JP2000196640A - Loop type data transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform N-to-N data transmission by using a SDLC(synchronous data link control) frame. SOLUTION: In this loop type data transmission system consisting of plural transmitting devices, each of transmitting devices 1 to 3 is provided with a frame transmission system which produces a frame having a destination address and a transmission source address field on the front side according to a data transmission request from the outside and transmits it to a transmission line 2 and a frame reception system which compares the destination address and transmission source address of a received frame with a self-address when it receives the frame, relays the received frame to devices on a downstream side when neither of the addresses coincides with the self-address and eliminates the received frame from the transmission line when either of the addresses coincides with the self-address.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a loop type data transmission system suitable for data transmission on a transmission path having a long transmission path and including a transmission delay element such as a railway control system.

[0002]

2. Description of the Related Art In recent years, with the development of computer communication technology, various data transmission network systems have been developed. Among such systems, there is a loop-type data transmission system in which a center for controlling a railway train and a plurality of stations are connected in a loop.

A loop-type data transmission system for controlling a railway train or the like is configured as shown in FIG.

In this data transmission system, a center transmission device 51 as a primary station and a transmission device 52 as a secondary station installed at each station form a loop network via a transmission line 53. The center transmission device 51 has a plurality of computers #
1, # 2 are connected, and a personal computer 54 and a station control device 55 are connected to the transmission device 52 of each station.

[0005] In such a data transmission system for controlling trains, since the distance between transmission devices is as long as several km, the transmission speed suitable for long-distance transmission is relatively low (from several hundred bits / sec.
(Several tens of kilobits / second) For example, a modem conforming to a standard such as 32 is adopted, and a one-to-N data transmission system in which data cannot be transmitted in a secondary station unless the transmission permission of the primary station is adopted. SDLC (Synchronous) proposed by IBM
Date Link Control (synchronous data link control) is used.

[0006] The data transmission method based on the SDLC method is as follows.
A data frame having an arrangement as shown in FIG. 17 is used. The flags arranged in this data frame are frame synchronization detection data, DA is a destination address, the control unit is information used for transmission control, the information unit is application-side information, and the FCS
(Frame Check Sequence) is frame error detection data.

The feature of this SDLC system is that there is one primary station and a plurality of secondary stations in the system, and the transmission device 52 of each station as the secondary station can transmit a data frame.
As shown in FIG. 18, transmission is possible only when polling (POLL) is received as a transmission permission signal from the center transmission device 51 of the primary station. Therefore, for example, when transmitting the frame I1C from the transmission device 52 of the station 1 to the transmission device 52 of the station 3, the transmission device 52 of the station 1 transmits when the polling is received from the center transmission device 51 as indicated by * 1. The data frame I1C is transmitted to the center transmission device 51. The center transmission device 51 converts the received frame I1C into a frame IC3 addressed to the transmission device 52 of the station 3 and transmits the frame IC3 to the transmission device 52 of the station 3 (illustrated * 1). When data is exchanged between secondary stations in this way, data is always transmitted to the target secondary station via the primary station as shown in FIG.

[0008]

Therefore, the following disadvantages have been pointed out when the above-mentioned SDLC system is used. (1) A plurality of frames cannot exist in the loop transmission path 53. As a result, idle time always occurs in the transmission path 53.

Normally, the length of one loop is short, there is no delay in each transmission device, the transmission speed of the frame is fast, and the head of the frame loops over the loop before the transmission of the rear end of the transmitted frame is completed. In the case of returning, the idle time Ts does not occur in the transmission line, and even if a slight idle time occurs, there is almost no problem.

However, in a network system having a time delay element in a transmission device such as a railway control data transmission system, for example, after the transmission of a frame is completed, it takes a time until the head of the frame returns through a loop. It takes considerable time. Also, since frame transmission by the secondary station is possible only when transmission is permitted on the primary station side, only one frame can exist simultaneously on the loop transmission path. For this reason, frames cannot be transmitted continuously, and the idle time on the transmission path increases, resulting in poor transmission efficiency. (2) Next, the data transmission method between stations is 1: N,
N-to-N data transmission is not possible.

