JPH066408A - Half-duplex communication control method - Google Patents

Abstract

PURPOSE:To provide a half-duplex communication control method which realize bidirectional and equal data transfer control and prevents a line use rate from being lowered even when transmitting data are competed because massive transmitting data are simultaneously existent between both of sides to be communicated each other. CONSTITUTION:At a communication control equipment 1a provided with a transmission control part 12a to execute transmission/reception while setting a data link with a communicating party according to a basic data transmission control procedure so as to perform data communication with the communicating party through a communication line 2 and a host processing part 13 to control the transmission/reception of telegraphic messages without being conscious of the basic data transmission control procedure by controlling the transmission control part 12a, the transmission control part 12a on the side of a priority station holds the state of competing the transmitting data when the transmitting data are competed with the communicating party. Only when the competition is generated, a retransmitting operation from the side of a non-priority station is preferentially performed within fixed time after those data are completely transmitted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a half-duplex communication control method in a communication control device for performing data communication with a communication partner in accordance with a basic data transmission procedure via a communication line, and particularly, to a mutual communication between both parties. The present invention relates to a half-duplex communication control method that realizes bidirectionally uniform data transfer control and does not reduce the line usage rate even if there is a large amount of transmission data at the same time and transmission data competition occurs.

[0002]

2. Description of the Related Art FIG. 5 is a block diagram showing a configuration example of a conventional communication control device of this type. In the figure, the communication control device 1 accommodates a communication line 2, and the components of the communication control device 1 include a line interface unit 11,
There are a transmission control unit 12 and an upper processing unit 13. Note that 121
Is a transmission / reception processing unit that transmits / receives a selecting sequence, a message, and a response code in accordance with an instruction from the upper processing unit 13, 122 is a timer processing unit that provides a timer function necessary for executing transmission / reception processing, and 123 is a higher processing unit. 13 are provided with a plurality of communication paths to simultaneously control transmission / reception requests from the plurality of communication paths, and the upper processing unit 13
It is a command processing unit that divides the message from (1) into transmission blocks defined by the basic data transmission control procedure. Further, reference numeral 1211 denotes a transmission / reception executing unit that performs an operation defined by the basic data transmission control procedure described above, and reference numeral 1212 denotes a priority state holding unit that holds a pre-specified priority / non-priority station state.

FIG. 6 is an example of a selecting sequence format for a data link establishment processing procedure in the above-mentioned communication control device, and FIG. 7 is an example showing a relationship between a transmission message and a transmission block format. 8 and 9 show an operation example of the conventional technique. The selecting sequence arriving from the communication line 2 is received by the transmission / reception processing unit 121 via the line interface unit 11. Transmission / reception processing unit 1
Upon receiving the selecting sequence after transmitting the selecting sequence, the 21 determines that a transmission process conflict has occurred, and the priority state holding unit 1212 recognizes whether it is a priority station or a non-priority station, If, the received selecting sequence is ignored. On the other hand, in the case of a non-priority station, the transmitted selecting sequence is invalidated and a response is returned to the received selecting sequence. The transmission / reception processing unit 121 continuously executes the transmission / reception process of the transmission block and the data link release process by the established data link, and notifies the upper processing unit 13 via the command processing unit 123 of the completion of the transmission / reception.

[0004]

In the above-mentioned prior art, when a large amount of transmission data is transmitted to the priority station, the next telegram transmission from the priority station and the transmission control unit of the non-priority station are performed as shown in FIG. Retransmission of the held message again causes a race condition, and the same processing as the above processing is performed again, and the transmission processing from the priority station is executed, and the data transmission from the priority station The transmission of the non-priority station will be kept waiting until it disappears. In order to make up for this drawback, FIG.
This is an example in which the upper processing unit 13 makes it possible to transmit a message from a non-priority station by activating a timer after a transmission completion notification and setting a certain time interval. However, with this method, since it is not possible to recognize whether or not there is transmission data in the non-priority station, even if the non-priority station does not have transmission data, the priority station waits for a certain period of time, which reduces the efficiency of reuse. There's a problem. Note that FIG. 8 shows an example of 1 telegram = 2 transmission blocks, and FIG. 9 shows an example of 1 telegram = 1 transmission block. The present invention has been made in view of the above circumstances, and it is an object of the present invention to solve the above-mentioned problems in the related art, and there is a large amount of transmission data at the same time between two communicating parties, It is an object of the present invention to provide a half-duplex communication control method that realizes even data transfer control in both directions even when contention occurs and does not reduce the line usage rate.

