JPH10215268A - Data transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the amount of data that one slave station can send in one transmission cycle by more than double by making one slave station, which needs to send data more than the amount of data that can be transmitted with single transmission acknowledgement, operate as more than one slave station. SOLUTION: A data transmission system 10 comprises slave stations 12 which send and receive data through a network and an administration station 11 which gives the slave stations 12 transmission acknowledgement of data blocks of less than a predetermined length in the transmission order of them. The slave station 12a with having the 1st place obtains transmission acknowledgement S1 from the administration station 11 and sends data S2. A slave station 12b allowed to have 2nd to 4th successive places in the transmission order obtains transmission acknowledgement S3 to send 1st data S4, obtains transmission acknowledgement S5 to send 2nd data S6, and obtains transmission acknowledgement S7 to send 3rd data S8. A similar data transmitting process is repeated and the final slave station 12n sends data S12 to the network in response to transmission acknowledgement S11, so that one cycle ends.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a management station connected to a network and one or more slave stations having a transmission order, and sets an upper limit on the data size that the slave station can transmit at one time. Data transmission device.

[0002]

2. Description of the Related Art FIG. 10 is a block diagram of a conventional data transmission system. In this data transmission system 1, one management station 2 exists on a network, and the management station 2
a, 3b, 3c,...

As shown in the time chart of FIG. 11, the management station 2 gives a transmission permission S1 to the slave station 3a having the highest transmission order, while the slave station 3a having the first transmission order has the data transmission S1.
Do 2. When the slave station 3a with the highest transmission order finishes transmitting the data S2, the management station 2 sets the slave station 3b with the second highest transmission order.
Is given a transmission permission S3, and so on.
, And transmission of data corresponding thereto is repeated, and data transmission is performed up to the last slave station 3n in the transmission order.
When the slave station 3n with the last transmission order finishes the transmission, it returns to the slave station 3a with the first transmission order and repeats the transmission. The period from when the transmission permission is given to the slave station 3a with the highest transmission order to when the last slave station 3n in the transmission order finishes transmitting is called one transmission cycle.

[0004]

There is an upper limit on the amount of data that each slave station 1B can transmit with one transmission permission. In the conventional data transmission system, the amount of data exceeding the upper limit is set. Is required to be divided and transmitted in two or more transmission cycles. For this reason, there is a problem that it takes a long time to send all the data to be sent.

[0005] The present invention has been made in view of such a point, and a single station operates as a plurality of slave stations for a slave station that wants to transmit more data than can be transmitted with one transmission permission. Accordingly, an object of the present invention is to provide a data transmission system in which the amount of data that can be transmitted by one slave station in one transmission cycle is doubled or more.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the invention of claim 1 is directed to one or more slave stations for transmitting and receiving data via a transmission line and a slave station via the transmission line. And a management station for sequentially granting transmission permission for data blocks of a predetermined length or less in accordance with the respective transmission orders. In the data transmission system, one of the slave stations has a plurality of consecutive transmission orders in one station. It is characterized by the following.

According to the first aspect of the present invention, a plurality of data blocks can be continuously transmitted by allowing a single slave station to have a plurality of transmission orders, and the data can be transmitted in one transmission cycle. The amount can be increased. This allows efficient data transmission even in a slave station having a large amount of transmission data.

In the data transmission system according to the present invention, the number of transmission orders that a slave station can have in one station is determined by the following: It is characterized in that the time required for one transmission cycle until the slave station finishes data transmission is limited so as not to exceed an allowable time.

According to the second aspect of the present invention, by limiting the number of data blocks that can be continuously transmitted by one slave station, the time of one transmission cycle can always be kept within a certain fixed time. In addition, it is possible to effectively suppress the time lag of the transmission data due to the fact that the transmission timing does not come.

According to a third aspect of the present invention, in the data transmission system of the first aspect, the slave stations having a plurality of consecutive transmission orders assign serial numbers to a plurality of data blocks to be transmitted according to the transmission order. I do.

According to the third aspect of the present invention, when the slave station transmits a plurality of data blocks in one transmission cycle, by assigning a serial number to each of the transmission data blocks, the slave station that has received the data, It can be determined that one slave station is dividing and sending data.