That is, in order to realize N-to-N data transmission between stations, it is necessary to perform direct data transmission from the station 1 to the station 3. Since the frame is transmitted to the center once, and the center decodes the content of the frame and transfers it to the station 3 again, it is only a so-called one-to-N transmission. Therefore, there is a problem that the procedure is complicated and data transmission takes time.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a loop-type data transmission system that enables N-to-N data transmission.

Another object of the present invention is to provide a data transmission system in which the idle time is minimized in the transmission path to improve the transmission efficiency.

Another object of the present invention is to provide a recording medium on which a program for realizing N-to-N data transmission is recorded.

[0015]

According to the present invention, in a loop type data transmission system in which a plurality of transmission devices are connected in a loop via a transmission line, each transmission device receives a data transmission request from the outside. A frame transmission system for creating a frame having a destination address field and a source address field on the head side and transmitting the frame to a transmission path; and, when receiving a frame, the destination address, the source address, and the own address of the field of the received frame. A frame receiving system that relays the received frame to a downstream device when any address does not match the own address, and removes the received frame from the transmission line when any address matches the own address. Is provided.

According to the present invention, by taking the above measures, when a frame is received, when a destination address or a transmission source address matches its own address, it is determined by itself that frame transmission has been completed, and the transmission path is determined. Since the frames are removed, the data can be transmitted by specifying the destination from each transmission device.
Further, since the frame is removed when the address of the received frame coincides with the own address, N-to-N data transmission can be realized, and the idle time of the transmission path can be reduced to increase the transmission efficiency.

According to another aspect of the present invention, there is provided a frame transmitting system for generating and transmitting a frame by setting request information such as a broadcast and a priority flag in a destination address field according to an external request, And a frame receiving system that, when the request information is set in a destination address field of the frame, executes a predetermined process preferentially based on the request information.

According to such a configuration of the present invention, when there is a broadcast set in the destination address field of the frame, the frame is sequentially relayed, or when there is a priority flag, the temporary processing is interrupted to receive the frame. Is preferentially relayed, so that frames can be transmitted efficiently.

Further, another invention provides that each transmission device includes:
At the time of frame transmission, a variable information field is provided at the beginning of the frame, a variable information field is set in this field, a frame transmission system that creates and transmits a frame by setting the variable information,
Loop-type data transmission provided with a frame receiving system that removes the frame from the transmission line without relaying the frame to a downstream device when the variable information of the variable information field in the frame is predetermined variable information. System.

According to the configuration of the present invention, by comparing the variable information in the variable information field in the received frame with the predetermined specified variable information, an illegal or unnecessary frame is found and easily removed from the transmission line. it can.

Further, as another invention, an illegal or unnecessary frame can be found and easily removed from the transmission line by appropriately combining and comparing the configurations of the above inventions.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. (Basic Configuration Example of Data Transmission System) FIG. 1 is a block diagram showing a configuration example of a loop type data transmission system according to the present invention applied to a railway control system.

In this railway control loop data transmission system, a transmission device 3 of each station as a secondary station is sequentially and serially connected to a center transmission device 1 as a primary station via a transmission line 2 to form a loop network. Make up.

Computers # 1 and # 2 for managing train operation are connected to the center transmission device 1, and these computers # 1 and # 2 are connected.
2, the center transmission device 1 is connected to the transmission device 3 of each station.
To the control signal.

On the other hand, a personal computer 5 and a station control device 6 are connected to the transmission device 3 of each station.
Each personal computer 5 is used for information management of each station and for notifying the management information to the center and other stations, and each station control device 6 has a role of controlling a train signal called an electronic interlocking device.

FIG. 2 is a diagram showing an example of a module configuration of each of the transmission devices 1 and 3.

Each of the transmission devices 1 and 3 is provided with a microprocessor (hereinafter referred to as an MPU) 11.
A bus line 12 derived from U11 has a recording medium 13 for recording a program and fixed data necessary for executing the program, a data buffer 14 for recording received data and processing data, and a serial interface 1
5 to 18 are connected.

As the recording medium 13, for example, a magnetic disk, a magnetic tape, a CD-ROM, or the like is used. In addition, DVD-ROM, floppy (registered trademark) disk, MO, MD, CD-R, A memory card or the like may be used.

The serial interfaces 15, 16
Are connected to modems 19 and 20 each having a transmission speed of about 600 to 28800 bps. The modems 19 and 20 are connected to adjacent transmission devices 1 and 3, respectively, and form a loop network.

