JPH04373255A - Isdn terminal equipment - Google Patents

Abstract

PURPOSE:To attain sure communication even when the terminal equipment is interconnected with a network with a different transmission speed by selecting other transmission speed when a prescribed data signal is not detected within a prescribed time, executing again the similar operation and executing the transmission protocol at a set transmission speed at that time when a prescribed data signal is detected. CONSTITUTION:When a facsimile equipment 201 does not receive a SABM frame regardless of lapse of a prescribed time, the speed is switched into, e.g. 56kbps operating state. Then a timer is started again and the reception of the SABM frame is monitored for a prescribed period Tb. When the facsimile equipment 201 reaches the operating state of 56kbps, since valid data of 7-bit in one octet is set and sent, a facsimile equipment 204 receives an HDLC frame correctly. Thus, the equipment 204 receives the flag signal to send the SABM frame. When the equipment 201 receives the frame, the equipment 201 implement a prescribed transmission control.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is an IS system suitable for data transmission by interconnecting with other networks having different transmission speeds.
It is related to a DN terminal device.

0002

2. Description of the Related Art ISDN is designed to be interconnected with other digital circuit networks in addition to ordinary telephone circuit networks, as required. This allows ISDN
terminal devices can communicate with terminal devices of other networks.

By the way, the transmission speed of ISDN basic service is 64 kbps. On the other hand, in addition to 64 kbps, other digital line networks include, for example, 56 kbps in the United States.

[0004] When ISDN is interconnected with, for example, a 56 kbps network and communicates between each terminal device,
The terminal equipment on the ISDN side is, for example, based on CCITT recommendation I.
．． In accordance with V.463 (V.110), it is necessary to perform speed matching processing for transmitted and received data.

[0005] Here, for example, an ISDN terminal device,
Consider the case where a call is received from a terminal in another network with a different transmission speed.

In this case, ISDN determines the transmission speed of interconnected networks and sends a call setup message "SE
When making a call by sending ``TUP,'' the transmission speed of the network on the originating terminal side can be set in the message. This results in
The destination terminal is able to perform predetermined communications by executing transmission and reception operations according to its transmission speed.

By the way, in ISDN, the exchange of control information between networks and stations is based on CCITT's NO. 7 common line signaling system.

[0008] Therefore, in order to determine the transmission speed of interconnected networks, ISDN needs to determine the transmission speed of the interconnected networks. 7 It is necessary to exchange control information using the common channel signaling method.

However, at present, the international IDSN
In the interconnection of NO. 7 common line signaling system is not adopted in many cases. For this reason, in many cases ISD
N cannot receive control information from the interconnected network and cannot notify the destination terminal of the transmission speed of the originating terminal.

[0010] In this case, since the destination terminal cannot determine the operating state of the transmission speed, it starts communication operation at the standard 64 kbps. That is, when the call setup is completed and the B channel communication link is formed, the transmission of the flag signal of the HDLC frame is started. However, since the predetermined rate matching process is not performed at this time, the originating terminal cannot detect the flag signal. As a result, neither the originating terminal nor the destination terminal was able to execute a predetermined transmission control procedure, and the communication operation was stopped as a communication error.

Next, consider a case where an ISDN terminal device makes a call to a terminal device of another network having a different transmission speed.

[0012] In this case, the originating terminal needs to perform the rate matching process according to the transmission rate of the destination terminal. Therefore, the operator of the calling terminal needs to perform a setting operation for speed matching processing on the device when making a call.

[0013] However, the operator may not know that such a setting operation is necessary and may proceed to make a call, or may not be able to make the setting because he or she does not know the transmission speed of the destination terminal.

[0014] If you continue to make a call, the terminal device will:
Communication operation is started at 64 kbps in the same manner as above. That is, when the call setup is completed and the B channel communication link is formed, the HDLC frame flag signal detection operation is started. However, since the predetermined speed matching process is not performed at this time, the flag signal cannot be detected. For this reason, a communication error occurs and the communication is canceled in the same way as above.

Furthermore, if the transmission rate could not be set, it was also impossible to make a call.

[0016]

[Problem to be solved by the invention] In this way, conventionally,
When ISDN is interconnected with networks having different transmission speeds, there is a problem in that it often becomes impossible to carry out predetermined communications between terminals.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and provide an ISDN terminal device that can reliably communicate even when interconnected with networks having different transmission speeds.

[0018]

[Means for Solving the Problems] To this end, the present invention, when making a call, detects a specific data signal sent from the destination terminal by setting one transmission rate after making the call, If the data signal is not detected within that certain period of time, switch to another transmission speed and detect the above data signal again, and when that data signal is detected, execute the transmission procedure at the then set transmission speed. I try to do that.

