Method and apparatus for data communication with improved transmission efficiency

1. Field of the Invention

The present invention relates to a communication apparatus such as a facsimile apparatus capable of communication using a DIS signal having a variable length FIF.

2. Related Background Art

In a conventional facsimile apparatus, a facsimile information field (FIF) of a DIS signal has a constant number of bytes, which signal is sent to a transmission side apparatus in order to notify a capability of a reception side apparatus.

FIF of the DIS signal had 4 bytes several years before, and has increased recently to 10 bytes. A facsimile apparatus shipped around 1985 was not designed to use a DIS signal having 10 bytes of FIF so that if this DIS signal is sent, a communication error occurs.

A facsimile apparatus capable of V. 8 or V. 34 communication, formally recommended by ITU-T in 1996 can receive as a DIS signal having 10 bytes of FIF. However, since a G3 facsimile apparatus manufactured in the first half of 1980's was recommended by ITU-T, FIF of a DIS signal was permitted up to 4 bytes. Therefore, the apparatus of that period can receive only a DIS signal having 4 bytes or smaller of FIF unless the apparatus was designed to expand FIF. As a fact, the V. 8, V. 34 facsimile apparatus cannot communicate with such an old type of facsimile apparatus.

It is an object of the present invention to provide reliable communication between new and old communication apparatuses having different byte numbers of FIF of a DIS signal.

FIG. 1 is a block diagram showing the structure of a facsimile apparatus according to a first embodiment of the invention.

FIG. 2 is a flow chart illustrating the operation of the first embodiment.

FIG. 3 is a flow chart illustrating the operation of the first embodiment.

FIG. 4 is a flow chart illustrating the operation of the first embodiment.

FIG. 5 is a flow chart illustrating the operation of a facsimile apparatus according to a second embodiment of the invention.

FIG. 6 is a flow chart illustrating the operation of a communication apparatus according to a third embodiment of the invention.

FIG. 7 is a flow chart illustrating the operation of the third embodiment.

FIG. 8 is a block diagram showing the structure of a facsimile apparatus according to a fourth embodiment of the invention.

FIG. 9 is a flow chart illustrating a communication control procedure of the apparatus shown in FIG. 8 .

FIG. 10 is a flow chart illustrating a communication control procedure of the apparatus shown in FIG. 8 .

FIG. 11 is a flow chart illustrating a communication control procedure of the apparatus shown in FIG. 8 .

FIG. 12 is a flow chart illustrating a communication control procedure of the apparatus shown in FIG. 8 .

FIG. 13 is a flow chart illustrating a communication control procedure of the apparatus shown in FIG. 8 .

FIG. 14 is a flow chart illustrating a communication control procedure of the apparatus shown in FIG. 8 .

FIG. 15 is a block diagram showing the structure of a facsimile apparatus according to a fifth embodiment of the invention.

FIG. 16 is a flow chart illustrating the operation of the apparatus of the fifth embodiment.

FIG. 17 is a flow chart illustrating the operation of the apparatus of the fifth embodiment.

FIG. 18 is a flow chart illustrating the operation of the apparatus of the fifth embodiment.

FIG. 19 is a flow chart illustrating the operation of the fifth embodiment.

FIG. 20 is a flow chart illustrating the operation of the apparatus of the fifth embodiment.

FIG. 21 is a flow chart illustrating the operation of a facsimile apparatus according to a sixth embodiment of the invention.

FIG. 22 is a flow chart illustrating the operation of the apparatus of the sixth embodiment.

FIG. 23 is a flow chart illustrating the operation of the apparatus of the sixth embodiment.

FIG. 24 is a flow chart illustrating the operation of the apparatus of the sixth embodiment.

FIG. 25 is a flow chart illustrating the operation of the apparatus of the sixth embodiment.

FIG. 26 is a flow chart illustrating the operation of a facsimile apparatus according to a seventh embodiment of the invention.

FIG. 27 is a flow chart illustrating the operation of the apparatus of the seventh embodiment.

FIG. 28 is a flow chart illustrating the operation of a facsimile apparatus according to an eighth embodiment of the invention.

FIG. 29 is a flow chart illustrating the operation of the apparatus of the eighth embodiment.

FIG. 30 is a flow chart illustrating the operation of a facsimile apparatus according to a ninth embodiment of the invention.

FIG. 31 is a flow chart illustrating the operation of the apparatus of the ninth embodiment.

FIG. 32 is a flow chart illustrating the operation of the apparatus of the ninth embodiment.

FIG. 33 is a flow chart illustrating the operation of the apparatus of the ninth embodiment.

FIG. 34 is a flow chart illustrating the operation of a facsimile apparatus according to a tenth embodiment of the invention.

FIG. 35 is a flow chart illustrating the operation of the apparatus of the tenth embodiment.

FIG. 36 is a flow chart illustrating the operation of a facsimile apparatus according to an eleventh embodiment of the invention.

First Embodiment

FIG. 1 is a block diagram showing the structure of a facsimile apparatus according to the first embodiment of the invention.

An NCU (network control unit) 2 is connected to a line terminal of a telephone network and performs a connection control to use the telephone network for data communication and the like. NCU 2 switches data communication lines and holds a loop. NCU 2 connects a telephone line 2 a to a telephone set 4 if a signal level (signal line 20 a ) from a control circuit 20 is “0”, and connects the telephone line 2 a to a facsimile apparatus if the signal level is “1”. In a normal state, the telephone line 2 a is connected to the telephone set 4 .

A hybrid circuit 6 separates a transmission signal and a reception signal. The hybrid circuit 6 sends the transmission signal from an adder circuit 12 via NCU 2 to the telephone line 2 a , and receives the reception signal from a partner from NCU 2 to send to a modem 8 via a signal line 6 a.

The modem 8 modulates and demodulates signals in accordance with ITU-T Recommendations, V. 8, V. 21, V. 27 ter, V. 29, V. 17, and V. 34. Each transmission mode is designated by a signal on a signal line 20 c . The modem 8 receives a signal on a signal line 20 b , outputs modulated data to a signal line 8 a , receives a reception signal on a signal line 6 a , and outputs demodulated data to a signal line 8 b.

An ANSam send-out circuit 10 is a circuit for sending an ANSam signal. The ANSam send-out circuit 10 sends the ANSam signal to a signal line 10 a when a signal of level “1” is output to a signal line 20 d , and it does not send any signal when a signal of level “0” is output to the signal line 20 d.

The adder circuit 12 receives information from the signal lines 8 a and 10 a , and outputs an addition result to the signal line 12 a . A reading circuit 14 reads an image of an original and outputs the read image data to a signal line 14 a . A recording circuit 16 records information from a signal line 20 e sequentially one line after another.