[0005]

The above object of the present invention is to establish a data link with a communication partner according to a basic data transmission control procedure in order to perform data communication with the communication partner via a communication line. In the communication control device having a transmission control unit for executing transmission / reception and a host processing unit for controlling transmission / reception of a message by controlling the transmission control unit, the communication partner, When the contention of the transmission data occurs between and, the transmission control unit of the priority station side holds the contention state of the transmission data, only when the contention occurs, after the data transmission completion time,
This is achieved by the half-duplex communication control method characterized in that the retransmission operation from the non-priority station side is prioritized within a fixed time.

[0006]

In the half-duplex communication control method according to the present invention,
If there is contention of transmission data with the communication partner,
The transmission control unit on the priority station side holds the state of occurrence of contention of transmission data, and only when contention occurs, after the data transmission completion time,
Within a certain period of time, the re-transmission operation from the non-priority station side is prioritized, so both parties communicating with each other
Even if there is a large amount of transmission data at the same time, and even if there is contention for the transmission data, a uniform data transfer control in both directions is realized, and a half-duplex communication control method that does not reduce the line usage rate is realized. It is possible. Further, the transmission control unit divides the transmission message received from the upper processing unit into a plurality of transmission blocks having a predetermined length.
By making it possible to freely set the number of transmission blocks to be transmitted in one data link, the above method can be applied to a long transmission message.

[0007]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a communication control device showing an embodiment of the present invention.
Is a communication control device, 2 is a communication line, 11 is a line interface unit, 12a is a transmission control unit in which a contention state holding function and a contention control function are added to the function of the transmission control unit 12 shown in FIG. Section, 121a is a transmission / reception processing section, 1
22 is a timer processing unit, and 123a is a command processing unit. Further, 1211a is a transmission / reception execution unit including the above-mentioned transmission contention control function, 1212 is a priority state holding unit that holds a pre-designated priority / non-priority station state, and 1213 is a state whether or not a conflict has occurred. Competing state holding unit, 12
Reference numeral 31 denotes a continuous transmission block number holding unit that divides a message into transmission blocks and holds the number of blocks to be transmitted within one data link. Note that the above-mentioned symbols with "a" added thereto are similar to the components of the conventional communication control device 1 shown in FIG.

2, 3, and 4 show an operation example of this embodiment. When the transmission / reception execution unit 1211a detects a race condition of transmission, the priority state holding unit 1212 recognizes whether it is a priority station or a non-priority station. 1213 is set, and the transmission / reception process of the transmission block and the data link release process are continuously executed by the established data link. After the data link release processing, the transmission / reception execution unit 1211a of the priority station refers to the race condition holding unit 1213, and if there is a race condition, cancels the state and activates the timer, and the non-priority station until the timeout. Prioritize data re-transmission from. Two types of methods can be considered as specific execution methods. In the example shown in FIG. 2, the data processing completion notification is temporarily suspended to the upper processing unit 13, and the transmission completion notification is issued when the selecting sequence is received from the communication partner or the above-mentioned timer times out. The higher-level processing unit 13 is notified via the route.

