JP3144966B2 - 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 apparatus for realizing communication by a G3 facsimile apparatus via a digital line.

[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 over one digital line using a communication control device that performs a process of time-division multiplexing a plurality of communications.

Hereinafter, data communication using a conventional digital line will be described with reference to the drawings. FIG. 3 is a system configuration diagram showing data communication via a conventional digital line. In FIG. 3, reference numeral 301 denotes a communication terminal device such as a personal computer (hereinafter referred to as DTE). 30
A modem 2 modulates digital data sent from the DTE 301 and converts the data into analog data.
An A / D converter 303 converts analog data from the modem 302 into digital data. Reference numeral 304 denotes a communication control device that performs time-division processing when transmitting digital data to a digital line and simultaneously transmits a plurality of communication data. A digital line 305 has a data transmission speed of 1 Mbps. Reference numeral 306 denotes a communication control device of the partner, 307 denotes an A / D converter of the partner, 308 denotes a modem of the partner, and 309 denotes a DTE of the partner. I do.

First, command data transmitted from the DTE 301 is transmitted to the modem 30 via a line such as RS-232C.
2 and modulated in modem 302. At the time of modulation, the data is converted into analog data and transferred to the A / D converter 303. In the A / D conversion unit 303, the data is converted into digital data for transmission on the digital line 305 and transferred to the communication control device 305. The data is subjected to a time division multiplexing process in the communication control device 204, and a plurality of communications are simultaneously transmitted onto the digital line 305.

On the receiving side, on the other hand, the received data is divided by the communication control unit 306 for each communication, then D / A converted and demodulated, and sent to the partner DTE 309.

As described above, data transmission and reception are repeated between transmission and reception, and data communication is executed.

[0007]

However, in the above-mentioned communication control apparatus of the prior art, communication over a digital line is performed by G3.
When applied to facsimile communication, the following problems have occurred with respect to the establishment of synchronization between transmission and reception.
That is, when communication is performed by a G3 facsimile apparatus via a digital line, it is essential to establish synchronization between transmission and reception as in normal facsimile communication. Synchronization methods for data transmission over digital lines include:
There are two types of systems: start-stop synchronous transmission and synchronous transmission.

Asynchronous transmission means that when transmitting one unit of data, a start bit is added to the beginning of the data and a stop bit is added to the end so that the data is intermittently transmitted on a digital line in units of one unit. On the other hand, the receiving side detects the start bit and determines that one unit of data has been received. That is, in this system, in the non-communication state, stop bits are continuously transmitted and 1
Since the start bit is transmitted when the transmission of the unit data is started, the start of the data transmission is detected at the transition point from the stop bit to the start bit. However, according to this method, a start bit and a stop bit are added for each data, so that the transmission efficiency deteriorates accordingly.

Synchronous transmission is a method of synchronizing by transmitting special synchronization establishment data before transmitting a series of transmission data. Unlike the case of start-stop transmission, synchronous transmission does not add a start bit and a stop bit, so that transmission efficiency can be improved accordingly.

[0010] Whether the above-described asynchronous transmission or synchronous transmission is appropriate for executing facsimile communication via a digital line cannot be determined unconditionally for the following reasons. That is, in facsimile communication, as in the case of the facsimile control signal, the HD
There is a phase in which each control signal subjected to LC claim intermittently moves between transmission and reception for each signal, and a phase C in which a series of bit strings are continuously transmitted as in the case of image data. Therefore, if the start-stop synchronous transmission is selected, the transmission efficiency is poor, so that when transmitting image data via a digital line, it becomes impossible to transmit the image data at high speed, and the transmission speed is reduced. In some cases, data transmission may not be able to keep up with the transmission speed of the digital line due to the large amount of data. In addition, if synchronous transmission is selected, it is necessary to always perform processing for synchronizing the intermittently transmitted facsimile control signal, and special synchronization establishment data is always transmitted on the digital line even when there is no signal. Must be sent to the
This causes a problem that the load on the device increases.

The present invention has been made to solve the above-mentioned problems, and has been proposed in order to reduce the transmission speed of image data and increase the load on the CPU without increasing the G3 transmission rate through a digital line.
It is an object of the present invention to provide a communication control device capable of smoothly executing communication by a facsimile machine.

