JPH066410A - Data communication system - Google Patents

Abstract

(57) [Summary] [Object] To realize a function for automatically determining the optimum retransmission interval time from the time required from data transmission to reception in a system having HDLC communication. [Structure] HD transmitting and receiving in HDLC format
Echo back periodically with LC control means 2 and 11,
Retransmission interval time calculation means 3 and 12 for measuring the time from the transmission to reception of the echo back data and calculating the optimum retransmission interval time, and storage means 5 and 14 for storing the calculated result, Control of each means and HD
A configuration that is composed of control means 4 and 13 for controlling the LC procedure and that can always automatically determine the optimum retransmission interval time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a retransmittable data communication system.

[0002]

2. Description of the Related Art A conventional example of the present invention will be described below with reference to the drawings. As a conventional example, a high-level data link control procedure (hereinafter referred to as an HDLC procedure) will be described as an example. FIG. 5 shows the system configuration of the HDLC procedure in the conventional example, FIG. 6 shows the data structure stored in the storage means, and FIGS. 7 and 8 show various processing flows. In FIG. 5, 51 and 60 are systems (1) and (2). 52 and 61 are for processing transmitted / received data according to the HDLC format.
DLC control means, 55 and 64 are storage means for storing retransmission interval time and the like, 54 and 63 are timer means (1) for periodically sending out control signals and requesting the control means to retransmit data.
Is. Reference numerals 53 and 62 are control means for controlling the HDLC control means, storage means, timer means (1), etc., and for performing HDLC procedure processing. Reference numeral 70 in FIG. 6 denotes a retransmission interval time storage area in which the retransmission interval time is stored.

A conventional HDLC configured as described above
In the procedure, the operation and control process will be described below with reference to the drawings. Here, each processing unit will be described assuming that data is transmitted from the system (1) 51 to the system (2) 60. In the data transmission process (FIG. 7A), the control means 53 of the system (1) 51 adds an address code and a control code to the data to be transmitted (S51) HDLC control means.
Hand it over to 52 (S52). Upon receiving the data from the control means 53, the HDLC control means 52 adds a flag, a frame check sequence (FCS), etc. to the data, converts it into the HDLC format, and sends it to the system (2) 60 (S5).
3). The data transmission processing of the system (1) has been described above, but the same applies to the case of the system (2). Next, in the data receiving process (FIG. 7 (b)), the system (1) 51 which has received the data from the system (2) 60 removes the flag of the received data and the HDLC format such as FCS by the HDLC control means 52. (S56), control means for pure data only
It is passed to 53 (S57), and the process according to the HDLC procedure is performed (S5
8). In the retransmission processing (FIG. 8), this processing is timer means (1) 54 (retransmission timer) that requests the control means 53 to retransmit the data at the time indicated by the value of the retransmission interval time storage area 70 (FIG. 6). The resending request from the device is transmitted to the control means 53 (S6
1). Upon receiving the retransmission request signal, the control means 53 creates retransmission data (S62) and performs data transmission processing (S63 (data transmission processing of FIG. 7 (a))). Although the retransmission process of the system (1) has been described above, the same applies to the case of the system (2).
As described above, in the conventional example, the retransmission interval time is fixed, and the retransmission is performed at a constant retransmission interval time regardless of the system load.

[0004]

However, in the above-mentioned conventional method, the retransmission interval time is fixed, and the retransmission is performed based on the data transmission rate and the time required for data transmission / reception at the maximum load of each system to be communicated. The interval time was calculated, and the retransmission was performed at the calculated retransmission interval time. Therefore, even when the processing load of each system is light, the retransmission interval time becomes long, and the efficiency of communication including retransmission is low. The present invention is intended to solve the above-mentioned conventional problems, and an object of the present invention is to provide a data communication method capable of controlling the retransmission interval according to the load of the system.