[0019] Furthermore, when a call is received, after the call is received, one transmission rate is set, a specific data signal is sent out, another data signal from the calling terminal is detected, and the other data is transmitted. If no signal is detected, switch to another transmission speed, send a specific data signal, detect another data signal, and when the other data signal is detected, the transmission speed set at that time will be changed. I am trying to execute the transmission procedure with .

[0020]

[Operation] If a predetermined data signal is not detected, the transmission speed is switched and operated, so that data signals can be transmitted and received even if the transmission speeds of the destination terminals are different. This makes it possible to reliably communicate even when interconnecting networks with different transmission speeds.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments 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 a first embodiment of the present invention. In the figure, a facsimile image processing section 1 performs data compression of image information obtained by reading an original image, or restores received image information and records it on recording paper. The B channel communication control section 2 executes a predetermined G4 facsimile transmission control procedure on the B channel to transmit and receive image information.

The transmission speed switching section 3 is composed of a 64k/56k speed matching circuit 31 and a switching circuit 32, and is configured to switch the transmission speed between 64 kbps and 56 kbps. The D channel call control unit 4 executes a call setup procedure on the D channel. The ISDN interface unit 5 is connected to the ISDN via a network termination device (not shown), and
It transmits and receives signals to and from the SDN.

The operation display section 6 is used by the operator to perform various operations and to display the operating status of the apparatus. The control section 7 is a microcomputer that monitors and controls each of the above sections.

With the above configuration, next, as shown in FIG.
The facsimile device 201 of this embodiment has an ISDN 202
and a facsimile device 204 via a digital network 203.
We will explain the case of communicating with. At this time, the transmission speed of the user line in the digital network 203 is 56K.
bps, and the ISDN 202 and digital network 203 are NO. 7. They shall not be interconnected using the common line signaling method.

Now, to make a call, the operator sets the destination number and activates the calling operation of the facsimile machine 201, as in a normal facsimile machine.

When the facsimile machine is activated, it sends out a call setup message "SETUP" and makes a call, as shown in FIG. At this time, one information element "communication ability"
64 kbps" (processing 101).

As shown in FIG. 4, upon receiving the call setup message "SETUP", the ISDN 202 responds with a call setup acceptance message "CALL PROC" and interconnects with the digital network 203. As a result, the digital network 203 sends a predetermined incoming call signal to the facsimile machine 204 to call the facsimile machine 204. In response, facsimile machine 204 sends out a communicable signal. After confirming the response from the facsimile device 204, the ISDN 202 sends a response message “CONN” to the facsimile device 201. These call setup messages are sent and received on the D channel.

When the facsimile machine 201 receives the response message "CONN" and completes the call setup (processing 1
02 Y), the transmission speed switching unit 3 is in the through state, that is, 64
The operating state is set to kbps (processing 103). Next, a timer on the control program is started (process 10).
4) For a certain period of time Ta, a flag signal detection operation of the HDLC frame is performed on the B channel (process 105, from N in process 105 to process 106, and from N in process 106 to process 105).

After transmitting the communication enable signal, the facsimile device 204 starts transmitting the flag signal of the HDLC frame. In this case, the facsimile device 204 has 5
Sends a signal at 6kbps.

[0031] ISDN 202 and digital network 203 are:
In this case, CCITT Recommendation I. 463 (V.110)
Accordingly, data signal speed matching processing is performed. That is, as shown in FIG. 5, from the 56 kbps data signal received from the facsimile device 204, 7 bits are extracted and 1 bit "1" is added to reconstruct 1 octet of data. Then, this data signal is 64kbp
S is sent to the facsimile machine 201 side. Furthermore, from the 64 kbps data signal received from the facsimile machine 201 side, 7 bits of one octet in which valid data is set are extracted and sent to the facsimile machine 204 side at 56 kbps.

[0032] Currently, the facsimile machine 201 has a 64k
bps operation and reads all bits within one octet of received data, so the flag signal is not detected. If the flag signal is not detected in this way and a certain period of time Ta has elapsed (Y in process 106)
, 64/56k speed matching circuit 31 in the transmission speed switching section 3
The operation is enabled and switched to the 56 kbps operation state (process 107). Then, the timer is restarted (process 108), and the flag signal detection operation is performed for a certain period of time Ta (process 109, process 109) in the same manner as described above.
(from N in process 110 to process 110, and from N in process 110 to process 109).

[0033] The facsimile device 201 has a speed of 56 kbps.
When the operating state is reached, the 7 bits in one octet of received data, which are set to valid data, are read. This makes it possible to detect the flag signal sent from the facsimile machine 204.

