JPS61224637A - Data transmission system - Google Patents

Abstract

PURPOSE:To prevent a fault in each terminal device from giving affect onto other terminal device and to make the chance of transmission of each terminal device equal to each other by providing a data sending order changing means moving down the data sending enable order of a terminal device to the lowest rank when one terminal device among plural terminal devices sends a data. CONSTITUTION:A bus supervision section 12 outputs a count start signal 105 to a synchronous counter SC and a terminal gap counter TG when a bus detection signal 104 changes. The SC has an end time longer than a count end time of any TG and the count end time of the TG differs from each terminal device. In order to make the transmission chance of each terminal device equal to each other, an operating time control section 16 controls the count end time of the TG so as to obtain the sending order listed in table according to the number of the terminal device itself and a sending terminal number signal 112. A transmission enable signal 108 is sent from the TG completing the count to a transmission section 14 to sends the data to a bus 100. When the detection signal 104 is outputted, a count stop signal 106 is outputted and the SC is stopped. The count of the SC is finished even without the signal 106 when no sending data exists at the terminal device.

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to a data transmission system, and in particular, it prevents failure of each terminal from affecting other terminals, and further improves the efficiency of use of data transmission media. The present invention relates to a data transmission method in which each terminal has the same opportunity to transmit data to a transmission medium.

(Prior art) When data is transmitted through a data transmission medium by several terminals, a collision of transmitted data occurs on the transmission medium due to asynchronous control of each terminal, and data transmission becomes impossible or transmission is interrupted. Even if it is possible, mD may occur as a result. Therefore, various improvements have been made.

One method is to provide a controller at one location and control all terminals. Since a single controller controls a plurality of terminals, there is no chance of data colliding at each terminal, but if the controller is damaged, data transmission itself becomes impossible.

Furthermore, a method has been proposed in which each terminal transmits data without permission, and if a data collision occurs, the data is retransmitted after a random delay. This method is not necessary and may not be able to transmit all data.

Furthermore, there is a method of forwarding transmission permission data to each terminal and transmitting data only when the terminal has the permission data. There is a restriction that permission to send data cannot be granted until each terminal has been visited.

Another method is to allocate time to each terminal and make it transmit periodically. In this case, collisions can be avoided, but data can only be sent periodically and the efficiency of using the transmission medium is low.

Therefore, the method described above is suitable for cases where there are many opportunities for data transmission, such as data transmission using data buses in aircraft and submarines, and high reliability requirements are required. There are advantages and disadvantages in cases where it is required that there be no impact on other departments.

(Problems to be Solved by the Invention) As mentioned above, the problems in the conventional technology that the present invention attempts to solve are that even if a failure occurs, it spreads to others, and even if data transmission opportunities are almost equal, Data transmission media cannot be used effectively due to time limitations, etc.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a data transmission system that solves the above-mentioned drawbacks.

(Means for Solving the Problems) The data transmission system according to the present invention is a f-1 transmission system in which data is transmitted through a data transmission medium by a plurality of terminals, when the data transmission on the transmission medium is completed. Putting each terminal into a state capable of transmitting data to the transmission medium at a time point that differs from the time point to the point in time for each terminal,
When all the terminals have passed the data transmission enabled state, if there is no data transmission to the transmission medium, one of the terminals becomes data transmission enabled and transmits dummy data to the transmission medium. Each of the terminals has a unique number and a rank in which it can transmit data, and when any one of the terminals transmits data, the rank in which it can transmit data is determined. This is a method of moving down to the lowest position. and data transmission order changing means for lowering the data transmission possible order of the terminal to the lowest when any one of the terminals transmits data.

(Example) Next, the present invention will be described in detail with reference to drawings showing examples. FIG. 1 is a block diagram showing an overview of the present invention, FIG. 2 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 3 is a time chart showing the time relationship of data transmission in the embodiment of the present invention, and FIG. FIG. 4 is a time chart showing the time relationship of dummy data transmission in the embodiment of the present invention.

