JPH0620227B2 - Data communication device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a data communication device, and more particularly to a data communication device capable of performing electric transmission at a plurality of electric transmission rates.

2. Description of the Related Art A conventional data communication device, particularly a G3 (group 3) facsimile device defined by CCITT Recommendation T4, etc., has a so-called fallback function, that is, depending on a line state in a pre-transmission procedure or a transmission rate of a partner device. A method is known in which each rate is tried in order from the highest, and image transmission is performed at a rate at which both sides can transmit and receive.

Here, FIG. 1 shows a procedure of determining a transmission rate in a pre-transmission procedure of a conventional facsimile apparatus. However,
Here, a facsimile apparatus having a G3 function that conforms to CCITT Recommendation T4 will be described as an example.

FIG. 1 shows the exchange of signals between transmission and reception during the pre-transmission procedure of the conventional G3 facsimile apparatus. As shown in FIG. 1, the called side apparatus is a calling side (image transmitting side) call signal. CED signal (called station identification signal) 1, NS
An F signal (non-standard device signal) 2 and a DIS signal (digital identification signal) 3 are transmitted. However, the NSF signal 2 may optionally be accompanied by a CSI signal (reception station identification signal) 2'as shown in the figure. This CSI
The signal is used to confirm the identification of the receiving station by a telephone number or the like.

Both the NSF signal 2 and the DIS signal 3 are known HDL.
This is a binary signal having a C (high level transmission procedure) frame format, and the 11th and 12th bits of the FIF (facsimile information field) of the DIS signal 3 have the maximum transmission rate that the receiver can perform according to a predetermined format, for example, 9600bps. Is set.

Next, the transmitter sends out an NSS signal (non-standard device setting signal) 4 and a DCS signal (digital command signal) 5 corresponding to the NSF signal and the DIS signal, respectively. These also have the HDLC frame format, and the FIF of the DCS signal is similarly loaded with the maximum transmission rate on the transmitter side. Here, in the DIS signal 3 and the DCS signal 5, the data indicating 9600 bps is the 11th and 1st.
It shall be set to 2 bits. Also, NSS
The signal 4 may optionally be combined with a TSI signal (transmitting station identification signal) 4 '. This signal is C
Like the SI signal 2 ', it is used to confirm the identification of the transmitting station.

At this stage, it was mutually shown that both transmission and reception could transmit at 9600 bps.
Then, the training signal 6 is transmitted. The data rate of this signal is 9600bps, and it is used for adjustment of carrier detection, AGC (automatic gain adjustment), timing synchronization, equalizer convergence, and descrambler synchronization in the called side (image receiving side) modem. . Further, a TCF signal (training check signal) 7 for checking whether or not this speed channel can be used is added to this training signal 6.

The criterion for determining the speed channel on the receiving side is determined by the receiving state of the TCF signal 11 from the transmitting side device. TC
Since the F signal 11 is a continuous transmission of “0” (hereinafter referred to as “0”) having a level of 1.5 s, it is determined that the CFR signal is transmitted when the TCF signal can be received for a predetermined time or longer. There are many devices

If the receiving side device succeeds in the training, the receiving side device sends out a CFR signal (reception preparation confirmation signal) 8, and in response to this, the transmitting side sends a message (image signal) 10 to which the training signal 6 is added. Will be sent.

Although the above example is for a case where the transmission rate is determined by one training without fallback, the fallback operation as shown in FIG. 2 is performed when the line condition is bad.

FIG. 2 is a diagram of the same format as FIG. 1, and it is assumed that a rate of 9600 bps, for example, has been confirmed by both sides until the TCF signal 7 is sent from the transmitting side by the same procedure as in FIG.

When the receiving side device cannot receive the training signal at the above data rate due to the line condition or the like, the receiver sends the FTT signal (train failure signal) 10. This signal requests the sender to retrain.

In response to the FTT signal 8, the transmission side device again performs training consisting of the NSS signal 4 and the TCF signal 7. At this time, the rate set in the FIF of the DCS signal 5 and the data rate of the training signal 10 are Those lower than 9600bps, such as 7200bps, are selected.