According to a fourth aspect of the present invention, in the data transmission system of the third aspect, the slave station receiving the serial numbered data detects an abnormality in one or more data blocks of the received data. All data blocks of the received data are processed as abnormal.

According to the fourth aspect of the present invention, when a plurality of data blocks transmitted with a serial number from a certain slave station are received, an abnormality such as a transmission error is detected in one or more of the data blocks. In this case, by processing all the received data blocks as abnormal data, these data blocks can be handled as one data.

According to a fifth aspect of the present invention, in the data transmission system of the first aspect, the slave stations having a plurality of consecutive transmission orders determine the number of data blocks to be transmitted in accordance with the amount of data to be transmitted in each transmission cycle. It is characterized by changing.

According to the fifth aspect of the present invention, a slave station having a plurality of transmission orders changes empty data by changing the number of data blocks to be continuously transmitted according to a data transmission amount required at that time. Waste such as transmission can be eliminated.

According to a sixth aspect of the present invention, in the data transmission system of the first aspect, the slave station having a plurality of consecutive transmission orders is the last slave station in the transmission order, and this slave station is set until a preset time. It is characterized in that data blocks are continuously transmitted.

According to the sixth aspect of the present invention, since the last slave station in the transmission order continues to transmit data until a preset time, one transmission cycle time can always be kept constant.

According to a seventh aspect of the present invention, there is provided one or more slave stations for transmitting and receiving data via a transmission path and transmitting a data block of a predetermined length or less to the slave stations via the transmission path in accordance with respective transmission orders. In a data transmission system comprising a management station for sequentially granting permission, the management station performs a previous transmission from the start of data transmission by the first slave station in the transmission order to the end of data transmission by the last slave station in the transmission order. The timing for giving the first transmission permission in the next transmission cycle is adjusted according to the time required in the cycle.

According to the seventh aspect of the present invention, the transmission permission timing given to the slave station having the highest transmission order is shifted according to the time required for the previous transmission cycle, so that the time of one transmission cycle is always kept. Can be kept constant.

[0020]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
An embodiment of the present invention will be described.

FIG. 1 shows a data transmission system 10 according to the present invention.
Is a block diagram showing a first embodiment of the present invention, in which one management station 11 and a plurality of slave stations 12
a, 12b, 12c,... In this embodiment, the first place in the transmission order is given to the slave station 12a, the second to fourth places in the send order are given to the slave station 12b, and the fifth place in the send order is given to the slave station 12c. That is, the slave station 12b
Are set so as to be able to act as slave stations for three stations with respect to data transmission. Also in this data transmission system 10, the management station 11 sends the
The transmission permission signals S 1, S 3, S 5,... Are sequentially transmitted from the slave station 12 a to the slave station 12 n in the last transmission order. , Data transmission is realized.

Next, the operation of the present embodiment will be described with reference to FIGS. FIG. 2 is a time chart showing the timing of the transmission permission signal and the data transmission.

The slave station 12a has the highest transmission order, and upon receiving the transmission permission signal S1 from the management station 11, transmits the data S2 to the network. Slave station 1 with the next transmission order
2b is a slave station that can behave as a plurality of slave stations, and has the second to fourth transmission orders. Therefore, the slave station 12b sends the first data S4 in response to the transmission permission signal S3 from the management station 11, and subsequently manages the second data S6 in response to the transmission permission signal S5 from the management station 11. The third data S8 is transmitted in response to the transmission permission signal S7 from the station 11. In response to the transmission permission signal S9 from the management station 11, the slave station 12c in the fifth place in the transmission order transmits data S10. The same data transmission process is repeated, and finally the slave station 12n, which is the last in the transmission order, transmits the data S12 to the network in response to the transmission permission signal S11 from the management station 11, and one transmission cycle ends.

As described above, according to the present embodiment,
By giving the slave stations 12b three transmission orders, data of an amount equivalent to three transmission cycles can be transmitted in one transmission cycle in the related art, and transmission to a slave station having a large transmission data amount is required. Time can be shortened.

