JP2549453B2 - Transmission method of data way for autonomous distributed control - Google Patents

Description

The present invention relates to a transmission method of an autonomous distributed control data way having both a cyclic data transmission function and an asynchronous frame multiplexing function, and particularly, a high transmission speed. Regarding conversion.

[Prior Art] Fig. 3 shows "Telecommunication".
ations) ”, Volume 21, No. 5 (issued in May 1987), is a block diagram showing an example of the configuration of a station of a control data way for realizing the FDDI (Fiber Distributed Data Interface) protocol. . In FIG. 3, the station (10) is connected to the line connecting part (2) connected to the line (1) and the line connecting part (2),
Token patrol timer (3a) and token retention timer (3
and b) a media access part (3).

A buffer memory (4) including a microprocessor (5), a DMA transfer control unit (6), a transmission buffer memory (4a) and a reception buffer memory (4b) is connected to the media access unit (3), and An external controller (9) is connected via the click memory (7) and the asynchronous frame two-port memory (8).

As shown in FIG. 4, a plurality of stations (10) having such a configuration are connected to the loop-shaped transmission line (11).

FIG. 5A is a block diagram of the token frame (12), which includes a start delimiter (12-SD) and a frame control (12-F).
C), and the end delimiter (12-ED).
Also, FIG. 5B is a configuration diagram showing the data frame (13), which includes a start delimiter (13-SD) and a frame control (13-).
FC), destination address (13-DA), source address (13-DA)
SA), information area (13-INFO), frame check sequence (13-FCS), end delimiter (13-ED), and frame status (13-FS).

Next, the operation of this configuration will be described. When the station (10) connected to the loop transmission line (11) acquires the token frame (12) having the structure shown in FIG. 5 (a), the station (10) is shown in FIG. 5 (b). Acquire the right to transmit the data frame (13) of the configured configuration. At this time, the value of the token circulation timer (3a) is copied to the token holding timer (3b), and the token circulation timer (3a) is set (reset) to a predetermined value.
Timing starts again. Here, the token patrol timer (3a) has started counting since the previous token acquisition,
The time from the previous token acquisition to the current token acquisition is counted by subtracting (down counting) from the preset value. Therefore, the asynchronous data transmittable time can be known from the value of the token circulation timer (3a) when the token is acquired, and this value is set in the token holding timer (3b). The preset value set in the token circulation timer (3a) is the token circulation target time which is the target value of the token circulation time.

At this time, the synchronization frame for transmitting the transmission cyclic data of the station (10) is queued in the transmission buffer memory (4a) and waits for transmission as a synchronization frame. Station transmits a dummy frame that cannot be received by the station to the loop-shaped transmission line (11), and the cyclic memory portion of the cyclic data in the synchronization frame queued in the transmission buffer memory (4a) during the transmission ( Update with the data in 7). In this way, the latest cyclic data is transmitted to the other station (10).
This is the cyclic data transmission method described in Japanese Patent Application No. 1-150887. The transmission time of this dummy frame is necessary only for the overhead time of the process of rewriting the data of the synchronization frame with cyclic data, and after the cyclic data of the synchronization frame is always rewritten to the latest data, the transmission time is changed to the loop transmission line (11). It only needs to have time to ensure that it is sent out. Therefore,
Only after all the data of the synchronization frame is rewritten to the latest data, the synchronization frame is transmitted in the loop transmission line (1
It does not need to be sent to 1), and it is sufficient that the sync frame is sent to the loop transmission line (11) while the sync frame data is rewritten from the beginning to the latest data.

In addition, by keeping the synchronization frame that a certain station (10) sends to the loop transmission line (11) every time a token is acquired at all times, all stations (10) send all tokens in one token circulation. By keeping the transmission time of the synchronization frame constant, fluctuations in the token circulation time are suppressed. This is the method extended in the specification of Japanese Patent Application No. 1-56709.

The synchronization frame transmitted in this way is received by all the other stations (10), and the cyclic memory (7) is received.
The cyclic memory (7) of all stations (10) can be always kept in the same content within a time close to the token circulation time.

Regarding transmission of an asynchronous frame, for example, if an asynchronous frame transmission request is in the asynchronous frame 2-port memory (8), it is queued in the transmission buffer memory (4a) for a certain period at a constant period, and then the loop transmission line (11) is transmitted. When there is a margin in the traffic state of), the asynchronous frame is automatically transmitted to the loop transmission line (11), and the station receiving the asynchronous frame stores it in its own 2-port memory for asynchronous frame (8). The method was used.

[Problems to be Solved by the Invention] Since the conventional transmission method of the distributed control data way has the above-mentioned configuration, the queuing speed of the frame to the transmission buffer memory and the transmission speed to the loop transmission line Is a close value, and the receiving speed from the loop-shaped transmission line and the reading speed from the receiving buffer memory are close to each other, if there is a request regardless of whether an asynchronous frame is sent on the transmission line, the transmission buffer Since the synchronous frame cannot be read during the queuing, the synchronous frame read is delayed and the response of the cyclic communication is deteriorated.

Further, if an attempt is made to reduce the queuing opportunity of the asynchronous frame, there is a disadvantage that the transmission throughput of the asynchronous frame is reduced even when the traffic on the loop-shaped transmission path has a sufficient margin.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a transmission method with good response and high transmission speed.

[Means for Solving the Problem] In the transmission method of a self-sustained distributed control data way according to the present invention, a station for issuing a token first after completion of a claim process cannot receive any station. A frame is transmitted as a synchronous frame each time a token is acquired, and asynchronous frames are queued in the transmission buffer memory only when the reception buffer memory becomes empty.