[0005]

In order to achieve the above object, the present invention provides a timer means (1) for periodically requesting the control means to transmit echo back data, and a process from the transmission to reception of the echo back data. Means for measuring the time of
(2), and has a retransmission interval time calculating means for calculating the optimal retransmission interval time from the time measured by the timer means (2), periodically echo back data transmission and reception,
The retransmission interval time is calculated from the time required for the transmission and reception, and the retransmission is performed at the calculated retransmission interval time.

[0006]

Since the present invention has the above-mentioned means, the retransmission interval time is periodically changed, so that it is always possible to perform the retransmission at the optimum retransmission interval time according to the load of the system. The data transmission efficiency can be improved.

[0007]

EXAMPLES Examples will be described below with reference to the drawings by taking the HDLC procedure as an example. FIG. 1 shows a system configuration of HDLC in one embodiment of the present invention, FIG. 2 shows a data structure stored in a storage means in one embodiment of the present invention, and FIGS.
The various processing flows in one embodiment of the present invention are shown in FIG.

In FIG. 1, 1 and 10 are systems (1),
It is (2). 2 and 11 are HDLC control means for processing transmission / reception data according to the HDLC format, 3 and 12 are retransmission interval time calculating means for calculating an optimum retransmission interval time from the time from the transmission of echo back data to reception, and 5 and 14 are Storage means for storing the results calculated by the retransmission interval time calculation means 3, 12 and 6 and 15 are timer means (1) for periodically sending a control signal and requesting the control means to retransmit the data. . 7 and 1
Reference numeral 6 is a timer means (2) that periodically sends a control signal and requests the control means to send echo back data. 8 and 17 are timer means (3) for measuring the time from the transmission of echo back data to the reception thereof. 4 and 13 are the HDLC control means, retransmission interval time calculation means,
Storage means, timer means (1), timer means (2), timer means
It is a control means for controlling (3) and the like, and for performing HDLC procedure processing. In FIG. 2, reference numeral 21 is an echo back data transmission / reception time measurement value storage area for storing the time required from the transmission of echo back data to reception, and 20 is a value from the echo back data transmission / reception measurement value storage area. It is an optimum retransmission interval time storage area for storing the result calculated by the retransmission interval time calculating means.

The HDL of this embodiment configured as described above
In the procedure C, the operation and control process will be described below with reference to the drawings. Here, system (1) 1
Each processing unit will be described assuming that data is transmitted from the computer to the system (2) 10. In the data transmission process (Fig. 3 (a)),
The control means 4 of the system (1) 1 adds an address code and a control code to the data to be transmitted (S1) and passes it to the HDLC control means 2 (S2). Upon receiving the data from the control means 4, the HDLC control means 2 flags the data, FC
S or the like is added and converted into the HDLC format and sent to the system (2) 10 (S3). The data transmission processing of the system (1) has been described above, but the same applies to the case of the system (2). Further, in the echo back data transmission process (FIG. 4 (a)), a timer means for periodically sending a control signal and requesting the control means to transmit the echo back data.
(2) The echo back data transmission request signal from 7 is transmitted to the control means 4 (S25). Upon receiving the echo back data transmission request signal, the control means 4 creates echo back data (S26) and activates the timer means (3) 8 (echo back transmission / reception time measuring timer) (S27) to perform data transmission processing. (S
28 (data transmission process of FIG. 3A)). System above (1)
Although the echo back data transmission process of is described, the same applies to the case of the system (2).

