JPH02243033A - Data terminal equipment for isdn - Google Patents

Abstract

PURPOSE:To decrease waste of communication operation by providing a reception error discrimination means to an ISDN terminal equipment and executing call interruption when a data error number reaches a prescribed number of times or over. CONSTITUTION:A facsimile equipment shown in figure connects to an ISDN via an ISDN interface section 6d. A caller side sends a call setting message by an LAPD through a D-channel at first in the case of transmission and receives a reply message by an LAPB from the called party and then the call connection is finished. Then the information transmission through a B channel is started. That is, the caller side sends an asynchronous parallel setting mode command (SABM), receives a confirmation response (UA) from the called party and sends the information. In this case, a fault data frame is counted while the called party receives the SABM and the caller is in the reception standby and after the frames are received by a preset prescribed number of times Ne, a call interruption protocol is executed immediately from the D-channel.

Description

[Detailed Description of the Invention] [Industrial Field of Application]
5 services Digital Netzork
) data terminal equipment.

[Conventional technology] In recent years, construction of ISDN has been progressing in various countries.
In Japan, commercialization of circuit switching services using a basic user/network interface began in April 1988.

For example, when a G4 facsimile machine communicates using this I5DN, the calling party sends a call setup message rsETUPJ using the D channel to make a call, and receives a response message rcONNJ from the called party. This completes the call connection and the B channel becomes available.

After this, using this B channel, CCITT Recommendation x
, 25 is executed.

In this case, the calling side first sends the asynchronous concurrent mode setting command rsABMJ or rsABM[EJ,
The called party receives the command and sends an acknowledgment response r.
Return UAJ.

By the way, in l5DN, if the line condition is very bad, as shown in Figure 6, the frame data such as the asynchronous parallel mode setting command rsABMJ sent by the transmitting side will be in error, and the receiving side will not be able to receive the frame correctly. When it disappears and burst noise X occurs frequently,
The noise X may be detected as a data frame.

In order to cope with such a communication failure state, the receiving side generally issues a disconnection command "DISC" if the asynchronous parallel mode setting command "SABMJ etc." is not detected for a certain period of time.
is sent to stop the communication. In addition, in the above recommendation, the sender:

If the confirmation response rUAJ is not received, as shown in the figure, it is specified that the asynchronous parallel mode setting command rsABMJ is retransmitted a maximum of eight times every fixed time t□. In this case, after a certain period of time t has elapsed, 1
Communication is now stopped, and from the sending of the first asynchronous parallel mode setting command rSABMJ, the disconnection command rD
It takes about 1 minute to send out IscJ.

If this disconnection command rDIscJ is sent, then D
send a disconnection message rDISC on the channel,
A release message rRELJ is received from the other party, and then a release completion message rREL COMPJ is sent to disconnect the call connection.

On the other hand, assume that the above-mentioned asynchronous parallel mode setting command rsABMJ and confirmation response rUA are successfully exchanged between the calling side and the called side through retransmission processing, and data transmission is started. However, in this case as well, if the above noise is received on the receiving side during data transmission,
Normal data transmission will no longer be possible, and communication will be interrupted midway.

[Problems to be Solved by the Invention] By the way, in the case of ISDN, communication charges are charged from the time a call connection is completed on the D channel. For this reason, conventionally, when the line condition is very bad as described above, even though communication is impossible, it takes time for the communication to be stopped, so one communication operation is wasted.
There was a problem of wasting communication charges.

SUMMARY OF THE INVENTION An object of the present invention is to provide a TSDN data terminal device that can improve the above problems, reduce wasteful communication operations, and save communication charges.

[Means for Solving Problems 91] To this end, the present invention, after starting a transmission control procedure using an information channel, determines a data error in a signal received from the information channel, and performs the first transmission control procedure in the transmission control procedure. If a predetermined procedure signal is not received and data errors in the received signal exceed a preset number of times, a call disconnection procedure is immediately executed using a signal channel. There is.

[Effect] If the line condition is very poor, the first procedure signals such as the asynchronous parallel mode setting command rsABMJ and confirmation response rLIAJ will not be transmitted correctly to the other party, and data errors may occur on the receiving side due to the generation of noise. occurs frequently. In this case, if the data error occurs more than a certain number of times, the call is immediately disconnected, so that it is possible to reduce wasteful communication operations and save on communication charges.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a block diagram of a facsimile apparatus according to an embodiment of the present invention. In the figure, a system control section 1 controls a device composed of a microcomputer system. The scanner 2 reads the original image and extracts image information, and the plotter 3 records the image information on recording paper. The encoding/decoding unit 4 performs encoding for data compression of image information and decoding for returning to the original data. The operation display section 5 is
It is equipped with various displays and operation keys, and displays the device status and operation guidance, and allows the operator to perform various operations on the device.

