JPH0533862B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a loop transmission method for mutual communication between terminal devices (eg, data terminal devices, telephones, facsimiles, etc.).

[Conventional technology]

FIG. 4 shows a configuration example of a communication system using this type of loop transmission method according to the prior art.

In the figure, 1 is a transmission device, 2 is a transmission path, 3 is a terminal,
4 is a management device. The terminal 3 is connected to the transmission device 1, and includes a copy of the transmission device 1 and one management device 4.
are connected in a ring by a transmission line 2.

Then, a frame consisting of a plurality of slots is circulated on the transmission path 2, and as the frame is circulated,
While the transmission device 1 loads data into the slot, the destination transmission device 1 sequentially takes in the data, thereby performing communication between the transmission devices 1.

FIG. 5 shows an example of the structure of a frame 5 used in the loop transmission method.

The frame 5 is composed of a frame management area 6, a synchronous signal area 7a, and an asynchronous signal area 7b.

The frame management area 6 stores status information, management information, and the like.

The synchronization signal area 7a includes the terminals 3, 3,
This area is used as a region for transmitting synchronization signals when it is necessary to ensure isochronism in transmission between, for example, telephones. The synchronization signal area 7a includes a channel management area 8a, a synchronization slot management area 9, and a first synchronization slot 10.
It consists of a to fifth synchronous slots 10e. Here, the first synchronization slot 10a to the fifth synchronization slot 10e are allocated and used for each transmission device 1 based on usage requests from each of the transmission devices 1.

Further, the asynchronous signal area 7b is used in transmission between the terminals 3, 3, . . . when isochronism is not required, such as data storage/exchange (packet exchange, etc.). be. The asynchronous signal area 7b is a channel management area 8.
b, and the first slot 11a to the sixth slot 1
It is composed of 1f. In the figure, reference numeral 12 indicates an access control area provided in each of the slots 11a to 11f. Three types of access control information are set in the access control area 12: "transmittable", "in use", and "neutral". If "transmittable" is set, the transmission device 1 that receives this acquires the right to transmit. Moreover, the second slot 11b
An area 22 for accommodating transmission data is secured in the fourth slot 11d. The area 22
As shown in the figure, it is composed of a data area 17 for storing transmission data, a transmission unit header 20, and a transmission unit trailer 21. The transmission unit header 20 includes a transmission destination address 13,
It includes a source address 14, control information 15, and effective data length 16.

The transmission unit trailer 21 also includes an error detection code 18 and a response area 19.

Next, the effect will be explained.

First, a conventional device for transmitting a synchronization signal will be explained.

When transmitting a synchronization signal, the transmission device 1 sends a common channel signal requesting the management device 4 to allocate the synchronization slot 10. Within the synchronous slot management area 9, there is provided an area of 1 bit or more allocated in advance to each transmission device 1, and the common line signal is transmitted from the transmission device 1 to the management device 4 using this area.
sent to. The management device 4, which has received this common line signal, searches the database within the device and detects an unused and vacant synchronization slot 10. The management device 4 changes the contents of the database so that the synchronization slot 10 is in use,
A synchronization slot 10 is assigned to the transmission device 1. Then, using the common channel signal, the transmission device 1 is notified that the synchronization slot 10 has been assigned. The common line signal is transmitted using the area allocated to the transmission device 1. The transmission device 1 uses the assigned synchronization slot 10 exclusively until the end of data transmission to perform data transmission. After sending,
The transmission device 1 requests the management device 4 to release the synchronization slot 10. This request uses a common channel signal similar to the request for assignment of synchronous slot 10 described above. The device 4 that has received the request changes the contents of the aforementioned database so that the synchronization slot 10 is empty. A method using such a common channel signal is described, for example, in "Modern Communication and Switching Engineering" by Minoru Akiyama, published December 25, 1971, Denki Shoin Co., Ltd., page 86, line 21 to page 87. It is well known as shown in the second line.

Next, the case of transmitting an asynchronous signal will be explained.