An outline of an embodiment of the present invention will be explained.

Referring to FIG. 1, an overview of an embodiment including the present invention includes a data bus 100, terminals DT connected thereto, -
...DTn, and peripheral devices P1, ....P, including interfaces connected through this.

Each terminal is connected to operate independently with respect to data transmission and reception, ie, without common control. The signals on the data bus 100 are constantly monitored through a receiving section in the terminal.
When there is a signal in , transmission permission is given to the terminal corresponding to the delay time of 7 after a certain time delay from the time when the transmission of the signal is completed. Therefore, prevention of double transmission of data signals and prevention of collision of data signals on the bus are ensured.

It does not transmit data unless the data to be transmitted is prepared to the terminal that has received transmission permission, and gives transmission permission to a terminal with a longer delay time. With such a configuration, even if multiple terminals fail and do not transmit, the failure will only affect that terminal and not other terminals.

In addition, if all terminals do not transmit even after receiving transmission permission, each terminal semi-biases the transmission of dummy data when a long delay time has passed for all terminals, and has the shortest delay time. Give the device permission to send.

In this manner, even when there is no data to be transmitted, when the transmission of dummy data within the data bus is completed, transmission permission is again given sequentially from the terminal with the shortest delay time, and the data transmission function is maintained. In the case of Jin, if one terminal fails and cannot send dummy data, that terminal can also send dummy data from a terminal with a long delay time, so other terminals are not affected. Become.

Here, we will discuss averaging the transmission opportunities of the terminal that has the longest delay time (its transmission ranking is the lowest).

Each terminal is independent and can be controlled differentially from the outside.The information available for each terminal is its own terminal number, which determines the transmission order at the time of initial setting, and the number of the transmitting terminal.

The number of the transmitting terminal is resolved by including the number of the transmitting terminal in the transmitted data and dummy data.

Therefore, when a terminal transmits, it is placed in the lowest position, and the transmission order of other terminals is determined by determining the transmission order of each terminal depending on the transmitting terminal number. That is, the transmitting terminal's transmission + lj 1st place is the lowest, and the terminals having the number next to the transmitting terminal number are sequentially numbered 1, 2, 3, and so on.
. . . The transmission order is determined, and after the terminal with the last number, the terminal returns to the terminal with number 1. In the same way, the transmission rank is sequentially ranked as I & 1, ending with the terminal with the number before the transmitting terminal number.

Table 1 (a) shows the transmission order of each terminal according to the sending terminal number that transmitted when the number of terminals is 7. It is clear that the transmission order of each terminal is relatively random. Table 1(b) is a version of Table 1(a) arranged in order of transmitting terminal number.If the transmitting terminal number is known, the transmitting order of each terminal can be determined, which simplifies the configuration of each terminal.

Below 1. 1 White Table 1 (a) Table 1 (b) Next, the operation of an embodiment of the present invention will be explained using a time chart.

Referring to FIGS. 3 and 4, terminals DT, . . . D
T, respectively, are terminal gap counters TG,...TG
, and indicates a high level when counting, and a low level when not counting.

Masu#! Referring to Figure 3, data signal 2 of the data bus
01 is transmitted, all terminals except the transmitting terminal receive it, and the terminal corresponding to the transfer destination of the data signal 201 captures it.

When the data signal 201 is completed, the terminal gap counter T
01 to T G * and synchronous counters SC1 to SC, which are longer than any of these count times and have substantially the same count time, start counting. Here, initially the terminal DTl e DTt * DTS *...
When the terminal DT is scheduled to send data, the terminal gap counter TG of the terminal DT completes counting and becomes ready for data transmission. do. However, since there is no data to send, when terminal DT completes the terminal gap count and becomes ready to send data, data 2 is sent from terminal DT.
Transmission of 02 is started. The transmission of the data 202 causes the terminal gap counters TG, ~TG, and synchronization counters 8C, . . . , SC, to stop.

With the transmission of data 202 from the terminal DT, the transmission order of the terminals determined by the count time of the terminal gap counter becomes the order shown by the transmitting terminal number 2 in Table 2.

