JPS6271348A - Loop type data transmission control system - Google Patents

Abstract

PURPOSE:To constitute a fault tolerance loop transmission system without missing the transmission of a message to a HOST by detecting the presence of the 1st message whose structure is changed even when a new message having the same serial number as the preceding received serial number when the structure of the transmission line is changed. CONSTITUTION:A message destination sets a structure change flag SF 79 and when the message returned to the sender is not detoured, that is, the level of the detour flag of the returned message is logic 0, the flag SF is brought into logic 0. When the returned message is detoured (when the detour flag is logic 1), the level of the structure change flag SF is brought into logic 1. Thus, the first message where the structure of the transmission system is recovered is discriminated and the message is set to the HOST.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a data transmission control system having a loop transmission line on opposite sides of a trapezoid for assigning serial numbers to data and transmitting the data. The present invention relates to a serial number management method suitable for completely preventing missed receptions.

[Background of the invention]

The conventional loop type transmission control method was
As described in 1, a message has a series of sequence numbers within a predefined range, and a detour flag is also provided to indicate that the message has been detoured, and it is determined whether the message should be transmitted to the 1HO8T computer. . However, in the conventional method, when each node detours/recovers and changes its structure, the previously received sequence number remains, and if the sequence numbers of the old and new messages match, HO8T No consideration was given to not sending the data to a computer.

[Purpose of the invention]

The purpose of the present invention is to solve the problem of matching serial numbers due to structural changes during detour/recovery caused by an abnormality in a transmission node or a line in a multi-loop loop data transmission control system, and to prevent duplex reception of each node. 'The prevention function causes messages to be missed in being sent to the HO8T computer, but by adding a structural change flag to the serial number of the gold transmission message to detect the above structural change, the HO8T
The object of the present invention is to provide a loop-type data transmission control system that completely prevents leakage of messages sent to a computer.

[Summary of the invention]

In the conventional loop-type transmission control method, as stated in the above purpose, a message may be missed to be sent to the HO8T computer due to a coincidence of serial numbers caused by an abnormality in the transmission node or line, but data detours can be detected. A means for detecting a structural change, and a sequence number added to the message are used to determine whether or not to send data to the HO8T computer, thereby preventing data from being omitted from being sent to the HO8T computer when the structure changes. It is something to do.

[Embodiments of the invention]

Embodiments of the present invention will be explained below with reference to FIGS. 1 to 4. FIG. 1 shows the overall configuration of a loop transmission control system. The system has loop transmission lines 1 and 2 that transmit all information in opposite directions, and a transmission control device (network control processor) is installed on the transmission line.
Network Control processor,
Hereinafter referred to as rNcPJ. ) 11-13 and 21-23
There are 100 to 30 detours between paired NCPs.
Connected with 0. In addition, each NCP pair has processing devices (hereinafter referred to as rHO8TJ) 31 to 33 connected to a transmission line 311.
-313 and 321-323 are connected as shown in the figure.

Now, when loop transmission paths 1 and 2 and each NCP are in a normal state, for example, when HO8T31 sends a message to NCPll, NcPll becomes the source, transmits the message to transmission path 1, and NCP12. 13
k via L-'(, returns to the source NCPII.
The figure shows an example of a message in a conventional transmission control system. The message 70 has a flag [F] 71. indicating that it is the beginning of the message. Function code (FC) indicating data content and function 72. Address of the NCP that created and sent the message (sender address: 5A)
73. Serial number of outgoing message for each source NCP (
Serial number: CC)74. Detour flag (LF) 75 indicating the detour status of the message. Detour color (LC) 76 indicating the number of times the message was detoured, Data 77
and a flag [F] 78 indicating the end of the message.

Here, the detour flag 75 is, for example, +1 Q II.

It takes two values: II and III, and when this value is ゛1'', the NCP that has received the message 7G unconditionally sends the message 1 to the transmission line. -178419) In the conventional loop transmission method, the detour flag 75 is
NCPs other than the originator that have received the message transmit the message to the HO8Ts connected to them. When the detour flag 75 is 1", no message is sent to )i0sT. In the case of FIG. 1, the loop transmission system is normal, and the detour flag of the message from the sender 11 is 'o.
#, so NCPs 12 and 13 on the same transmission path 1 are
Send the received message to 'eHO8T.