When the receiving side device fails in this retraining, the FTT signal 10 is again sent from the receiving side device.

When the transmitting side device receives the FTT signal, it further reduces the transmission rate to, for example, 4800 bps, and the NSS signal 4 ...
A signal block consisting of the TCF signal 7 is transmitted.

If the receiving device succeeds in training at this rate, the aforementioned CFR signal 8 is sent out, and the transmitting device responds by sending the training signal 6 and the message 10 based on the final rate.

In the above-described pre-transmission procedure of the conventional facsimile apparatus, the transmission rate indicated by the DIS signal or the DCS signal should be unique according to the capability of the apparatus. Therefore, a device installed in a place where the line condition is not good will always try the rates that cannot be communicated in order, and then the rate will be determined. There is a drawback that is bad. In view of this point, there are known devices that can switch and set the fastest transmission rate, but if the maximum rate is lowered by such means, even if the line condition is good, communication can only be done at that rate. There is an inconvenience.

Therefore, it is conceivable to store the data rate used for the previous data transmission and start the current data transmission at the stored data rate. However, if an error occurs in the current data transmission, the data rate is lowered and the data is transmitted at a lower data rate than the previous one, so that the data rate used this time is stored as a lower data rate than the previous one. As a result, from the next time onward, data transmission will be started at a lower data rate than the one used this time. However, the error that occurred this time is a noise-type error that occurred accidentally, and normally, if communication at the data rate used last time is possible, from the next time onwards, the data rate will be lower than the normally usable data rate. Because data is transmitted,
There is a disadvantage that the efficiency of data transmission is lowered.

The present invention has been made in order to eliminate the above-mentioned conventional defects, and shortens the time required to transmit predetermined document information, and it is normally used due to an accidental noise-like error. For the purpose of preventing the transmission from being started in the transmission mode that takes longer than the possible transmission mode, specifically, the first transmission mode in which it takes a predetermined time to transmit the predetermined document information and the predetermined document information In a data communication device having a second transmission mode in which it takes longer than the predetermined time to transmit, storage means for storing history information, and communication means for starting transmission of document information in the transmission mode stored in the storage means When the storage means stores the first transmission mode, the communication means that has started communication in the first transmission mode loses a plurality of times in transmitting the document information. In response to being defeated, storing the second transmission mode in the storage means,
It is an object of the present invention to provide a data communication device characterized in that the communication means has a control means for setting the next transmission of original information to start in the second transmission mode.

Examples Hereinafter, details of the present invention will be described based on examples shown in the drawings.

In the following embodiments, a G3 facsimile transmitter conforming to CCITT recommendation T4 will be described as an example.

In the facsimile apparatus of the present invention, the transmission rate used up to that point is statistically analyzed, and the transmission rate to be used is determined based on the result.

FIG. 3 shows a facsimile transmitter adopting the present invention.
Control device 3 including a microcomputer
9 shows a circuit configuration around 9, and each block shown on the right side of the figure and a circuit (not shown) at the subsequent stage are configured in the same manner as the conventional one.

On the other hand, each circuit block shown on the left side of the drawing is a memory circuit, which is a random access memory or a control device 39.
It is composed of internal arithmetic registers and the like.

Reference numeral 31 denotes a transmission rate storage circuit, which is connected to the control device 39 by signal lines 31a and 31b. This transmission rate storage circuit 31 stores the transmission rate which this transmitter should first try. For example, in this case,
When the rate is 9600 bps, "3" is set to 7200 bps, "2" is set, when it is 4800 bps, "1" is set, and when it is 2400 bps, "0" is set.

Further, a count value storage circuit 32 is connected to the control device 39 via signal lines 32a and 32b, and the count value storage circuit 32 is actually transmitted by the transmitter at the transmission rate first tried by the transmitter. The data about how many times has been performed consecutively is stored.

