 3 bytes or more is accumulated in the buffer, one byte of data is transmitted to the digital network 6 (ST5). As described above, instead of waiting for the frame data to be stored in the buffer for all 9 bytes, the data is not converted, but the data is converted at the predetermined byte and the data is transmitted. Can be reduced.

After transmitting the data, it is determined whether a closing flag has been detected (ST6). If the closing flag has not been detected, data reception is subsequently performed (ST2). When a closing flag is detected, an operation is performed on a frame checking sequence (hereinafter, referred to as FCS), and the operation result is held (ST
7) Go to step 8.

In step 8, it is determined whether or not the data stored 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, if the frame data is a normal frame based on the calculation result,
<D indicating the end of the data and that the data is normal
LE><ETX> is transmitted (ST11). When the frame data is an error frame, it indicates the end of the data and indicates that the data is an error frame <D
LE><ESC> is transmitted (ST12). As described above, by changing the type of data indicating the end of data, whether the transmission data is normal or error is transmitted to the communication control device 4, which type of data has been received by the partner communication control device 4. Thus, the frame data can be reliably reproduced 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 network 6
More data is received (ST1). Next, it is determined whether or not the received data is data of the type <DLE><***> (ST2). If the received data is not <DLE><***>, the received data is stored in the FIFO memory (ST3). Subsequently, the received data is transmitted to the facsimile machine 1
The data is stored in the transmission buffer in the DCE control unit 45 for transmission to the transmission buffer. If an empty area is created in the transmission buffer (ST4), the reception data is sequentially taken out from the FIFO memory and stored in the transmission buffer (ST5).

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

In step 6, if the data transfer is completed, <DLE><***> is changed to <DLE>
<ETX> or <DLE><ESC> (ST
9) If <DLE><ETX>, generate frame data including a normal FCS and transmit it to facsimile apparatus 1 (ST10); if <DLE><ESC>, generate a frame including an FCS that results in an error 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 data of a predetermined byte or more, the receiving side stores all the frame data. Without waiting for
Since the data is sequentially transmitted on the digital line, it is possible to reduce the delay in data transmission due to the transmission speed of the line. In addition, the transmission side can reliably reproduce the frame data to be transmitted to the facsimile apparatus in the transmission side communication control device 4 by determining the type of data indicating the end of the received data.

In this embodiment, the type of data indicating the end of data to be transmitted on a digital line is changed.
The data indicating the end may be configured to add invalid data in the case of error frame data as the same data.
In this case, unlike the above case, the facsimile machine 1 or 11 determines the invalidity of the data.

The above explanation is for the case where the transmission speed of the private line 2 or 5 is lower than the transmission speed of the digital line network 6. If the speed is lower than the speed, an overflow condition occurs on the digital network 6, which leads to a communication disabled state.

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

Hereinafter, description will be made with reference to FIGS. FIG. 6 is a flowchart 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 a facsimile information field (hereinafter, referred to as FIF) in the DIS signal of the present embodiment. It is.

First, the facsimile machine 11 on the receiving side sets the DI
When S is transmitted, the receiving-end communication control device 8
Is converted into a data form for data communication and sent to the digital network 6. When the transmission-side communication control device 4 receives the data, the data is stored in the memory in the DTE control unit 42 therein (ST1). It is determined which type of facsimile control signal the stored data is (S
T2). If it is DIS, go to step 3 and DT
If it is C (digital transmission command signal), similarly, step 3
Proceed to. If it is DIS, the transmission speed of the digital network 6 is checked (ST3), the maximum transmission speed of the receiving facsimile machine 11 is checked from the FIF of DIS, and the two are compared (ST4). The transmission speed of the digital network 6 is set in the communication control device in advance. When the transmission speed of the digital network 6 is lower, for example, when the transmission speed of the digital network 6 is 8 Kbps and the maximum transmission speed of the receiving facsimile apparatus 11 is 14, 4 Kbps, the contents of the DIS FIF are shown in FIG. As shown by 14,
V. indicating 4 Kbps. 17 indicating 7200 bps. 27ter + V. A process of rewriting to display 29 is performed (ST5). When the rewriting of the DIS FIF is completed, the DTE control unit 42 transfers the data to the modem 41 (ST6). In this way, even when the transmission speed of the digital network 6 is lower than the maximum transmission speed of the receiving facsimile device 11, the content of the DIS sent from the receiving facsimile device 11 is made slower than the actual rewriting, so that the transmission is performed. Since the side facsimile apparatus 1 specifies a transmission speed lower than the actual maximum transmission speed, it is possible to prevent the occurrence of an overflow state on the digital network 6 and continue the communication.