[Operation] In the transmission method of the autonomous decentralized control data way according to the present invention, a dummy frame that cannot be received by any station is included in the final part of the synchronization frame issued after the claim process is completed. After the token is issued, the synchronous frame is read from the reception buffer memory, the reception buffer memory becomes empty, and then the asynchronous frame is queued in the transmission buffer memory. Therefore, the delay of reading the synchronization frame from the reception buffer memory is minimized and the accumulation is completely eliminated.

Embodiment Next, the present invention will be described in more detail with reference to the drawings.

FIG. 1 shows a frame sequence according to the invention queued in the transmission buffer memory (4a). According to this embodiment, a plurality of synchronization frames (16) having cyclic data (15) are prepared next to the dummy frame (14) for updating the cyclic memory, and the final part of the synchronization frame (16) is according to the present invention. Dummy frame for system (17)
Are arranged as a synchronization frame sequence (18). Also,
(19) is an asynchronous frame sequence.

In this embodiment, the token frame (12) and the data frame (13) have the same structure as the conventional example shown in FIGS. 5 (a) and 5 (b), and the token cycle timer (3a). The handling of the token holding timer (3b) is also the same as the conventional one.

In this embodiment, the station (10) enters the complaint process when the ring is started up, issues the complaint frame shown in FIGS. 5 (a) and 5 (b), and receives the complaint frame from the station (10). ) Also enters the claim process and relays the claim frame of another station (10) or transmits its own claim frame. One of them (10)
However, when it receives the claim frame that it issued, it exits the claim process and issues the first token,
When the other station (10) also receives the token, it exits the claim process and resumes communication.

A feature of this embodiment is that the station (10) receiving its own claim frame transmits a certain amount of system dummy frames which none of the stations (10) receives as a synchronization frame. If there is a cyclic data transmission area, this station (10) transmits looped data while updating the synchronous frame that has been queued after transmitting dummy frames with the latest cyclic data at the same time as the token acquisition, as in the conventional case. Send to road (11). After this, if there is a margin in the token holding timer (3b), send buffer memory (4
Asynchronous frames queued in a) will be sent to the loop transmission line (11). The station (10) that has not received its own claim frame transmits the synchronous frame and the asynchronous frame to the loop-shaped transmission line (11) in the same manner as the conventional method.

Further, the characteristic feature of this embodiment is that, as shown in the flow chart of FIG.
When the receiving buffer memory (4b) becomes empty and there is a request to send an asynchronous frame, the asynchronous frame (19) is queued in the sending buffer memory (4a). .

A dummy frame (17) for the system is transmitted every token circulation, and this does not become a burden of reception processing because neither station (10) receives it, and there is no processing load idle time for any station (10). Become. Since such time is given, the problem that the read delay from the reception buffer memory (4b) due to queuing the asynchronous frame (19) in the transmission buffer memory (4a) is solved. Moreover, receive buffer memory (4b)
Since the asynchronous frame (19) is queued only when is empty, the read delay of the reception buffer memory (4b) is minimized and the deterioration of the cyclic communication response is suppressed.

In other words, the asynchronous frame queuing process ends while the station (10) somewhere is transmitting the dummy frame (17) for the system, and both the asynchronous queuing process time is secured and the reception buffer read delay is suppressed. Will be achieved.

In addition, the asynchronous frame (19) queued in the transmission buffer memory (4a) is actually the loop transmission line (11).
When it is transmitted to the station (10), the reception frame is not stored in the reception buffer memory (4b) for this time and the reception buffer memory (4b) becomes empty earlier. By doing so, queuing of the asynchronous frame (19) to the transmit buffer memory (4a) can be performed, and time is automatically allocated to the queuing process of the asynchronous frame (19) while suppressing the read delay time of the receive buffer. To be done.

[Effect of the Invention] As described above, the present invention employs a transmission method in which a system dummy frame is transmitted together with a synchronous frame to give a margin time to all stations for queuing asynchronous frames. ,
There is an effect that a transmission method of a distributed control data way which has both a cyclic data transmission function with good response and a sufficient asynchronous transmission function is obtained.

[Brief description of drawings]

FIG. 1 is an explanatory view of a data frame according to the present invention, and FIG.
FIG. 3 is a flow chart of queuing of an asynchronous frame according to the present invention, FIG. 3 is a block diagram of a station connected to a data way, FIG. 4 is an explanatory diagram of a loop data way, and FIG. FIG. 5B is an explanatory diagram of a token frame, and FIG. 5B is an explanatory diagram of a data frame. In the figure, (1) is a line, (2) is a line connection unit,
(3) Media access unit, (4) Buffer memory, (4a) Send buffer memory, (4b) Receive buffer memory, (5) Microprocessor, (6) DAM
Transfer control unit, (7) cyclic memory, (8) two-port memory for asynchronous frame, (9) external controller, (10) station, (11) loop transmission line,
(12) is a token frame, (13) is a data frame,
(14) is a dummy frame for updating cyclic memory,
(15) is cyclic data, (16) is a sync frame,
(17) is a system dummy frame, (18) is a synchronous frame sequence, and (19) is an asynchronous frame sequence. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

(57) [Claims] 1. A transmission of data other than cyclic data to the ring-shaped transmission line between a plurality of stations connected to a ring-shaped transmission line for transmitting a synchronization frame including cyclic data and an external control device. Asynchronous frame multiplexing function that queues the data as an asynchronous frame in the transmission buffer memory when a request is generated and transmits the transmission data to the ring transmission line when traffic on the ring transmission line has a margin In the provided data way, the station that first issues the token after the end of the claim process sends a certain amount of system dummy frames that cannot be received by any station as a synchronous frame every time the token is acquired, thereby transmitting the asynchronous frame. Gives the opportunity to queue in memory, asynchronous Method for transmitting autonomous distributed control data Way frame is queued to the transmission buffer memory, which comprises carrying out only when the reception buffer memory is empty.