Since the slave station 12b has three transmission ranks of the second to fourth transmission ranks, compared to the case where each slave station 12 performs transmission once, as shown in FIG. The time required for one transmission cycle becomes longer by the time corresponding to two data packets. If the slave station 12b has three or more transmission orders, the time of one transmission cycle further increases. One child station 12
If there is no restriction on the number of devices that can have the transmission order, one transmission cycle may be very long, and the function of the data transmission system may be impaired. For this reason, the number of stations in the transmission order that each slave station can have is limited. As a result, it is guaranteed that the transmission order of each slave station always comes within a certain period of time, so that the present invention can be applied to a network that requires real-time processing such as a control device network.

FIG. 4 shows a data transmission system 10 according to the present invention.
Of the second embodiment is shown in a time chart. In this embodiment, when the slave station 12 transmits a data packet, a slave station such as the slave station 12a, the slave station 12c, and the slave station 12n, which has only one transmission order in one transmission cycle, transmits the data packet. The data S2, S10, and S12 do not have serial numbers in the transmission data.
The transmission data S4, S6, and S8 of the slave stations having a plurality of transmission orders in the transmission cycle have serial numbers in the transmission data.

As described above, serial numbers are assigned to transmission data S4, S6, and S8 from slave stations 12b having a plurality of transmission orders, so that a station that has received a data packet has a transmission order of 1 during one transmission cycle. It is possible to easily distinguish whether the data is transmission data from a slave station or a transmission station from a slave station having a plurality of transmission orders.

Also, a certain slave station on the network that has received the serially numbered data packets S4, S6 and S8 from the slave stations 12b having a plurality of transmission orders detects a transmission error when receiving the data packet S6. In this case, even if the data packets S3 and S8 received before and after are normal, since the three data packets S4, S6 and S8 have serial numbers, they can be recognized as data transmitted from one slave station. Therefore, these can be collectively discarded as abnormal.

As described above, when an abnormality is detected in at least one of the data transmitted separately from one slave station, all the data are processed as abnormal, so that only a part of the transmission data is transmitted. Can be avoided on the receiving station side to prevent the continuity of data from being maintained.

Next, a third embodiment of the data transmission system 10 of the present invention will be described with reference to time charts shown in FIGS. In this embodiment, three slave stations 12 (slave stations 12a, 12b, 12c) are provided on the network.
And the slave station 12b is a station having a plurality of transmission orders.

When there is much data to be transmitted, the slave station 12b transmits data in the second to fourth places in the transmission order as shown in FIG.

On the other hand, when the data to be transmitted is small,
As shown in FIG. 6, transmission is performed only in the second place in the transmission order. If data transmission is not performed within a certain period of time after outputting the transmission permission signal, the management station 11 outputs the next transmission permission signal at an earlier timing than usual.

Thus, the size to be actually transmitted can be flexibly changed according to the amount of data to be transmitted.
Since unnecessary data such as dummy data is not sent, transmission overhead can be minimized.

Next, a fourth embodiment of the data transmission system 10 of the present invention will be described with reference to time charts shown in FIGS. In this embodiment, there are five slave stations 12 on the network, and the slave station 12e having the final transmission order is a station having a plurality of transmission orders. The slave station 12e having the final transmission order measures the time required for data transmission by the slave stations 12a to 12d of the first to fourth order in the transmission order, and transmits the data packet so that one transmission cycle is always constant. It has a function to send.

As shown in FIG. 7, when the slave stations 12a to 12d having the first to fourth order of transmission are transmitting fixed-length data packets, the slave station 12e having the final transmission order
Also transmits one fixed-length data packet. Now, when the slave stations 12b and 12c are out of order and the corresponding data transmission is not performed, the time of one transmission cycle is normally shortened as shown in FIG.

However, in this embodiment, as shown in FIG. 9, the slave station 12e measures the time required for the slave stations 12a to 12d to transmit data, and one transmission cycle is always constant. A plurality of data packets are transmitted as described above. Thereby, one transmission cycle time shown in FIG. 9 can be made the same as one transmission cycle time shown in FIG. 7 which is a standard state.

As described above, according to the present embodiment, since the transmission cycle time can be kept constant at all times, it can be applied to a system in which it is desired to keep the transmission cycle constant at all times.