[0012]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a converting means for converting a facsimile signal transferred from a facsimile apparatus into communication data used for data communication, and converting the communication data to a digital line. When performing facsimile communication via a digital line with a transmission control means for transmitting, in phase C of the facsimile communication procedure, the data transmission synchronization method is switched from start-stop transmission to synchronous transmission, and the transmission of the communication data is performed to the transmission control means. And control means for performing the following.

[0013]

According to the present invention, when communication is performed by a G3 facsimile apparatus via a digital line and the phase B of the facsimile communication procedure is performed, the synchronous system is switched from the synchronous system to the start-stop synchronous transmission. When transmitting and receiving signals and executing phase C, the synchronous system is switched from start-stop synchronous transmission to synchronous system and image data is transmitted. Furthermore, when moving to phase D,
The synchronous system is switched from the synchronous system to the start-stop synchronous transmission again to transmit and receive the control signal.

Thus, since the synchronization method is switched for each phase of the facsimile communication procedure, the G3 facsimile transmission via the digital line can be performed without lowering the transmission speed of the image data and without increasing the load on the CPU. The device can execute facsimile communication.

[0015]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sequence diagram showing a communication sequence by a G3 facsimile apparatus via a digital line in one embodiment of the present invention. In FIG. 1, 1
Reference numeral 2 denotes a calling side facsimile apparatus, and reference numeral 2 denotes a communication control apparatus which converts a facsimile signal from the facsimile apparatus 1 into a data form used for data communication and transmits the data form to the digital line 3. 3 is a digital line. Reference numeral 4 denotes a communication control device on the other side, which performs processing for converting data received from the digital line into a facsimile signal and transmitting the facsimile signal to the called facsimile device 5. Reference numeral 5 denotes a called facsimile machine.

FIG. 2 is a hardware configuration diagram of the communication control device 2. The communication control device 2 includes a CPU 21 and a ROM 2
2, a RAM 23, an interface circuit 24, a bus 25 connecting these, and an amplifier for input and output to and from the CPU 21. The CPU 21 converts a facsimile signal input from the facsimile machine 1 into a data form used for data communication based on the contents stored in the ROM 22, and converts the signal into a digital form via the interface circuit 24.
Output to On the other hand, communication data input from the digital line 3 via the interface line 24 is converted into a facsimile signal based on the contents of the ROM
To the facsimile machine 1 via the

Hereinafter, an outline of facsimile communication by a digital line using the communication control device configured as described above will be described.

First, at the time of calling, the communication control devices 2 and 4
Set the synchronization method to synchronous transmission (hereinafter, referred to as synchronous mode). The calling-side facsimile apparatus 1 sends out a CNG (calling tone) indicating that the calling side is a non-voice terminal (ST1). Data to start facsimile communication instead of voice call (F
AX) (ST2). On digital line 3,
Since not only facsimile communication but also voice communication by telephone can be executed, it is necessary to inform the communication control unit 4 of the other party what kind of communication is to be executed at the start of communication.

Upon detecting data (FAX) indicating that the facsimile communication is to be performed, the other party's communication control device 4 switches the synchronization mode from the synchronous mode to the start-stop synchronous transmission (hereinafter referred to as the start-stop synchronous mode). The internal data processing is switched from the voice encoding / decoding unit to the facsimile modem to prepare for facsimile communication.

Subsequently, the other party's communication control device 4 returns an acknowledgment signal (ACK) to the communication control device 2 (ST3), and sends the data for performing the facsimile communication to the CNG in the facsimile communication procedure. It is converted and sent to the called facsimile machine 5 (ST4).

Next, upon receiving the ACK signal from the partner communication control device 4, the communication control device 2 switches the synchronization mode from the synchronous mode to the start-stop synchronization mode, and performs internal data processing for voice encoding / decoding. Section to switch to the facsimile modem and prepare for facsimile communication.