The count value storage circuit 33 is a circuit similar to the count value storage circuit 32, but conversely stores therein data relating to how many times the first attempted transmission at the transmission rate has failed.

The training / TCF signal transmission circuit 34 on the right side of the drawing is
9600, 7200, in response to the pulses 50-53 respectively generated on the signal lines 34a-d by the controller 39.
The training signal and the TCF signal set at 4800 or 2400 bps are transmitted to the modem at the subsequent stage via an adder or the like.

The NSS, TSI, DCS signal transmission circuit 35 responds to the pulses 54-57 generated on the signal lines 35a-d by the control device 39, respectively, and sets the NSS set to 9600, 7200, 4800, or 2400bps. The TSI and DCS signals are sent to a subsequent modem via a adder or the like at a predetermined timing.

On the other hand, the NSF, CSI, DIS signal detection circuit 36 receives the NSF, CS signals transmitted from the receiving side at a predetermined timing.
It detects I and DIS signals and generates pulses according to the rates set for those signals. That is, the above signals are 9600, 7200, 4800,
Or 2400 bps, pulses 58 to 58 are sent to the control device 39 via the signal lines 36a to 36d, respectively.
61 is sent.

Further, the CFR signal detection circuit 37 is used by the CFR from the other side.
When the signal is detected, the pulse 62 is generated on the signal line 37a. Similarly, when the FTT signal detection circuit 38 detects the FTT signal from the other party, the pulse 6 is applied to the signal line 38a.
3 is generated.

As described above, the data rate and each signal on the receiving side are detected and reported to the control device 39.

The transmission rate control of the control device 39 is performed as follows. The control device 39 stores the transmission rate from the next when the image transmission is succeeded or failed three times consecutively by the certain transmission rate which the transmitter first tries stored in the count value storage circuit 32 or 33. Control each part to perform the pre-procedure for raising or lowering by one step.

That is, when image transmission is performed three times or more at the transmission rate that the transmitter first tried (that is, the rate specified by the data in the transmission rate storage circuit, hereinafter referred to as the initial test rate), In the pre-procedure of (1), the test is performed by performing fallback from the rate one higher than the transmission rate a in order. On the other hand, when the image transfer at the initial test rate a is not performed three times in a row, the procedure is started from the rate one lower than a. At this time, when the value of a is the maximum or minimum rate of the device and the rate cannot be further increased or decreased, the procedure is started at that rate.

Next, the above control will be described in detail with reference to FIGS. 4 (A) to (F).

4 (A) to 4 (F) are flowcharts for explaining the control procedure of the above-mentioned control device 39, and the portions having the same numbers in each drawing are to be connected there.

When the power of the device is turned on, the control device 39 controls the transmission rate storage circuit 31 to the count value storage circuit 32, 3 in steps S100 to S102 of FIG.
3 initialization is performed. That is, in step S100, the control device 39 first writes "3" indicating 9600 bps in the transmission rate storage circuit 31 via the signal line 31b.

Further, in steps S101 and S102, "0" is written to the count value storage circuit 32 and the count value storage circuit 33 through the signal lines 32b and 33b, respectively. By this, image transmission succeeded at the first test rate,
And the number of consecutive failures is reset.

Then, in the determination loop from step S103 to step S106, the following determination is made.

First, in step S103, it is determined whether or not the pulse 50 is generated on the signal line 36a to determine whether the received MSF, CSI, or DIS signal is set to 9600 bps.

Similarly, in step S104, by checking the state of the signal line 36b, the received NSF, CSI, or D
Determine if the IS signal is set to 7200 bps.

In step S105, the state of the signal line 36c is checked in the same manner, and the received NSF, CSI, or DIS signal is 48
Determine whether it is set to 00bps.

In step S106, the state of the signal line 36d is checked in the same manner, and the received NSF, CSI, or DIS signal is 24
Determine whether it is set to 00bps.

The above determination loop is repeated in order until one of the rates is detected, but when the rate is detected in the above steps, the respective steps are shifted to the following steps.

