JPH0671264B2 - Communication control device - Google Patents

Description

The present invention relates to a communication control device used in a distributed data processing system or the like.

[Conventional technology]

FIG. 4 shows, for example, Japanese Patent Application No. 63-264174 (JP-A-02-1120).
FIG. 44 is a configuration diagram showing a communication system in which a plurality of conventional communication control devices (stations) shown in the drawings according to Japanese Patent Laid-Open No. 44) are connected. In the figure, 1 is a transmission line, 2a to 2c are communication control devices connected to the transmission line 1 and a main device (not shown),
3a to 3c are couplers that connect the transmission line 1 and the respective communication control devices 2a to 2c, 4a to 4c are connected to the transmission line 1 via the couplers 3a to 3c, and receive data from the transmission line 1, In addition, the transmission line 1
A communication control unit for sending the transmission data to 5a to 5c, a transmission buffer memory for storing the transmission data, 6a to 6c, a reception buffer memory composed of a plurality of reception buffers for temporarily storing the reception data, and 7a to 7c for communication It is a central processing unit (hereinafter referred to as CPU) of the control devices 2a to 2c.

Next, the operation will be described. Information indicating a transmission right, which is also called a baton right, is passed between the communication control devices 2a to 2c. Now, for example, if the baton right is passed to the communication control device 2a and the CPU 7a recognizes this, and if there is transmission data in the transmission buffer memory 5a connected to the CPU 7a, the CPU 7a sends this transmission data to the communication control unit 4a. To send. If this transmission data is data to be sent to the main device connected to the communication control device 2b, the communication control unit 4a adds address information indicating the communication control device 2b and sends it to the transmission line 1. .

When the communication control unit 4b of the communication control device 2b recognizes the address information indicating its own station, it notifies the CPU 7b that the received data will be received. At this time, if there is an empty reception buffer in the reception buffer memory 6b, the communication control unit 4b stores the reception data in this reception buffer. Then, the CPU 7b is the communication control unit 4
Causes b to send response information.

This response information includes the communication control device 2a that sent the transmission data.
The communication control unit 4a, which has recognized that the information is for the local station, accepts this response information and notifies the CPU 7a that the response information has been received. C
Upon receiving the response information and recognizing that the communication has been normally completed, the PU 7a causes the communication control unit 4a to send information for passing the baton right to the next communication control device 2b. Communication controller 4b
Upon receiving this information, notifies the CPU 7b that the baton right has been received. The CPU 7b causes the communication control unit 4b to send information indicating that the baton right has been acquired. As described above, the communication control device 2b acquires the baton right. Then, when there is no transmission data to be sent to the transmission buffer memory 5b of the communication control device 2b, the baton right is immediately passed to the next communication control device 2c.

FIG. 5 is a timing diagram showing a communication state of each of the communication control devices 2a to 2c. In the figure, Da and Dc are transmission data sent by the communication control devices 2a and 2c, DA is response information to the transmission data, B is information to pass the baton right, and BA is information indicating that the baton right is acquired. is there. The information B for passing the baton right and the baton right acquisition information BA are the communication control device 2a.
Between ~ 2c, it is always performed regardless of the presence or absence of transmission data.

[Problems to be Solved by the Invention]

Since the conventional communication control devices 2a to 2c are configured as described above, even if there is transmission data to be transmitted, the baton right must be transmitted separately from the transmission data, and transmission is required twice. In addition, there is a problem that it is not suitable for communication that requires the periodicity of passing the baton right to each communication control device at a constant period.

The present invention has been made in order to solve the above problems, and improves the efficiency of use of the transmission line by not separating the information regarding the baton right from the transmission data to be transmitted, and described in the conventional example. An object of the present invention is to obtain a communication control device suitable not only for such event-like information communication (N: N communication) but also for information communication (cyclic communication) that requires a constant periodicity.

[Means for Solving the Problems]

In the communication control device according to the present invention, the transmission constant calculation means calculates the data length of the transmission data and the inter-slot time based on the number of communication control devices connected to the transmission path and the set communication cycle, and transmits the data. The timing determining means includes the transmission right information set by the transmission right information setting means at a timing determined from the transmission timing of the transmission data and the reception timing of the reception data and the calculated inter-slot time. The transmission data to be transmitted is transmitted.

[Action]

The communication control unit according to the present invention sends the transmission data including the transmission right information set by the transmission right information setting unit to the transmission line at the timing determined by the transmission timing determination unit by the data length determined by the transmission constant calculation unit. To do.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. The configuration of the communication control device according to this embodiment is the same as that of the conventional one shown in FIG. 4, but a transmission constant calculation means, a transmission timing determination means, and a transmission right information setting means are added to the CPUs 7a to 7c. The point is different from the conventional case.

The next operation will be described with reference to the flowchart shown in FIG. The CPUs 7a to 7c perform initialization processing of the communication control devices 2a to 2c by power-on or reset operation (steps ST11 to ST12). Here, the CPUs 7a to 7c perform constant setting according to the communication type. That is, when performing cyclic communication, the transmission buffer length L and the inter-slot time TA are calculated from the number of communication control devices 2a to 2c connected to the transmission path 1 and the set communication cycle T. N:
When performing N communication, the transmission buffer length L and the inter-slot time TA are arbitrary fixed values. Therefore, it is not calculated (step ST11). Next, the timer is started with the time interval TA determined in step ST11 as a time limit value (step ST12).