When the called facsimile machine 5 receives the CNG, the called facsimile apparatus 5 displays a CED indicating that the called side is a non-voice terminal.
Is transmitted (ST5). When the CED is detected, the other party communication control device 4 converts the command into a CONNECT command and sends it to the communication control device 2 (ST6). Since CED is not data but simply a 2100 Hz signal, here CE
The command CONNECT is used as data representing D. When the communication control device 2 detects the command CONNECT from the communication control device 4 on the other end, the communication control device 2 converts the command into a CED in the facsimile communication procedure and sends it to the facsimile device 1 (ST7). Subsequently, the called facsimile machine 5 sends out a DIS (digital identification signal) (ST8). On the other hand, when the communication control device 2 receives data from the communication control device 4 on the other side, the command AT + FRH =
Is transmitted (ST9). In the case of FRH of AT + FRH = 3, the modulation method used when receiving data is V.CCITTT. 21
AT + FRH = 3 = 300 bps
At a transmission rate of HDLC framing data. Upon detecting the command AT + FRH = 3, the communication control device 4 on the other end detects the command CONNECT.
T is transmitted (ST10). The command CONNECT indicates to the communication control device 2 that data is to be transmitted according to the specified modulation method. As a result, the communication control device 2 transmits the HDLC framing data from the partner communication control device 4 at the transmission rate of 300 bps and the specified modulation scheme V.40. 21 allows reception.

Subsequently, the other party communication control device 4 converts the DIS from the called facsimile device 5 into a data format used for data communication, and sends it out to the digital line 3. At this time, since data communication is performed in the start-stop synchronization mode in the phase B, the start data and the stop bit are added before and after the transmission data, and the transmission data is transmitted onto the digital line 3 (ST11).

When the communication control device 2 detects a start bit from the digital line 3, it determines that data has arrived, and then analyzes the detected subsequent data. If the data is determined to be a DIS in the facsimile communication procedure, the data is converted into a DIS in the facsimile communication procedure and sent to the facsimile apparatus 1 (ST12). Further, a command OK indicating that the command has been correctly executed is transmitted to the other communication control device 4 with the start bit and the stop bit added (ST13). Upon receiving the DIS, the facsimile machine 1 sends out a DCS (digital command signal) to the called facsimile machine 5 (ST14).

When detecting the DCS, the communication control device 2 transmits a command AT + FTH = 3 to the communication control device 4 on the other side in order to specify a modulation method and a transmission rate before transmitting data (ST15). AT + FTH =
FTH of CCITT V.3. 21 indicates that data is to be transmitted by the modulation method of 21, and 3 of AT + FTH = 3 is 30
This indicates that HDLC framing data is transmitted at 0 bps.

The other party's communication control device 4 receives the command AT +
When FTH = 3 is detected, a command CONNECT is transmitted to notify the communication control device 2 that data is to be received according to the specified modulation method (ST16). As a result, the communication control device 2 transmits 30 modulation by 21 modulation methods
Data can be transmitted at a transmission rate of 0 bps. On the other hand, the other party's communication control device 4 uses the command CONNECT.
At the time of transmitting the CT, the carrier for transmitting the facsimile control signal to the called facsimile machine 5 is transmitted (ST17).

The communication control device 2 receives the command CONNECT
Is detected, the DCS from the calling facsimile machine 1
Is converted into a data form used for data communication, and a start bit and a stop bit are added to the data form and transmitted to the other party's communication control device 4 (ST18).

The other party's communication control unit 4 detects the start bit and, when judging that the data has arrived, analyzes the following data. When it judges that the data is DCS based on the analysis result, it converts it into DCS in the facsimile communication procedure. And sends it to the called facsimile machine 5 (ST19). Subsequently, the other party communication control device 4 sends a command OK indicating that the data has been correctly executed to the communication control device 2 with the start bit and the stop bit added (ST
20).

After transmitting the DCS, the facsimile apparatus 1 starts training (ST21). When the adjustment of the high-speed modem in the facsimile machine 5 is completed by the training, the facsimile machine 5 sends out a CFR (reception preparation confirmation signal) to urge the facsimile machine 1 to send out image data (ST22).

The partner communication control device 4 converts the CFR into a data format used for data communication, adds a start bit and a stop bit, and sends the data to the communication control device 2 (ST23).

When the communication control device 2 detects the data, the communication control device 2 converts the data into a CFR in a facsimile communication procedure and sends it to the facsimile device 1 (ST24). Thereafter, the communication control device 2 switches the synchronization mode from the start-stop synchronization mode to the synchronization mode.