A memory circuit 18 stores raw information of read data, coded information, reception information, decoded information, and the like.

A call signal detecting circuit 22 is a circuit for detecting a call signal from a line. The call signal detecting circuit 22 receives information from the signal line 2 b , outputs a signal of level “1” to a signal line 22 a when a call signal is detected, and outputs a signal of level “0” to the signal line 22 a when the call signal is not detected.

An intervening telephone number detecting circuit 24 is a circuit for detecting an intervening telephone number from a line. This circuit 24 receives information from the line 2 b and outputs an intervening telephone number to a line 24 a.

A memory circuit 26 is a circuit for storing the number of bytes of FIF of a current DIS, the number of consecutive communication errors, the number of effective bytes of FIF of DIS, respectively for each destination (calling station identified by intervening telephone number). Data is input/output, via a line 26 a to/from the memory circuit 26 .

A control circuit 20 controls the whole of the facsimile apparatus of this embodiment. In the first embodiment of the invention, the contents of the memory circuit 26 are compared with the partner telephone number detected by the telephone number detecting circuit 24 , and in accordance with the comparison result, transmission control is performed by changing the number of bytes of FIF of a transmission signal.

Specifically, if a communication error occurs after a DIS signal having 10 bytes as a default of FIF is sent at reception of a call, it is stored that FIF of the DIS signal of the destination (calling station) is 10 bytes, and if three times of errors occur consecutively, a DIS signal having 7 bytes of FIF is sent to the destination. If a communication error occurs when a DIS signal having 7 bytes of FIF is sent at reception of a call, it is stored that FIF of the DIS signal of the destination is 7 bytes, and if three times of errors occur consecutively, a DIS signal having 4 bytes of FIF is sent.

FIGS. 2 to 4 are flow charts illustrating the operation of the control circuit 20 according to the first embodiment of the invention.

The control operation starts at S 0 , and at S 2 the number of bytes of FIF of DIS is set to 10, the number of consecutive communication errors is set to 0, and the number of effective bytes of FIF of DCS is set unknown, via the signal line into in the memory circuit 26 for each destination.

At S 4 a signal of level “0” is output to the signal line 20 a to turn off CML. At S 6 a signal of level “0” is output to the signal line 20 d so as not to send the ANSam signal.

At S 8 information is received from the signal line 22 a to check whether the call signal is detected or not. If detected, the flow advances to S 12 , whereas if not, the flow advances to S 10 to perform another process and return to S 4 .

At S 12 the intervening telephone number is input from the signal line 24 a and stored. At S 14 a signal of level “1” is output to the signal line 20 a to turn on CML. At S 16 a T 1 timer is set to 35 seconds.

At S 18 an NSF/CSI/DIS signal of V. 21 is sent. In this case, information is input from the signal line 26 a , and the number of bytes of FIF of DIS is set to the value stored in the memory circuit 27 for the corresponding intervening telephone number. At S 20 a T 4 timer is set to 3 seconds.

At S 22 it is checked whether or not the NSS/TSI/DCS signal of V. 21 is received. If received, the flow advances to S 28 , whereas if not, the flow advances to S 24 .

At S 24 it is checked whether or not the T 4 timer is time-out. If time-out, the flow advances to S 26 , whereas if not, the flow advances to S 22 .

At S 26 it is checked whether or not the T 1 timer is time-out. If time-out, the flow advances to S 24 , whereas if not, the flow advances to S 18 .

At S 28 the remaining pre-procedure of V. 21, image signal reception, and post-procedure of V. 21 are executed. At S 30 it is checked whether a communication error occurs. If occurs, the flow advances to S 34 , whereas if not, the flow advances to S 32 .

At S 32 the number of consecutive communication errors is set to 0 via the signal line 26 a into the memory circuit 26 for the current destination, and the flow returns to S 4 .

At S 34 the number of consecutive communication errors is incremented by 1via the signal line 26 a into the memory circuit 26 for the current destination. At S 36 it is checked whether the number of consecutive communication errors incremented by 1at S 34 reaches 3 or larger. If 3or larger, the flow advances to S 37 , whereas if not, the flow returns to S 4 .

At S 37 the number of consecutive communication errors is set to 0 via the signal line into the memory circuit 26 for the current destination.

At S 38 the number of bytes of FIF of the DIS signal stored in the memory circuit 26 for the current destination is checked via the signal line 26 a . If the number is 10 bytes, the flow advances to S 40 whereat the number of bytes of FIF of the DIS signal is set to 7 into the memory circuit 26 for the current destination, and the flow returns to S 4 . If the number is 7 bytes, the flow advances to S 42 whereat the number of bytes of FIF of the DIS signal is set to 4 into the memory circuit 26 for the current destination, and the flow returns to S 4 . If the number is 4 bytes, the flow returns to S 4 .

Second Embodiment

Next, the second embodiment of the invention will be described.

In the second embodiment, the number of bytes of FIF of a DCS signal sent from a partner apparatus in the first embodiment and FIF data are analyzed to determine the minimum number of bytes of FIF of the DIS signal.

FIG. 5 is a flow chart illustrating the operation of the control circuit 20 of the second embodiment, the flow chart showing different portions from the first embodiment (FIGS. 2 to 4 ). The structure of the apparatus is the same as that of FIG. 1 .

Referring to FIG. 5, S 50 corresponds to YES at S 22 . At S 52 FIF of the sent DCS is checked to determine effective up to FIF set with “1” excepting extension bits as 6. If the numbering effective bytes is larger than the number of effective bytes of FIF of DCS registered in the memory circuit 26 for the current destination, it is registered, and at S 54 the flow returns to S 28 .

S 56 corresponds to S 38 when the number of bytes of FIF of the DIS signal registered in the memory circuit 26 for the current destination is 10 bytes.

At S 58 information is received from the signal line 26 a to check whether the number of effective bytes of FIF of DCS registered in the memory circuit 26 for the current destination is 8 or larger. If 8 or larger, the flow advances to S 60 (S 54 ), whereas if not, the flow advances to S 62 (S 40 ).

S 64 corresponds to S 38 when the number of bytes of FIF of the DIS signal registered in the memory circuit 26 for the current destination is 7 bytes.

At S 66 information is received from the signal line 26 a to check whether the number of effective bytes of FIF of DCS registered in the memory circuit 26 for the current destination is 5 or larger. If 5 or larger, the flow advances to S 68 (S 4 ), whereas if not, the flow advances to S 70 (S 42 ).