As another embodiment of the data transmission system for keeping the transmission cycle time constant, the management station 11 changes the time required for data transmission from the first slave station in the transmission order to the last slave station in the transmission order. And a function of outputting a transmission permission signal to the first slave station in the transmission order so that the transmission cycle time is always constant.

[0039]

As described above, according to the present invention, by allowing a single slave station to have a plurality of transmission orders,
One slave station can transmit beyond a predetermined data size in one transmission cycle.

Further, according to the present invention, by limiting the number of transmission orders that can be held by one slave station, the time of one transmission cycle can always be kept within a certain fixed time.

According to the present invention, when a slave station having a plurality of transmission orders performs data transmission, a serial number is assigned to each transmission data block, so that the reception station can
The data can be easily recognized as data divided and transmitted from one slave station. Also, when an abnormality such as a transmission error is detected in one or more data blocks among data sent with a serial number from one slave station, the received serial number 1
To n can be processed as abnormal data.

According to the present invention, the time required for one transmission cycle can be kept constant because the last slave station in the transmission order has a plurality of transmission orders.

Further, according to the present invention, the time required for one transmission cycle can be kept constant by adjusting the transmission permission timing given to the slave station whose transmission order is first.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of a data transmission system of the present invention.

FIG. 2 is a time chart showing transmission timings of the first embodiment shown in FIG.

FIG. 3 is a time chart showing a transmission timing of a comparative example with respect to FIG. 2;

FIG. 4 is a time chart showing a second embodiment of the data transmission system of the present invention.

FIG. 5 is a time chart for explaining a third embodiment of the data transmission system of the present invention.

FIG. 6 is a time chart for explaining a third embodiment of the data transmission system of the present invention.

FIG. 7 is a time chart for explaining a fourth embodiment of the data transmission system of the present invention.

FIG. 8 is a time chart for explaining a fourth embodiment of the data transmission system of the present invention.

FIG. 9 is a time chart showing a fourth embodiment of the data transmission system of the present invention.

FIG. 10 is a block diagram showing a conventional data transmission system.

FIG. 11 is a time chart showing transmission timing of a conventional data transmission system.

[Explanation of symbols]

 1, 10 data transmission system 2, 11 management station 3a, 12a slave station in first transmission order 3n, 12n slave station in last transmission order

Claims (7)

[Claims] 1. An apparatus according to claim 1, wherein one or more slave stations for transmitting and receiving data via a transmission path and one or more slave stations via said transmission path are sequentially permitted to transmit data blocks of a predetermined length or less according to their respective transmission orders. A data transmission system comprising: a given management station, wherein one of the slave stations has a plurality of consecutive transmission orders in one station. 2. The number of transmission orders that the slave station can have in one station is as follows: the first slave station in the transmission order starts data transmission and the last slave station in the transmission order ends data transmission. 2. The data transmission system according to claim 1, wherein the time required for one transmission cycle up to the predetermined time is limited so as not to exceed an allowable time. 3. The data transmission system according to claim 1, wherein the slave stations having the plurality of consecutive transmission orders assign serial numbers to the plurality of data blocks to be transmitted according to the transmission orders. 4. The slave station receiving the serial numbered data, when detecting an abnormality in one or more data blocks of the received data, processes all the data blocks of the received data as abnormal. The data transmission system according to claim 3, wherein: 5. The data station according to claim 1, wherein the slave stations having the plurality of consecutive transmission orders change the number of data blocks to be transmitted in accordance with the amount of data to be transmitted in each transmission cycle. Transmission system. 6. The slave station having the plurality of consecutive transmission orders is the last slave station in the transmission order, and the slave station continues transmitting data blocks until a preset time. 2. The data transmission system according to 1. 7. One or more slave stations for transmitting and receiving data via a transmission path and sequentially permitting the slave stations via the transmission path to transmit data blocks of a predetermined length or less in accordance with respective transmission orders. In the data transmission system, the data transmission system comprises: a management station that transmits data from the first slave station in the transmission order to start data transmission until the last slave station in the transmission order finishes data transmission; A data transmission system which adjusts the timing of giving the first transmission permission in the next transmission cycle according to the time required in a cycle.