If the transmission rate on the receiving side is 9600 bps, go to step S107. If it is 7200 bps, go to step S1.
91 (FIG. 4 (F)), step 4195 bps to step S195 (FIG. 4 (F)), and 2400 bps to step S199 (FIG. 4 (F)). To do.

NSF, CSI, or DIS signal on the receiving side is 9600 bps
In step S107, the control device 39 controls the signal on the signal line 31a, that is, the transmission rate storage circuit 31.
The output of the data indicating the initial test rate stored therein is input, and then the signal is discriminated by the discrimination routine of steps S108 to S110.

First, in step S108, the signal input from the signal line 31a is "3", that is, the initial test rate is 9600.
bps, whether the input signal is “2” in step S109, that is, whether the initial test rate is 7200 bps, and whether the input signal is “1” in step S110,
That is, it is determined whether or not the initial test rate is 4800 bps.

If any of the above steps S108 to S110 is affirmed, step S122 (FIG. 4 (B)), step S151 (FIG. 4 (D)) or step S171 (FIG. 4 (E)), respectively. ). If all the above steps are denied, it is determined that the initial test rate is 2400 bps, and step S11 is performed.
Move to 1. Here, according to the procedure described in detail later, “0”, that is, the initial test rate is stored in the transmission rate storage circuit 31.
Assuming that the data indicating 2400 bps has been stored, the process proceeds to step S111 to continue the description.

In step S111, the pulse 57 is output to the signal line 35d, and the NSS, TSI, and DCS signal transmission circuit 35 outputs 24 pulses.
The NSS, TSI, or DCS signal set to 00 bps is sent to the other party via the line.

In addition, subsequently, in step S112, the signal line 34d
A pulse 53 is output to the TCF and the training signal set to the transmission rate of 2400 bps and transmitted to the other party.

When the above training is completed, step S113-
In the determination loop of S114, the CFR signal or the FTT signal from the other party is waited for.

First, in step S113, it is checked whether or not the pulse 63 is generated from the CFR signal detection circuit 37 to the signal line 37a in order to check whether or not the CFR signal from the other party is detected.

If the CFR signal is received, the process proceeds to step S117, and if not, the signal line 38 is sent in step S114.
Check if a pulse 63 is generated in a and
Check if a TT signal was sent. Step S11
When 4 is denied, the process returns to step S113 and repeats the above determination, but when the FTT signal is received, that is, when step S114 is affirmed, the process proceeds to step S115 and the count value is stored via the signal line 32b. Circuit 32
After writing "0" in step S116, the process ends in error in step S116, and the process returns to step S103 to prepare for the next communication. This is because the training at the minimum rate of 2400bps of this device failed.

When the states when step S117 is reached are sorted out in the above order, the initial test rate of the other party is 9600 bps, and the initial test rate shown by the data in the transmission rate storage circuit 31 of this side is 2400 bps. With this, training was successful in one time, that is, image transmission can be performed at the first tried rate of 2400 bps.

Therefore, in step S117, the signal line 33b is
“0” is written in the count value storage circuit 33 via.
That is, the number of consecutive times when image transfer cannot be performed at the initial test rate is reset to zero.

Subsequently, in steps S118 to S120, the count value storage circuit 32 indicating the number of consecutive image transmissions at the initial test rate is incremented, and the initial test rate for the next communication is transmitted according to the contents of the count value storage circuit 32. Write to the memory circuit 31.

First, in step S118, the signal on the signal line 32a is input, and the number of times of continuous image transmission at the initial test rate in the count value storage circuit 32 is extracted.

Subsequently, in step S118a, it is checked whether or not the taken out signal is "2", that is, whether or not the number of times of continuous image transmission at the first test rate has already reached 2.

If the result in step S118a is negative, the number K of consecutive image transmissions at the first test rate including the current transmission is less than 3. Therefore, the process proceeds to step S119, and 1 is added to the input signal, and then in step S120. The value is written in the count value storage circuit 32.