Third Embodiment

In the third embodiment, in a facsimile apparatus having a means for executing transmission by changing the number of bytes of FIF of a transmission signal DIS, if a communication error occurs when a DIS signal having a predetermined number D of bytes (e.g., 10) is sent at reception of a call, a DIS signal having a predetermined number E of bytes (e.g., 4 bytes) of FIF is sent at reception after a predetermined time after the error occurred.

FIGS. 6 and 7 are flow charts illustrating the operation of the control circuit 20 of the third embodiment, the flow charts showing different portions from the first embodiment (FIGS. 2 to 4 ). The structure of the apparatus is the same as that of FIG. 1 .

Referring first to FIG. 6, S 80 corresponds to S 0 . At S 82 a flag DISRED is cleared. It is assumed that a DIS signal having 4 bytes of FIF is sent if DISRED is “1” and a DIS signal having 10 bytes is sent if DISRED is “0”. At S 84 the flow returns to S 4 .

Next, S 86 corresponds to YES at S 8 . At S 88 it is checked whether or not the flag DISRED is 0. If 0, the flow advances to S 90 (S 14 ), whereas if 1, the flow advances to S 124 .

S 92 corresponds to S 16 , and S 94 corresponds to NO at S 26 . At S 96 an NSF/CSI/DIS signal is sent. It is assumed that the number of bytes of FIF of the DIS signal is 10. At S 98 the flow returns to S 20 .

S 100 corresponds to NO at S 30 . At S 102 the flow directly returns to S 4 . Namely, it means to omit the process of S 32 . S 104 corresponds to YES at S 30 . At S 106 the flag DISRED is set to “1” and a timer is set to 5 minutes. Thereafter, the flow returns to S 4 . Namely, the processes from S 34 to S 42 are not executed.

S 112 corresponds to S 10 . At S 114 it is checked whether or not the flag DISRED is “1”. If 1, the flow advances to S 116 , whereas if 0, the flow advances to S 118 (S 4 ).

At S 116 it is checked whether or not the timer is time-out. If time-out, the flow advances to S 120 whereat the flag DISRED is set to “0”, and at S 122 the flow returns to S 4 . If not time-out, the flow advances to S 118 .

S 124 corresponds to S 14 and S 16 . Namely, a signal of level “1” is output to the signal line 20 a to turn on CML and set the T 1 timer to 35 seconds.

At S 126 an NSF/CSI/DIS signal is sent. It is assumed herein that the number of bytes of FIF of the DIS signal is 4 bytes.

Next, at S 128 the process of S 20 is executed. Namely, the T 4 timer is set to 3seconds.

At S 130 the judgement at S 22 is performed, i.e., it is checked whether the NSS/TSI/DCS signal of V. 21 is received. If received, the flow advances to S 138 (S 28 ) whereat the remaining pre-procedure of V. 21, image signal reception, and post-procedure of V. 21 are executed, and at S 140 the flow returns to S 4 .

If it is judged at S 130 that the NSS/TSI/DCS signal of V. 21 is not received, the flow advances to S 132 (S 24 ) whereat it is checked whether the T 4 timer is time-out or not. If time-out, the flow advances to S 134 (S 26 ), whereas if not, the flow advances to S 130 (S 22 ).

At S 134 (S 26 ) it is checked whether the timer T 1 is time-out. If time-out, the flow advances to S 136 (S 4 ), whereas if not, the flow advances to S 126 .

The above operation of the control circuit is executed by a CPU in the control circuit in accordance with a program stored in ROM, RAM or the like of the control circuit. The present invention may be reduced in practice by storing such a program in an external storage medium such as a floppy disk, a hard disk, a magnetooptical disk, and a CD-ROM, by reading the program with a dedicated reading apparatus and storing it in the memory of the control circuit, and by executing the program by CPU.

In the above embodiments, a facsimile apparatus of a stand-alone type has been described by way of example. The invention is not limited only thereto, but is also applicable to data communication control of a synthetic data processing system with a communication function combined with a copy function, an electronic file function, and a data processing function. The invention can also be applied to a communication apparatus with separated reading and recording circuits.

As described above, according to the first to third embodiments, reliable communication can be performed between communication apparatuses having different FIF of a DIS signal. It is also possible to provide maximum performances between latest apparatuses using an extended number of bytes of FIF.

According to the second embodiment, even if an older communication apparatus having a smaller number of bytes of FIF of a DIS signal can realize communication with a maximum performance, without limiting the performance of the apparatus.

According to the third embodiment, reliable communication can be performed between communication apparatuses having different bytes of FIF of a DIS signal, through re-dialing.

Fourth Embodiment

The fourth embodiment will be described with reference to FIGS. 8 to 13 .

FIG. 8 is a block diagram showing the structure of a facsimile apparatus embodying the invention, the facsimile apparatus being provided with two lines. The circuit elements similar to those shown in FIG. 1 are represented by identical reference numerals, and the description thereof is omitted.

Referring to FIG. 8, reference numeral 120 represents a control circuit constituted of a microprocessor, a memory and the like. The control circuit 120 controls the operation of the whole apparatus in accordance with a program, to be described later, stored in an internal memory such as a ROM of the control circuit 120 or a ROM of a memory circuit 18 .

It is assumed that the control circuit 120 executes a facsimile communication protocol in conformity with ITU-T Recommendations T 30 . The control circuit 120 conducts the following control. First, an initial identification signal containing a DIS signal having a length A (e.g., 10 bytes) of FIF is sent. If an effective response signal from the partner cannot be received consecutively a predetermined number C of times (e.g., twice), an initial identification signal containing a DIS signal having a length of a predetermined byte number (e.g., 4 bytes) of FIF is sent. This control of FIF of a DIS signal is executed in generally the same manner even in an intermediate procedure (e.g., when an EOM signal is received) to be executed between pages during a transmission of a plurality of pages.

The control circuit 120 uses timers (T 1 , . . . ) and a counter (DISCNT) during the communication procedure. These timers and counter ( 120 f in FIG. 8) may be configured by hardware or by software of the control circuit 120 . Implementing such timers and counters are well known, and the detailed description thereof is omitted.

The operation of the facsimile apparatus having the above structure will be described in detail with reference to FIGS. 9 to 13 . FIGS. 9 to 13 illustrate the sequence of a communication control to be executed by the control circuit 120 . The sequence shown in FIGS. 9 to 13 is stored as a program of the control circuit 120 in an internal memory such as a ROM of the control circuit 120 or in a ROM of the memory circuit 18 . It is noted that the same numbers in FIGS. 9 to 13 are directly connected thereat.

Referring to FIG. 9, Step S 200 corresponds to a process start such as power-on and reset. At Step S 202 a CML relay of NCU 2 is turned off. The line 2 a is therefore connected to the telephone set 4 .

At Step S 204 a signal of level “0” is output to the signal line 20 d so as not to send the ANSam signal.

