JPH03116351A - Communication order determining device - Google Patents

Abstract

PURPOSE:To eliminate a need of a means for centralized control of bus arbitration by recognizing the order of communication based on the state of a communication request on a communication bus at the time of issue of the communication request and recognizing coming of turn for communication start by counting to start communication. CONSTITUTION:In the cycle of issue of the communication request, a communication control system 6 outputs a signal to a specific bit of a communication request signal on the communication bus which is determined in accordance with communication bus use priority levels set to respective boards 2. When each board 2 issues the communication request, the number of boards which start the communication before the start of communication of this board is recognized in accordance with transmission requests of the other boards issued before issue of the communication request from this board and the number of boards, which issue communication requests simultaneously with issue of the communication request from this board and whose communication bus use priority levels are higher than that of this board, and this value is stored. The stored value is counted down at each time of the communication request issue cycle or the communication cycle to recognize that the board can start communication. Thus, the means for centralized control of arbitration of the communication bus is unnecessary.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to communication order determining means for a communication bus.

〔overview〕

In the communication order determining means of a communication bus to which a plurality of boards are connected, the present invention recognizes the order of communication based on the status of the communication request on the communication bus at the time of a communication request, and indicates that it is the turn to start communication. By recognizing by counting and starting communication, it is possible to eliminate the need for centralized management of bus arbitration and improve the expandability of the bus.

[Conventional technology]

In the conventional example, a means was provided on the communication bus to determine the communication order based on the order and priority in which communication requests were issued from each board on the communication bus, and to give communication permission to each board.

[Problem that the invention seeks to solve]

In such a conventional example, there is an arbitration means that arbitrates communication requests sent by multiple boards on a communication bus and determines the order in which each board uses the bus, and a many-to-one arrangement from each board to the arbitration means. A communication request signal to be sent and a communication permission signal to be sent from the arbitration means to each board on a one-to-many basis at the start of communication are required. Therefore, in order to expand the communication bus, it is necessary to prepare a communication request signal and a communication permission signal for each board in the expansion section, which complicates the structure of the communication bus itself and makes it difficult to expand. There were drawbacks.

SUMMARY OF THE INVENTION An object of the present invention is to provide a communication order determining device that eliminates such drawbacks and allows easy board expansion.

[Means for solving problems]

The present invention provides a communication bus having a first cycle for handling communication request signals and a second cycle for handling communication data;
In a communication order determining device included in a system including a plurality of boards connected to the communication order determining device, each of the plurality of boards has a use priority setting means for setting the use priority of its own board with respect to the communication bus. , in the first cycle, a signal sending means for giving a signal to a specific bit corresponding to the usage priority set for the own board among the bits of the communication request signal; recognition storage means for recognizing the number of other boards and the number of other boards that have been set with a higher usage priority than the own board among the other boards that issued the communication request signal at the same time, and storing the total number; communication start state recognition means for counting the number of second cycles for each second cycle and permitting the own board to start communication when the counted value reaches the total number stored in the recognition storage means of the own board. It is characterized by

[Effect]

Set the communication bus usage priority of each board that uses the communication bus, and specify the specific communication request signal on the communication bus determined according to the communication bus usage priority set for each board at the time of the communication request issuing cycle. Give a signal to the bit. Also,
When each board issues a communication request, the number of boards that have a higher communication bus usage priority than that board among the communication requests that were issued at the same time as the communication requests of other boards that were issued before that board issued the communication request. The number of boards with which the board communicates is recognized and memorized, and this memorized value is counted down for each cycle in which a communication request is issued or communication is performed, until the board starts communicating. Recognize that you are ready to start.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an embodiment of the present invention. Second
The figure is an internal block diagram of the communication control system 6 on the board 2. FIG. 3 shows an example of a communication bus system, and FIG. 4 shows a case where the communication bus system shown in FIG. 3 is expanded by one board.

The communication bus 1 is composed of a data line 3, a synchronous clock line 4, and a cycle recognition signal line 5, and the data line 3 is used by switching between a communication request and data according to a signal on the cycle recognition signal line 5.

The board 2 is composed of a communication control system 6, an internal processing system 7, and an internal data line 8. The communication control system 6 receives operation instructions from the internal processing system 7 through the internal data line 8, and starts communication. When it becomes possible to do so, a communication start recognition signal 9 is used to notify the on-board processing system 7 to start communication.

The communication control system 6 is composed of a communication request state recognition means 10, a data input/output means 11, and a communication start recognition means 12. The data input/output means 11 receives data between the data line 3 and the on-board data line 8. A communication request status notification signal 1 is sent to the communication request status recognition means 10 and output of the communication request.
4, the communication request state recognition means 10 determines the number of times that other boards communicate before starting communication, and notifies the communication start recognition means 12 of a count number notification signal 13 until the start of communication; The communication start recognition means 12 counts down every communication cycle, and when it is the turn to communicate, outputs a communication start recognition signal 9 to the on-board processing system to start communication. Figure 3 shows boards 2a s 2b.

4 shows an example of a communication bus system consisting of 2C and 2d and a communication bus 1. FIG. An example is shown in which a board 2e is added by connecting and expanding the communication bus.

