JP3206037B2 - Synchronous line controller and communication control system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data communication system in which a central processing unit and a terminal device are connected via a communication line, and a communication control device connected to the central processing unit and a synchronous system connected to the communication line. The present invention relates to a synchronous line controller provided between a modem and a modem, and a communication control system including the synchronous line controller and a communication controller.

[0002]

2. Description of the Related Art A conventional technique will be described with reference to FIGS. FIG. 3 is a block diagram showing an example of a conventional data communication system, and FIG. 4 is a timing chart for explaining an operation of the line control device in FIG. 3, particularly showing a case of frame synchronization.

In the data communication system shown in FIG. 3, a central processing unit 11 includes a communication control unit 12, a synchronous line control unit 20, a synchronous modulation / demodulation unit 13, a communication line 14, and a synchronous It is connected to a synchronous terminal device 16 via a modem 15. The transmission / reception of the interface signal group 100 is performed between the synchronous line controller 20 and the synchronous modulation / demodulation device 13, and the transmission / reception of the interface signal group 200 is performed between the synchronous terminal device 16 and the synchronous modulation / demodulation device 15. Has become. Here, the communication control device 12 has an interface with the central processing unit 11, a function of controlling the synchronous line control device 20, and the like. The synchronous line controller 20 has functions such as serial / parallel reception data and parallel / serial conversion of transmission data.

[0006] The synchronous line controller 20 has a communication transceiver 21. The communication transceiver 21 is controlled by the communication control device 12 to transmit and receive data to and from the communication control device 12, and to transmit and receive data to and from the synchronous modulation / demodulation device 1.
3, the transmission data (SD) 101 and the reception data (R
D) 102, received signal element timing (RT) 1
03, data channel received carrier detection (CD) 104
And the like.

[0005] The data from the synchronous terminal 16 is transmitted to the synchronous modem 15, the communication line 14, and the synchronous modem 1.
3 and is supplied to the communication transceiver 21 via the received data (RD) 102 in the synchronous line controller 20. The communication transceiver 21 receives a received signal element timing (RT) 103.
, Data is sampled from the received data (RD) 102, and when the data becomes 8 bits, a request to pick up a character is sent to the communication control device 12. When the data transmission is completed, the synchronous terminal device 16 transmits the framing pattern (F) of the end, turns off the transmission request signal (RS signal) in the interface signal group 200, and ends the data transmission. Then, since the transmission request signal (RS signal) is turned off, the synchronous modulation / demodulation device 15 transmits the training pattern to the synchronous modulation / demodulation device 13 and turns off the carrier. Here, the framing pattern (F)
Is a block delimiter in the F-synchronous system, and is arranged before and after data. The training pattern is a pattern for re-establishing synchronization between the modems after the block transfer is completed, and is generated by the modem. Since the training pattern is unnecessary for the central processing unit 11 and the communication control device 12, it may be referred to as dust.

At this time, a framing pattern (F) and a training pattern appear in the received data (RD) 102 of the synchronous modulation / demodulation device 13 as shown in FIG. When this is received by the communication transceiver 21, the framing pattern (F) reception is notified to the communication control device 12. Since the framing pattern (F) is an end code and also has a meaning of a start code, the next training pattern is notified to the communication control device 12 as data.

[0007] Therefore, the communication control device 12 processes the training pattern as data.
At the timing indicated by reference numeral 41 in (b), it is determined that the data is a training pattern which is an unnecessary pattern which is not output by the partner terminal only after detecting that the data channel reception carrier detection (CD) 104 is turned off. The pattern was being processed.

[0008]

As described above, conventionally, the communication control device performs extra processing due to the training pattern generated by the synchronous modulation / demodulation device, so that the control becomes difficult and the load on the communication control device becomes large. Had become.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a synchronous line controller and a communication system which can automatically remove a training pattern from data received from a synchronous modem and reduce the load on the communication controller. It is to provide a control system.

[0010]

According to a first aspect of the present invention, there is provided a synchronous line controller which transmits transmission data to a synchronous modulator / demodulator connected to a communication line under the control of a communication controller, and transmits the transmission data to a synchronous modem. A communication transceiver for sampling reception data based on a reception timing signal from a modulation / demodulation device; a reception timing signal stop instruction means for instructing a stop of the reception timing signal in response to a request from a communication control device; and a synchronous modulation / demodulation device. Receiving carrier disconnection detecting means for detecting a change from ON to OFF of the receiving carrier detection signal from the receiver and instructing release of the stop of the receiving timing signal, and receiving from the synchronous modulation / demodulation device according to an instruction from the receiving timing signal stop instructing means. Stop the supply of the timing signal to the communication transceiver, and release the supply stop by the instruction from the reception carrier disconnection detection means. Is obtained and a timing signal control means.

