JPS5871750A - Loop data communication system - Google Patents

Abstract

PURPOSE:To realize a loop transmission in an economical way, by making full use of an optical transmission line. CONSTITUTION:Transmission controlling stations 12 (12-1-12-n) are connected to a loop transmission line 11 of an optical cable to stoe many data communication devices 13 (13-1-13-m). Thus mutual communication is carried out between a device 13 belonging to an optional station 12 and another device 13 of another station 12. In this case, the station 12 divides the telegrams sent from the device 13 to the telegram unit or subblocks and composes the information frames. The information fame including the data addressed to the device 13 of another station 12 is fed to the line 11 based on the prescribed order of transmission. Then the other station 12 receives the information frame and then distributes the data addresses to the own device 13 to the corresponding device 13 when the data is found out. When the transmission is over for the information frame of a station 12, the right of transmission is shifted to the subsequent station 12.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to data communication line systems, particularly to the field referred to as high-speed networks. Traditionally, in this field, huge loop transmission lines known as data highways and data freeways have been developed using lines such as coaxial cables, but recently advances in optical cables are expanding the range of applications. The main application areas are process control and office automation, so-called internal transmission.

The conventional loop transmission method in Todoro is MSD from (1).
LC! Loop, (2) Bucket method represented by However, method (2) has advantages and disadvantages, such as a large transmission delay time.

On the other hand, the characteristics of the optical transmission line are significantly better than those of conventional electric wire transmission lines, and errors can be virtually ignored in practice. For this reason, (3) fixed slot time division method has been proposed as a low-cost loop method, but it has drawbacks such as poor matching to asynchronous lines and generation of idle (invalid) time slots on the transmission path. [The literature using method (3) above is based on (1) M
5ynchronous Data LinkCont
rol GeneralInformation GA
27-5095゜IBM, (2) f: IC engineering TT r
ecomen, aation X, 25.

(3) NEC data highway equipment, Nichiden Technical Report A
[January 13756] The present invention was made to eliminate the drawbacks of the conventional system as described above, and aims to economically realize loop transmission by utilizing the high quality of the optical transmission line. . The present invention is SY
This is particularly effective for systems that connect existing data communication equipment such as N-synchronization and start-stop synchronization to a loop-shaped transmission path. The present invention will be explained below with reference to the drawings.

Figure yp1 is a side view of the configuration of a loop data communication system embodying the present invention, in which a plurality of transmission control stations (referred to as Tcs) 12 are connected to a loop-shaped transmission line 11, and each TC81
2 is a case in which a large number of data communication devices (referred to as DTEs) 13 are connected to perform communication between arbitrary DTEs connected in a loop.

The loop transmission line 11 is a high-speed transmission line such as an optical cable.

Spear 2 is the TC in Spike 1! 812 is a block diagram of a configuration example of 812. In the figure, 21 is the same number of DTP buffers as DTICs for each DTE, 22 is a control unit that controls the flow of data, 25 is a loop transmission buffer, 24 is a loop reception buffer, 25
is a loop switch.

Figure 5 shows the transmission time chart and data transmission format (transmission format) of Figure 1.

In the following explanation, one of the DTEs DTP13-1 connected to one TC812-1 of the TO812 to TC!
For example, take the case of transmission to DTE 13-m connected to DTE 812-n. Before I get into the explanation, let me clarify the symbols in Figures 1 to 3. 51 is a transmission message of DTK, 52 is an information frame, 33 is a transmission header, 34 is a transmission trailer, 5
5 is the message subblock, 36 is the subblock header, 5
7 is the DTE telegram in the information frame, 38 is the DTE15-
Each of the messages shown in FIG.

Note that each TO 812 divides and organizes the message received from the DTE 15 that it accommodates into message units or subblocks, and sends the information frame 32 containing data addressed to the DTE accommodated in multiple TOEs to the loop transmission path. TCB of
While the Toe is transmitting, the other Toe receives the information frame 32, finds the data addressed to the DTE that it contains, and distributes it, and when the transmission of one information frame is completed, the transmission right is granted in a predetermined order. Another T (38) performs data communication between any DTEs connected to the loop.

Now, the data from DTE13-1 is temporarily stored in the corresponding DTK buffer 21 in TO812-1,
When the TC 812-1 has the right to transmit, it collects these data and creates an information frame 32.

DTK13-1 at the top of FIG. 13 occupies a part of the transmission time of TO812-1, and information frame 5
2 is a transmission header 55.2 as shown in the lower part of Figure 3. It consists of a plurality of message sub-blocks 55 and a transmission trailer 34, and the message sub-block includes a sub-block header 36 for identifying the destination and length, and transmission data 3 from the DTE.
1 and 37, which have the same content. The information frame 52 is created in the loop transmission buffer 25 and then sent out to the loop transmission line 11 via the loop switch 25.