After the initialization process (steps ST11 to ST12) is completed, the transmission start process (steps ST21 to ST24) and the transmission completion process (steps)
ST31 to ST33), reception completion processing (steps ST41 to ST43),
The transmission data generation process (steps ST51 to ST52) and other processes (step ST6) are repeatedly executed.

First, the transmission activation process will be described. First, at the end of the initialization process, it is determined whether or not the timer started at the time of completion of transmission or completion of reception has timed up, that is, whether or not the inter-slot time TA has elapsed (step ST21). . When the time is up, it is judged whether or not the baton right exists in the own station (step ST22),
When the time has not expired or when the baton right does not exist, the transmission start processing ends. If the baton right exists in the own station, the transmission buffer memories 5a to 5c
The transmission header information such as address information is set in a predetermined area of. Here, the transmission header information also includes information on the baton right (step ST23). And the communication control unit
Start transmission for 4a to 4c. The communication control units 4a-4c are
When the transmission buffer memories 5a to 5c have valid transmission data, the transmission header information and the valid transmission data are transmitted to the transmission line 1
Send to. If there is no valid transmission data, only the transmission header information is transmitted as transmission data.

Next, the transmission completion process will be described. First, it is determined whether there is a transmission completion notification from the communication control units 4a to 4c (step ST31). If there is no notification, the transmission completion process ends.
If there is a notification, the timer is started with the inter-slot time TA as a time limit value (step ST32). At this time, when N: N communication is performed and valid transmission data is transmitted, the completion of transmission is notified to the main control devices connected to the communication control devices 2a to 2c.

Next, the reception completion process will be described. First, it is determined whether or not there is a reception completion notification (step ST41). The reception completion notification indicates that the communication control units 4a to 4c have received the transmission data from the other communication control devices 2a to 2c via the transmission path 1 and stored the received data in the reception buffer memories 6a to 6c. It is a thing. If there is no notification, the reception completion processing ends. If there is a notification, a timer is started with the inter-slot time TA as a time limit value (step ST42). Then, the received data is processed (step ST43). That is, the receive buffer memory
The contents of 6a to 6c are read and the transmission header information is judged. When the transmission header information is checked and it is determined that the transmission data is not addressed to the own station, the received transmission data is discarded. Also, if there is information indicating that the baton right has been passed, a flag indicating that the baton right exists in the own station is set. If the transmission data is addressed to the own station, the presence / absence of further effective transmission data is determined. Then, the effective transmission data is processed. For example, when N: N communication is being performed, the reception completion is notified to the connected main device, and the received valid transmission data is passed.

Next, the transmission data generation process will be described. First, the presence / absence of a data generation request is determined (step ST51). If there is no request, the transmission data generation process ends. If there is a request, valid transmission data is set in the transmission buffer memories 5a to 5c. (Step ST52). Here, in the case of N: N communication, the data length of the set transmission data is the data length designated by the main device as long as it does not exceed the transmission buffer length L. In the case of cyclic communication, it is the transmission buffer length L sent in the initialization process (step ST11).
In the case of cyclic communication, processing is always performed with a data generation request. That is, data is always present in the transmission buffer memories 5a-5c. In this way, the data length of the transmission data will always be the same.

FIG. 2 is a timing diagram showing the transmission timing during N: N communication. As shown in the figure, after the inter-slot time TA has elapsed from the completion of transmission of transmission data or reception of reception data, transmission data (B + Da), (B + Db) including baton right and valid transmission data, or transmission including only baton right Data B is transmitted. Further, FIG. 3 is a timing chart showing the transmission timing at the time of cyclic communication. As shown in the figure, after the inter-slot time TA has elapsed, the transmission data (B + Da), (B including the baton right and the data of the data length L)
+ Db) and (B + Dc) are transmitted, and the communication cycle T is kept constant.

〔The invention's effect〕

As described above, according to the present invention, the communication control device transmits the transmission right information together with the valid transmission data, and the data length and the transmission timing of the transmission data are determined from the number of communication control devices and the communication cycle. Since the calculated constant value is used, the use efficiency of the transmission path is improved and one type is suitable not only for N: N communication but also for cyclic communication.

[Brief description of drawings]

FIG. 1 is a flow chart showing the operation of the communication control apparatus according to an embodiment of the present invention, FIG. 2 is a timing chart showing the transmission timing in the case of N: N communication, and FIG. 3 is a transmission timing in the case of cyclic communication. Timing diagram showing the 4th
FIG. 5 is a configuration diagram showing a communication system in which a plurality of communication control devices are connected, and FIG. 5 is a timing diagram showing a state of communication by a conventional communication control device. 1 is a transmission line, 2a to 2c are communication control devices, 3a to 3c are couplers,
4a to 4c are communication control units, 5a to 5c are transmission buffer memories, 6a
6a to 6c are reception buffer memories, and 7a to 7c are central processing units (control unit, transmission constant calculation means, transmission timing determination means, transmission right information setting means). In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. Transmitting transmission data to a transmission line,
A communication control unit that receives received data from this transmission path, a transmission buffer memory that stores the transmission data and gives the communication control unit, and a reception buffer that stores the received data input via the communication control unit. A communication control device comprising: a memory; and a control unit for transmitting the transmission data to the communication path after acquiring transmission right information from the transmission path via the communication control unit, Transmission constant calculation means for calculating the data length of the transmission data and the inter-slot time based on the number of stations connected to the transmission line and the set communication cycle, transmission timing of the transmission data, reception of the reception data A new timing for sending the transmission data to the transmission path is determined based on the timing and the inter-slot time. Communication control apparatus characterized by comprising: a transmission timing determining means, and a transmission right information setting means for setting the transmission right information in the transmission data.