The above is the facsimile communication procedure phase B
Has been described for solving the problem caused by the data transmission speed difference between the private line 2 and the digital line network 6 in the above, but when the image information is actually transmitted as long as the transmission speed difference exists,
That is, the transmission speed difference also affects the facsimile communication phase C. That is, since the transmission speed of the digital network 6 is usually faster than the transmission speed of the private line 2, the data to be transmitted on the digital network 6 when transmitting image information cannot be made in time, causing an underflow and interrupting the communication. Problem arises. Therefore, according to the present invention, when an underflow occurs, a specific transmission pattern <DLE><NULL> is transmitted to prevent 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 facsimile communication procedure phase C. FIG.
In PIX, 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 form for data communication on a digital line. <DLE><ETX> after RTC is data indicating the end of one unit of data and indicating that the data is normal.

As shown in FIG. 8, when <DLE><ETX> is added to notify the presence or absence of an error in the transmitted image data after the image information is transmitted, the meaning of the transmitted image data as image data is indicated. <DLE><ETX> and <DLE><ESC> may appear as data. That is, <DLE><ETX> and <DLE><ES
C> merely preliminarily determines that the information indicates the presence or absence of an error between the communication control devices 4 and 8, and <DLE> is <10> of the ASCII code, and the usage mode is specified. Since it is not data, it can naturally appear in transmission image data. Therefore, in the communication control device 8, <DLE><ET>
X> may be erroneously recognized as data indicating the end of transmission of image data, and if erroneously recognized, reception of image data may be interrupted halfway. The problem is solved by using the transmission processing of

FIG. 9 is a flowchart showing a process when a specific transmission pattern is transmitted in the communication control device. In FIG. 9, the image information transferred from the facsimile device 1 is transmitted to the communication control device 4 in <11><DL
E><0><DLE><DLE> will be described in the order and transmitted on the digital 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
Proceed to. In ST3, it is determined whether or not a buffer in the interface control unit 43 has a free space. If there is a vacancy, it means that the transfer of data from the facsimile apparatus 1 is delayed and an underrun occurs. However, here, since <11> has already been stored in the buffer, ST
Proceed to 4. In ST4, it is determined whether the final transmission data is DLE. Here, since there is no data before <11>, the final transmission data is not DLE, and the process proceeds to ST5 where <11> is transmitted to the digital line. The process is terminated by setting the final transmission data to <11> (ST6).

Next, processing for transmitting the next data, <DLE>, is performed. In this case, the above determination is repeated again. That is, the process proceeds from ST1 to ST2 to ST3 to ST4. ST
In 4, since the final transmission data is <11>, S
Proceed to T5 to send <DLE>. The process is terminated with the final transmission data as <DLE> (ST6).

Next, processing for transmitting <0> is performed. In this case, the process proceeds from ST1 to ST2 to ST3 to 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 transmits <DLE> 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 from ST1 to ST2 to ST3 to ST4 to ST5.
Send <0>. 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 machine 1 to the communication control device 4 cannot be completed in time and an underrun occurs. In this case, the process proceeds from ST1 to ST2 to ST3.
In ST3, an underrun occurs, and there is an empty buffer in the interface control unit 43.
Proceed to ST10. In ST10, it is determined whether or not transmission of the transmission image data has been completed. Here, since the image information is being transmitted, the process proceeds to ST11. In ST11, since the final transmission data is not <DLE> but <0>, the process proceeds to ST12 and transmits <DLE>. NULL
The transmission flag is set, and the process ends (ST13).

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

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

Next, it is assumed that an underrun occurs again.
In this case, the process proceeds from ST1 to ST2 to ST3. In ST3, since an underrun has occurred, the process proceeds to ST10. In ST10, since the transmission of the image data is in the middle, the process proceeds to ST11. In ST11, since the final transmission data is <DLE>, the process proceeds to ST16. ST16
, A <NULL> is sent, the DLE flag is set, and the process ends (ST17). That is, <DLE><NULL> has been transmitted due to the occurrence of the underrun.