The serial interfaces 17, 18
Are connected to computers # 1 and # 2 or personal computers 5 and station control devices 6, respectively.

Each of the transmission devices 1 and 3 can transmit data at any time unless a frame is being relayed.
If the frame is being relayed, the transmission data is stored in the data buffer 14 as a temporary transmission waiting state, and transmission is started when the relay is completed. On the other hand, when a frame to be relayed is received during data transmission, the frame data is temporarily stored in the data buffer 14 as a relay standby state, and the frame relay is started when the data transmission is completed. (First Embodiment) In this embodiment, in addition to the basic configuration examples shown in FIGS. 1 and 2 described above, the content of the SDLC frame is devised, and the frame is relayed or copied according to the content of the SDLC frame. In this configuration, N-to-N data transmission is performed by performing frame removal. Specifically, there are two embodiments as described below. (1) In this embodiment, an SDLC frame having a configuration as shown in FIG. 3 is used as an SDLC frame handled in a loop-type data transmission system. This SDLC frame adds not only the destination address DA but also the source address SA, and the flag, the destination address DA, the source address SA, the control unit,
The configuration is made up of an information section, an FCS and a flag. Here, the flag is data for frame synchronization detection, the control unit is information used for transmission control, the information unit is information on the application side, and the FC is
S (Frame Check Sequence) is frame error detection data.

The transmission system of each of the transmission devices 1 and 3 has the following configuration.

That is, the MPU 11 of each of the transmission devices 1 and 3
Receives a frame transmission request from the computers # 1 and # 2, the personal computer 5, or the station control device 6, and has a function of creating and transmitting a data frame at any time according to the request unless the frame is already being relayed.

On the other hand, the MPU of the receiving system of each of the transmission devices 1 and 3
11 is the first two bytes of the received frame (flag and D
A), the destination address DA is compared with its own address, and when the destination address DA does not match the own address, the frame is relayed (repeat) as it is. When the destination address DA matches the own address, While copying the frame into the data buffer 14,
It has the function of removing the frame from the transmission path without relaying it.

Next, the operation of the above system will be described with reference to FIG.

When the operation starts, the MPU 11 of the transmission device 1 or 3 reads out the program recorded on the recording medium 13 and clears unnecessary data and the like in the data buffer 14 according to the program (S1). In this state, it is determined whether there is a frame transmission request from the computers # 1, # 2, the personal computer 5, or the station control device 6 (S
2) If there is a transmission request, after setting a flag (S3), it is determined whether or not another data frame is being received (relaying) (S4).

Here, if no frame is being received, it is checked whether there is a flag (S5). If there is a flag, it is determined that the request is a frame transmission request, and the own data frame is created and transmitted (S6). During the transmission of this data frame, it is determined whether or not a frame has been received from another station. If the frame has been received, the frame is fetched and buffered in the data buffer 14 (S7, S8). And
It is determined whether the transmission of the own data frame is completed (S
9) If the transmission of the own frame is completed, it is checked whether or not there is buffering of another data frame (S10). If there is, the process proceeds to step S11.

In step S11, if another data frame is being received at the time of requesting transmission of the own frame in step S4, or if there is another data frame buffered during transmission of the own frame, the destination address of the other data frame is set to the own address. It is determined whether they match. Here, if they do not match, a repeat process for relaying to the downstream station is performed as it is (S12), and if they match, another data frame is copied to the data buffer 14 and transmitted without relaying the frame. Get off the road (S13, S14).

If another data frame is being received at the time of requesting transmission of the own frame in step S2, the above-mentioned steps S12 and
After the process of S13 is completed, it is confirmed whether or not there is a flag (S1).
4) If there is a flag, the process proceeds to step S6, and the own data frame is transmitted.

Therefore, as is clear from the above description,
A plurality of data frames exist simultaneously on the loop network.

FIG. 5 is a time chart showing a state in which a plurality of data frames are transmitted on the transmission line 2. In this example, the center transmission device 1 as the master station and the station 1 as the slave station 1 are shown.
And the transmission device 3 of the station 3 which is the slave station 3 individually and simultaneously transmits the frames IC2, I1C and I3C. At this time, the frame IC2 is addressed to the station 2, the frame I1C is addressed to the center, and the frame I3C is addressed to the center. The transmission device 3 and the center transmission device 1 of the station 2 copy the relevant frame and transfer the frame from the transmission path. Has been removed.