The communication control section 6 transmits and receives various signals to and from ISDN according to a predetermined procedure, and the shared memory 7 temporarily stores transferred data. The system bus 8 includes a system control section 1, a scanner 2, a plotter 3, an encoding/decoding section 4,
It is connected to an operation display section 5, a shared memory 7, etc., and is used to transfer data between them. Further, data transfer between the system path 8 side and the communication control unit 6 is performed via the shared memory 7.

In the communication control section 6, the CPU 6a is for controlling communication, and the ROM 6b is for storing the control program. The frame buffer memory 6C temporarily stores transmission data in the data link layer,
This is for data transmission using predetermined flow control.

The 15DN interface unit 6d has a layer 1 function as a user/network interface, and is connected to the network termination bag HINT through an interface defined as the S/7 point to input and output signals. be. The LAPD controller 6e has layer 2 and layer 3 functions, and supports LAP (Link Access Proto) on the D channel.
col). The LAPB controller 6f executes LAP on the B channel and transmits image information according to a predetermined procedure.

The local bus 6g is for data transfer between each section within the communication control section 6.

With the above configuration, the communication procedure between the facsimile machines of this embodiment will be explained first.

The calling party first uses the D channel to send a call setup message rsV!, as shown in FIG. , TUPJ is sent. The called party receives this call setup message rsETUPJ via the l5DN and sends a response message rcONNJ.
Send out. The calling party sends a response message r C0NN
” is received, the call connection is completed.

After this, the transmission control procedure on the B channel is started. That is, as shown in FIG. 3, the calling side first receives the count value N2. N, is set to a preset constant value (process 101). This count value N2 is the limit number of times to retransmit the asynchronous parallel mode setting command rsABMJ, which is defined as a maximum of 8 times in CCITT Recommendation x, 25. Then, the asynchronous parallel mode setting command rsAB
Send MJ (process 102). Although rsABMEJ with a different modulo number in flow control may be used as the asynchronous parallel mode setting command, in this embodiment, it is assumed that "SABM J" is used as an example.

Next, a timer Ti specified in the above recommendation is started as a time to wait for the confirmation response rUAJ from the first called party (process 1o3). Then, the received data frame is monitored until the timer T□ times out (process 104, from N in process 104 to process 105, and from N in process 105 to process 104).

On the other hand, as shown in FIG. 4, the first called party first sets the count value N to a preset constant value (process 201), and also receives the asynchronous parallel mode setting command rSABM J from the calling party. A timer T0 is started as a time to wait for (processing 202), and.

Monitor five received data frames until the timer T times out (Process 203, from N in Process 203 to Process 204, from N in Process 204 to Process 203)
.

During this time, when a data frame is received (Y in process 203), it is determined whether the asynchronous parallel mode setting command rSABMJ has been normally received (process 205).

Now 5 Asynchronous parallel mode setting command rs from the calling side
Assume that the ABMJ data frame is received without error. In this case, the normal asynchronous concurrent mode setting command r
sABM” (Y in process 205),
A confirmation response rUAJ is sent (process 206).

On the other hand, when the calling side receives some data frame (Y in process 104 in FIG. 3), the data frame is
It is determined whether the confirmation response rUAJ has been received normally (process 106).

Assume now that the confirmation response rUAJ from the called side is transmitted to the calling side without error. In this case, the process 106 is performed to determine whether the confirmation response rUAJ is normal.
(Y), the timer T□ is stopped (process 107). After this, the calling side and the called side sequentially execute the predetermined transmission control procedure of each layer starting from the network layer to transmit the image information. .

By the way, as described above, if the ISDN line condition is very poor, the transmitted frame data may have an error, making it impossible for the other party to receive it correctly, and also causing noise to be detected as a data frame.

Suppose now that such a situation occurs, and the called side cannot correctly receive the asynchronous parallel mode setting command rsABMJ, and also detects a large number of noises as data frames.

In this case, the called side determines whether the received data frame is abnormal (N in process 205 in FIG. 4), subtracts the count value N by 1 (process 207), and determines the value (process
8). Here, if the count value N is not II O'1 (N in process 208), the process returns to monitoring the received data frame (proceeds to process 203).

In this case, each time a noise data frame is received, the count value N is decremented by 1.

As a result of this operation, when the count value N reaches #j 071 (Y in process 208), the timer T6 is stopped (process 2
09), the communication on the B channel is stopped and a call disconnection procedure is executed. That is, first, the called side sends a disconnection message rDIscJ to the calling side via the D channel, as shown in FIG. Also, in this case, the disconnection message r
Predetermined information indicating that the B channel is abnormal and that a re-call is requested is set in the user-to-user information of DIscJ and sent.

The calling side receives the above-mentioned disconnection message rDIscJ through the interrupt process (Y in process 108 in FIG. 3), and sends a release message rRELJ through the D channel.

In response, the called party sends a release completion message “REL
Send COMPJ. In this way, the call disconnection procedure is executed between the two parties (process 109 in FIG. 3 and process 210 in FIG. 4).