In this synchronous line controller, the reception timing signal stop instruction means instructs the reception timing signal control means to stop the reception timing signal in response to a request from the communication control device. With this instruction, the reception timing signal control means stops supplying the reception timing signal from the synchronous modulation / demodulation device to the communication transceiver. The reception carrier disconnection detection means detects a change from ON to OFF of the reception carrier detection signal from the synchronous modulation / demodulation device, and instructs the reception timing signal control means to cancel the stop of the reception timing signal. In response to this instruction, the reception timing signal control means releases the suspension of the supply of the reception timing signal from the synchronous modem to the communication transceiver. Data sampling is not performed during the stop period of the reception timing signal.

A communication control system according to a second aspect of the present invention includes a synchronous line controller and a communication controller. The synchronous line controller transmits a transmission data to a synchronous modem connected to a communication line and samples a reception data based on a reception timing signal from the synchronous modem. Reception timing signal instructing means for instructing the stop of the reception timing signal in response to the request, and instructing the release of the stop of the reception timing signal by detecting a change from ON to OFF of the reception carrier detection signal from the synchronous modem. The supply of the reception timing signal from the synchronous modulation / demodulation device to the communication transceiver is stopped by an instruction from the reception carrier disconnection detection means and the reception timing signal stop instruction means, and supplied by an instruction from the reception carrier disconnection detection means. Receiving timing signal control means for canceling the suspension. The communication control device is connected to the central processing unit, controls the synchronous line control device, and, when receiving the end code via the communication transceiver, transmits the reception timing signal to the reception timing signal stop instruction means. Request a stop.

In this communication control system, when the data transmission from the terminal device ends, the communication control device receives the end code and requests the reception timing signal stop instruction means to stop the reception timing signal. In the line control device, the reception timing signal stop instruction means instructs the reception timing signal control means to stop the reception timing signal in response to a request from the communication control device. With this instruction,
The reception timing signal control means stops supplying the reception timing signal from the synchronous modulation / demodulation device to the communication transceiver. The reception carrier disconnection detection means detects a change from ON to OFF of the reception carrier detection signal from the synchronous modulation / demodulation device, and instructs the reception timing signal control means to cancel the stop of the reception timing signal. In response to this instruction, the reception timing signal control means releases the suspension of the supply of the reception timing signal from the synchronous modem to the communication transceiver. Data sampling is not performed during the stop period of the reception timing signal.

A communication control system according to a third aspect of the present invention is the communication control system according to the second aspect, wherein the end code is a framing pattern which is a block delimiter code.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 relate to one embodiment of the present invention.

FIG. 1 is a block diagram showing a data communication system including a synchronous line controller and a communication control system according to this embodiment. As shown in this figure, the central processing unit 1
The communication control devices 1 are arranged in this order from the central processing unit 11 side.
2. Synchronous line controller 30, synchronous modem 13,
It is connected to a synchronous terminal 16 via a communication line 14 and a synchronous modem 15. An interface signal group 100 is transmitted and received between the synchronous line controller 30 and the synchronous modem 13, and an interface signal group 200 is transmitted between the synchronous terminal 16 and the synchronous modem 15.
Is transmitted and received. Here, the communication control device 12 has functions such as an interface with the central processing unit 11, control of the synchronous line control device 30, and the like. The synchronous line controller 30 has functions such as serial / parallel reception data and parallel / serial conversion of transmission data. This communication control device 1
2 and the synchronous line controller 30 constitute a communication control system.

The synchronous line controller 30 has a communication transceiver 31. The communication transceiver 31 is controlled by the communication control device 12 to assemble characters,
Processing such as disassembly is performed, data is transmitted / received to / from the communication control device 12, and transmission data (SD) 101, reception data (RD) 102, reception signal element timing (RT ) 103, and transmission / reception of signals such as data channel reception carrier detection (CD) 104. The communication transceiver 31
Is the received data (RD) based on the received signal element timing (RT) 103 from the synchronous modem 13.
102 is sampled.

In this embodiment, upon receiving the framing pattern (F) via the communication transceiver 31, the communication controller 12 requests the synchronous line controller 30 to stop the received signal element timing (RT). It is supposed to.

The synchronous line controller 30 according to the present embodiment transmits a received signal element timing (R
In response to a request to stop T), the reception clock stop circuit 33 instructs to stop the clock of the reception signal element timing (RT) and the data channel reception carrier detection (CD) 104 from the synchronous modem 13 from on to off. To the received signal element timing (R
A data channel reception carrier disconnection detection circuit 34 for instructing the release of the clock stop in T);
, The supply of the reception signal element timing (RT) 103 from the synchronous modulation / demodulation device 13 to the communication transceiver 31 is stopped. The element timing (R
T) 103 and a reception clock control circuit 35 for canceling the suspension of the supply to the communication transceiver 31. The element timing (R
T) 103 is supplied to the communication transceiver 31 as a reception signal element timing (RT) 105 via the reception clock control circuit 35.

Next, the operation of this embodiment will be described with reference to FIG. FIG. 2 is a timing chart for explaining the operation of the synchronous line controller of the present embodiment.