Similarly, in the other party's communication control device 4,
The synchronization method is switched from the start-stop synchronization mode to the synchronization mode.

In the phase C, the facsimile machine 1 starts sending image data (ST25).
When the transmission of the image data is completed, the communication control devices 2 and 4 switch the synchronization mode from the synchronous mode to the start-stop synchronous mode again.

Post processing of the facsimile communication procedure is executed between the facsimile apparatuses 1 and 5, a DCN (line command signal) is transmitted, the process proceeds to phase E, and the communication is terminated. In the meantime, data transmission and reception are performed between the communication control devices 2 and 4 in the start-stop synchronization mode similar to the case of the phase B.

The above is the outline of the communication by the G3 facsimile apparatus via the digital line. The switching process of the synchronization system in each of the above-mentioned communication control devices will be described below in detail with reference to FIG.

FIG. 3 is a diagram showing the timing of switching the synchronization method of the communication control device in one embodiment of the present invention. In FIG. 3, the components are the same as those in FIG. First, here, a state is shown in which a line is connected between the facsimile apparatus 1 and the facsimile apparatus 5 via the digital line 3 and the facsimile apparatus has already shifted to the phase C of the facsimile communication procedure. When the phase shifts to phase C, the communication control device 2
Sends a Break signal, which is a continuous signal of 0, to the other party's communication control device 4. At the same time, the communication control device 2 waits for detection of a response signal returned from the partner communication control device 4 for the Break signal (ST21). Note that the Break signal is configured in a form in which 0 bits are continuous for 12 bits. That is, since a signal in which 12 bits 0 are normally continuous does not exist in data communication in the start-stop synchronization mode, the Break signal is used as a signal for switching from the start-stop synchronization mode to the synchronization mode.

Next, when the other party's communication control device 4 also enters the phase C, it starts detecting the Break signal.
Upon detecting the Break signal, the communication control device 4 returns the Break signal to the communication control device 2 as a response signal (ST22).

Upon detecting the response signal, the communication control device 2 stops sending the Break signal and switches the synchronization mode from the start-stop synchronization mode to the synchronization mode. Thereafter, the communication control device 2 sends out SYNC which is special data for establishing synchronization (ST23). As a result, the synchronization method is switched, and communication in phase C is started.

On the other hand, in the other party's communication control device 4,
When data other than the Break signal is detected, transmission of the response signal (Break signal) is stopped, and the synchronization method is switched from the start-stop synchronization mode to the synchronization mode. As a result, the synchronization method is switched also in the other party's communication control device 4, and communication in phase C is started. After that, the communication control device 2 has Ma, which has a configuration opposite to that of the Break signal.
An rk signal ('FF') is transmitted to start detection of SYNC (ST24).

Subsequently, the other party's communication control device 4 sets the SYNC
Is detected, a SYNC is sent to the communication control device 2 to start detecting image data (ST25).

When the communication control device 2 detects SYNC,
It is determined whether there is image data to be sent. If there is no image data, SYNC is continuously transmitted.
If there is image data, the image data is transmitted (ST26).

For the communication control device 2, SYNC is continuously transmitted from the communication control device 4 on the other side, but is ignored, and the SYNC is ignored.
Only when data CMD other than NC (CMD in the figure indicates an arbitrary command) is detected, analysis of the detected data is performed. For example, if a command indicating the interruption of communication is detected, the processing shifts to communication interruption processing.

On the other hand, when the partner communication control device 4 detects image data from the communication control device 2, it enters a normal data reception mode. At this time, even if SYNC is detected between image data, it is handled as image data (S
T27).

When the transmission of one page of image data is completed in the communication control device 2, the RTC (Return) is completed.
to Control), and then <DLE><ETX> indicating the end of the continuous data is transmitted to the other party communication control device 4.
Send to After that, while maintaining the synchronization mode, SY
It sends out the NC and waits for a Mark signal from the partner communication control device 4 to switch the synchronization method (ST28). That is, the switching from the synchronous mode to the start-stop synchronous mode after the end of the phase C is performed by detecting the Mark which is a continuous one.

