JPH02288633A - Communication controller - Google Patents

Abstract

PURPOSE:To improve the utilizing efficiency of a transmission line by sending token information together with a valid transmission data and making the data length of the transmission data and the transmission timing to be a prescribed value calculated from the number of communication controllers and their communication period. CONSTITUTION:A transmission constant calculation means, a transmission timing decision means and a token information setting means are added to central processing units(CPU) 7a-7c of communication controllers 2a-2c. Then communication control section 4a-4c send a transmission data including token information set by a token information setting means by a data length decided by the transmission constant calculation means in the timing decided by the transmission timing decision means to a transmission line 1. Since the information relating to a baton right and the transmission data to be sent are not separated in such a way, then the utilizing efficiency of the transmission line 1 is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a communication control device used in distributed data processing systems and the like.

[Prior Art] FIG. 4 is a block diagram showing a communication system in which a plurality of conventional communication control devices (stations) are connected, as shown in the drawings, for example, in Japanese Patent Application No. 63-264174. In the figure, 1 is a transmission line, 2a to 2C are communication control devices connected to the transmission line 1 and the main device (not shown), and 3a to 3c are connection lines 1 to each communication control device 28 to 2c. a coupler,
48 to 4c are connected to transmission line 1 via couplers 38 to 3c, receive received data from transmission line 1, and also receive data from transmission line 1.
5a to 5c are transmission buffer memories that store transmission data; 68 to 6c are reception buffer memories composed of a plurality of reception buffers that temporarily store reception data; 78 to 7c are communication controllers; Control device 2a
~2C central processing unit (hereinafter referred to as CPU).

Next, the operation will be explained. Each communication control device 28 to 2c
Information indicating transmission rights, also known as baton rights, is passed between the two. Now, for example, when the baton is handed over to the communication-controlled i-press device 2a and the CPU 7a recognizes this, the
If transmission data exists in the transmission buffer memory 5a connected to the PU 7a, the CPU 7a
send this transmission data. If this transmission data is data to be sent to the main device connected to the communication system GFa-, IE2b, the communication control unit 4a adds address information indicating the communication control device 2b, and
Send to.

When the communication control unit 4b of the communication control device 2b recognizes the address information indicating its own station, it sends a message to the CP indicating that it will receive the received data.
Notify U7b. 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. And C.P.
U7b causes the communication control pusher 4b to send response information.

This response information includes the communication control device 2 that sent the transmission data.
Since the address information indicating "a" is added, the communication control section 4a recognizes that the information is for its own station, accepts this response information, and notifies the CPU 7a that the response information has been received. When the CPU 7a receives the response information and recognizes that the communication has ended normally, the CPU 7a causes the communication control unit 4a to send information for passing the baton to the next communication control device 2b. When the communication control unit 4b receives this information, the communication control unit 4b
7b is notified 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. In the manner described above, the communication control device 2b acquires the baton right.

If 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 chart showing the communication status of each communication control device 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 for passing the baton,
BA is information indicating that the baton right has been acquired. Information B for passing the baton right and information BA for acquiring the baton right
is always performed between the communication control units fi2a to fi2C, regardless of the presence or absence of transmission data.

[Problem to be Solved by the Invention] Since the conventional communication control devices 28 to 2C are configured as described above, even if there is transmission data to be sent, the baton right must also be transmitted in addition to the transmission data. Not,
This method requires two transmissions and is not suitable for communications that require periodicity in which the baton is passed to each communication control device at regular intervals.

This invention was made in order to solve the above-mentioned problems, and it improves the efficiency of using the transmission path by not separating the information regarding the baton right from the transmission data to be sent, and also improves the efficiency of using the transmission path. It is an object of the present invention to provide a communication control device that is suitable not only for event-based information communication (N:N communication), but also for information communication that requires periodicity (cyclic communication).

[Means to solve the problem]

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

[Effect]

The communication control unit in this invention sends the transmission data including the transmission right information set by the transmission right information setting means to the transmission path by the data length determined by the transmission constant calculation means at the timing determined by the transmission timing determination means. do.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. The configuration of the communication system i-button device according to this embodiment is the same as 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. This is different from the conventional case.

The next operation will be explained with reference to the flowchart shown in FIG. When the power is turned on or a reset operation is performed, the CPUs 7a to 7c perform initialization processing of the communication control devices 2a to 2C (steps 5T11 to 5T12).
The CPUs 7a to 7c perform constant setting according to the type of communication. In other words, when performing cyclic communication, the transmission path l
The transmission buffer length and the inter-slot time TA are calculated from the number of communication control devices 28 to 2C connected to and the set communication cycle T. When performing NUN communication, the transmission buffer length and the inter-slot time TA are arbitrary fixed values. Therefore, no calculation is performed (step 5TI
I). Next, a timer is activated with the inter-slot time TA determined in step 5TII as a time limit (step 5T12).

After the initialization processing (steps 5T11 to ST12) is completed, transmission start processing (steps ST21 to 5T24), transmission completion processing (steps 5T31 to ST33), reception completion processing (steps 5T41 to ST43), and transmission data generation processing ( Steps ST51 to 5T52) and other processes (step 576) are repeatedly executed.