At Step S 206 it is checked whether reception (manual) is selected. If selected, the flow advances to Step S 212 , whereas if not, the flow advances to Step S 208 . The reception selection at Step S 206 is used when a reception start is instructed by manually depressing a start button or the like after the reception.

At Step S 208 it is checked whether “incoming” (auto) is selected. If selected, the flow advances to Step S 212 , whereas if not, the flow advances to Step S 210 . This incoming selection is used when a call signal is received during an automatic reception mode.

At Step S 210 another process is performed such as a known image transmission operation and an original copy operation.

At Step S 212 , a signal of level “1” is output to the signal line 20 a to turn on the CML relay and connect the line 2 a to the hybrid circuit 6 .

At step S 214 , the T 1 timer is set to 35 seconds (initial identification period).

At Step S 216 the counter DISCNT is cleared. This counter DISCNT counts the number of transmissions of a DIS signal having 10 bytes of FIF during the initial identification period.

At Step S 218 an NSF/CSI/DIS signal of Recommendation V. 21 (300 bps) is sent. It is assumed that the number of bytes of FIF of the DIS signal sent at Step S 218 is 10 bytes. Transmission/reception of a procedure signal is performed via the modem 8.

At Step S 219 the value of the counter DISCNT is incremented by 1.

At Step S 220 (FIG. 10) it is checked whether the apparatus is in the manual mode. If in a manual mode, the flow advances to Step S 222 , whereas if not, the flow advances to Step S 224 .

At Step S 222 the timer T 4 is set to 4.5 seconds, and at Step S 224 , it is set to 3 seconds.

Steps S 226 , S 228 , and S 230 constitute a loop having a period set by the timer T 4 . At Step S 226 it is checked whether the NSS/CIG/DTC signal of Recommendation V. 21 is received. At Step S 228 it is checked whether the NSS/TSI/DCS signal is received.

If the NSS/CIG/DTC is received, the flow advances to Step S 232 , whereas if the NSS/TSI/DCS signal is received, the flow advances to Step S 246 (FIG. 11 ). Reception of these signals continues until the timer T 4 becomes time-out at Step S 230 . When the timer T 4 becomes time-out, the flow advances to Step S 238 .

At Steps S 232 , S 234 , and S 236 in response to a reception of the NSS/CIG/DTC signal, the remaining pre-procedure, polling image transmission, and post-procedure are executed.

At Step S 238 it is checked whether the timer T 1 is time-out, indicating the end of the initial identification period. If the initial identification period is passed, the flow advances to Step S 240 whereat an error process is executed, whereas if not, the flow advances to Step S 242 (FIG. 11 ).

At Step S 242 it is checked whether the value of the counter DISCNT is 2 or larger. If 2 or larger, the flow advances to Step S 244 , whereas if not, the flow advances to Step S 218 .

If the counter DISCNT is 2 or larger, it should be judged that the DIS signal having 10 bytes of FIF and first sent is not recognized by the partner apparatus. Therefore, at Step S 244 , the NSF/CSI/DIS signal of V. 21 Recommendation is sent. At this Step S 244 it is assumed that the length of FIF of the DIS signal is 4 bytes and the format of a conventional DIS signal is used.

If the NSS/TSI/DCS signal is received at Step S 228 (FIG. 10 ), the remaining pre-procedure is executed at Step S 246 (FIG. 11 ), and the image reception and image recording by the recording circuit 16 are executed at Step S 248 .

At Step S 250 it is checked whether image reception of one page is completed. If completed, the flow advances to Step S 252 , whereas if not, the flow returns to Step S 248 to repeat the image reception and recording.

At Step S 252 the timer T 2 is set to 6 seconds and thereafter the flow advances to Step S 254 (FIG. 12 ).

Steps S 254 , S 256 , S 258 , and S 260 constitute a loop having a period of 6 seconds set by the timer T 2 . It is checked at Step S 254 whether an MPS (multi page) signal of V. 21 Recommendation is detected, it is checked at Step S 256 whether an EOP (procedure end) signal of V. 21 Recommendation is detected, and it is checked at Step S 258 whether an EOM (end of message) signal of V. 21 Recommendation is detected. If the time T 2 has counted 6 seconds at Step S 260 , it means a preset procedure signal is not received between pages, so that an error process is executed at Step S 262 . If the timer T 2 has not counted 6 seconds at Step S 260 , the flow returns to Step S 254 .

If the MPS signal is received at Step S 254 , an MCF signal indicating an acknowledge of multi-page reception is sent at Step S 264 .

If the EOP signal is received at Step 256 , an MCF signal indicating an acknowledge of the procedure end is sent at Step S 266 and a DCN signal is sent at Step S 268 to disconnect the call.

If the EOM signal is received at Step S 258 , the flow advances to Step S 270 shown in FIG. 13 to execute a multi page reception process. First, at Step S 270 the MCF signal is sent, the operation enters a standby state for 6 seconds at Step S 272 , the timer T 1 is set to 35 seconds to again set the initial identification period at Step S 274 , and at Step S 276 it is checked whether the count of the counter DISCNT set in the pre-procedure is 2 or larger.

If 2 or larger at Step S 276 , the flow advances to Step S 280 whereat the number of bytes of FIF of the DIS signal is set to 4 bytes and the NSF/CSI/DIS signal of V. 21 Recommendation is sent, whereas if not, the flow advances to Step S 278 whereat the number of bytes of FIF of the DIS signal is set to 10 bytes and the NSF/CSI/DIS signal of V. 21 Recommendation is sent.

At Step S 282 the timer T 4 is set to 3 seconds, and it is checked at Step S 286 whether the NSS/TSI/DCS signal is detected. If detected, the flow returns to Step S 246 (FIG. 11) to receive the next page, and if the next page cannot be received, the flow advances to Step S 286 (FIG. 14 ).

At Step S 286 (FIG. 14) it is checked whether the timer T 4 is time-out. If not, the flow returns to Step S 284 whereat the NSS/TSI/DCS signal is waited for, whereas if time-out, the flow advances to Step S 288 .

At Step S 288 it is checked whether the timer T 1 (35 seconds) is time-out (over the initial identification period between pages). If the timer T 1 becomes time-out without receiving the effective response signal, an error process is executed at Step S 290 . If the timer T 1 is not time-out, the flow returns to Step S 276 (FIG. 13) to repeat the above operation.

As described above, according to the fourth embodiment, the initial identification signal containing a DIS signal having a length A (e.g., 10 bytes) of FIF is sent, and if the effective response signal from the partner apparatus is not consecutively received a plurality number C of times (e.g., twice), the initial identification signal containing a DIS signal having a predetermined number B of bytes (e.g., 4 bytes) of FIF is sent. Accordingly, communication with even an older facsimile apparatus of a partner having the predetermined number B (four) of bytes can be made, initial identification can be made reliably although the communication time is prolonged more or less, and a failure in image communication becomes less.