On the other hand, in the other party communication control device 4, R
When TC or <DLE><ETX> is detected, detection of SYNC sent from the communication control device 2 is started (ST29). When detecting SYNC from the communication control device 2, detection of Mark is started next. At the same time, the partner communication control device 4 stops sending SYNC to the communication control device 2 and sends Mark to the communication control device 2 (ST30). When the communication control device 2 detects a mark from the partner communication control device 4, it switches the synchronization mode from the start-stop synchronization mode to the synchronous mode, and sends the mark to the partner communication control device 4 (ST31). Accordingly, the communication control device 2 switches the synchronization mode from the synchronization mode to the start-stop synchronization mode, and shifts to phase D.

On the other hand, in the other party communication control device 4, M
When the ark is detected, the synchronization system is switched from the start-stop synchronization mode to the synchronization mode (ST32). Thereby, the other party's communication control device 4 similarly switches the synchronization mode from the synchronous mode to the start-stop synchronization mode, and shifts to phase D.

As described above, according to the present invention, the digital line 3
When communication is performed by the G3 facsimile apparatuses 1 and 5 via the PC, the synchronous mode in the data communication is switched to the start-stop synchronous mode when a control signal in the facsimile communication procedure is transmitted and received, and the bit string continues for one page. When transmitting image data, the communication is switched to the synchronous mode and the communication is executed, so that the transmission efficiency of the image data is not reduced as in the case of the facsimile communication via the digital line only in the start-stop synchronous mode. Further, unlike in the case of facsimile communication via a digital line in the synchronous mode only, there is no need to always perform processing for synchronizing the intermittently transmitted control signal, so that the load on the CPU is not increased, Facsimile can be executed via a digital line.

In the case of polling, the communication control device 2
And the position of the communication control device 4 are reversed. At this time, when the communication control device 2 is ready to receive the image data, the communication control device 2 sends a DC2 signal to the other communication control device 4 to delegate the transmission right of the image data, and The controller 4 is urged to send a Break signal. When the other party's communication control device 4 detects the DC2 signal, it sends out a Break signal, and thereafter switches the synchronization method by the same processing as described above.

[0050]

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 phase C of the facsimile communication procedure is realized.
In the case of performing a process other than the phase C for intermittently transmitting the control signal converted into the HDLC frame by performing a process of switching the synchronous system from the asynchronous synchronous transmission to the synchronous transmission, the synchronous system is switched from the synchronous system to the synchronous system. When switching to start-stop synchronous transmission and executing phase C for transmitting image data that is a continuous bit string, since the synchronous method is switched from start-stop synchronous transmission to synchronous method, the transmission speed of image data is reduced. G3 via a digital line without causing the CPU load to increase.
An effect that facsimile communication can be performed by the facsimile apparatus can be realized.

[Brief description of the drawings]

FIG. 1 is a sequence diagram showing a sequence of facsimile communication via a digital line in one embodiment of the present invention.

FIG. 2 is a block diagram showing a hardware configuration of a communication control device used in one embodiment of the present invention.

FIG. 3 is a diagram showing switching timing of a data transmission synchronization method in a communication control device used in an embodiment of the present invention;

FIG. 4 is a system configuration diagram showing communication via a conventional digital line.

[Explanation of symbols]

 1 facsimile device 2 communication control device 3 digital line

Claims (2)

(57) [Claims] 1. A conversion means for converting a facsimile signal transferred from a facsimile apparatus into communication data used for data communication, a transmission control means for transmitting the communication data to a digital line, and a facsimile communication via the digital line. When performing the facsimile communication procedure, when the phase shifts from phase B to phase C of the facsimile communication procedure, the transmission control means switches from the start-stop transmission to the synchronous transmission and controls the transmission control means to transmit the communication data. A communication control device characterized by the above-mentioned. 2. A converter for converting a facsimile signal transferred from a facsimile apparatus into communication data used for data communication, a transmission controller for transmitting the communication data to a digital line, and performing facsimile communication via the digital line. When performing, when the facsimile communication procedure shifts from phase C to phase D, control means for switching the data transmission synchronization method from synchronous transmission to start-stop transmission and causing the transmission control means to transmit the communication data is provided. A communication control device characterized by the above-mentioned.