In the data transmission process (FIG. 3 (b)), the system (1) 1 which has received the data from the system (2) 10.
The HDLC control means 2 removes the flag of the received data and the HDLC format such as FCS (S11), and passes only pure data to the control means 4 (S12). The control means 4 which has received the data from the HDLC control means 2 checks whether the data is echo back data (S13). If it is not echo back data, processing according to the HDLC procedure is performed (S20). If it is echo back data, it is checked whether or not it is data transmitted from its own system (S14). If it is the echo back data from the own system, the timer means (3) 8 started by the echo back data transmission process (Fig. 4 (a))
(Echo back transmission / reception measurement timer) is stopped, and the timer value is set to the echo back data transmission / reception time measurement value storage area 21.
It is stored in (FIG. 2) (S15), the received echo back data is passed to the retransmission interval time calculation means 3 (S16), and the retransmission interval time calculation means 3 performs the retransmission interval time calculation processing (S17). If the received echo back data is not the data sent from the local system, send data having the same contents as the received echo back data is created (S1
8), data transmission processing is performed (S19 (data transmission processing of FIG. 3A)). Although the data receiving process of the system (1) has been described above, the same applies to the case of the system 2.

Regarding the retransmission interval time calculation processing
(FIG. 4 (b)) In this process, the value (provisionally, that value is A) in the echo back data transmission / reception time measured value storage area 21 (FIG. 2) is read (S30), and the read value A is fixed. A value added with the value α (correction value) is stored in the retransmission interval time storage area 20 (S31). The retransmission interval time calculation processing of the system (1) has been described above, but the same applies to the case of the system (2). Next, the retransmission process (FIG. 4 (c)) will be described. In this processing, a retransmission request from the timer means (1) 6 (retransmission timer) requesting the control means to retransmit the data at the time indicated by the value of the retransmission interval time storage area 20 is transmitted to the control means 4 (S35). Control means 4 which has received the retransmission request signal
Creates retransmission data (S36) and performs data transmission processing
(S37 (data transmission process of FIG. 3A)). In the system above
Although the retransmission process of (1) has been described, the same applies to the case of system (2).

As described above, according to the present invention, the retransmission interval time is periodically changed according to the periodic echo back data transmission / reception time, and the optimum retransmission interval time is always set according to the system load. It is possible.

[0013]

As is apparent from the above-described embodiment, the present invention changes the retransmission interval time periodically according to the periodic transmission / reception time of echo back data, and always keeps the optimum retransmission interval according to the system load. This has the effect of enabling retransmission in time and improving the data transmission efficiency including retransmission.

[Brief description of drawings]

FIG. 1 is a system configuration diagram in an embodiment of the present invention.

FIG. 2 is a diagram showing a structure of data stored in a storage unit according to an embodiment of the present invention.

FIG. 3 is a flowchart of a data transmission process and a data reception process in the embodiment of the present invention.

FIG. 4 is a flowchart of an echo back data transmission process, a retransmission interval time calculation process, and a retransmission process according to an embodiment of the present invention.

FIG. 5 is a configuration diagram of a system in a conventional example.

FIG. 6 is a diagram showing a structure of data stored in a storage unit in a conventional example.

FIG. 7 is a flowchart of a data transmission process and a data reception process in a conventional example.

FIG. 8 is a flowchart of a retransmission process in a conventional example.

[Explanation of symbols]

1,51… System (1), 10,60… System (2), 2,
11, 52, 61 ... HDLC control means, 3, 12 ... Retransmission interval time calculation means, 4, 13, 53, 62 ... Control means,
5, 14, 55, 64 ... storage means, 6, 15, 54, 63 ... timer means (1), 7, 16 ... timer means (2), 8, 17 ... timer means (3), 20, 70 ... resend Interval time storage area,
21 ... Echo back data transmission / reception time measurement value storage area.

Claims (1)

[Claims] 1. In a data transmission procedure capable of retransmitting data, a frame control means for performing frame control at the time of data transmission / reception according to the data transmission procedure, a timer means group for periodically sending a control signal, and an optimum And a retransmission interval time calculating means for calculating a unique retransmission interval time,
The storage unit stores the result of calculating the optimum retransmission interval time, the data transmission procedure, the control unit for controlling each unit, and the transmission / reception of echo back data. The echo back data is transmitted periodically. A data communication method in which the retransmission interval time of the data is periodically changed from the time from the transmission of the transmitted echo back data to the reception, and the retransmission can be performed within the retransmission interval time.