If step S118a is affirmed, the number K of consecutive image transmissions at the initial test rate is performed three times in succession this time, so the next initial test rate is increased by 1 to 4800 bps. , Step S118
b, the transmission rate storage circuit 3 via the signal line 31b
Write "1" in 1.

Then, in step S118c, "0" is written in the count value storage circuit 32 via the signal line 32b in order to start a new count.

When the above counter control is completed, the process proceeds to step S121, where the control device 39 controls each part by a known procedure to perform image transmission at a transmission rate of 2400 bps,
The process returns to step S103 to prepare for the next communication.

On the other hand, in step S103, the transmission rate of the other party is
At 9600 bps, the initial test rate on this side indicated by the transmission rate storage circuit 31 in step S108 is also set.
If it is 9600 bps, the process proceeds to step S122.

In steps S122 to S123 of FIG. 4B, the pulse 54 is generated on the signal line 35a and the pulse 50 is generated on the signal line 34a. This enables NSS, TSI, or DCS at 9600 bps in the same manner as above.
The signal, the TCF signal, and the training signal are sent to the line, and training is performed at 9600 bps.

Subsequently, in the determination loop of steps S124 and S127, the training result is determined by detecting the CFR signal or the FTT signal. This operation is performed by checking the states of the signal lines 37a and 38a, as described above.

When the CFR signal is received in step S124, the process proceeds to step S125, and after writing “0” indicating the number of continuous image non-transmissions at the first test rate to the count value storage circuit 33 through the signal line 33b, Then, the process proceeds to step S126, the image is transmitted at 9600 bps, and then the process returns to step S103 to prepare for the next communication. Here, the reason why the count value storage circuit 32 is not incremented is that the next initial test rate shown by the contents of the transmission rate storage circuit 31 is 9600 bps and cannot be further increased.

On the other hand, when the FTT signal is received in step S127, the process proceeds to step S128, and "0" indicating the number K0 of continuous image transmissions at the initial test rate is written in the count value storage circuit 32 via the signal line 32b. This is because the image transfer cannot be performed at the first test rate this time, so that the number of continuous image transfer at the first test rate is counted again from the next communication.

If you reach here, the first training at 9600bps has already failed, so in the following steps
The training is performed again by falling back to a rate of 7200 bps or less, but prior to that, the contents of the transmission rate storage circuit 31 and the count value storage circuit 33 are controlled as follows.

First, in step S129, the contents of the count value storage circuit 33 are input via the signal line 33a, and then step S1
At 30, it is determined whether the signal is "2", that is, whether the number of continuous image non-transmissions at the initial test rate has already become 2.

If the result at step S130 is affirmative, the number of continuous image non-electrical transmissions at the initial test rate is 3 this time, so the initial communication test rate for the next communication is decreased by 1 to 7200bp.
In order to set s, in step S131, “2” indicating 7200 bps is written to the transmission rate storage circuit 31 via the signal line 31b, and subsequently in step S132, “0” is written to the count value storage circuit 33 via the signal line 33b. Write. This is because the number of times of continuous image non-transmission at the first test rate is newly counted from the next communication.

On the other hand, if it is determined in step S130 that the number of times of continuous image non-transfer by the first test slate is not 2, the count value storage circuit 3 is set in steps S133 and S134.
The contents of the count value storage circuit 33 are incremented by 1 via the signal line 33b in the same manner as in the case of the increment of 2.

When the control of the count value storage circuit 33 and the transmission rate storage circuit 31 is completed, steps S135 and S13 are performed.
In the routine of No. 6, the pulse 55 and the pulse 51 are sequentially given to the NSS, TSI, DCS signal sending circuit 35 and the training, TCF signal sending circuit 34, and retraining at 7200 bps is performed.

Then, in steps S137 and S139, it is determined whether the signal from the other party is the CFR signal or the FTT signal in the same manner as in steps S124 and S127.