First, the transmission activation process will be explained. First, it is determined whether the timer activated at the end of the initialization process, at the end of transmission, or at the end of reception has timed up, that is, whether or not the inter-slot time TA has elapsed (step 5T21).

When the time is up, it is determined whether or not the baton right exists in the local station (step 5T22). When the time is not up or the baton right does not exist, the transmission activation process ends. do. When the baton right exists in the own station, transmission header information such as address information is set in a predetermined area of the transmission buffer memories 58 to 5C. Here, the transmission header information also includes information regarding the baton right (step 5T23). Then, the communication controllers 48 to 4C are activated to transmit. Communication control unit 48
-4C transmits the transmission header information and valid transmission data to the transmission path 1 when there is valid transmission data in the transmission buffer memories 58-5C.

Send to. If there is no valid transmission data, only the transmission header information is sent as transmission data.

Next, the transmission completion process will be explained. First, it is determined whether there is a transmission completion notification from the communication control units 4a to 4C (step 5T31). If there is no notification, the transmission completion process ends. If there is a notification, a timer is started with the inter-slot time TA as the time limit (step 5T32). At this time,
When performing NUN communication and transmitting valid transmission data, the main control device connected to the communication control devices 2a to 2C is notified of completion of transmission.

Next, the reception completion process will be explained. First, it is determined whether there is a reception completion notification (step 5T41). The reception completion notification indicates that the communication control units 48 to 4c have received transmission data from other communication control devices 28 to 2C via the transmission path 1, and have stored the received data in the reception buffer memories 68 to 6c. It is something. If there is no notification, the reception completion process ends. If there is a notification, a timer is started with the inter-slot time TA as the time limit (step 5T42), and the received data is processed (step 5T43).

That is, the contents of the reception buffer memories 6a to 6C are read and the transmission header information is determined. If the transmission header information is inspected and it is determined that the transmission data is not addressed to the local station, the received transmission data is discarded. Further, if there is information indicating that the baton right has been handed over, a flag indicating that the baton right exists in the own station is set. If the transmission data is addressed to the own station, it is further determined whether there is valid transmission data. Then, valid transmission data is processed. for example,
If NUN communication is being performed, the connected main device is notified of reception completion and the received valid transmission data is passed.

Next, the transmission data generation process will be explained.

First, it is determined whether there is a data generation request (step 5T).
51). 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 58 to 5C.

(Step 5T52). Here, in the case of N:N communication, the data length of the set transmission data is the data length specified by the main device as long as it does not exceed the transmission buffer length. In the case of cyclic communication, the length is the transmission buffer length sent in the initialization process (step 5TII). Note that in the case of cyclic communication, processing is always performed as if there was a data generation request. In other words, data is always present in the transmission buffer memories 58 to 5c (.

If this is done, the data length of the transmitted data will always be the same.

FIG. 2 is a timing diagram showing transmission timing during NUN communication. As shown in the figure, after the inter-slot time TA has elapsed from the completion of transmission of transmission data or the completion of reception of reception data, transmission data (B+Da) (B+Db) containing the baton right and valid transmission data or transmission data containing only the baton right B is sent. Further, FIG. 3 is a timing diagram showing transmission timing during cyclic communication. As shown in the figure, after the inter-slot time TA has elapsed, transmission data (B+D
a), (B+Db), and (B+Dc) are sent, and the communication cycle T is kept constant.

〔Effect of the invention〕

As described above, according to the present invention, the communication control device is configured to transmit transmission right information together with valid transmission data, and the data length and transmission timing of the transmission data are determined based on the number of communication control devices and the communication cycle. Since the configuration is configured so that the calculated constant value is obtained, the usage efficiency of the transmission path is improved, and there is an effect that one type is suitable not only for NUN communication but also for cyclic communication.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing the operation of a communication control device according to an embodiment of the present invention, FIG. 2 is a timing diagram showing transmission timing in the case of NUN communication, and FIG. 3 shows the transmission timing in the case of cyclic communication. FIG. 4 is a configuration diagram showing a communication system to which a plurality of communication control devices are connected, and FIG. 5 is a timing diagram showing communication by a conventional communication control oil device. 1 is a transmission path, 28 to 2c are communication control devices, 3a to 3c are couplers, 48 to 4c are communication control sections, 5a to 5C are transmission buffer memories, 6a to 6c are reception buffer memories, 7
a to 7c are central processing units (control unit, transmission constant calculation means,
(transmission timing determining means, transmission right information setting means). In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Patent applicant Mitsubishi Electric Corporation Figure 1 Figure b C

Claims (1)

[Claims] a communication control unit that sends out transmission data to a transmission path and receives reception data from the transmission path; a transmission buffer memory that stores the transmission data and provides it to the communication control unit; a reception buffer memory that stores the input received data; and a control unit that acquires transmission right information from the transmission path via the communication control unit and then causes the communication control unit to transmit the transmission data to the transmission path. a communication control device comprising: a transmission constant calculation means for calculating a data length of the transmission data and an inter-slot time based on the number of stations connected to the transmission path and a set communication cycle; Based on the data transmission timing, the reception timing of the received data, and the inter-slot time, a new
A communication control device comprising: transmission timing determining means for determining the timing of transmitting the transmission data to the transmission path; and transmission right information setting means for setting the transmission right information in the transmission data.