Next, <DLE> as the original data is transmitted with <NULL> added thereto, so that the receiving-end communication control device 8 recognizes the data as indicating underrun. Therefore, the process returns to ST1 and proceeds to ST2. In ST2, since the DLE transmission flag is set, 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
LL> → <DLE>, the receiving-end communication control device recognizes <DLE><NULL> as data meaning underrun, and <DLE> as meaningful data in the image data. Therefore, no erroneous recognition occurs in the receiving-side communication control device 8.

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

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

A process in which the data converted by the transmission process as described above is reproduced in the receiving-side communication control device 8 will be described with reference to FIG. Specifically, <11><DL
E><DLE><0><DLE><NULL><DL
Description will be made on the assumption that data is received in the order of E><NULL><DLE><SUB>. FIG. 10 is a flowchart showing a process in which the receiving-side communication control device 8 reproduces the data subjected to the transmission process.

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

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

Returning to ST1, the next data <DLE>
And proceeds 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 a is <NULL>. a is not <NULL> but <DL
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 or not 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, where <0> is stored in the reception data buffer of the interface control unit 43.

Next, <DLE> is received. In this case, a
<DLE> (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 fetched 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 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 to T1, ST2, ST3, and 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,
The process proceeds from ST1 to ST2 to ST6 to ST9, and the process 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 to T1, ST2, ST3, and 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, <SUB> is received. In this case, a
<SUB> (ST1), and proceeds to ST2. ST
In 2, since the DLE flag is set, the process proceeds to ST6. Since a is <SUB>, ST6 → ST7 → S
Proceed to T10. In ST10, since a is <SUB>, the process proceeds to ST11, where <SUB> is converted into two <DL>
E> Data is stored in the reception data buffer of the interface control unit 43 as data. Lower the DLE flag (S
T9) The process ends. Also, in ST10, when a is other than <SUB>, that is, <ET
If X> or <ESC>, the process proceeds to ST12.

In ST12, the receiving side communication control device 8
Is <DLE><ETX> or <DLE><ESC>
Is received, the data reception for one page is completed, and <DLE><ETX> or <DLE><ES
C>.

As described above, the SI in the communication control device on the receiving side is
<11><DLE><0> in the O reception data buffer
Since <DLE> and <DLE> are stored, it can be seen that the transmission data is correctly reproduced.

With the above processing, when an underrun occurs due to a transmission speed difference between the private line 2 and the digital line network 6, the specific data <DLE><NULL> is transmitted by the transmission-side communication control device 4. Insertion and removal of <DLE><NULL> by the receiving-end communication control device 8
The no-signal state on the digital network 6 can be prevented without increasing the load on the PU. When an underrun occurs, a 0-fill may be sent to the digital network 6 until the data of the next line is transferred from the transmitting facsimile machine 1. In this case, the receiving-side communication control device 8 performs the process of extracting the 0-fill. However, instead of extracting all the 0-fills, the 0-fills are extracted in consideration of the minimum transmission time and sent to the receiving-side facsimile device 11. Must be transferred. That is, since the zero fill is inserted between the lines, the recording time of the receiving-side facsimile apparatus is correspondingly delayed. Therefore, it is necessary to extract the 0 fill in consideration of the minimum transmission time in order to prevent a delay in the recording time. Note that the process of extracting the 0 fill is a transmission 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 load on the CPU increases accordingly.

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

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

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

In ST3, when the count value of the counter exceeds the minimum transmission time, it means that the data amount longer than the minimum transmission time has been transferred to the modem 41. Will do.
That is, the process proceeds to ST4. In ST4, it is determined whether or not the 1-byte data taken in a is eight consecutive 0s. If it is not eight consecutive 0s, it is determined that the data is meaningful rather than 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 eight consecutive 0's, there is a possibility that this is a 0-fill 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 “0” s. That is, in the MH encoding method, data in which 0s continue for 10 or more cannot exist other than EOL (0000000000001).
If there is one continuous 0, it is understood that the fill is 0. Thus, in ST5, if 11 consecutive 0s are present before a, eight consecutive 0s are not transferred to the modem transmitting unit (ST6). When the line changes, the count value is reset to zero.

Thus, in the transmission-side communication control device 4, the inserted 0-fill can be extracted 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 via the digital line,
The same number of digital lines can be used to transmit more communications at the same time, and at that time the line is disconnected by preventing the adverse effects caused by the difference in transmission speed between the local line and the digital line. , Facsimile communication can be surely continued without being caused.