When the CFR signal is received in step S137, the process proceeds to step S138, image transmission is performed at 7200 bps by a known procedure, and then the process returns to step S103 to prepare for the next communication. As described above, the count value storage circuit 32 or the count value storage circuit 33 is operated depending on whether image transmission at the first test rate is continuously performed or not continuously. Therefore, the fallback operation below this is performed. Does not control the count value storage circuit 32 or the count value storage circuit 33.

On the other hand, when the FTT signal is received in step S139, the process proceeds to steps S140 to S141, pulse 56 and pulse 52 are sequentially generated on the signal lines 35c and 34c, respectively, and fallback to 4800 bps is performed for training again. After that, the process shifts to the determination loop of steps S142 and S144 of FIG. 4C, and waits for a CFR or FTT signal from the other party.

When the CFR signal is received in step S142, the process proceeds to step S143 in the same manner as described above, the image transmission is performed at 4800 bps, and then the process returns to step S103.
Prepare for the next communication.

Alternatively, when the FTT signal is received in step S144, the process proceeds to the routine of steps S145 and S146,
Similarly to the above, pulse 5 is applied to the signal lines 35d and 34d, respectively.
7 and pulse 53 are sequentially generated, fall back to 2400 bps, and train again.

Further, thereafter, in the determination loop of steps S147 and S149, the CFR or FTT signal is waited for in the same manner as described above, and if the CFR signal is received here, step S is performed.
After transmitting the image at 2400 bps at 148, the process returns to step S103. On the other hand, when the FTT signal is received, further fallback cannot be performed, and the line is disconnected as a pre-procedure error, and the process returns to step S103 to prepare for the next communication.

On the other hand, in step S103, the transmission rate of the other party is
At 9600 bps, the initial test rate on this side indicated by the transmission rate storage circuit 31 in step S109 is
If it is 7200 bps, step S in FIG. 4 (D)
The process moves to 151.

In the routine of steps S151 and S152 of FIG. 4D, the pulse 55 and the pulse 51 are sequentially generated on the signal lines 35b and 34b, respectively, and the training at 7200 bps is performed in the same manner as described above.

Then, in the determination routine of steps S153 and S163, the CFR or FTT from the other party is performed in the same manner as described above.
Wait for the signal. If the CFR signal is received, step S
If the FTT signal is received, the process proceeds to step S164.

If the CFR signal is received here, image transmission can be performed at the initial test rate, and therefore, step S154 to
In S158, the count value storage circuit 32 similar to that described above is used.
Then, the transmission rate storage circuit 31 is operated.

That is, in step S154, the count value storage circuit 33
After clearing, the data of the count value storage circuit 32 is input in step S155, and it is checked in step S156 whether it is "2". If it is the third consecutive transmission, the value "3" is written in the transmission rate storage circuit 31 in order to step up the next initial test rate to 9600 bps in step S157, and then step S15.
At 8, the count value storage circuit 32 is cleared.

On the other hand, if the data in the count value storage circuit 32 is not 2 in step S156, steps S160 and S160 are performed.
At 161, the content of the count value storage circuit 32 is incremented by 1.

The routine of steps S154 to S161 is equivalent to the routine of steps S117 to S120 except that "3" indicating 9600 bps is written in the transmission rate storage circuit 31 in step S157 for determining the next initial test rate. is there. Therefore, the above equivalent routine may be a subroutine which is called after setting the parameters relating to the initial test rate set in the transmission rate storage circuit 31.

When the above operation is completed, the process proceeds to step S159.
After performing image transmission at 7200 bps, step S103
Return to.

When the FTT signal is received in step S163, the first image transfer at the initial test rate cannot be performed, so
Moving to the routine consisting of steps S164 to S170,
The transmission rate storage circuit 31 and the count value storage circuit 33 are operated in the same manner as described above. Step S164 above
The routines of to S170 are also equivalent to the routine of steps S128 to S134 except that "1" indicating 4800 bps is written in the transmission rate storage circuit 31 in step S167 for determining the next initial test rate. For the operation of a part, refer to that part. Therefore, the above equivalent routine can be made into a subroutine.