When the facsimile machine 201 detects the flag signal (Y in process 109), it sends out the SABM frame. This frame is transmitted to facsimile device 204, which in turn sends the UA
Send a frame. This frame is transmitted to the facsimile machine 201 side, and the facsimile machines 201 and 20
4, a predetermined transmission control procedure is executed between them. As a result, image information is transmitted (process 111).

By the way, if the flag signal is not detected even after switching to the 56 kbps operating state (Y in process 110), a communication error is displayed (in process 11).
2) Stop communication.

On the other hand, if the call connection is not executed because the facsimile machine 204 is unable to communicate, etc. (processing 10
2N), cancel the calling operation.

Further, if the ISDN 202 is not interconnected with another digital network, or if the interconnected digital network is 64 kbps, the flag signal is detected in the 64 kbps operating state. In this case (processing 1
05 Y), the image information is immediately transmitted according to a predetermined transmission control procedure (proceed to process 111).

Next, a case where the facsimile machine 201 receives a call will be explained.

When making a call, the facsimile machine 204 sends out a predetermined call signal, as shown in FIG. When the digital network 203 receives the call signal, the ISDN
202 side. As a result, ISDN202
The call setup message “SETU” is sent to the facsimile machine 201.
P” is sent. Incidentally, currently, the ISDN 202 and the digital network 203 are NO. ISDN 202 is connected to digital network 203 because it is not interconnected by 7 common line signaling system.
The actual transmission speed on the other side cannot be determined. Therefore, the "transmission capacity" of the above message is set to "64 kbps".

As shown in FIG. 7, when the facsimile machine 201 receives the call setup message "SETUP" (process 301), it executes a call connection procedure. That is, first, a response message "CONN" is sent. IS
When the DN 202 receives this message, it responds with a response confirmation message "CONN ACK". Also,
The digital network 203 responds with a communicable signal to the facsimile device 204 (process 302).

After that, the facsimile machine 201 checks the content of one information element "transmission capability" of the call setup message "SETUP" (process 303). here,"
When “Transmission Capacity” is “64 kbps” (Processing 303 “
64k''), and the transmission rate switching unit 3 sets the operating state to 64kbps (processing 304). Then, H on the B channel
Start sending out the DLC frame flag signal (processing 3
05).

Next, start the timer (processing 3
06), monitor the reception of SABM frames for a certain period of time Tb (process 307, from N in process 307
8. From N in process 308 to process 307).

In this case, ISDN 202 and digital network 2
03, the speed matching process is executed in the same manner as described above. At this time, the facsimile machine 201 sends out the HDLC frame with all bits of one octet valid as usual, so the facsimile machine 204 cannot detect the flag signal. Therefore, the facsimile machine 204
Do not send BM frame.

If the facsimile machine 201 does not receive the SABM frame even after the predetermined period of time has elapsed (Y in process 308), the facsimile machine 201 switches to the 56 kbps operating state (
Processing 309). Then, the timer is started again (process 310), and the reception of the SABM frame is monitored for a certain period of time Tb (process 311, from N in process 311 to process 312, and from N in process 312 to process 311).

[0045] The facsimile device 201 has a speed of 56 kbps.
When the operating state is reached, 7 octets are recorded as described above.
Since the valid data of the bit is set and sent, the facsimile machine 204 can correctly receive the HDLC frame. As a result, facsimile device 204 receives the flag signal and sends out the SABM frame.

[0046] When the facsimile machine 201 receives the SABM frame (Y in process 311), it sends out a UA frame and executes a predetermined transmission control procedure. This results in
Image information is transmitted (process 313).

By the way, if the SABM frame is not received even after switching to the 56 kbps operating state (N in process 312), a communication error message is displayed (process 314) and communication is stopped.

On the other hand, there are cases where the ISDN 202 and other digital networks are not interconnected, or where the interconnected digital networks are 64
kbps, the SABM frame is received in an operating state of 64 kbps. In this case (Y in process 307), the image information is immediately transmitted using a predetermined transmission control procedure (proceed to process 313).

Furthermore, ISDN 202 and digital network 20
3 is NO. 7 common line signaling, the ISDN 202 is notified that the transmission speed on the digital network 203 side is 56 kbps. In this case, I
The SDN 202 selects “SETUP” in the call setup message “SETUP”.
Specify "56 kbps" in "Transmission Capacity".

[0050] The facsimile machine 201 is thus configured as follows.
If "56 kbps" is specified in "transmission capacity"("56k" in process 303), the operation state is immediately switched to 56 kbps and the above operation is executed (process 309).
fart).

As described above, in this embodiment, when a call is connected to a destination terminal by making/receiving a call, the transmission rate is first set to 64K.
bps and monitors the detection and transmission of flag signals or the reception of predetermined frames, and if the predetermined operation is not executed, the transmission rate is switched to 56 kbps and the same operation is re-executed. There is.