Table 2 When the transmission of data 202 is completed, all the counters start operating, and the terminal gap counters sequentially finish counting according to the 11th transmission position in Table 2, and at that point the terminal becomes ready for data transmission. The terminal gap counter TG3 of the terminal DT has finished counting, and the transmitted data is further transmitted to the terminal D.
When the terminal gap counter ends counting, data 203 is transmitted and the terminal gap counter and synchronization counter stop.

Here, the transmission order of the terminals is as shown in transmission terminal number 4 in Table 2. When the transmission of data 203 is completed, the terminal gap counter and synchronization counter start operating again, and the terminal DT with transmission data, When the terminal gap counter TG finishes counting 30, the data is 20.
4 is sent from terminal DT3, resulting in stopping all synchronization counters.

The method of enabling data transmission in this manner has been explained using the time chart.

Next, with reference to FIG. 4, the situation when the terminals DT, -DT do not plan to transmit data will be explained.

First, terminal DT! When the transmission of the data 205 sent from 1 is completed, all terminal gap counters TG, ~
TG, synchronous color/re 8 Ct -8Ca starts counting, and terminal gap counters TGt to TG m complete counting one after another according to the transmission order of the terminals and become ready to transmit data, but data transmission is scheduled. Since the terminal gap counter completes counting, the synchronization counters SC1 to SCB start counting, and dummy data is scheduled to be transmitted at the same time.

Therefore, the dummy data 206 is transmitted at the time when the terminal gap counter TGt of the terminal DT having the highest transmission rank 11 completes counting. Since the gap counters of other terminals stop at the same time as the transmission of dummy data 206 starts, preparation for transmission of dummy data is canceled. After this, there is no data to be transmitted at the next data transmission opportunity, and furthermore, the terminal DT,
Even when dummy data cannot be sent due to a malfunction,
Dummy data 207 is transmitted from terminal DT. The method of transmitting dummy data in this way has been explained using the time chart.

Next, an embodiment of the present invention will be described, focusing on its configuration and operation.

Referring to FIG. 2, this embodiment includes a data bus 100, a terminal DT, and peripheral equipment P. Also, the terminal DTF
i reception section 11, bus monitoring section 12, dummy data generation section 13, transmission selection section 14, transmission section 15, operating time control section 16, insulation coupler 17, synchronization counter SC, terminal gap counter It is equipped with TG.

The data signal of the data bus 100 is constantly supplied to the receiving section 11 through the insulating coupler 17, and the data signal is transmitted to the terminal D.
If the data signal is labeled to be captured at T, this data signal is supplied to the peripheral device P. When there is a signal on the data bus, a high-level bus detection signal 104 including the transmitting terminal number of the data signal is output to the bus monitoring section 12. The bus monitoring unit 12 outputs a count start signal 105 to the synchronization counter SC and the terminal gap counter TG at the time when the bus detection signal 104 changes from high level to low level.

The synchronization counter SC is the terminal gap counter T.
The count completion time of the terminal gap counter TG is controlled by the count control signal 110 outputted from the operation time control section 16, and the terminal gap counter TG has a completion time longer than the count completion time of the terminal gap counter TG that is connected to the data path 100. It is different from that.

In order to equalize the transmission opportunities of each terminal, the operation time control unit 16 adjusts the transmission order so that the transmission order obtained from Table 2 is obtained according to the terminal's own number and the transmission terminal number signal 112 outputted from the bus monitoring unit. outputs a count control signal 110 to control the count completion time of the terminal gap counter TG.

From the terminal gap counter TG that has finished counting,
At that point, a transmission enable signal 108 is sent to the transmission selection section 14. At this time, data that needs to be transmitted from the peripheral device P is supplied to the transmission selection section 14, and the data is sent to the transmission section 15.
and is transmitted to bus 100 through insulating coupler 1. The bus detection signal 104 changes from a low level to a high level through the insulating coupler 17 and the receiver 11.
At this point, a count stop signal 106 is output to the synchronous counter SC and the terminal gap counter TG, and the synchronous counter 8C stops.