Therefore, in the conventional SDLC, the data frame transmitted on the transmission line 2 can be dropped only by the transmission device of the center (master station).
The data frame could not be freely transmitted from the slave station transmission device.

However, in the system of the present invention, as shown in FIG. 5, the data frames can be dropped from the transmission line by the transmission devices of the plurality of destination stations, so that the data frames can be transmitted from the plurality of transmission devices simultaneously, and In the transmission devices of a plurality of destination stations, N-to-N data transmission capable of simultaneously receiving the corresponding data frame can be realized.

Incidentally, the data transmission system of this embodiment and the data transmission system of the conventional SDLC system are
When compared under the following preconditions, the following transmission performance is obtained. (A) Prerequisites-Modem is V.600 with a transmission speed of 9600 bps. 32 models ・ Number of stations (number of transmission devices such as centers and stations): 32 stations ・ Amount of information: capacity of the information part of the frame Center → station: 5 bytes / station Frequency Once to each station /
2 seconds Station → Center: 10 bytes / station Frequency 1 time / sec from each station ・ Transmission delay: Modem delay Approx. 20 ms / station ・ Ignore the delay in processing time in MPU 11 of the transmission device. (B) Comparison of transmission performance between arbitrary stations When sending an information amount of 10 bytes in the information part from an arbitrary transmission device to a transmission device 16 stations ahead (assuming 32 stations / intermediate station of a loop), Let's examine the transmission time when the information arrives. (A) In the case of a data transmission system of the SDLC system.

When data is transmitted using the SDLC method, a permission signal is required from the parent transmission apparatus, and the average waiting time is set to half the time required for one round of the loop.

Average waiting time + transmission delay × 16 stations = 20 m
s × 32/2 + 20 ms × 16 = 640 ms (b) The case of the data transmission system according to the present embodiment.

(20 ms + 2 × 8 / 9.6) × 16 stations =
346.7 ms (c) Transmission time reduction effect in the present embodiment From the above calculation, 346.7 ms / 640 ms = 54.
2%, which enables data transmission in a transmission time of slightly more than half.

Therefore, according to the above-described embodiment, since the data frame can be dropped from the transmission line 2 in each of the destination-side transmission devices 1 and 3, N-to-N data transmission that can transmit data frames at the same time, buffer other data frames from other transmission devices during transmission of own data frame, and process other data frames after completion of transmission of own data frame The system can be realized. (2) Another example of the first embodiment will be described.

This embodiment has the following configuration in addition to the basic configuration examples shown in FIGS. 1 and 2 described above. The data frame has the same configuration as that of FIG.

When the transmission devices 1 and 3 receive a data frame, they read 3 bytes (flag, destination address DA and source address SA) of the data frame and read the destination address DA, source address SA and own address. If any address does not match its own address, it is relayed to the downstream transmission device (repeat)
When one of the destination address DA and the source address SA matches the own address, the packet is dropped from the transmission line 2 without relaying, and the frame is copied only when the destination address DA matches the own address. is there.

According to such a configuration, if the transmission devices 1 and 3 having the destination address DA set in the data frame do not exist on the transmission line 2, the first embodiment will Is infinitely relayed on the transmission path 2, but in the present embodiment, it can be removed from the transmission path 2 when it is received by the transmission apparatus at the transmission source, which contributes to improvement in reliability.

Also in this embodiment, the time required for transmission to 16 stations ahead under the same conditions as in the above embodiment is (20 ms + 3 × 8 / 9.6) × 16 stations = 360 ms. Although the transmission time is slightly longer than that of the embodiment, 360 ms / 640 ms =
56.3%, and the transmission time is still shorter than that of the conventional system, and the reliability can be improved. Second Embodiment (1) An example of this embodiment has the following configuration in addition to the basic configuration example of FIGS. 1 and 2 described above. The data frame has the same configuration as that of FIG. 3 shown in the first embodiment.