If the calling party has set the B channel abnormality and re-call request information in the user-to-user information of the disconnection message rDIsc as described above, the calling party will wait for a certain period of time, for example 3 minutes, after partially disconnecting. later.

As shown in FIG. 5, the call setup message rsETUPJ
and re-call in the same manner as above. in general.

Since the line condition is restored when the call is made again, in many cases, image information can be correctly transmitted by making the call again.

Next, assume that the ISDN line condition has become so bad that the calling side cannot correctly receive the confirmation response "UAJ" from the called side, and there is a lot of noise detected as data frames.

When the calling side determines that such an abnormal frame has been received (N in process 106 in FIG. 3), it subtracts 1 from the count value N (process 110) and checks the value (process 111).
). Then, if the count value N is not #j 071, the received frame is further monitored (proceed to process 104)
.

In this case, each time a noise data frame is received, the count value N is decremented by 1.

Here, if this count value N becomes 71071 (Y in process 111), contrary to the case in FIG. Execute (process 109).

Further, the called side receives the disconnection message rDIscJ by interrupt processing (Y in process 211), and executes the corresponding call disconnection procedure (process 210).

After partially disconnecting in this way, the calling party calls again as in the case of FIG.

Also, if the calling side does not receive the confirmation response rUAJ and the timer times out, 105
Y), the count value N is decremented by 1 (processing 112), and the value is checked (processing 113).Here, if the count value N2 is not 20'' (N of processing 113), the asynchronous parallel mode is selected. The setting command rsABMJ is sent again (processing 102).

As a result, if the confirmation response rUAJ is not received, the asynchronous parallel mode setting command rs is sent every - stagnation time.
ABMJ will be retransmitted. Then, the retransmission is repeated the number of times of the count value N2, and when the count value N2 becomes "0" (Y in process 113), the disconnection message rDIscJ is sent out and the call is disconnected ( Processing 109).

Also, on the first called side, the asynchronous parallel mode setting command rsABMJ is not received, and timer T is activated. has timed out (Y in process 204 in FIG. 4), sends a disconnection message rDIscJ to the calling party and disconnects the call (
Process 210).

As described above, in this embodiment, after starting the transmission control procedure on the B channel, the called side is waiting to receive the asynchronous parallel mode setting command rsABMj.

The calling party responds with the confirmation response “Waiting to receive υAノ.

Immediately after each abnormal data frame is received the number of times corresponding to the count value N,
I am trying to perform call disconnection procedures.

When the ISDN line condition is very poor, abnormal data frames occur frequently, so the above operation allows communication to be stopped within a short time after communication starts, reducing the waste of one communication operation. You will be able to save on communication charges.

In one or more of the embodiments, there may be a case where the line condition does not improve even though the calling party makes a call again, and communication is interrupted again in the same way. In consideration of such a case, the number of re-calls may be limited to a certain number of times. To this end, one called party may send a disconnection message rD.
When sending IscJ, if it has already been re-called a certain number of times, information requesting re-call may not be set in the user-user information.

In addition, although the above embodiments have been explained using a facsimile machine as an example, the present invention can be similarly applied to various data terminal devices that are used in 15DN and execute specific transmission control on the B channel after call connection. Of course it can be done.

[Effects of the Invention] As described above, according to the present invention, if the number of data errors in the received signal exceeds a certain number of times after transmission control is started via the information channel, the call is immediately disconnected. If the line condition is poor, communication will be stopped in a short time, reducing wasteful communication operations and saving communication charges.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a G4 facsimile machine according to an embodiment of the present invention, FIG. 2 is a sequence diagram showing a normal transmission control procedure, and FIG. 3 is a diagram showing transmission control on the calling side on the B channel. FIG. 4 is an operation flowchart showing part of the transmission control on the called side in the B channel, FIG. 5 is a sequence diagram showing an example of the transmission control procedure when the line condition is poor, and FIG. 6 1 is a sequence diagram showing an example of a conventional transmission control procedure when a line condition is poor; FIG. 1... System control unit, 2... Scanner, 3...
Plotter, 4... Encoding/decoding section, 5... Operation display section, 6... Communication control section, 6a-CPU, 6b-RO
M, 6cm frame buffer memory, 6d...l5D
N interface engineering section, 6e... LAPD controller, 6f... LAPB controller, 6g... local bus, 8... system bus. -GSa+zu parable)l Fig. 2 1 Ginbin j Fig. 4 Fig. 5 Fig. 6 〆j

Claims (1)

[Claims] In an ISDN data terminal device that executes a call connection procedure using an ISDN signal channel and then executes a specific transmission control procedure using an information channel to transmit data, after starting the transmission control procedure using the information channel, reception error determination means for determining a data error in a signal received from the information channel; ISDN data terminal equipment, characterized in that it is equipped with a communication canceling means for immediately executing a call disconnection procedure using a signal channel when the number of calls exceeds the number of times.