JPH01140835A - Data delivery system - Google Patents

Abstract

PURPOSE:To improve reliability and transmission efficiency by duplexing receiving source equipment and bus, and fetching reception data into a self system if the sequence numbers of reception data in an opposite system are continued when the discontinuity of the sequence numbers is detected. CONSTITUTION:The receiving source equipments (man machine interface unit) 1a and 1b receive data to which the sequence numbers are added through the buses 2a and 2b. Respective receiving source equipments 1a and 1b check the continuity of the sequence numbers by respective sequence number detection means 11. When they are continuous, the means 11 decides reception data to be accurate, and stores them in a memory area. When the discontinuity of the sequence numbers in the opposite system is detected in either of the receiving source equipments 1a and 1b, the continuity of the sequence numbers in the opposite system is recognized through a data link 5, and the reception data is fetched into the self system when the sequence numbers in the opposite system are normal.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a data transfer method, particularly a man-machine interface unit in a remote monitoring and control system in which a man-machine interface unit is connected to a plurality of transmission units via a bus. This relates to a data transfer method on the machine interface unit and on the bus.

[Conventional technology]

FIG. 4 is a block diagram showing a conventional data delivery system disclosed in, for example, Japanese Patent Application Laid-Open No. 152142/1982. 2 is a bus to which this man-machine interface unit l is connected; 3 is a bus to which the man-machine interface unit l is connected; each of them is equipped with a sequence number adding means 31 and a retransmission detecting means 32; A transmission unit 4 is a controlled device connected to each of the transmission units 3, which are connected to a plurality of transmission units as data transmission source devices.

Next, the operation will be explained. When each transmission unit 3 receives data to be transferred to the man-machine interface unit I from the controlled device 4 connected to it,
A sequence number adding means 31 adds a sequence number to the data and sends it to the bus 2. This sequence number changes continuously each time the transmission unit 3 transmits data. The data to which this sequence number has been added is received by the man-machine interface unit 1 from the bus 2, and is received by the sequence number detection means 11.
The continuity of the sequence numbers is checked at . As a result, if the sequence numbers are consecutive, the received data is assumed to be correct and stored in the corresponding memory area.

If the data is discontinuous, the man-machine interface unit 1 determines that there is a data loss between them, and sends a data retransmission request from the retransmission request means 12 to the transmission unit 3 that sent the data. Send. Retransmission detection means 3 detects the retransmission request sent via bus 2.
The corresponding transmission unit 3 that has received the data in step 2 uses the sequence number adding means 31 to add the same nullification number as the previous data to the data requested to be retransmitted, and retransmits the data. The man-machine interface unit that received this retransmitted data! The sequence number detecting means 11 checks the sequence number again, and if the sequence number is that of the data requested to be retransmitted, the data is regarded as correct and stored in a predetermined memory area. Furthermore, if the data is not the data for which retransmission was requested, the data is regarded as missing and an alarm is output.

[Problem that the invention seeks to solve]

Since the conventional data transfer method is configured as shown below, each time the man-machine interface unit 1 detects discontinuity in sequence numbers, it sends a retransmission request to the corresponding transmission unit 3 and requests retransmission. Since the transmission unit 3 that receives the request retransmits the corresponding data to the man-machine interface unit 1, not only does the transmission efficiency decrease, but a failure in the man-machine interface unit 1 or the bus 2 may cause the system to go down. There was a problem that there was a direct connection and the reliability of the entire system was lost.

This invention was made to solve the above-mentioned problems, and aims to provide a data transfer method with high transmission efficiency and high reliability of the entire system.

[Means for solving problems]

The data transfer method according to the present invention duplicates the receiving device and the bus, connects the receiving devices of both systems with a data link, and assigns a continuously changing sequence number to the data sent from the sending device. The receiving device checks the continuity of the sequence numbers, and if they are discontinuous,
If the sequence numbers of the received data of the receiving device of the other system are consecutive, the received data of the other system is imported into the own system as correct data, and if it is also discontinuous, a retransmission request is sent to the sending device. This is what we do.

[Effect]

The data delivery method in this invention increases the reliability of the entire system by duplicating the receiving device and the bus, and further adds a sequence number that changes continuously to the data sent from the sending device and sends it out. The receiving device that receives this checks the continuity of the sequence number, and
If discontinuity is detected, check the sequence numbers of the data received by the receiving device of the other system, and if they are consecutive, the received data of the receiving device of the other system is treated as correct data and the own system By making a retransmission request to the source device only when the received information is discontinuous, the number of retransmission requests can be reduced and transmission efficiency can be improved.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, 3 is a transmission unit as a source device d;
4 is a controlled device, 11 is a sequence number detection means, 12
3I is a retransmission request means, 3I is a sequence number addition means, 32
4 is a retransmission detection means, which is the same as, or corresponds to, those in the prior art denoted by the same reference numerals in FIG. 4, and therefore detailed description thereof will be omitted. In addition, Ia and lb are man-machine interface units as duplexed receiving source devices, and are equipped with the sequence number detection means 11 and retransmission request means 12 as in the conventional unit, and 2a and 2b are duplexed man-machine interface units. This is a bus corresponding to each of the man-machine interface units Ia and Ib. Further, 5 is a data link connecting the man-machine interface units Ia and ib of both systems.