A DIS signal having a large number of bytes of FIF is first used, and if the communication can be established, this procedure becomes effective. Accordingly, if the partner apparatus has an extended number of bytes of FIF, image communication of high quality can be made by using the extended number of bytes of FIF without losing a chance of call connection.

In the fourth embodiment, when the EOM signal is received at Step S 258 shown in FIG. 12, the length of FIF of a DIS signal is determined by using the count of the counter DISCNT set in the pre-procedure. Accordingly, the intermediate procedure can be executed reliably by using a compatible DIS signal without using time wastefully in the intermediate procedure.

In the above embodiment, the length of FIF of a DIS signal is controlled. It is obvious that FIF of another procedure signal can be controlled by using similar techniques. In the above embodiment, the facsimile apparatus having the reading and recording circuits is described by way of example. It is obvious that the same configuration as the embodiment can be applied to a digital copier having a facsimile communication function, a FAX modem and a facsimile system made of a combination of a FAX modem, a computer, a word processor, a printer and the like.

Fifth Embodiment

FIG. 15 is a block diagram showing the structure of a facsimile apparatus according to the fifth embodiment of the invention. Like elements to those shown in FIG. 1 are represented by using identical reference numerals, and the description thereof is omitted.

A console unit (operation unit) 222 has a one-touch dial, abbreviated dial, ten-keys, an * key, a # key, a set key, a start key, a registration key for registration circuits 224 , 226 , and 230 , other function keys, and the like. Key information of a depressed key is output to a signal line 222 a from the console unit 222 .

The registration circuit 224 registers a predetermined number D of times. In the sixth embodiment to be described later, the predetermined number D of times is set to 2, in the seventh embodiment to be described later, the predetermined number D of times is set to 3 for the automatic mode, and 2 for the manual mode, and in the eighth embodiment to be described later, the predetermined number D of times is set to 2 with the CSI signal, and 3 without the CSI signal.

The registration circuit 226 registers a predetermined number E of times. In the sixth embodiment to be described later, the predetermined number E of times is set to 4, in the seventh embodiment the predetermined number E of times is set to 5, and in the eighth embodiment the predetermined number E of times is set to 3 with the CSI signal, and 4 without the CSI signal.

The registration circuit 230 is a circuit for registering a method of controlling the number of bytes of FIF of a DIS signal. If a pre-procedure error occurs after a DIS signal having 10 bytes of FIF is sent, whether a DIS signal having 4 bytes of FIF is sent only at the next reception, or at the reception after a predetermined lapse of time (e.g., 20 minutes) is registered via a signal line 230 a.

A control circuit 220 controls the whole of the facsimile apparatus. In the fifth embodiment of the invention, the control circuit 220 operates in the following manner. If a CM signal is received from the partner apparatus after an ANSam signal is sent at the reception, the number of bytes of FIF of a DIS signal at the following reception is set to a predetermined byte number A. If the CM signal is not received from the partner apparatus, a DIS signal having the predetermined number A of V. 21 is sent, and if the effective response signal from the partner apparatus cannot be received consecutively by a predetermined number C of times, a DIS signal having a predetermined byte number B of V. 21 is sent.

Further, if the CM signal from the partner apparatus is detected after the ANSam signal is sent or if a CI signal of V. 8 is received after a DIS signal having the predetermined byte number A of V. 21 is sent, and if the control is shifted to the protocol sequence of V. 34, then a DIS signal having the predetermined byte number A is always sent. In this embodiment, it is assumed that the predetermined byte number A is 10 bytes, the predetermined byte number B is 4 bytes, and the predetermined number C of times is 2 bytes.

FIGS. 16 to 20 are flow charts illustrating the control of the control circuits 220 according to the fifth embodiment of the invention.

Referring to FIG. 16, the operation starts at S 300 . At S 302 a signal of level “0” is output to the signal line 20 a so as not to send the CML signal. At S 304 a signal of level “0” is output to the signal line 20 d so as not to send the ANSam signal.

At S 306 it is checked whether the incoming (auto) is selected. If selected, the flow advances to S 310 , whereas if not, the flow advances to S 308 to execute another process and return to S 302 .

At S 310 a signal of level “1” is output to the signal line 20 a to send the CML signal. At S 312 , a timer T 0 is set to 4 seconds. At S 314 a timer T 1 is set to 60 seconds.

At S 316 the ANSam signal is sent, and at S 318 (FIG. 17) it is checked whether the CM signal of V. 8 is detected. If detected, the flow advances to S 322 , whereas if not, the flow advances to S 320 .

At S 320 it is checked whether the time T 0 is time-out. If time-out, the flow advances to S 342 , whereas if not, the flow advances to S 316 .

At S 322 a JM signal of V. 8 is sent, at S 324 a CJ signal of V. 8 is received, at S 326 a line probing signal of V. 34 is received, and at S 328 a long training signal of V. 34 is received.

At S 330 parameters of V. 34 are exchanged. In this case, a DIS signal having 10 bytes of FIF is always sent. At S 332 a primary channel of V. 34 is received, and at S 334 communication of a control channel of V. 34 is executed.

At S 336 it is checked whether there is a next page. If there is a next page, the flow advances to S 338 , whereas if not, the flow advances to S 340 .

At S 338 it is checked whether there is a mode change. If there is the mode change, the flow returns to S 330 , whereas if not, the flow returns to S 332 .

At S 340 communication of the control channel of V. 34 is executed. At S 342 (FIG. 18) a DIS signal of V. 21 is sent, and the counter DISCNT for counting the number of times of non-response from the partner apparatus is cleared.

At S 344 an NSF/CSI/DIS signal of V. 21 is sent. In this case, the DIS signal has 10 bytes of FIF and a presence of a V. 34 communication function is notified by using the DIS signal. At S 346 a T 4 timer is set to 3 seconds.

At S 348 , S 350 , S 353 , and S 354 it is checked whether the CI signal of V. 8 is received, whether the NSC/CIG/DTC signal of V. 21 is received, and the NSS/TSI/DCS signal of V. 21 is received, until the T 4 timer becomes time-out. If the CI signal of V. 8 is received, the flow advances to S 316 , if the NSC/CIG/DTC signal of V. 21 is received, the flow advances to S 356 , and if the NSS/TSI/DCS signal of V. 21 is received, the flow advances to S 372 , and if the T 4 becomes time-out, the flow advances to S 362 .