When the above-described operation of the transmission rate storage circuit 31 and the count value storage circuit 33 is completed, the routine proceeds to step S140 and the subsequent steps in FIG. 4B, and the training and the image transmission are performed by sequentially falling back from 4800 bps. .

Further, in step S110, "1" indicating 4800 bps
Is stored in the transmission rate storage circuit 31, the process proceeds to step S171 in FIG. 4 (E).

Steps S171 to S190 of FIG. 4 (E) are equivalent to steps S151 to S170 of FIG. 4 (D), and each step of both FIG. 4 constitutes an equivalent routine. To do. Therefore, although detailed description is omitted, these routines can be made into subroutines like the above-mentioned routines.

The difference is 4800bp in steps S171 to S172.
The NSS, TSI, and DIS signals of s, the training signal, and the TCF signal are transmitted, and “2” indicating 7200 bps is transmitted in step S177.
Writing into the transmission rate storage circuit 31, "0" indicating 2400 bps in step S187,
The four points are that the image transmission in step S179 is performed at 4800 bps.

Here, basically, when the training at 4800 bps is successful, the count value storage circuit 33 is cleared and then the state of the count value storage circuit 32 is checked. If it is 2, 7200 bps is sent to the transmission rate storage circuit 31. Write "2" shown, and if not 2, count value storage circuit 3
2 is incremented by 1 and image transmission is performed at 4800 bps.

If the training of 4800 bps fails, the count value storage circuit 32 is cleared and the state of the count value storage circuit 33 is checked. If it is 2, "0" indicating 2400 bps in the transmission rate storage circuit 31. Write 2
If not, the count value storage circuit 32 is incremented by 1 and then the process proceeds to step S145 in FIG.
Fall back to 00bps.

In the above, all the routines that can be fallen from and passed when the transmission rate that the other party has stated is 9600 bps have been described. Steps S104 to S in FIG. 4 (A)
At 106, if the other side has specified any of the rates of 7200 bps or less, the process proceeds to the routine shown in FIG. 4 (F), and from there, jumps to a predetermined position in the routine described above. Fallback and rate statistical control are provided.

First, step S104 is affirmed. That is, when the other party specifies 7200 bps, the process proceeds to step S191 of FIG. 4 (F). In step S191, the signal line 31
Data in the transmission rate storage circuit 31 is input via a, and the data is designated as "3", "2", or "1" in the following steps S192 to S194, that is, is designated by the transmission rate storage circuit 31. Determine whether the initial test rate on this side is 9600, 7200, or 4800bps.

If the result at step S192 is affirmative, the process proceeds to step S135 in FIG. 4B, and the training is performed by falling back from 7200 bps. In this case, the initial test rate is determined by the maximum rate of the partner machine. Therefore, only in this case, the transmission rate storage circuit 31 and the count value storage circuit 32
The count value storage circuit 33 is not operated and the statistical data is frozen.

If step S193 is affirmed, it is possible to fall back from 7200 bps, so step S1 in FIG. 4 (D).
It shifts to 51 and starts fallback from 7200 bps.

If the result at step S194 is affirmative, the process proceeds to step S171 in FIG. 4 (E) to fall back from 4800 bps.

If the above steps are denied, the initial test rate specified in the transmission rate storage circuit 31 is 2400.
Since it is bps, the process proceeds to step S111 in FIG. 4 (A), and training is performed at 2400 bps.

On the other hand, step S105 of FIG. 4 (A) is positive,
That is, when the partner machine specifies 4800 bps, the process proceeds to step S195. Steps S195 to S198 are the same as steps S191 to S194 described above, and the same determination as described above is performed here.

If steps S196 and S197 are affirmed, communication is possible only at 4800 bps or less in any case. Therefore, the process proceeds to step S140 in FIG. 4 (B) to fall back from 4800 bps. Also in this case, the statistical data is frozen.

If step S198 is affirmed, it is possible to fall back from 4800 bps, so the process proceeds to FIG.
Fall back from bps.