Data from the synchronous terminal 16 is transmitted to the synchronous modem 15, the communication line 14, and the synchronous modem 1.
3, the data is input to the synchronous line controller 20 and supplied to the communication transceiver 31 via the received data (RD) 102 in the synchronous line controller 20. The communication transceiver 31 samples data from the reception data (RD) 102 based on the reception signal element timing (RT) 105 from the reception clock control circuit 35 and, when it becomes 8 bits, picks up a character to the communication control device 12. Make a request. When the data transmission is completed, the synchronous terminal device 16 transmits the framing pattern (F) of the end, and the transmission request signal (RS signal) in the interface signal group 200.
To turn off the data transmission. Here, since the transmission request signal (RS signal) is turned off, the synchronous modulation / demodulation device 15 changes the training pattern to the synchronous modulation / demodulation device 13.
Send to and turn off the carrier.

At this time, a framing pattern (F) and a training pattern appear in the received data (RD) 102 of the synchronous modulation / demodulation device 13 as shown in FIG. When this is received by the communication transceiver 21, the framing pattern (F) reception is notified to the communication control device 12. In response to this notification, the communication control device 12 requests the reception clock stop circuit 33 to stop the reception signal element timing (RT). When receiving a request to stop the reception signal element timing (RT) from the communication control device 12, the reception clock stop circuit 33 instructs the reception clock control circuit 35 to stop the clock at the reception signal element timing (RT). Send 43. In response to the instruction 43, the reception clock control circuit 35
2 (c) and (d) show the signal timing (RT) 1 of the received signal from the synchronous modulation / demodulation device 13.
03, the supply to the communication transceiver 31 is stopped. Thus, the training pattern is discarded without sampling the received data (RD) 102 thereafter.

When the data channel reception carrier detection (CD) 104 changes from ON to OFF as shown in FIG. 2B, the reception carrier disconnection detection circuit 34 detects this, and the reception clock control circuit 35 To cancel the clock stop of the received signal element timing (RT) 44
Send. In response to the instruction 44, the reception clock control circuit 35 controls the reception signal element timing (R) from the synchronous modulation / demodulation device 13 as shown in FIGS.
The suspension of the supply to the communication transceiver 31 in T) 103 is released. As a result, the clock of the received signal element timing (RT) 103 from the synchronous modulation / demodulation device 13 is supplied to the communication transceiver 31, so that the received data (RD) 102 can be received again.

[0024]

As described above, according to the present invention, the reception timing signal from the synchronous modulation / demodulation device is prevented from being supplied to the communication transceiver in response to a request from the communication control device that has received the end code. By re-supplying the received carrier detection signal according to the change from ON to OFF, the training pattern in the received data from the synchronous modulation / demodulation device can be automatically removed to reduce the load on the communication control device. effective.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a data communication system including a synchronous line controller and a communication control system according to one embodiment of the present invention.

FIG. 2 is a timing chart for explaining the operation of the synchronous line controller of one embodiment.

FIG. 3 is a block diagram illustrating an example of a conventional data communication system.

FIG. 4 is a timing chart for explaining an operation of the line control device in FIG. 3;

[Explanation of symbols]

 REFERENCE SIGNS LIST 11 central processing unit 12 communication control device 13, 15 synchronous modulation / demodulation device 14 communication line 16 synchronous terminal device 30 synchronous line control device 31 communication transceiver 33 reception clock stop circuit 34 data channel reception carrier disconnection detection circuit 35 reception clock Control circuit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04L 29/08

Claims (3)

(57) [Claims] 1. A communication transmission / reception for sending transmission data to a synchronous modem connected to a communication line under control of a communication control unit and sampling received data based on a reception timing signal from the synchronous modem. A reception timing signal stop instructing unit for instructing a stop of a reception timing signal in response to a request from the communication control device; and detecting a change from on to off of a reception carrier detection signal from the synchronous modulation / demodulation device. Receiving carrier disconnection detection means for instructing the release of the stop of the reception timing signal, and stopping the supply of the reception timing signal from the synchronous modem to the communication transceiver by an instruction from the reception timing signal stop instruction means. And a reception timing signal control means for canceling the supply stop according to an instruction from the reception carrier disconnection detection means. A synchronous line controller. 2. A communication transceiver for sending transmission data to a synchronous modulation / demodulation device connected to a communication line and sampling reception data based on a reception timing signal from the synchronous modulation / demodulation device, and a request from a communication control device. Reception timing signal stop instructing means for instructing stop of the reception timing signal in response to the instruction, and detecting a change from on to off of the reception carrier detection signal from the synchronous modulation / demodulation device to instruct release of the stop of the reception timing signal. Receiving carrier cutoff detecting means, and stopping the supply of the reception timing signal from the synchronous modulation / demodulation device to the communication transceiver by an instruction from the reception timing signal stop instructing means; A synchronous line controller having reception timing signal control means for canceling the supply stop by Connected to an apparatus, controls the synchronous line controller, and, when receiving an end code via the communication transceiver, requests the reception timing signal stop instruction means to stop the reception timing signal. A communication control system, comprising: a communication control device. 3. The communication control system according to claim 2, wherein the end code is a framing pattern that is a block delimiter code.