That is, this embodiment is included in a system consisting of a communication bus having a first cycle for handling communication request signals and a second cycle for handling communication data, and a plurality of boards connected to the communication bus, and a plurality of boards connected to the communication bus. Each of the boards includes a use priority setting means for setting the use priority of the own board with respect to the communication bus, and in the first cycle, the use priority setting means corresponds to the use priority set for the own board among the bits of the communication request signal. A signal sending means for giving a signal to a specific bit, the number of other boards that have issued a communication request signal before the own board issues it, and a usage priority higher than the own board among the other boards that have issued a communication request signal at the same time are set. In addition, communication request state recognition means 10 is a recognition storage means for recognizing the number of other boards and storing the total number, and counts the number of times of the second cycle for each second cycle, and the counted value is recorded as the own board. A communication start recognition means 12 is provided as a communication start state recognition means for permitting communication start of the own board when the total number stored in the recognition storage means of the board is reached.

Next, the operation of this embodiment will be explained.

In the communication bus system shown in FIG. 3, boards 2a, s, and 2b.

The priority order of the communication buses is set in the order of 2c and 2d. However, this priority order applies to cases in which communication requests are issued in the same cycle, and communication requests issued in previous cycles are always given priority. If a communication request for boards 2b and 2d is issued in one communication request cycle, and a communication request for boards 2a and 2c is issued in the next communication request cycle, the communication request for board 2a is is board 2
priority is given to communication requests from boards 2b and 2d, but not to communication requests from boards 2b and 2d. Communication requests are sent to data lines 3 according to their priorities in the communication request cycle.
The above specific bits are used to output whether or not there is a communication request.

Therefore, by monitoring the communication state notification signal 14 outputted from the data input/output means 11 by the communication request state recognition means 10, the state of the data line 3 in the cycle in which the communication request is issued can be determined by monitoring the state of the data line 3 in the cycle in which the communication request is issued. By comparing the state of No. 3 with the previous time, it is possible to recognize how many times the board communicates before that board starts communication. In this example, when board 2c issues a communication request, it recognizes that three communication requests from boards 2a, 2b, and 2d have been issued, and the communication request from board 2d was issued in the cycle in which the previous communication request was issued. Board 2a has higher priority than board 2c, so board 2c
recognizes that other boards will communicate twice before starting communication. The value recognized by the communication request state recognition means 10 is sent to the communication start recognition means 12 as a count notification signal 13 until the start of communication. The communication start recognition means 12 counts down the value for each cycle of communication thereafter, and when it reaches "0", notifies the on-board processing system 7 by the communication start recognition signal 9.

By monitoring the state of the data line 3 in the cycle of issuing a communication request in this way, it is possible to recognize the time to start communication, so as shown in FIG. To expand the bus by adding code 2e, simply add data line 16, synchronous clock line 17 and and cycle recognition signal line 18 in parallel, and connect the new board 2a.
It is only necessary to set board 2e with a different priority than s 2b s2C and 2d. By connecting the communication bus system of the expansion part and the communication bus system before expansion in parallel in this way, the communication bus can be expanded.

〔Effect of the invention〕

As explained above, the present invention uses the data line of the communication bus to issue a communication request in the cycle in which each board on the communication bus issues a communication request, and the state of the communication request in the cycle in which the communication request is issued when the communication request is output. By the time the board that outputs the communication request starts communication, it recognizes the number of boards it is communicating with, counts down that value, and recognizes that it is its turn to start communication, so it can arbitrate the communication bus. This has the effect of eliminating the need for centralized management. In addition, the communication bus can be expanded simply by connecting it in parallel to the data lines and control signals on the communication bus, so the structure of the communication bus itself can be simplified and costs can be reduced. This has the effect of realizing a highly expandable communication bus.

[Brief explanation of drawings]

FIG. 1 is a block configuration diagram showing the overall configuration of an embodiment of the present invention. FIG. 2 is a block diagram showing the configuration of the communication control system in FIG. 1. FIG. 3 is a schematic diagram showing a communication bus system composed of four boards. FIG. 4 is a schematic diagram showing a communication bus system in which one board is added to the communication bus shown in FIG. 3 to expand the communication bus. 1... Communication bus, 2a, 2b, 2C, 2d
, 2e...board, 3.16...data line,
4.17... Synchronous clock line, 5.18... Cycle recognition signal line, 6... Communication control system, 7... In-board processing system, - In-board data line, 9... communication start recognition signal, 10...communication request state recognition means, 11.
...Data person output means, 12...Communication start recognition means,
13... Count number notification signal, 14... Communication request status notification signal, 15... Communication priority setting signal.

Claims (1)

[Claims] 1. Communication order determination included in a system consisting of a communication bus having a first cycle for handling communication request signals and a second cycle for handling communication data, and a plurality of boards connected to the communication bus. In the apparatus, each of the plurality of boards includes a use priority setting means for setting a use priority of the own board with respect to the communication bus; a signal sending means that sends a signal to a specific bit corresponding to the priority of use; the number of other boards that issued a communication request signal before the own board issued the communication request signal; and the number of other boards that issued a communication request signal at the same time. recognition and storage means for recognizing the number of other boards to which a high usage priority has been set and storing the total number; and counting the number of times of the second cycle for each second cycle, and the counted value is the same as that of the own board. 1. A communication order determining device comprising communication start state recognition means for permitting the own board to start communication when the total number stored in the recognition storage means has been reached.