The transmission device 1 connects the asynchronous slot 1 in the asynchronous signal channel 7b at a predetermined timing.
The access control area 12 within 1 is searched. Three conflicting values are set in the area 12: "transmittable", "in use", and "neutral", and each transmission device 1
controls access to the transmission path 2 based on the value.

However, in this case, all the transmission devices 1, 1,...
Assume that there is no transmission or reception between them. In this case, the access control area 12 in any one asynchronous slot 11 is set to "transmission enabled", and all other asynchronous slots 11 are set to "neutral". After that, the transmitted data is
When this occurs in a certain transmission device 1, the transmission device 1 searches for an asynchronous slot 11 whose access control area 12 is set to “transmission enabled.” When "sendable" is detected, the value is changed to "in use" and the send data 22 is stored in the asynchronous slot 11.
and send it. When the transmission data 22 cannot be loaded into the asynchronous slot, the following asynchronous slot 11 is used. In this case, the transmission device 1 sets the value of the access control area 12 of all the asynchronous slots 11 carrying the transmission data 22 to "in use". After data transmission is completed, the value of the access control area 12 of the next asynchronous slot 11 is set to "sendable". Then, the asynchronous slot 1 is loaded with the transmission data 22 that has made a round on the transmission path 2.
1, the transmission device 1 sets the value of the access control area 12 of the asynchronous slot 11 to "neutral" and removes the transmission data 12 from the transmission path 2.

[Problem that the invention seeks to solve]

However, the loop transmission method according to the prior art has the following problems.

That is, during frame construction, each slot is fixedly set for synchronous signals and asynchronous signals, respectively. For this reason, there has been a problem in that it is difficult to flexibly respond to changes in the transmission amount of synchronous signals and asynchronous signals.

Therefore, the present invention has been made in view of the problems of the prior art described above, and its purpose is to reduce the transmission amount of synchronous signals and asynchronous signals by setting a synchronous signal area or an asynchronous signal area for each slot. An object of the present invention is to provide a loop transmission device that can flexibly respond to changes in ratio.

[Means for solving problems]

The present invention provides for the access control area to have three values, independent of the conventional three values ``sendable'', ``in use'', and ``neutral''.
If the management device sets contradictory values of ``synchronous'' or ``asynchronous,'' and each transmission device determines these values and transmits a synchronous signal, ``synchronous'' must be set in the access control area. When transmitting an asynchronous signal using a slot that is set to ``asynchronous'', use a slot that is set to ``asynchronous''.

[Effect]

In the present invention, the management device sets the access control area of each slot to "synchronous" or "asynchronous" using the transmission amount of synchronous signals and asynchronous signals on the transmission path as a parameter, thereby controlling the synchronous signal area and the asynchronous signal area. The ratio can be changed depending on the amount of transmission. Further, the configuration of the synchronous signal area and the asynchronous signal area on the frame can be arbitrarily set.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 3.

Therefore, the frame 31 according to the present invention is not fixedly divided into the synchronous signal area 7a and the asynchronous signal area 7b as in the prior art, but the synchronous signal area and the asynchronous signal area can be arbitrarily divided. It is configurable.

That is, the frame 31 according to the present invention is composed of a plurality of slots 23, 23, . . . . The access control area 12 of each slot 23 contains access control information such as "synchronous", "asynchronous", "sendable",
"Transmitting" and "neutral" information are now set.

Therefore, the transmission device 32 according to the present invention uses the access control area 12 when transmitting the synchronization signal.
When transmitting an asynchronous signal, the slot 23 whose access control area 12 is set to "asynchronous" is used. The setting of "synchronization" and "asynchronous" for the access control area 12 is performed by the management device 33.

Next, the access control to the slot during data transmission in this embodiment will be explained below.

When transmitting a synchronization signal, the synchronization slot 10 is allocated and released using the synchronization slot management area 9 in the slot 23 allocated for synchronization.
This is done using a common line signal as in the conventional example.