The transmission system of each of the transmission devices 1 and 3 is a computer #
When a data transmission request is received from the PC # 1, # 2, the personal computer 5 or the station control device 6, it is determined whether or not the request is a broadcast request. Is configured to be transmitted. On the other hand, the receiving system of each of the transmission devices 1 and 3 copies a received frame when a broadcast address is included in the destination address field at the time of receiving a frame. If the address matches, the received frame is copied. In addition, the frame is removed from the transmission line 2 without relaying only when the destination address of the frame does not match the own address, but when the broadcast address is present, and only when the source address matches the own address. .

Next, the operation of the above system will be described.

The frame transmission operation of each of the transmission devices 1 and 3 is as follows.
When the MPU 11 receives a broadcast request cast or other data request from the computers # 1 and # 2, the personal computer 5 or the station control device 6 as shown in FIG. 6, after the initialization processing (S21), it determines whether there is a transmission request. (S22),
If there is a transmission request, it is determined whether it is a broadcast request (S23). If it is not a broadcast request, a data frame similar to that described in the first embodiment is created and transmitted (S24, S25).

When it is determined in step S23 that there is a broadcast request, the broadcast address (OFFh) is set in the destination address field, and the data frame is transmitted (S26 to S28).

The frame receiving operation of each of the transmission devices 1 and 3 is as follows.
After the MPU 11 performs the initialization processing as shown in FIG.
1) It is determined whether or not a frame has been received (S32). If a frame has been received, it is determined whether or not the destination address of the data frame matches its own address (S3).
3).

When the destination address matches the own address, a match flag is set (S34), and it is determined whether or not the set value of the destination address field includes a broadcast address (S35). Copies the received frame (S3
6). Even if there is no broadcast address, if there is a match flag, the received frame is copied (S37).

Further, in addition to the absence of the match flag, when there is a broadcast address, the frame is removed from the transmission path 2 without relaying when the transmission address matches the own address (S38, S39).

FIG. 8 is a time chart showing a transmission state of a broadcast frame in the data transmission system of the present embodiment.

In this system, when a data frame including a broadcast address is transmitted from the center transmission device 1 which is the master station, all the slave station transmission devices 3 on the transmission line fetch the data frame and return it to the center transmission device 1. . After receiving the broadcast frame, the center transmission device 1 removes the frame from the transmission path.

Therefore, according to such an embodiment,
When broadcasting any command from the master station to all slave stations, by setting a broadcast address in the destination address field and transmitting the frame, each slave station copies the frame from the broadcast address in the destination address field, Necessary information can be transmitted to all slave stations more efficiently than individually transmitted to all slave stations as in the first embodiment. (2) Another example of the second embodiment will be described.

This example has the following configuration in addition to the basic configuration example of FIGS. 1 and 2 described above.

First, the data frame has a configuration as shown in FIG. The meaning of each field is basically the same as in FIG. 3, but particularly when the broadcast flag is set in the destination address field, the source address is set.

The transmission system configuration of each of the transmission devices 1 and 3 is as follows.
In addition to the first embodiment, when a broadcast request is received from the computer # 1, # 2, the personal computer 5, or the station control device 6, the own address and the broadcast flag are set in the destination address field, and the data frame is transmitted. Configuration.

On the other hand, as a receiving system configuration of each of the transmission apparatuses 1 and 3, when a broadcast flag (priority information) is set in the destination address field at the time of receiving a frame, the frame is copied to the data buffer 14 and When the address set in the destination address field is its own address, the frame is removed from the transmission line 2 without relaying (repeat), thereby enabling broadcast communication.

Therefore, according to the above-described embodiment, the relay delay is 3 bytes in the above embodiment, but only 2 bytes, so that the broadcast transmission can be performed more efficiently. (3) Still another example of the second embodiment will be described.

This embodiment has the following configuration in addition to the basic configuration examples of FIGS. 1 and 2 described above.

For the frame handled in this embodiment, a priority flag is set in the destination address field as shown in FIG. Note that the priority flag may be set in the source address field.

The transmission system configuration of each of the transmission devices 1 and 3 is as follows.
When a priority transmission request is received from the computers # 1 and # 2, the personal computer 5 or the station control device 6, a priority flag is set in the destination address field of the data frame and the own data frame is transmitted. At this time, if there is a frame being relayed, the own data frame is transmitted as soon as the frame processing is completed.

The receiving system configuration of each of the transmission devices 1 and 3 is as follows.
When a data frame is received, if the priority flag is set in the destination address field, the frame being transmitted is saved in the data buffer 14 even if the frame is being transmitted, and the received frame is relayed preferentially. Transmission device.