At S 356 the pre-procedure of V. 21 is executed, at S 358 the polling transmission of V. 27 ter, V. 29, and V. 17 is executed. At S 360 , the post-procedure of V. 21 is executed. At S 362 the count of the counter DISCNT is incremented by 1.

Next, at S 364 it is checked whether the timer T 1 is time-out. If time out, the flow advances to S 366 to execute an error process and return to S 302 , whereas if not, the flow advances to S 368 .

At S 368 it is checked whether the count of the counter DISCNT is 2 or larger. If 2 or larger, the flow advances to S 370 , whereas if not, the flow advances to S 344 .

At S 370 an NSF/CSI/DIS signal of V. 21 is sent. In this case, the DIS signal having 4 bytes of FIF is sent and a presence of the V. 34 communication function is not notified by using the DIS signal.

At S 372 (FIG. 20) a remaining pre-procedure of V. 21 is executed, at S 374 an image signal reception of V. 27 ter, V. 29, and V. 17 is executed, and at S 376 an intermediate procedure of V. 21 is executed. At S 378 it is checked whether there is a next page. If there is no next page, the flow advances to S 382 to execute a post-procedure of V. 21, whereas there is the next page, the flow advances to S 380 .

At S 380 it is checked whether there is a mode change. If not, the flow returns to S 374 , whereas if there is the mode change, the flow returns to S 368 .

Sixth Embodiment

Next, the sixth embodiment will be described.

In the sixth embodiment of the invention, a control circuit 220 has a means for controlling to change the number of bytes of FIF of a DIS signal of the initial identification signal. With this control, a DIS signal having F bytes of FIF is sent as the initial identification signal at the reception, until it is sent a predetermined number D of times a DIS signal having G bytes of FIF is sent as the initial identification signal, from the time in excess of the predetermined number F of times to a predetermined number E of times and a DIS signal having H bytes is sent as the initial identification signal from the time in excess of the predetermined number E of times. In this embodiment, it is assumed that F is 10, G is 6, H is 4, D is 2, and E is 4.

FIGS. 21 to 25 are flow charts illustrating the control operation of the control circuit 220 .

Referring to FIG. 21, at U 0 the operation starts, and at U 2 an initial value 1of the predetermined number D of times is registered via the signal line 224 a into the registration circuit 224 . At U 4 an initial value 2 of the predetermined number E of times is registered via the signal line 226 a into the registration circuit 226 .

At U 6 a signal of level “0” is output to the signal line 20 a so as not to send the CML signal.

At U 8 a signal of level “0” is output to the signal line 20 d so as not to send the ANSam signal. At U 10 information is received from the signal line 222 a to check whether registration into the registration circuit 224 is selected. If selected, the flow advances to U 12 whereat the predetermined number D of times, e.g., 2, is registered via the signal line 224 a into the registration circuit 224 to thereafter advance to U 14 , whereas if not selected, the flow advances directly to U 14 .

At U 14 information is received from the signal line 222 a to check whether registration into the registration circuit 226 is selected. If selected, the flow advances to U 16 whereat the predetermined number E of times, e.g., 4, is registered via the signal line 226 a to thereafter advance to U 18 , whereas if not selected at U 14 , the flow advances directly to U 18 .

At U 18 it is checked whether incoming is selected. If selected, the flow advances to U 24 , whereas if not, the flow advances to U 20 .

At U 20 it is checked whether reception is selected. If selected, the flow advances to U 24 , whereas if not, the flow advances to U 22 whereat another process is executed to thereafter return to U 6 .

At U 24 a signal of level “1” is output to the signal line 20 a to turn on the signal CML. At U 26 a CED signal is sent, and at U 28 the timer T 1 is set to 35 seconds.

At U 30 the counter DISCNT is set to 0, the counter counting the number of times that the DIS signal is sent during the initial discrimination procedure (pre-procedure).

At U 32 information is received from the signal line 224 a to check whether the count of the counter DISCNT is the predetermined number D of times, e.g., 2 or smaller, registered in the registration circuit 224 . If 2 or smaller, the flow advances to U 34 , whereas if not, the flow advances to U 48 .

At U 34 an NSF/CSI/DIS signal of V. 21 is sent. FIF of the DIS signal has 10 bytes. At U 36 it is checked whether the mode is an automatic mode. If it is an automatic mode, the flow advances to U 38 whereat the T 4 timer is set to 3 seconds, whereas if it is a manual mode, the flow advances to U 40 whereat the timer T 4 is set to 4.5 seconds.

At U 42 , U 44 , and U 46 it is checked whether the NSC/CIG/DTC signal of V. 21 is received and it is checked whether the NSS/TSI/DCS signal of V. 21 is received, until the T 4 timer becomes time-out. If the NSC/CIG/DTC of V. 21 is received, the flow advances to U 54 , whereas if the NSS/TSI/DCS signal of V. 21 is received, the flow advances to U 60 , and if the timer T 4 becomes time-out, the flow advances to U 66 .

At U 48 information is received from the signal line 226 a to check whether the counter of the counter DISCNT is the predetermined number E of times, e.g., smaller than 4, registered in the registration circuit 26 . If smaller than 4, the flow advances to U 50 , whereas if not, the flow advances to U 52 .

At U 50 the NSF/CSI/DIS of V. 21 is sent. FIF of the DIS signal has 6 bytes. At U 52 the NSF/CSI/DIS signal of V. 21 is sent. FIF of the DIS signal is 4 bytes. Thereafter, the flow returns to U 36 .

At U 54 the remaining pre-procedure is executed, at U 56 polling transmission is executed, and at U 58 the post-procedure is executed, to thereafter return to U 6 .

At U 60 the remaining pre-procedure is executed. At U 62 image signal reception/recording is executed. In this case, if a mode is changed, FIF of the DIS signal is set to the number of bytes same as that of FIF of the DIS signal received as an effective response from the partner apparatus (i.e., the last sent DIS signal in the pre-procedure). At U 64 the post-procedure is executed to thereafter return to U 6 .

At U 66 the count of the counter DISCNT is incremented by 1. At U 68 it is checked whether the timer T 1 is time-out. If time-out, the flow advances to U 70 whereat an error process is executed to thereafter return to U 6 , whereas it not time-out, the flow returns to U 32 .

Seventh Embodiment

Next, the seventh embodiment of the invention will be described.

In the seventh embodiment, different from the sixth embodiment, the predetermined numbers D and E of times are set differently for the automatic mode and manual mode.

FIGS. 26 and 27 are flow charts illustrating only a partial operation of the seventh embodiment, which is different from that of the sixth embodiment (FIGS. 21 to 25 ).

