JPS6075147A - Semi-duplex communication method - Google Patents

Abstract

PURPOSE:To allow the system to cope instantly with restoration of a fault by switching the mode to the reception mode when a reception request signal representing that an opposite device cannot receive any signal and transmitting a signal every time a transmission signal is received to ensure one-side communication with other communication line even if one communication line has a fault. CONSTITUTION:When the 2nd unit 4 detects the absence of a reception signal for a prescribed time, the 2nd unit 4 transmits a reception request signal X to the 1st unit 1 while the unit 4 regards there occurs a fault on a signal line 2. The 1st unit 1 receives the signal X and is set to the reception mode. The 2nd unit 4 transmits a signal B in succession to the signal X. When the 1st unit 1 receives a signal B succeeding to the signal X, the unit 1 transmits the signal A. Then the 1st unit 1 repeats the transmission operation in response to the signal B from the 2nd unit 4.

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a half-duplex communication method in which communication is carried out alternately via two communication lines, and in particular, when an abnormality occurs in one of the communication lines, This relates to a half-duplex communication method that can secure one-sided communication using 1=it-.

Background Art In recent years, with the rapid development of electronic technology, two types of
A half-duplex communication method is used in which data communication I^ is sent and received alternately for each character via the book communication Iw. In this case, the biggest problem with the half-duplex communication method is
If a failure occurs on one side of the communication line, all communications 16 will become impossible because they are synchronized by each other's (i@K).

One possible solution to this problem is to use complex communication control procedures such as those used in large-scale computers, but due to the increase in program capacity and the number of check processes, Therefore, the transfer time becomes longer. Furthermore, when using the above method, there is a problem that the system becomes large and extremely expensive.

DISCLOSURE OF THE INVENTION Accordingly, the present invention has five objectives: Even if one communication line fails, it is possible to ensure one-sided communication using the other communication line, and when the faulty communication line is restored, The object of the present invention is to provide a half-duplex communication method that allows normal communication.

In order to achieve such an object, the present invention enables the other party to enter the reception mode by a reception request signal that is sent back when reception cannot be performed for a predetermined period of time, and to enter the reception mode following this reception request signal. Each time a transmission signal sent at a time interval of more than one character and less than two characters is received, a signal for one character is transmitted.

Therefore, according to the half-duplex communication method according to the present invention, it is possible to reliably detect the occurrence of a fault in the communication line on the transmitting side, and it is also possible to detect the occurrence of a fault in the communication line on the receiving side even after the fault has occurred. The reception of information can be ensured through the Internet. Also,
Since the transmission mode and reception mode are repeated even after a failure has occurred, it has various excellent effects such as being able to return to the normal state as soon as the failure to the transmission side communication line is recovered.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram for explaining an embodiment of a half-duplex communication method according to the present invention. In the same 11, l is the first unit containing a microcomputer, and %
It inputs signals INII and IN1m from the bucket center, etc., and also controls a terminal (not shown).

In addition, this 15th-nit 1 transmits the serial signal in units of t-1 characters to the communication line 2 in the transmission mode, and receives the serial signal sent via the communication line 3 in the reception mode. Receive. Reference numeral 4 denotes a second unit having the same configuration as the first unit, which takes in a serial signal sent through the signal line 2 and sends out a transmission signal to the signal line 3 according to the serial signal configuration. Therefore, these first. The second units 1 and 4 are connected to each other via two communication lines 2.3 so that two-way communication can be performed. The operation of the system with the above configuration will be explained below using the flowchart shown in FIG.

First, 1. When the second unit 1.4 is started,
The microcomputer provided therein operates and resets the register N in steps 7' to 8x shown in FIG. 2, and then proceeds to step 2'S2. In step 82, a start bit is detected,
The start bit located at the head of the serial signal sent from the other unit in units of one character is detected. When this start bit is detected, the register N is reset in the Stella f83 and the reception error ring 2 is set to zero in step 'S4. Next, in step 8s, the serial data sent from the second unit 4 via the communication a3 is received in units of one character. When the first unit 1 finishes receiving this one-character serial number (i), the received data is processed in step S6, and then the process moves to step S7.Step S7
In step S8, a signal supplied from the terminal is taken in, and in step S8, processing for supplying the signal to the terminal is executed. When the process like C is completed, step S
In step 810, the transmission data prepared in step 9 is sent as a serial signal Δ shown in FIG. Send. When the process of step 810 is completed, the process returns to step S2 to repeat the same operation as before.
In return, transmission and reception are performed character by character.

Next, if a failure occurs in a part of the a-multiple line 3, the start bit cannot be received, so the process moves to step 811 and it is determined whether the time t1 has elapsed. In this case, the time t1 is set to a time that is greater than or equal to one character and less than or equal to two characters. In step S11, t
When it is determined that the i waiting time has elapsed, it is determined in step sH whether the value obtained by adding 1 to the register N is part of a predetermined set value n. If the determination in step 8sz is NO, step S
7, the reception of signals from the terminal, terminal control, preparation of transmission data, and serial data transmission operations are repeated. When such an operation is performed n times, if the determination in Step 81m is YES and the result is YES, it is detected that a failure has occurred in another Ig gland 3, and in Step 813 Low 1 in register N
After is set, the communication error is set to 1'' in step S14.

When the process of Stella 7'' S14 is completed, the process returns to step S7 and the transmission process is interrupted.

Next, in Figure 3, T! At the time indicated by , P of communication m2
If a fault occurs at the point 43N(a), the transmission 1B signal A shown in FIG. Therefore, this second unit 4 detects the generation of the transmission signal 16B in response to the previous reception signal Wji at the time T.
2, it is determined whether or not the received signal A' is no signal for 12 hours of 2 characters or more. Then, if this determination is YES, the signal a2
By transmitting the reception request signal Xf assuming that a failure has occurred in 2) Il-
1: When the reception of the signal sent from the second unit 4 following the reception request signal X is completed, the signal A shown in FIG. 3(a) is transmitted in response to this reception signal. and,
After that, by repeating the transmission operation in response to No. 18B sent from M2 unit 4, the first unit 1
This will ensure the reception operation.

Next, when the fault in the communication line 2 is recovered, the first unit 1 continues the transmission operation in response to the transmission signal B from the second unit 4, and therefore returns to the normal transmission/reception mode.

As explained above, in the half-21 communication method according to the present invention, when the transmitted signal is not received by the other party for a preset period of time or more, the transmitting side communicates using the reception request signal that is sent back. It is possible to detect that a fault has occurred in the line, and to continue to ensure reception using the other signal line. In addition, even if a failure occurs in the communication line on the transmitting side, the transmission operation continues in response to the received signal, so it has various excellent effects such as being able to quickly return to the normal communication mode when the line is restored. - have.

[Brief explanation of the drawing]

FIG. 1 is a block diagram for explaining an embodiment of the half-duplex communication method according to the present invention.The second figure is a flowchart showing the operation of FIG. FIG. 2 is a waveform diagram of the operation of each part of the block shown in FIG. 1; l...Ml unit), 2.3... Communication line, 4...
2nd unit.

Claims (1)

[Claims] (υ If the units with built-in microphones and computers are connected to each other via two wires #J, 9
In a half-duplex communication method that alternately sends and receives serial signals in units of one character, the communication line on the sending side when receiving a reception request signal that is sent back when one partner cannot receive a signal for a predetermined period of time. When it is determined that a failure has occurred, the mode is switched to reception mode, and the half-duplex mode is set to half-duplex mode, which sends a serial signal for one frame each time the signal is received. Communication method.