FIG. 11 shows that when the transmission device 3 of the slave station 1 continuously transmits frames to the transmission device 3 of the slave station 2, it receives a frame with a priority flag set from the center transmission device 1 of the master station. 6 is a time chart for transmitting the frame to the transmission device 3 of the slave station 2 by preferentially relaying the frame.

Therefore, according to such an embodiment, even if there is a transmission device that continues to occupy the loop transmission path,
By setting the priority flag, it is possible to temporarily stop and transmit necessary data within a predetermined time. Third Embodiment (1) One example of this embodiment has the following configuration in addition to the basic configuration example of FIGS. 1 and 2 described above. The frame handled in the present system has a configuration in which a TTL (Time to Live) field is provided, for example, next to the flag as shown in FIG.

The transmission system configuration of each of the transmission devices 1 and 3 is as follows.
When transmitting a frame from its own transmission device, the T
When the number of stations on the transmission line is 32 in the TL field, an initial value “31” which is one less than the number is set, and the data frame is transmitted.

On the other hand, the configuration of the receiving system of each of the transmission devices 1 and 3 is such that when a frame is received, the setting content is fetched from the TTL field of the frame and the setting content value falls within a predetermined range "1 to 31" set in advance. TTL to determine if
When the set value content is within a specified range by the content determination means and the TTL content determination means, "-1" is set from the set value content.
After the number is reduced, the frame is repeated to the downstream transmission device, and when the set value is out of the specified range, the frame is removed from the transmission path.

Hereinafter, the frame receiving operation will be described with reference to FIG.
This will be described with reference to FIG.

After performing the initialization process based on the program (S41), the MPU 11 of each of the transmission devices 1 and 3 determines whether or not a frame has been received at predetermined intervals (S4).
2). When the frame is received, the setting content is fetched from the TTL field of the frame (S43), and it is determined whether or not the setting content value is within a predetermined range "1 to 31" (S44). If it is within the specified range, the content of the setting value of the TTL field is reduced by 1 (S45), and the frame is repeated to the transmission device on the downstream side of the transmission path (S46). On the other hand, if it is out of the specified range, for example, if it exceeds the initial value or if it is 0, the frame is determined to be invalid or unnecessary, and the frame is removed from the transmission line without repeating (S47).

Therefore, according to the above embodiment, the TTL field is provided in the data frame,
If an initial value corresponding to the number of stations is set in the TL field and each transmission apparatus receives and repeats the frame by subtracting one, the frame may be in an incorrect or unnecessary state in addition to the cycle of the frame. Understandably, the frame can be reliably removed from the transmission line without repeating. (2) Another example of the third embodiment will be described.

This embodiment has the following configuration in addition to the basic configuration examples of FIGS. 1 and 2 described above. The frame handled by the present system has a configuration in which a time information field is provided next to a flag, for example, as shown in FIG.

The transmission system configuration of each of the transmission devices 1 and 3 is as follows.
When a frame is transmitted, the internal time information variable value at the time of transmission is set in the time information field of the frame, and the frame is transmitted. Each of the transmission devices 1 and 3 has an internal clock, and the internal clock operating in synchronization with the system can advance in, for example, a one-second cycle to change the set value of the internal time information variable.

The receiving system configuration of each of the transmission devices 1 and 3 is as follows.
When a frame is received, the setting content of the time information field of the frame is compared with the internal time information variable value of the transmission device at the time of receiving the frame, and whether the difference between the values is within a predetermined time, for example, 2 seconds or not is determined. Means for judging whether or not the setting content is less than 2 seconds, and if the setting content is less than 2 seconds, repeats the frame to a downstream transmission device on the transmission path. Is determined to be illegal or unnecessary, and means for removing the frame from the transmission path without repeating the frame is provided.

Therefore, according to the above-described embodiment, the frame can be reliably removed from the transmission line without repeating while judging whether the frame is illegal or unnecessary. (3) This embodiment has the following configuration in addition to the basic configuration example of FIGS. 1 and 2 described above. The frame handled in the present system has a configuration in which a serial number field is provided next to, for example, a flag as shown in FIG.