Referring to FIG. 26, U 80 corresponds to YES at U 10 . At U 82 the predetermined number D of times, e.g., 3 for the automatic mode and 2 for the manual mode, is registered via the signal line 224 a into the registration circuit 224 . The flow advances to U 84 and then returns to U 14 .

U 86 corresponds to YES at U 14 . At U 88 the predetermined number E of times, e.g., 5 for the automatic mode and 3 for the manual mode, is registered via the signal line 226 a into the registration circuit 226 . The flow advances to U 90 and then returns to U 18 .

U 92 corresponds to U 30 . At U 94 it is checked whether the mode is an automatic mode. If it is a manual mode, the flow advances to U 100 , whereas if it is an automatic mode, the flow advances to U 96 .

At U 96 it is checked whether the count of the counter DISCNT is the predetermined number D of times for the automatic mode, e.g., smaller than 3, registered in the registration circuit 224 . If smaller than 3, the flow advances to U 104 (U 34 ), whereas if not, the flow advances to U 98 .

At U 98 it is checked whether the count of the counter DISCNT is the predetermined number E of times for the automatic mode, e.g., smaller than 5, registered in the registration circuit 226 . If smaller than 5, the flow advances to U 106 (U 50 ), whereas if not, the flow advances to U 108 (U 52 ).

At U 100 it is checked whether the count of the counter DISCNT is the predetermined number D of times for the manual mode, e.g., smaller than 2, registered in the registration circuit 224 . If smaller than 2, the flow advances to U 104 , whereas if not, the flow advances to U 102 .

At U 102 it is checked whether the count of the counter DISCNT is the predetermined number E of times for the manual mode, e.g., smaller than 3, registered in the registration circuit 226 . If smaller than 3, the flow advances to U 106 , whereas if not, the flow advances to U 108 (U 52 ).

Eighth Embodiment

Next, the eighth embodiment of the invention will be described.

In the eighth embodiment, different from the sixth embodiment, the predetermined numbers D and E of times are determined differently in accordance with a presence/absence of transmission of the CSI signal.

FIGS. 28 and 29 are flow charts illustrating only a partial operation of the eighth embodiment, which is different from that of the sixth embodiment (FIGS. 21 to 25 ).

Referring to FIG. 28, U 110 corresponds to YES at U 10 . At U 112 the predetermined number D of times, e.g., 3 for the absence of the CSI signal and 2 for the presence of the CSI signal, is registered via the signal line 224 a into the registration circuit 224 . The flow advances to U 114 and then returns to U 14 .

U 116 corresponds to YES at U 14 . At U 118 the predetermined number E of times, e.g., 4 for the absence of the CSI signal and 3 for the presence of the CSI signal, is registered via the signal line 226 a into the registration circuit 226 . The flow advances to U 120 and then returns to U 18 .

U 122 corresponds to U 30 . At U 124 it is checked whether the CSI signal is to be sent. If it is to be sent, the flow advances to U 120 , whereas if it is not to be sent, the flow advances to U 130 .

At U 126 it is checked whether the count of the counter DISCNT is the predetermined number D of times for the presence of the CSI signal, e.g., smaller than 2, registered in the registration circuit 224 . If smaller than 2, the flow advances to U 134 (U 34 ), whereas if not, the flow advances to U 128 .

At U 128 it is checked whether the count of the counter DISCNT is the predetermined number E of times for the presence of the CSI signal, e.g., smaller than 3, registered in the registration circuit 226 . If smaller than 3, the flow advances to U 136 (U 50 ), whereas if not, the flow advances to U 138 (U 52 ).

At U 130 it is checked whether the count of the counter DISCNT is the predetermined number D of times for the absence of the CSI signal, e.g., smaller than 3, registered in the registration circuit 224 . If smaller than 3, the flow advances to U 134 , whereas if not, the flow advances to U 132 .

At U 132 it is checked whether the count of the counter DISCNT is the predetermined number E of times for the absence of the CSI signal, e.g., smaller than 4, registered in the registration circuit 226 . If smaller than 4, the flow advances to U 136 , whereas if not, the flow advances to U 138 (U 52 ).

Ninth Embodiment

Next, the ninth embodiment of the invention will be described.

In the ninth embodiment, the control circuit 220 bytes of FIF of a DIS signal. With this control, a DIS signal having 10 bytes of FIF is sent as the initial identification signal at the reception, and if a pre-procedure error occurs, a DIS signal having 4 bytes of FIF is sent as the initial identification signal at the next reception.

FIGS. 30 to 33 are flow charts illustrating the control operation of the control circuit 220 according to the ninth embodiment.

Referring to FIG. 30, the operation starts at W 0 , and at W 2 a flag DISTRN is set to 0 to set FIF to 10 bytes. The flag indicates whether FIF of a DIS signal is to be set to 4 bytes or 10 bytes.

At W 4 a transmission of a DIS signal having 10bytes of FIF and if there is a pre-procedure error a transmission of a DIS signal having 4 bytes of FIF only at the next reception, are registered via the signal line 230 a into the registration circuit 230 .

At W 6 a signal of level “0” is output to the signal line 20 a so as not to send the CML signal. At W 8 a signal of level “0” is output to the signal line 20 d so as not to send the ANSam signal.

At W 10 information is received from the signal line 222 a to check whether the reception is selected. If selected, the flow advances to W 14 , whereas if not, the flow advances to W 12 whereat another process is executed to thereafter return to W 6 .

At W 14 a signal of level “1” is output to the signal line 20 a to turn on the CML signal. At W 16 the timer T 1 is set to 35 seconds. At W 18 a CED signal is sent.

At W 20 it is checked whether the flag DISTRN is 0. If 0, the flow advances to W 22 , whereas if the flag is 1, the flow advances to W 24 .

At W 22 the NSF/CSI/DIS signal of V. 21 is sent. FIF of the DIS signal is 10 bytes.

At W 24 the NSF/CSI/DIS signal of V. 21 is sent. FIF of the DIS signal is 4 bytes.

At W 26 the timer T 4 is set to 3 seconds. At W 28 , W 30 , and W 32 it is checked whether the NSS/TSI/DCS signal of V. 21 is detected and it is checked whether the NSC/CIG/DTC of V. 21 is detected, until the timer T 4 becomes time-out. If the NSS/TSI/DCS signal of V. 21 is detected, the flow advances to W 48 , whereas if the NSC/CIG/DTC signal of V. 21 is detected, the flow advances to W 42 and if the timer T 4 becomes time-out, the flow advances to W 34 .

At W 34 it is checked whether the timer T 1 is time-out. If time-out, the flow advances to W 36 , whereas if not, the flow returns to W 20 .