If steps S196 to S198 are denied, the process proceeds to step S111 in FIG. 4 (A), and training is performed at 2400 bps.

Further, step S106 of FIG. 4 (A) is affirmed,
That is, if the partner machine specifies 2400 bps, the process proceeds to step S199, and the same determination as described above is performed in steps S199 to S202. Here, the transmission rate storage circuit 3
Even if the content of 1 indicates 9600 to 4800 bps, the communication is possible only at 2400 bps, so if any of steps S200 to S202 is affirmed, step S1 of FIG.
Move to 45 and train at 2400 bps. Also in this case, the statistical data is frozen.

If the transmission rate storage circuit 31 indicates 2400 bps, the process proceeds to step S111 in FIG. 4 (A) and training is performed at 2400 bps.

As described above, since the number of transmissions at the transmission rate that was tried first is statistically analyzed and training is started from a suitable rate, training should be performed at a rate suitable for the line condition of the place where the device is installed. It can be started and the time required for the pre-transmission procedure can be shortened.

In the above embodiment, the number of continuous transmissions or the number of continuous non-transmissions at the initial test rate for changing the initial test rate is set to three, but other numbers may be used.
Further, the statistical analysis method is not limited to the above, and various methods such as an average fallback number or the maximum use rate may be considered.

Further, the present invention can be applied to a receiving side device and the like. Even if the training is not started from the statistically determined rate as described above, but the rate is specified in the initial identification signal or the like, the same effect can be obtained. Can be obtained.

Further, the above embodiment is a facsimile machine, but it goes without saying that the present invention can be applied to other data communication apparatuses.

As is apparent from the above description, according to the present invention, the history information is stored in the storage means, the transmission of the original document information this time is started in the transmission mode stored in the storage means, and the storage means is stored. When the first transmission mode is stored, the second transmission mode is stored in the storage unit in response to the fact that the communication unit that has started communication in the first transmission mode has failed to transmit the document information a plurality of times. Then, the communication means is caused to start the transmission of the next document information in the second transmission mode. Therefore, even if the error that has occurred this time is an accidental noise-type error,
The transmission mode stored in the storage means is not changed from the first transmission mode to the second transmission mode until the transmission of the image information fails a plurality of times, and the first transmission mode is usually the first transmission mode due to an accidental noise-like error. It is possible to prevent the next transmission of the document information from being started in the second transmission mode which requires a longer transmission time than the first transmission mode, although the document information can be transmitted in the second transmission mode. it can.

[Brief description of drawings]

1 and 2 are explanatory views showing a procedure of determining a transmission rate in a conventional facsimile apparatus, FIG. 3 is a block diagram showing a configuration of a facsimile apparatus adopting the present invention, and FIGS. 4 (A) to 4 (F). 4) is a flow chart for explaining the operation of the apparatus of FIG. 31 ... Transmission rate storage circuit 32 ... Count value storage circuit 33 ... Count value storage circuit 39 ... Control device

Claims (3)

[Claims] 1. A data communication apparatus having a first transmission mode in which a predetermined time is required for transmission of predetermined document information and a second transmission mode in which a time longer than the predetermined time is required for transmission of the predetermined document information. Storage means for storing information; communication means for starting transmission of document information in the transmission mode stored in the storage means; and the first transmission mode stored in the storage means for storing the first information. The communication means, which has started communication in the transmission mode of (1), stores the second transmission mode in the storage means in response to the failure to transmit the document information a plurality of times,
A data communication device, comprising: the communication means, and a control means for setting the next transmission of document information to start in the second transmission mode. 2. The data communication device according to claim 1, wherein the first transmission mode has a higher transmission speed than the second transmission mode. 3. The data communication device according to claim 1 or 2, wherein when the storage means stores the second transmission mode, the control means controls the second transmission mode. Even if the communication means that has started communication in step 2 fails to transmit the document information, the communication mode does not change the transmission mode of the storage means, and the communication means transmits the next document information by the second transmission.
The data communication device, wherein the data communication device is set to start in the transmission mode of.