Each of the transmission devices 1 and 3 has an internal serial number variable for transmission and an internal serial number variable for monitoring for each source address in advance, and sets the internal serial number variable for transmission in the serial number field of the frame when transmitting the frame. Is transmitted, and the transmission internal serial number variable inside the own transmission device is incremented by one.

The configuration of the receiving side of each of the transmission devices 1 and 3 is as follows.
At the time of receiving a frame, at the time when the serial number field and the source address SA are received, a serial number for determining whether or not the serial number in the serial number field is a subsequent (larger) number with respect to the monitoring internal serial number variable corresponding to the source address. A determining means for repeating the frame to a downstream transmission device on the transmission line if the serial number is later (not including the value of the internal monitoring variable at that time) based on the determination result, and A serial number changing means for resetting the internal serial number for transmission, which is the content of the serial number field of the frame, to the serial number variable, and the internal serial number variable for transmission is previous (including the value of the internal serial number variable for monitoring at that time) , The frame is determined to be invalid or unnecessary, and is removed from the transmission line without repeating the frame.

Therefore, according to the above-described embodiment, whether the frame is illegal or invalid based on the magnitude relationship between the transmission internal serial number variable of the received frame and the monitoring internal serial number variable corresponding to the source address SA of the received frame. It can be determined whether the data is unnecessary data, and when it is determined that the data is fraudulent or unnecessary, the frame can be reliably removed from the transmission path without repeating the frame. (4) This embodiment has the following configuration in addition to the basic configuration example of FIGS. 1 and 2 described above. It should be noted that the frame handled in this system has the same configuration as that shown in FIG.

Each of the transmission devices 1 and 3 has a transmission internal serial number variable for each destination address and a monitoring internal serial number variable for each combination of the destination address and the transmission source address.
At the time of frame transmission, the value of the transmission internal serial number variable corresponding to the destination address is set in the serial number field of the frame, the frame is transmitted, and the transmission internal serial number variable is incremented by one.

The receiving system configuration of each of the transmission devices 1 and 3 is as follows.
At the time of receiving the destination address field, source address field and serial number field when receiving a frame, the serial number of the serial number field follows the value of the monitoring internal serial number variable corresponding to the combination of the destination address and source address. Serial number determining means for determining whether or not the transmission internal serial number variable is based on the determination result (if the internal serial number variable for monitoring is not included at that time), the frame is transmitted A serial number changing unit that repeats to the downstream transmission device on the road and resets the internal serial number variable for transmission, which is the content of the serial number field of the frame, to the internal serial number variable for monitoring; (Including the value of the monitoring internal serial number variable), the frame is judged to be invalid or unnecessary, and It is constituted by a frame removing means for removing from the transmission path without.

Therefore, according to the above-described embodiment, the size of the internal serial number variable for transmission of the received frame and the internal serial number variable for monitoring corresponding to the combination of the destination address and the source address of the received frame is determined. It can be determined whether the data is fraudulent or unnecessary data of the frame, and when it is determined that the data is fraudulent or unnecessary, the frame can be reliably removed from the transmission path without being repeated. (Fourth Embodiment) This embodiment has the following configuration in addition to the basic configuration examples of FIGS. 1 and 2 described above. It should be noted that the frames handled in this system have the same configuration as any one of FIGS. 11, 13, and 14.

In the normal mode, the receiving system of each of the transmission devices 1 and 3 determines whether or not the destination address which is the setting content of the field at the time of receiving the destination address field of the frame matches its own address. If they do not match, the frame is relayed to the downstream device. If they match, the frame is copied to the data buffer and the frame is removed from the transmission line without relaying.

However, the destination address alone cannot always be said to be sufficient due to an address setting error or the like. Therefore, it is also possible to make a complementary use of a portion other than the address field of the frame, that is, the variables described in the third embodiment. That is, the TTL other than the address field, the time information, or the serial number and others (FC
(S error or abort frame error) to determine the validity of the frame. When the frame that has transited to the downstream device and transmitted to the downstream device propagates through the transmission path and returns to the transmission device, the frame may be removed from the transmission line and return to the normal mode.

[0091]

As described above, according to the present invention, since the contents of a frame are individually judged by each transmission device and the frame is removed from the transmission line, N-to-N data transmission is realized. be able to.

Further, if N-to-N data transmission becomes possible as described above, data can be transmitted with as little time as possible on the transmission path, and transmission efficiency can be improved.