At W 36 the value of the flag DISTRN is checked. If the value is 0, the flow advances to W 38 whereat the flag DISTRN is set to 1, whereas if the value is 1, the flow advances to W 40 whereat the flag DISTRN is set to 0.

At W 42 the remaining pre-procedure of V. 21 is executed, and at W 44 polling transmission of V. 27 ter, V. 29, and V. 17 is executed. At W 46 the post-procedure of V. 21 is executed to thereafter return to W 40 .

At W 48 the remaining pre-procedure of V. 21 is executed, and at W 50 image signal transmission of V. 27 ter, V. 29, and V. 17 is executed. If there is a mode change and if the flag DISTRN is 0, the NSF/CSI/DIS signal of V. 21 is sent with the DIS signal having 10 bytes of FIF, whereas if the flag DISTRN is 1, the NSF/CSI/DIS signal of V. 21 is sent with the DIS signal having 4 bytes of FIF. At W 52 , the post-procedure of V. 21 is executed to thereafter return to W 40 .

Tenth Embodiment

Next, the tenth embodiment of the invention will be described.

The tenth embodiment is a modification of the ninth embodiment. A DIS signal having 10 bytes of FIF is sent as the initial identification signal at the reception, and if a pre-procedure error occurs, a DIS signal having 4 bytes of FIF is sent as the initial identification signal during the period of 20 seconds after the error is detected.

FIGS. 34 and 35 are flow charts illustrating only a partial operation of the tenth embodiment, which is different from the ninth embodiment (FIGS. 30 to 33 ).

Referring to FIG. 34, W 60 corresponds to W 2 . At W 62 a transmission of a DIS signal having 4 bytes of FIF only at the reception during a period of 20 minutes thereafter is registered via the signal line 230 a into the registration circuit 230 to thereafter advance to W 64 whereat the flow returns to W 6 .

W 66 corresponds to W 12 . At W 68 it is checked whether the flag DISTRN is 1or not. If 1, the flow advances to W 70 , whereas if 0, the flow advances to W 74 (W 6 ).

At W 70 it is checked whether a DIS timer is time-out. If time-out, the flow advances to W 72 whereat the flag DISTRN is set to 0 to thereafter advance to W 74 (W 6 ), whereas if not time-out, the flow advances to W 74 (W 6 ).

W 76 corresponds to YES at W 34 . At W 78 the flag DISTRN is set to 1. Next, at W 80 the DIS timer is set to 20 minutes. Thereafter, the flow returns to W 6 .

At W 84 and W 86 , the flow from W 46 to W 6 is executed, and at W 88 and W 90 , the flow from W 52 to W 6 is executed. Namely, it means that the process of W 40 is not executed (0 is set to the flag DISTRN).

Eleventh Embodiment

Next, the eleventh embodiment of the invention will be described.

The eleventh embodiment is a combination of the ninth and tenth embodiments. A transmission of a DIS signal having 4 bytes of FIF is executed only for the next one reception or for the reception during 20 minutes after the DIS signal having 10 bytes of FIF is sent and a pre-procedure error occurs, is registered in the registration circuit 230 . In accordance with this registration information, reception control is performed.

FIG. 36 is a flow chart illustrating only a partial operation of the eleventh embodiment, which is different from the ninth and tenth embodiments (FIGS. 30 to 35 ).

Referring to FIG. 36, W 100 corresponds to W 12 . At W 102 information is received from the signal line 222 a to check whether the registration into the registration circuit 230 is selected. If selected, the flow advances to S 104 whereat a transmission of a DIS signal having 4 bytes of FIF is executed only for the next one reception or for the reception during 20 minutes after the DIS signal having 10 bytes of FIF is sent and a pre-procedure error occurs, is registered via the signal line 230 a into the registration circuit 230 . The flow then advances to W 108 (W 6 ). If the registration is not selected, the flow advances directly to W 106 (W 6 ).

W 108 corresponds to YES at W 10 . At W 110 information registered in the registration circuit 230 is received via the signal line 230 a . If a transmission of the DIS signal having 4 bytes of FIF only for the next one reception is registered, the flow advances to W 112 whereat the above-described control from W 14 to W 52 is executed to thereafter return to W 6 . If a transmission of the DIS signal having 4 bytes of FIF for the reception during a period of 20 minutes thereafter is registered, the flow advances to W 114 whereat the above-described control from W 66 to W 90 in place of the control from W 14 to W 52 is executed to thereafter return to W 6 .

The operation of the control circuit described above is executed by a CPU in the control circuit in accordance with a program stored in ROM, RAM or the like of the control circuit. The present invention may be reduced in practice by storing such a program in an external storage medium such as a floppy disk, a hard disk, a magnetooptical disk, and a CD-ROM, by reading the program with a dedicated reading apparatus and storing it in the memory of the control circuit, and by executing the program by CPU.

In the above embodiments, facsimile communication in conformity with ITU-T Recommendations V. 8 and V. 34 are described. The invention may also be applied to various other communication apparatuses which follow the communication protocol having a function similar to the above Recommendations.

Also in the above embodiments, a facsimile apparatus of a stand-alone type has been described by way of example. The invention is not limited only thereto, but is also applicable to data communication control of a synthetic data processing system with a communication function combined with a copy function, an electronic file function, and a data processing function. The invention can also be applied to a communication apparatus with separated reading and recording circuits.

As described so far, according to the fifth and sixth embodiments, in a facsimile apparatus having the functions of V. 8 and V. 34, it is possible to always send a DIS signal having 10 bytes of FIF, with a maximum performance of the V. 8 protocol and V. 34 protocol. If a DIS signal having 10 bytes of FIF of V. 21 is transmitted and there is no effective response, then a DIS signal having 4 bytes of FIF is sent so that reliable communication can be made although the performance lowers more or less.

According to the fifth to eleventh embodiments, even if a data communication apparatus communicates with an apparatus not compatible with an extended FIF of a DIS signal, communication can be made by using the maximum performance of the partner apparatus having the number of bytes of FIF of a DIS signal recommended at the design time of the partner apparatus.

According to the seventh embodiment, although the re-transmission interval of a DIS signal is different, 4.5 seconds for the manual mode and 3seconds for the automatic mode, the predetermined numbers D and E of times can be properly set so that reliable communication can be made.

According to the eighth embodiment, although one initial identification signal NSF/CSI/DIS has a period changing with a presence/absence of a CSI signal, the predetermined numbers D and E of times can be properly set so that reliable communication can be made.

According to the ninth to eleventh embodiments, even if a partner communication apparatus is not compatible with an extended FIF of a DIS signal, since a pre-procedure error occurs, reliable communication can be executed through re-dialing. High performance communication can be made with a partner communication apparatus having an extended FIF of a DIS signal.