Next, when transmitting an asynchronous signal, the slot 23 whose access control area 12 is set to "asynchronous" is used. When the transmission data 22 of the asynchronous signal is not generated in any of the transmission devices 32, any one slot 23 of all the slots 23 whose access control area 12 on the transmission path 2 is set to "asynchronous" The access control area 12 of the slot 23 is set to "transmission allowed", and the access control area 12 of the other slots 23 is set to "neutral".
The transmission device 32 that has generated the transmission data 22 selects the slot 2 in which "sendable" is set in the access control area 12 of the frame 31 circulating on the transmission path 2.
Monitor 3. Then, when the slot 23 arrives, the transmission device 32 changes the slot 23's "transmission enabled" to "in use", and
The transmission data 22 is transmitted using. If the transmission is not completed in the slot 23, the transmission device 32 continuously uses the subsequent slot 23 whose access control area 12 is "asynchronous" to transmit data. Here, the transmission device 32 sets the value in the access control area 12 to "in use" in each slot 23 to which the data has been transmitted.

When the data transmission is completed, the transmission device 32 detects the slot 23 whose subsequent access control area 12 is set to "asynchronous", and sets the access control area 12 to "sendable".

In FIG. 1, the transmitting device 32 is connected to the third slot 23.
c is detected as “sendable”, and the subsequent 4th slot 2
3d and the fifth slot 23e are used to transmit the transmission data 22. At this time, the 6th slot 23
"Sendable" is set to f.

FIG. 3 shows an example of changes in the access control area 12 in the loop transmission method according to this embodiment.
Thus, 25 is for transmission, 27 is for releasing the transmission right, 28 is for releasing the slot 23, and 26 is for access control area 1.
When a slot 23 with "synchronization" set to 2 is detected, the next slot 23 is waited for. F indicates "sendable", N indicates "neutral", B indicates "in use", P indicates "asynchronous", and C indicates "synchronized". In Fig. 3, there are six slots 2 on the annular transmission line 2.
3 indicates the case where the number rotates, and the symbols F, N, B, P, and C written in the areas obtained by dividing the circle into six equal parts indicate the values of the access control area 12 of each slot. The plurality of circle symbol patterns indicate the value of each access control area 12 after one slot has elapsed each time one circle is moved from left to right. If no asynchronous signal is transmitted at all, in the slot 23 for which "asynchronous" is set in the access control area 12, only one slot has "transmission allowed" in the access control area 12.
is set, and the other slots are set to "neutral" and circulate counterclockwise on the transmission path 2.

Now, assume that the transmission device 1 having the transmission data 22 is located on the right side of the circle. When this transmission device 32 receives "sendable" F on the transmission path 2, it changes it to "in use" B and performs transmission 25. In FIG. 3, two slots 23 are required for data transmission 25.
is being carried out. When the transmission 25 is finished, the value of the access control area 12 is set to "neutral" in the next slot 23.
The transmission right is released 27 by changing from N to "sendable" F. If a "synchronized" slot 23 is detected during data transmission, that slot 23 skips 26 and waits for the next slot 23 before transmitting.

After the transmission right is released 27 and three slots have elapsed, the slot 23 transmitted by the own device is returned to the transmission device 32. The transmission device 32 releases the slots 23 by changing the values in the access control area 12 of the two slots 23 used for the transmission 25 from "in use" B to "neutral" N.

FIG. 3 shows a case in which transmission requires two slots 23, but when transmitting long asynchronous signal data of six slots or more, once the transmission device 32 acquires the right to transmit, it cannot transmit. The slot 23 sent by the own device 32 will be returned before the processing is completed. In this case, the transmission device 32 places the next data on the slot 23 while keeping the slot 23 "in use" B. When the transmission is completed, the transmission device 32 sets "sendable" F in the access control area 12 of the next slot 23, and further sets "neutral" in the access control area 12 of the slot 23 used by the subsequent own device for transmission. do.

Furthermore, if there are transmission requests from multiple transmission devices 32 at the same time, only one slot 23 that is set to "send" is circulating on the transmission path 2, so among these multiple transmission devices 32, One of the devices fills the "send enabled" slot 23 first. The transmission device 1 that has supplemented that slot 23 uses subsequent slots 23 continuously for transmission. When the transmission is completed, the slot 23 which is set to "asynchronous" in the access control area 12 immediately after is set to "send enabled". Another transmission device 1 captures the slot 23 that has this "sendable" status and transmits data.