The loop switch 25 connects only the TO 812-1 that has the transmission right between the transmission buffer 23 and the loop transmission line 11, and
T O'812 size 2 ~ without transmission rights other than C812 = 1
At 12-n, loop reception data is input. Such control of the loop switch 25 is performed by the control section 22.

On the other hand, the TOs 812-2 to 12-n, which do not have transmission rights, perform only reception operations, analyze the ladder 36 into sub-blocks in the information frame 32 received in the loop reception buffer 24, and store (WM) them in their own 12. If there is data addressed to the destination DTE, it is transferred to the DTE buffer 21 and then sent to the destination DTE 5. In the example of Figure 3, DT
It shows the progress in which the transmitted telegram 51 of Ei 3-1 becomes the received telegram 38 of DTE 15-m. The solid line part of each TC8 in Figure 3 is the transmission right acquisition time, and the hatching is the DTE during ToS.
The broken lines indicate the time during which each TC8 is receiving a message. Note that the transmission delay time T is the time from when a transmission message is input to the DTE until it is sent from the ToS.

Next, when TO812-1 finishes transmitting the information frame 32, the transmission right moves to T (3S12-2), which has the next transmission order, and transmits that information frame. In this way, the transmission right moves through the ToS in the loop in order, and by repeating this, data transmission between arbitrary DTEs (data communication equipment) can be performed. As described above, the amount of data stored in the D'TF and buffer 21 is determined in accordance with the period in which the ToS acquires the transmission right.

It can be seen that this period is close to the transmission delay time (T) shown in Figure 5. In a system that uses a high-speed transmission line such as an optical transmission line, this T can be set to a value that can be ignored in normal data communication.

Figure 4 is a time chart of an example in which checking the transmitted data is added to the above method. In this example, the transmission control station TC! which has the right to transmit! 512-1
The self-transmitted information frame 32 goes through the loop and confirms that the received information frame 41 is normal, and then sends the transmission right transfer command frame 42, which is the next in order, TO812-2. starts transmitting when it receives frame 42, and TC! 812-2 are controlled only to receive operation. If the information frame 41 that has passed through the loop is abnormal, a retransmission identification code is added and the information frame 32 is retransmitted. If the received information frame 41 does not return to normal, abnormality handling operations such as generating an alarm are performed.

As is clear from the above description, according to the present invention, it is possible to economically create a loop transmission method by utilizing the characteristics of high-quality transmission lines such as optical cables, and communication between arbitrary DTEs connected to the loop is possible. It has the advantage that it can be used regardless of the synchronization method because it is a buffer method.

[Brief explanation of drawings]

Figure 1 is a configuration example diagram of the loop data communication method of the present invention.
Figure 2 is an example of the configuration of transmission control station TC8 in Figure 1, Figure 3 is the time chart and data transmission format of the transmission shown in Figure 1, and Figure 4 is the transmission when the transmission data confirmation function is added. This is a time chart. 11... Loop transmission path, 12... Transmission control station (ToS), 15... Data communication device (
DTE). 21...DTE buffer, 22...control unit, 23.
...Loop transmitting buffer, 24...Loop receiving buffer, 25...Loop switch, 51...DTE
Transmission message, 62... Information frame, 53... Transmission header, 64... Transmission trailer, 55...
Message sub-block, 56...Sub-block header, 5
7...DTEt sentence in information frame, 38...D
TI received message, 41... Information frame that has gone through the loop, 42... Transmission right transfer command frame. Patent Applicant Kokusai Denki Co., Ltd. Agent Otsuka 1 external person Figure 3 → Time 2 254- Figure 4 □ Time

Claims (2)

[Claims] (1) Mutual communication between data communication devices belonging to any transmission control station and data communication devices belonging to other transmission control stations by connecting multiple transmission control stations accommodating a large number of data communication devices in a loop-shaped transmission path To perform this, each transmission control station divides the message from the data communication device it accommodates into message units or sub-blocks, organizes an information frame, and then divides the message from the data communication device it accommodates into data communication devices accommodated in other transmission control stations other than itself. The information frame containing the destination data is sent to the loop transmission path in a predetermined transmission order, and all other transmission control stations receive the information frame and find the data addressed to the data communication device they accommodate. The loop data communication system is characterized in that when one transmission control station finishes transmitting an information frame, the transmission right is transferred to the next transmission control station. (2) A patent claim characterized in that the transmission control station that holds the transmission right goes around the loop-shaped transmission path, confirms that the self-sent information frame that arrived is normal, and then transfers the transmission right to the next one. The loop data communication method described in Clause 1.