JPS61228755A - Communication control equipment - Google Patents

Abstract

PURPOSE:To prevent the deterioration in the line utilizing efficiency due to excess error processing and data retransmission by avoiding the reception of incorrect data caused by an RD noise due to a residual carrier of a MODEM. CONSTITUTION:A program sets a reception status register 18 to the reception stop state at the end of reply reception. Signals 16 and 17 generated by a 1-character reception end detection circuit 14 are stopped by the setting and the reception is stopped. When a carrier detection signal CD changes to the OFF state, an interruption signal is sent from a CD OFF supervisory circuit 6 and a main control unit 1 rewrites a reception status register 18 into the reception start state according to the command of the program. The signals 16, 17 generated by the circuit 14 are produced through the rewrite and the reception is started. Thus, the incorrect data reception caused by the RD noise due to the residual carrier is avoided and the program overhead for the incorrection data reception processing and the deterioration of the line utilizing efficiency due to data retransmission are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a communication control device that is connected to a terminal device or the like via a modem and a communication line to transmit and receive data, and particularly relates to a communication control device that transmits and receives data via a modem interface and a carrier detection signal ( CD
This invention relates to improvements in data transmission/reception control performed by monitoring the off state of signals (signals).

[Background of the invention]

In a system that uses a multi-point communication line, when transmitting a boring sequence from a primary station to a secondary station, it is common to check that the CD signal is off and then transmit it to the next secondary station. , The reason is as follows.

This will be explained using FIGS. 2 and 3. In Figure 2, CCU is a communication control device of 1M, M+M2 is a modem,
T+ and T2 represent terminal devices, which transmit and receive data in a multipoint configuration. FIG. 3 shows SD and terminal device TI on the CCU side, SD on the T2 side, R8 and modem M1. M2
Indicates the status of the carrier.

Suppose that the CCU sends a polling sequence to T1. After receiving the polling sequence 1yX, T1 returns a response sequence to the CCU. At this time, T1
Turn on R8 and set it to 5DIII.

After that, R8 is turned off.

M1 transmits the carrier when RS is on and stops transmitting when RS is off, but depending on the characteristics of the modem and line, the carrier remains for a certain period of time as shown in FIG. If the CCU side sends the boring sequence to the next terminal T2 without monitoring CD off, when the response sequence from T2 is sent to the CCU, the modem If the residual carrier of M1 overlaps the carrier of modem M2, the response sequence may not be received normally.

For the above reasons, it is necessary to confirm that the CD is off before transmitting. Also, when using full-duplex communication, T2
Noise from residual carriers 1 and 3 can be received even during polling transmission to the terminal, so countermeasures are also required.

Next, the conventional method will be described below.

When the CCU side receives the response sequence to the polling sequence, it monitors the CD off according to the monitoring command issued from the program at certain time intervals, and when the CD turns off, sends the polling sequence to the next terminal according to the transmission command from the program. . Regarding reception processing, invalid data taken in between the reception of the response sequence and the completion of transmission of the boring sequence to the next terminal is read and discarded by the program (see FIG. 4).

This method has the following drawbacks.

(1) R due to residual carrier after receiving response sequence
After synchronization is established due to D noise (for example, in the case of HDLC procedure, X'7E' pattern is received) and the polling sequence is sent to the primary terminal (4N), a report of invalid data reception by the remaining carrier may occur. . In this case, it is assumed that the response to the polling is invalid and retransmission processing is performed. This reduces line usage efficiency.

(2) In (1) above, even if the fraudulent data reception report is received before the polling transmission to the next terminal is completed, the program needs to perform read-discard processing, which increases program overhead.

(5) It is necessary to design a program that takes into account the state of the CD.

Note that related devices of this type include, for example, Japanese Unexamined Patent Publication No. 18383/1983.