In the above embodiment, the case where the annular transmission line 2 was time-divided into six slots was explained.
The present invention is not limited to this, and may be used when the transmission line 2 is time-divided into an arbitrary number. However, if the number of divisions is increased, the size of the slot becomes smaller, and a larger proportion of the transmission capacity is taken up by the access control area 12, resulting in poor transmission efficiency. On the other hand, if the number of divisions is reduced, the size of the slot becomes larger, and when short data is transmitted in the transmission of an asynchronous signal, the slot area is left over and the transmission efficiency deteriorates.

〔Effect of the invention〕

As described above, in the present invention, the synchronous signal area and the asynchronous signal area can be set by setting each slot as access control information, so it is relatively easy to set the synchronous signal area and the asynchronous signal area. It has the effect of changing the ratio of For example, when setting "synchronous" and "asynchronous" access control information for all slots in a frame in the frame management area, each transmission device needs to store this information.
In the present invention, this is not necessary, and it is sufficient to check each slot passing through the transmission device. In addition, when a synchronous signal area and an asynchronous signal area are mixed on a frame, when transmitting an asynchronous signal,
This has the effect that asynchronous signal areas scattered on a frame can be used continuously.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of data transmission by a transmission device to which a loop transmission method according to an embodiment of the present invention is applied, FIG. 2 is a block diagram of the transmission device of the present invention, and FIG. 3 is an embodiment of the present invention. 4 is a diagram showing an example of the configuration of a communication system using a conventional loop transmission device, and FIG. 5 is a diagram showing an example of a change in access control information in an access control area in a loop transmission method using FIG. 3 is a diagram showing an example of transmission. 1, 32...Transmission device, 2...Transmission line, 4, 3
3...Management device, 10...Synchronization slot, 11...
...Asynchronous slot, 12...Access control area,
13... Destination address, 17... Transmission data, C
... "Synchronized", P ... "Asynchronous", F ... "Ready to send", N ... "Neutral", B ... "In use". Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] 1. A frame consisting of a plurality of time-divided slots is circulated on a circular transmission path connecting one management device and a plurality of transmission devices, and along with the circulation, the transmission device In the loop transmission method, communication between the transmission devices is carried out by loading data into the above slots, and the destination transmission device among the above transmission devices takes in the above data. , an access control area is provided in which access control information of "sendable", "in use", and "neutral" is set, and the management device sets either "synchronous" or "asynchronous" to each of the access control areas. However, in data transmission using a synchronization slot in which "synchronization" is set in the access control area, the transmission device that has the transmission data sends a message to the management device about the synchronization slot between the destination transmission device and the transmission device. requesting allocation, exclusively using the allocated synchronous slot to transmit data, requesting the transmission device to release the allocation of the synchronous slot after data transmission is completed, and the management device releasing the synchronous slot; On the other hand, in data transmission using an asynchronous slot in which "asynchronous" is set in the access control area, the management device performs an asynchronous transmission using one of the plurality of asynchronous slots in the absence of the above-mentioned transmission device that has transmission data. The frame is circulated on the transmission path by setting "sendable" in the slot access control area and "neutral" in the access control area of other asynchronous slots, and then, when transmission data is generated, the transmission device , When receiving the above asynchronous slot for which "send allowed" is set in the access control area, it continuously uses the required number of asynchronous slots after that asynchronous slot to transmit data, and The access control information is set from "sendable" or "neutral" to "in use," and after data transmission is completed, the access control information of the subsequent asynchronous slot is set to "sendable," and the above transmission device transmits. When the asynchronous slot that was used for the asynchronous slot goes around the circular transmission path and returns to its own device, if the data transmission on the own device has not been completed, the data being sent to the asynchronous slot will continue to be overwritten, and the data will continue to be overwritten until the data is completed. If so, the access control information of the asynchronous slot is set from "in use" to "neutral".