Further, according to the present invention, it is possible to provide a recording medium on which a program for realizing N-to-N data transmission and reducing the idle time in the transmission path to improve the transmission efficiency is recorded.

[Brief description of the drawings]

FIG. 1 is a diagram showing a basic configuration example of a loop-type data transmission system according to the present invention.

FIG. 2 is a hardware configuration diagram illustrating a specific example of each transmission device.

FIG. 3 is a configuration diagram of a frame used in the first embodiment in the loop data transmission system according to the present invention.

FIG. 4 is a flowchart illustrating the operation of each transmission device.

FIG. 5 is a diagram illustrating a state in which a plurality of frames are simultaneously present on a transmission path.

FIG. 6 is a flowchart illustrating an operation of a frame transmission system according to the second embodiment in the loop data transmission system according to the present invention.

FIG. 7 is a flowchart illustrating an operation of a frame receiving system according to the second embodiment.

FIG. 8 is a diagram showing a state where each slave station side transmission device is sequentially copying a specific frame.

FIG. 9 is a configuration diagram of a frame illustrating another example of the second embodiment.

FIG. 10 is a configuration diagram of a frame illustrating still another example of the second embodiment.

FIG. 11 is a diagram illustrating an example in which priority processing is performed based on a priority flag of a received frame.

FIG. 12 is a configuration diagram of a frame used in the third embodiment in the loop data transmission system according to the present invention.

FIG. 13 is a diagram illustrating an operation of the third embodiment.

FIG. 14 is a configuration diagram of a frame illustrating another example of the third embodiment.

FIG. 15 is a configuration diagram of a frame illustrating still another example of the third embodiment.

FIG. 16 is a configuration diagram of a conventional loop-type data transmission system.

FIG. 17 is a configuration diagram of a frame used in a conventional loop-type data transmission system.

FIG. 18 is a diagram illustrating a frame transmission state in a conventional system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Center transmission apparatus 2 ... Transmission path 3 ... Station transmission apparatus 11 ... Microprocessor 13 ... Recording medium

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akihiko Yamaguchi 1 Toshiba-cho, Fuchu-shi, Tokyo Inside the Toshiba Fuchu Plant, Inc. Terms (reference) 5K031 AA07 BA03 CB01 CB06 CC04 DA01 DA02 DB03

Claims (4)

[Claims] In a loop-type data transmission system in which a plurality of transmission devices are connected in a loop via a transmission path, when each transmission device receives a data transmission request from outside, a destination address field and a destination address field A frame transmission system that creates a frame provided with a source address field and transmits the frame to the transmission path; and, at the time of frame reception, compares the destination address and the source address of the field of the received frame with its own address. A frame receiving system that relays the received frame to the downstream device when the address does not match the own address, and removes the received frame from the transmission line when any address matches the own address. A loop type data transmission system. 2. In a loop-type data transmission system in which a plurality of transmission devices are connected in a loop via a transmission path, each transmission device sets request information in a destination address field in accordance with a request from the outside and transmits a frame. A frame transmitting system for creating and transmitting, and a frame receiving system for executing a predetermined process preferentially based on the request information when the request information is set in a destination address field of the frame when the frame is received. A loop-type data transmission system, comprising: 3. In a loop-type data transmission system in which a plurality of transmission devices are connected in a loop via a transmission line, each transmission device provides a variable information field at the head of a frame when transmitting a frame, and the variable information field is provided in this field. A frame transmission system for creating and transmitting a frame by setting variable information, and when receiving a frame, when the variable information of a variable information field in the frame is predetermined variable information, the frame is transmitted to a downstream device. A loop-type data transmission system, comprising: a frame receiving system that removes from the transmission path without relaying. 4. In a loop-type data transmission system in which a plurality of transmission devices are connected in a loop via a transmission path, each transmission device, in a normal mode, transmits a destination address which is a setting content of a destination address field of a received frame. A normal mode receiving system that relays the frame to the downstream device when the destination address does not match the own address, copies the frame when it matches, and removes the frame. An absorption mode receiving system that determines the validity of the frame from information other than the address field of the frame and removes the frame when it is determined that the frame is invalid or unnecessary, and selectively or both these mode receiving systems as appropriate. A loop-type data transmission system, wherein a frame is received by using the method.