[Purpose of the invention]

The purpose of the present invention is to avoid a reduction in line usage efficiency due to redundant error processing and data retransmission by avoiding incorrect data reception caused by RD noise caused by residual carriers of modems in full-duplex communication multipoint lines. The goal is to provide and provide means to prevent this.

[Summary of the invention]

The present invention is characterized by: a program-controlled communication control device that connects to a terminal device, etc. via a modem and a communication line to transmit and receive data; A first register that stores data, a second register that is used to take in the data in the first register and send it serially to the line, and a CD of the modem interface until the CD is turned off. means for repeatedly transmitting the data placed in the first register; and a means for reading and transmitting the data stored in the memory to the first register when the CD is turned off, and sequentially reading data from the memory thereafter. means for transmitting data by setting it in the first register; means for sending a report signal to the program when the CD is turned from on to off and the data in the memory is read out to the first register; By providing a status register that is used to execute and stop receiving operations, it simplifies the CD monitoring process in the program, avoids incorrect data reception caused by RD noise due to the residual carrier of the modem, and eliminates unnecessary error processing and This is to prevent a decrease in line usage efficiency due to data retransmission.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 and 5.

FIG. 1 is a block diagram of an embodiment in which the present invention is applied to a line control section of a communication control device.

1 is a main control unit, which sends and receives data to and from the line control unit, processes messages, and handles errors.

etc. are performed by program processing. 2 is a memory for storing transmission data, and under the control of the data write bus 19 and the address bus 21.7'-/event write instruction signal 20 from the main control unit 1, transmission data is written and the transmission data is stored. be done. 3 is the 1/1st transmission register, and C
The contents of the transmission data storage memory 2 are taken in by the set signal 9 from the D-off monitoring circuit 6. 4 is the second transmission register.

After taking in the contents of the first transmission register 3 by the set signal 8 from the 1-character transmission completion detection circuit 5, it performs a 1-bit shift according to the line speed, and transmits the bit series data to the SD signal 31. put on. Reference numeral 5 denotes a one-character transmission completion detection circuit, which outputs a set signal 8 for the register 4 when detecting the completion of transmission of data in the second transmission register 4. Reference numeral 6 denotes a CD off monitoring circuit, which outputs a first transmission register set signal 9 and an address update instruction signal 10 for the memory 2 if the CD is off when data transmission from the second transmission register 4 is completed. In addition, when the data transmission of register 4 is completed and a change to CD OFF is detected,
An interrupt signal 11 is sent to the main control unit 1. 7
is an address generation circuit, which generates an address according to the address bus 21 when writing transmission data from the main control unit 1, and otherwise generates an address update instruction signal from the CD-off monitoring circuit 6. 10 to generate an address. 12 is a memory for storing received data;
The received data is written under the control of the received data write instruction signal 17 and the address update instruction signal 16, and the received data is stored. A receiving register 13 assembles bit serial data from the line into characters. 14 is a one-character reception completion detection circuit, and when the reception status register 18 indicates a start state, reception register 1 is detected.
When character assembly/completion in step 3 is detected, an address update instruction signal 16 and a received data write instruction signal 17 are output, and if the register 18 indicates a stopped state, the output of the signals 16 and 17 is stopped. 15 is an address generation circuit, and when the main control unit 1 reads received data, 1' is an address bus 21. In other cases, an address is generated according to the address update instruction signal 16 from the circuit 14. 1B is a reception status register, into which a data write bus from the main control unit 1 is used to write the data specifying the reception status.

The operation when the CD signal is on and off in the above configuration will be explained with reference to FIGS. 1 and 5.

First, the operation when the CD is on will be described. - When the data transmission of the second transmission register 4 is completed, the signal 8 is output from the first character transmission completion detection circuit 5.

At this time, signal 9 is not output because the CD is on. Therefore, the previous data remains in the first transmission register 3, and the contents of the first transmission register 3 are transferred to the second transmission register 4, that is, the same data is transmitted. Repeat this operation until the CD is turned off. In FIG. 5, the first transmitting register 3
An example is shown in which the F TJ A G pattern in the HDLC procedure is included, and the FLAG pattern is continued to be sent until the CD is turned off.