However, when the terminal connected to the data bus 100 has no data that needs to be transmitted, the count stop signal 10
Counting of the synchronization counter SC is completed even without 5.

At this time, the dummy data transmission trigger signal 107 from the synchronous counter 8C triggers the bus monitoring section 12 to start counting (outputs the %f number 105, and the synchronous counter S
C and the terminal gap counter T() start counting, and is also supplied to the dummy data generating section 13 to prepare for transmitting dummy data. Signal 1 that can be sent after this
08 is added to the transmission selection section 14, dummy data is outputted from the dummy data generation section 13 to the data bus 100 through the transmission selection section 14 and the transmission section 15.

Note that the count completion time (delay time) by the terminal gap counter TG, taking into account the data transfer time on the data bus, the difference in the count completion time of each terminal is at least the time required for data to propagate over the entire data bus ( For example, when the length of the data bus is 30 m, it requires 0.1 μs or more.

In addition, in this case, the transmission order of each terminal when transmitting dummy data is the same as the transmission order of each terminal when transmitting data, but when transmitting dummy data, each terminal has the same transmission opportunity. Since it is not necessary to organize the terminals in the order of their terminal numbers, the transmission order of each terminal may be arranged in order of terminal number. In this case, if there is a terminal that is unable to send dummy data due to a failure, it can be determined that the terminal whose number is the highest by one by detecting the dummy data transmission terminal number is malfunctioning.

Furthermore, in the above-mentioned embodiment, the explanation has been given on the assumption that all terminals are in operation from the beginning. However, depending on how it is used, some terminals may be added later and become operational. At this time, if there are no duplicates in the terminal numbers of the data transmission devices, terminals that join later and start operation stop their transmission function after joining, and start normal operation only when data or dummy data appears on the data bus. Just do it like this.

In this way, the sending terminal number can be determined, and the sending order can be determined from this and the own terminal number. That is, the delay time of the terminal Gyazzo counter based on the transmission 1111 position is controlled through the count control signal according to the transmission terminal number obtained until the data or dummy data completes transfer on the data bus. Then, when transmission becomes possible, if there is data that needs to be transmitted, it is caused to be transmitted. If you do it like Jin, when another terminal joins later, there will be no problem in operation even if the relationship between the terminal number and the transmission order is unique.

(Effects of the Invention) As explained in detail above, the data transmission method of the present invention prevents collisions within the data transmission medium during data transmission, prevents the spread of failure to other terminals when a failure occurs in a terminal, and reduces reliability. This has the effect that the data transmission medium can be used effectively.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an overview of the present invention, Fig. 2 is a block diagram showing the configuration of an embodiment of the invention, and Fig. 3 shows the timing and timing of data transmission in an embodiment of the invention. Time Chart FIG. 4 is a time chart showing the time relationship of dummy data transmission in one embodiment of the present invention. 11... Receiving section, 12... Bus monitoring section, 13... Dummy data generating section, 14...
...Transmission selection section, 15... Transmission section, 16...
...Operating time control section, 17...Insulating coupler%
"l~P,...peripheral equipment, DT1~DT,...
...Data terminal, T01-TG, ...Terminal gap counter, SC1-SC, ...Phase synchronization counter.

Claims (1)

[Scope of Claims] In a data transmission method in which data is transmitted through a data transmission medium by a plurality of terminals, a point in time that differs for each terminal from the time when data transmission through the transmission medium ends sets each terminal in a state in which it is possible to send data to the transmission medium, and when all the terminals have passed the state in which they can send data, when there is no data to be sent to the transmission medium, they become in a state in which they can send data. Any one of the terminals transmits dummy data to the transmission medium, each of the terminals has a different unique number and a rank that allows transmission of different data, and one of the terminals A data transmission method characterized in that when one terminal transmits data, the data transmission possible rank of that terminal is lowered to the lowest.