Next, the operation will be explained. Here, FIG. 2 is a flowchart showing the operating procedure of the transmission unit 3, and FIG. 3 is a flowchart showing the operating procedure of the man-machine interface units la and lb.

Each transmission unit 3 has a controlled device 4 connected to it.
When transferring data from the man-machine interface units Ia and Ib to the man-machine interface units la and Ib, first, it is determined whether there is a retransmission request from the man-machine interface units Ia or Ib (step ST1).

If there is no retransmission request, the sequence number adding means 31 adds a sequence number to the data taken in from the controlled device 4 and sends it to each of the buses 2a and 2b of both systems (
Step 5T2). This sequence number changes continuously each time the transmission unit 3 transmits data.

The man-machine interface units 1a and 1b receive the data to which this sequence number has been added via the corresponding bus 2a or 2b (step 5TI).
O). Each man-machine interface unit Ia,
Ib checks the continuity of sequence numbers by each sequence number detection means 1 in step 5T.
11) If the sequence numbers are consecutive, the received data is regarded as correct and stored in the corresponding memory area (step ST+2). Also, man-machine
If discontinuity in sequence numbers is detected in either interface unit Ia or 1b,
The continuity of the sequence numbers of the other party's man-machine interface unit 1b or 1a is confirmed via the data link 5 (step 5T13). As a result, if the sequence number of the partner system is normal, the data received by the man-machine interface unit Ib or 1a of the partner system is taken into the own system (step ST14).

Also, if the sequence number of the other system is also abnormal,
It is determined that there is a data loss during that time, and the retransmission request means 12 requests the transmission unit 3 that transmitted the data to retransmit the data (step 5T15).

When the corresponding transmission unit 3 detects that the retransmission request sent via the bus 2 has been received by the retransmission detection means 32 (step 5TI), the corresponding transmission unit 3 transmits the data with the sequence number for which the retransmission request has been made. It is added and retransmitted to buses 2a and 2b (step 5T3). The man-machine interface units 1a and 1b receive and receive the retransmitted data from the transmission unit 3 via the corresponding buses 2a and 2b (step ST+6), and check the normality of the sequence number of the retransmitted data using the sequence number detection means 11. Check (step ST] 7). As a result, if the sequence number is normal, the process is passed to step ST+2, and the retransmission data is stored in a predetermined memory area as correct data. Furthermore, if the sequence number of the retransmitted data is abnormal and different from the sequence number of the data that requested retransmission, the data is regarded as missing and an alarm is output (step 5TI8).

In addition, in the above example, the received data is treated as having the same reliability even when both systems are healthy and when only one system is healthy, but data that is healthy on both systems is treated as "GOOD". , “po” is used for data where only one line is healthy.
A quality code called "oR" may be added to weight the reliability of the data. By doing so, the reliability of the data can be further improved.

〔Effect of the invention〕

According to the present invention, the receiving device and the bus are duplicated, and when the receiving device detects discontinuity in the sequence number added to the transmitted data, it changes the sequence of the received data of the other system. If the numbers are consecutive, the received data is imported into the own system, and only if the numbers are discontinuous, a retransmission request is made to the source device, so the reliability of the entire system is high. This has the effect of providing a data transfer method with high transmission efficiency.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a data transfer method according to an embodiment of the present invention, FIGS. 2 and 3 are flow charts showing its operation, and FIG. 4 is a block diagram showing a conventional data transfer method. Ia and Ib are reception source devices (man-machine interface units), 2a and 2b are buses, 3 is a transmission source device (transmission unit), and 5 is a data link. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Figure 1 rU 5; Chi 7'Jn 7

Claims (1)

[Claims] In a data transfer method in which a receiving device is connected to a sending source device via a bus, and data is transmitted from the sending device to the receiving device, the receiving device and the bus are duplexed, and the duplexed receiving device is The source devices are connected by a data link, and the source device adds a sequence number that changes continuously each time data is transmitted to the data to be transmitted, and the receiving device If it is detected that the sequence numbers added to the data are discontinuous, check the sequence numbers of the data received by the receiving device of the other party via the data link, and check whether the sequence numbers are consecutive. If you are
If the received data from the receiving device of the partner system is taken into the own system as correct data, but it is also discontinuous,
A data delivery method characterized in that a retransmission request is made to the transmission source device.