[0052] As a result, even if the transmission speed of the digital network to which the ISDN network is interconnected or the transmission speed of the destination terminal device is 56 kbps, there will be no communication error as in the past.
You will be able to communicate reliably.

In the above embodiment, an example was explained in which the transmission speed is switched from the standard 64 kbps to another speed of 56 kbps, but if a predetermined signal is not detected at 56 kbps, it is possible to switch to another speed. You can. Furthermore, it goes without saying that the transmission speed to be switched can be arbitrarily set depending on the destination terminal.

Furthermore, although the case of interconnection with other digital networks has been described, it goes without saying that the same applies to interconnection with other ISDN networks having different transmission speeds.

Furthermore, in the transmission procedure of the above-described embodiment, the destination terminal first sends out the flag signal, but a procedure in which the originating terminal first sends out the flag signal is also conceivable. In this case, ISD
The N terminal only needs to detect the flag signal when receiving a call in the same way as when making a call.

Furthermore, although a facsimile machine has been described as an example of an ISDN terminal, it goes without saying that the present invention can be similarly applied to various ISDN data terminal devices.

[0057]

As described above, according to the present invention, after starting communication by making and receiving calls, data signals are sent and detected to the other party's terminal at one transmission rate, and within a certain period of time. If the predetermined data signal is not detected at that time, switch to another transmission speed and re-execute the same operation, and when the predetermined data signal is detected, execute the transmission procedure at the then set transmission speed. This makes it possible to reliably communicate even when interconnecting networks with different transmission speeds.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a facsimile apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an example of a communication form.

FIG. 3 is an operational flowchart of the facsimile machine when making a call.

FIG. 4 is an explanatory diagram showing a transmission control procedure when the facsimile device makes a call.

FIG. 5 is an explanatory diagram showing transmission rate matching processing.

FIG. 6 is an explanatory diagram of a transmission control procedure when the facsimile device receives a call.

FIG. 7 is an operation flowchart of the facsimile machine when receiving a call.

[Explanation of symbols]

1 Facsimile image processing section 2 B channel communication control section 3 Transmission speed switching section 4 D channel call control unit 5 ISDN interface section 5 6 Operation display section 7 Control section 31 64k/56k speed matching circuit 32 Switching circuit 201, 204 Facsimile machine 202 ISDN 203, 203 Digital network

Claims (3)

[Claims] [Claim 1] Means for making a call to terminals of various transmission speeds, and means for transmitting and receiving data one bit at a time at a constant cycle;
Means for arbitrarily switching to a lower transmission rate by limiting the number of effective bits in one octet of data to be transmitted and received, and means for executing a transmission procedure when a specific data signal sent by a calling terminal after receiving a call is detected. I which has
In the SDN terminal device, after making a call, the signal detection means sets one transmission rate and detects the above-mentioned specific data signal from the destination terminal, and when the above-mentioned data signal is not detected within a certain time, another transmission speed is set. and a signal detection re-execution means for detecting the data signal by switching the speed, and a transmission procedure execution means for executing the transmission procedure at the transmission speed set at that time when the specific data signal is detected. An ISDN terminal device characterized by: [Claim 2] Means for receiving calls in response to calls originating from terminals of various transmission speeds, means for transmitting and receiving data one bit at a time at fixed intervals, and limiting the number of effective bits within one octet of data to be transmitted and received. means for arbitrarily switching to a lower data transmission rate, means for transmitting a specific data signal after an incoming call, and means for executing a transmission procedure when another data signal transmitted from the originating terminal is detected. In the ISDN terminal device equipped with the above-mentioned ISDN terminal device, a signal sending detection means sets the transmission rate to one transmission rate and sends out the specific data signal after receiving a call, and detects another data signal from the originating terminal; signal transmission detection re-execution means for switching to a different transmission speed and re-executing transmission of the specific data signal and detection of the specific data signal when the other data signal is not detected; An ISDN terminal device comprising: transmission procedure execution means for executing a transmission procedure at a transmission rate set at that time when a signal is detected. [Claim 3] Means for incoming calls in response to calls originating from terminals with various transmission speeds, means for transmitting and receiving data one bit at a time at a fixed cycle, and limiting the number of effective bits in one octet of data to be transmitted and received. After receiving a call, an ISDN terminal equipment is equipped with means for arbitrarily switching to a lower data transmission rate due to a signal detecting means that detects the data signal from the originating terminal by setting one transmission rate; and a signal that switches to another transmission rate and detects the data signal if the data signal is not detected within a certain period of time; detection re-execution means;
An ISDN terminal device comprising: data transmission means for executing a transmission procedure at a transmission rate set at that time when the data signal is detected.