[0079]

As is apparent from the above description, according to the present invention, when the communication by the G3 facsimile apparatus is realized via the digital line, the data transferred from the facsimile apparatus is sampled as it is in the communication control apparatus and the digital data is digitally converted. By performing a process of demodulating and converting to digital data once instead of converting to data, analog data can be converted to digital data without increasing the amount of data. A larger number of communications can be transmitted simultaneously without additional equipment.

Further, when the communication by the G3 facsimile apparatus is realized via a digital line, adverse effects on the communication such as data delay and underflow caused by a difference in transmission speed between the private line and the digital line are described first. When converting to a data format for data communication,
Rather than storing all facsimile data and then performing conversion processing, if the amount of data that can be converted to the data format for data communication is stored, it is converted sequentially without waiting for storage of all data, and it is transferred to a digital line Since the sending process is performed, it is possible to prevent a delay of data corresponding to the sending process.

Second, when the transmission rate of the digital line is lower than the maximum transmission rate of the receiving facsimile apparatus, the maximum transmission rate of the DIS sent from the receiving facsimile apparatus is made lower than the actual maximum transmission rate. Since the process of notifying the transmitting facsimile apparatus is performed, the transmission speed difference between the digital line and the private line when transmitting the fraction information can be reduced, and the state in which communication cannot be performed can be avoided. .

Third, when an underflow occurs,
By transmitting a specific transmission pattern on the digital line in the transmission-side communication control device, a no-signal state on the digital line is prevented. In the receiving side communication control device, since the process is to extract the specific transmission pattern,
This can be performed without increasing the load on the CPU.

Fourth, when an underflow occurs,
Since the transmitting-side communication control device sends out the 0-fill and the receiving-side communication control device performs the process of extracting the 0-fill in consideration of the minimum transmission time, without delaying the recording operation of the receiving-side facsimile device, Communication interruption can be prevented.

[Brief description of the 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 according to 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 data format conversion processing in the communication control device of the present invention.

FIG. 5 is a flowchart showing a frame generation process of the 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 a facsimile communication procedure phase C;

FIG. 9 is a flowchart showing processing when a specific transmission pattern is transmitted in the communication control device.

FIG. 10 is a flowchart showing a process in which the communication control device on the receiving side reproduces data that has been subjected to transmission processing;

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

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Facsimile apparatus 2 Premise line 4 Communication control device 5 Digital line 41 Modem 42 DTE control unit 43 Interface control unit 44 Multiplexing control unit 45 DCE control unit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tsuyoshi Shida 2-3-8 Shimomeguro, Meguro-ku, Tokyo Inside Matsushita Electric Transmission System Co., Ltd. (72) Inventor Shiken Dai 2-3 2-3 Shimomeguro, Meguro-ku, Tokyo 8 Matsushita Electric Transmission System Co., Ltd.

Claims (4)

[Claims] A modem for analyzing a facsimile control signal transferred from the facsimile terminal device, and comparing the maximum transmission speed of the facsimile terminal device with the transmission speed of a digital line based on the analysis result. When the transmission speed of the line is slower, the maximum transmission transfer speed is rewritten to be slower, and the facsimile control signal is converted into a data form used for data communication, and a transmitting unit that sends the converted data to the digital line,
A communication control device comprising: 2. A modem for receiving facsimile data from a facsimile terminal device, conversion means for converting the facsimile data into a data form used for data communication, and transmission means for transmitting the converted data to a digital line. A communication control device, wherein when the underrun occurs during transmission of one page of transmission image data, the conversion unit performs control to transmit specific data indicating underrun at any time. 3. A receiving device for receiving digital data from a digital line, a converting device for converting the digital data into a data format used for facsimile communication, and a modem for transferring the converted data to a facsimile terminal device. A communication control device, wherein when the receiving means detects specific data indicating underrun in the received image data, the receiving means performs control not to transfer the specific data to the converting means. 4. A receiving means for receiving digital data from a digital line, a converting means for converting the digital data into a data format used for facsimile communication, and a modem for transferring the converted data to a facsimile terminal device. A communication control device, wherein the receiving means performs control for extracting a bit number 0 fill in consideration of a minimum transmission time when a 0 fill is inserted in the received image data.