Next, the operation when the CD signal is turned off is as follows. When data transmission from the second transmission register 4 is finished, one circuit 5
Signal 8 comes out from. At this time, the CD signal 32 is off, so
A first transmission register set signal 9 is output. Therefore, the transmission data stored in the transmission data storage memory 2 is read into the second register 5, and the second
The read data of the register will be transferred. Thereafter, the data in the second register is repeatedly bit-shifted and sent to the line. Further, the address generation circuit 7 that receives the address update instruction signal 10 updates the memory address to enable access to the next transmission character.

After this, data is sequentially read from the memory 2 and the data is read from the first transmitting register 3. Furthermore, the second transmission register is set to 4 and data is transmitted.

On the other hand, regarding the reception operation, when the response reception is completed (part shown in Figure 5), the program executes the reception status register 18.
Set the reception stop state.

With this setting, the signals 16 and 17 generated by the one character reception completion detection circuit 141 stop and the reception operation stops. This state corresponds to part a in FIG. Then C
When the D signal turns off, an interrupt signal is sent from the CD off monitoring circuit 6, and the main control unit 1 rewrites the reception status register 18 to the reception start state according to the instructions of the program. As a result of this rewriting, the signals 16 and 17 generated by the circuit 14 are outputted, and the receiving operation is started.

〔Effect of the invention〕

According to the present invention, the following effects can be obtained.

(1) After receiving a response from a terminal, when sending a boring sequence to the next terminal, monitor the CD off, report to the program when the CD is off, and start receiving according to the reception start instruction from the program program. Therefore, it is possible to avoid illegal data reception due to RD noise caused by residual carriers, and it is possible to improve program overhead for processing illegal data reception and decrease in line usage efficiency due to data retransmission.

(2) When there is a transmission instruction from the program, the CD
Until the CD is turned off, it continues to send an arbitrary pattern (for example, the

By making it possible to start sending data (after the address field in order), the program only needs to issue an instruction to start sending without being aware of the state of the CD signal, which simplifies program processing.

The diagrams showing the 8D, RD, and CD signals and reception status in Figure 1 during evening transmission/reception, Figures 3 and 4 show the need to confirm that the CD signal of the modem interface is off before starting data transmission. FIG. 5 is a diagram illustrating the conventional technology.

DESCRIPTION OF SYMBOLS 1... Main control unit, 2... Transmission data storage memory,... 3... First transmission register, 4... Second transmission register, 5... 1 character transmission completion detection circuit, 6. ...CD off monitoring circuit, 7.Address generation circuit (transmission side), 8..Second transmission register set signal 19..First transmission register set signal, 10..Address update instruction signal (transmission side). side),
11... Reception start report interrupt signal, 12... Reception data storage memory, 13... Reception register, 14... 1 character reception completion detection circuit, 15...
Address generation circuit, 16...Address update instruction signal (receiving side), 17...
・Receive data write instruction signal, 1st...Receive status register, 19...Data write bus, 20...Transmit data write instruction signal, 21...Address bus, 30...RD double signal receive data ), 31...8D signal (transmission data), 32...CD signal (carrier detection).

Claims (1)

[Claims] 1. A memory for storing transmission data, a first register for storing transmission data read from the memory, a second register used for transmitting the transmission data in the first register to the line in bit series, and a modem interface. CD
means for monitoring (carrier detection signal) and repeatedly sending the data in the first register until the CD is turned off, and reading out and transmitting the data in the memory to the first register when the CD is turned off; Means for sequentially reading data from the memory, setting it in the first register, and transmitting the data, and sending a report signal to the program when the data in the memory is read out to the first register when the CD is turned on and the CD is turned off. 1. A communication control device comprising: means for instructing reception to start and stop receiving; and means for executing and stopping a reception operation using a signal generated from the state register.