FIG. 3 shows that in a loop transmission system with the same configuration as in FIG. If it is detected by the check data (see Japanese Patent Publication No. 58-47111 for details), the detour flag LF'z of the message sent by the NCP II is inverted to "1", and the message is detoured to the NCP 22. The NCP 22 transmits the message as is onto the transmission line 2. Source NCP
The NCP 21 of II inverts this detour flag t'''O# and transmits the message onto the transmission path 2.
The NCP 23 that received the message No. 21 normally
Since the NCPII message is received as a new message, the message is transmitted as is onto the transmission path, and the entire message is transmitted to the HO8T33. Normally, when the serial number (CC) 74 of the message matches the serial number of the same source address received last time, the message is determined to have received the same data, that is, is determined to be retransmission data, and is not transmitted to the HO8T.

However, when each NCP and transmission line fails and recovers, depending on the failure mode, there may be an NCP through which the detoured message does not pass.

For example, in FIG. 3, detour 5 does not pass through NCP 13. Therefore, the serial number of the old message that was previously received remains in the NCP 13, and when the failure of the transmission line 6 is recovered, the serial number (CC) 74 of the new message and the serial number of the old message match, and , a new message that should be transmitted to HO8T is not transmitted to HO8T. This is because there can only be a finite number of serial numbers, and the probability of occurrence is the reciprocal of that number.

Therefore, in the present invention, as shown in FIG. 4, a message 80 is added with a structural change flag (SF) 79'e.

Structural change flag (SF) 79 indicates that the message sender is
When a message that returns to the sender is not detoured, that is, when the detour flag of the returned message is "O", all SFs are set to "'0".

When the call message is being detoured (the detour flag is set to
”), the structural change flag 5Fft is set to “1”.

In this way, as shown in Fig. 3, if a detour is configured and the failed transmission line 6 is restored, the NC
Even if the serial number (CC) 74 of the NCPII message newly received by P13 matches the previous received serial number, the detour flag is "0" and the structure change flag SF is still 1, and the call is sent on the same loop. Since the original message is received, it can be determined that this is the first message when the structure of the transmission system has been restored, and the entire message can be transmitted to HO8T.

Here, we have described the case when a message with 5F=1 is received, but also when a message with SF20 is received, the structure of the transmission system has changed and it is possible to fully detect that the first message has been received. Even if the serial numbers match, a new message can be sent to 1HO8T.

Note that the above example is just one method, and the structural change flag SF is set to 11111 only immediately after a change occurs.
The method for realizing this is not entirely limited, such as a method in which the next data is set to "O" and treated as new data only when SF2"IH.

〔Effect of the invention〕

According to the present invention, in a multiplex loop transmission system, when the structure of the transmission path changes, even if a new message with the same serial number as the previous reception serial number is received, the first message whose structure has changed Since it can be detected that H
This has the effect of configuring a fault-tolerant loop transmission system that does not fail to send messages to the O8T.

[Brief explanation of drawings]

Figure 1 shows the overall configuration of the loop transmission system, Figure 2 shows the overall configuration of the loop transmission system.
Figure 3 shows the message transmission format of the conventional transmission method (Figure 3), Figure 3 is a diagram explaining the entire operation when an abnormality occurs, and Figure W4 shows an example of the message transmission format used in the present invention. . 1.2...Loop transmission line, 11.12.13.21.
22゜23 ・N CP, 31.32.33-M physical equipment (HO8T>, 100.200,300... detour, 3-11.312.313゜321.322,32
3...Processing device, NCP transmission line, 70.80...
Message, 79... Structural change flag. Agent Patent Attorney Katsuo Ogawa 1 Figure 32 Figure 100 3 Figure 4 Figure 8ρ

Claims (1)

[Claims] In each transmission control device of a double-loop transmission system consisting of a plurality of paired transmission control devices and loop transmission paths with transmission directions opposite to each other, failure/recovery of the transmission control device or transmission path is required. The method includes a first means for detecting that the transmission path of the transmission system has changed, a second means for detecting that the data has been detoured, and a third means for adding a series of sequence numbers to the data. When a change occurs in the transmission path of the loop transmission path, information indicating the change is added to the transmission data, and the transmission control device that receives the data sets the sequence number to the same as the sequence number of the data received in the past. 1. A loop data transmission control system characterized in that even if the data has a structure change, if the information indicating the structural change indicates a change in the route, the data is received as new data.