Further, in the example shown in FIG. 3, the upper processing unit 13
The completion of data transmission is notified, but during the period until the above-mentioned timer times out, even if there is a transmission request from the upper processing unit 13, this is held and the selecting sequence from the non-priority station is re-received. Is what you are doing. In the example shown in FIG. 4, the continuous transmission block number holding unit 123
Although the value set to 1 is 1, the operation is shown when the high-order processing unit 13 requests data transmission in which the message length is long and divided into two blocks. In this case, since the value set in the continuous transmission block number holding unit 1231 is 1, one electronic message is transmitted by establishing the data link twice. In the transmission of a message having a long message length and divided into a plurality of transmission blocks, if the set value of the continuous transmission block number holding unit 1231 is large, the set number of the plurality of transmission blocks are transmitted by one data link establishment. ,
Since the direction of data transfer on the communication line 2 is biased, this can be prevented by a method similar to the control method shown here. In this sense, it is preferable that the value set in the continuous transmission block number holding unit 1231 be a small value.

Needless to say, the race condition holding unit 1
When referring to 213, if the contention state is not set, the above timer is not set, and a notification of transmission completion is immediately notified to the higher-level processing unit 13 via the command processing unit 123a. The transmission / reception execution unit 1211 in the non-priority station performs the same process as the conventional one.
According to each of the above-described embodiments, in the half-duplex communication control method, there is a large amount of transmission data for both parties to communicate,
Even if there is a conflict of transmission data, on the communication line,
Since even data transfer control can be realized bidirectionally, even for non-priority stations, the time from the transmission request generation to the end of transmission to the other party does not depend on the transmission data amount of the priority station,
It is possible to make it uniform and to improve the transfer efficiency of the entire system without lowering the line utilization rate. It is needless to say that the above-mentioned embodiments show examples of the present invention and the present invention should not be limited to these.

[0011]

As described above in detail, according to the present invention, even if there is a large amount of transmission data at the same time between the communicating parties, even if there is contention of the transmission data, even data is bidirectionally transmitted. This has the remarkable effect of realizing the transfer control and realizing the half-duplex communication control method without lowering the line usage rate.

[0012]

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a communication control device showing an embodiment of the present invention.

FIG. 2 is a diagram illustrating an operation example (1) of the communication control device according to the embodiment.

FIG. 3 is a diagram showing an operation example (No. 2) of the communication control device of the embodiment.

FIG. 4 is a diagram showing an operation example (No. 3) of the communication control device of the embodiment.

FIG. 5 is a block diagram showing a configuration example of a conventional communication control device.

FIG. 6 is a diagram showing an example of a selecting sequence format for a data link establishment processing procedure in a conventional communication control device.

FIG. 7 is an example showing a relationship between a transmission message and a transmission block format in a conventional communication control device.

FIG. 8 is a diagram showing an operation example (1) of a conventional communication control device.

FIG. 9 is a diagram showing an operation example (No. 2) of the conventional communication control device.

[Explanation of symbols]

1, 1a: communication control device, 2: communication line, 11: line interface unit, 12, 12a: transmission control unit, 13: upper processing unit, 121, 121a: transmission / reception processing unit, 1211,
1211a: transmission / reception execution unit, 1212: priority state holding unit, 1213: contention state holding unit, 122: timer processing unit, 123, 123a: command processing unit, 1231: continuous transmission block number holding unit.

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Claims (2)

[Claims] 1. A transmission control unit which sets up a data link with the communication partner according to a basic data transmission control procedure and performs transmission / reception in order to perform data communication with the communication partner via a communication line, and the transmission. By controlling the control unit, in a communication control device having a host processing unit that controls transmission / reception of a message without being aware of the basic data transmission control procedure, contention of transmission data with the communication partner has occurred. In this case, the transmission control unit on the priority station side holds the transmission data contention state, and only when the contention occurs, the retransmission operation from the non-priority station side can be performed within a certain time after the completion of the data transmission. A half-duplex communication control method characterized by giving priority. 2. A transmission control unit which sets a data link with the communication partner according to a basic data transmission control procedure and performs transmission / reception in order to perform data communication with the communication partner via a communication line, and the transmission. In a communication control device having a host processing unit that controls transmission / reception of a message by controlling the control unit without being conscious of the basic data transmission control procedure, the transmission that the transmission control unit sends in one data link The number of blocks can be freely set in advance, and when the transmission message received from the upper processing unit is long, it is divided into a plurality of transmission blocks of a predetermined length and transmitted. The half-duplex communication control method according to claim 1.