JPS61276443A - Communication control system - Google Patents

Abstract

PURPOSE:To utilize effectively communication capacity of a line by executing communication for plural number of times while the control right of communication is held within a range where a cyclic communication number exceeds a prescribed value when the communication number is less than a prescribed value and plural communication requests exist in the own station. CONSTITUTION:Stations S1, S2 having a communication control function are connected via a common transmission line Ln. A master station acquiring a communication control token and performing communication compares a communication number M of the entire communication system during the cycle of preceding token with a station number N connected to the line Ln, and when the number N is larger than the number M, and the difference is taken as a communication permitting number L this time. A count M of the counter counting the communication number of one cycle of next time is initialized to 0, and when communication request exists, it is processed and 1 is added to the counter. When M<L exists, the communication request is processed, and when the communication request is lost or M<L does not exist, the token is sent to the next station and the master right is taken over. Thus, the line communication capacity is utilized effectively.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a communication control method applied when a plurality of communication stations communicate by using a common transmission line in a time-sharing manner. .

A talk/pass (or baton pass) in which communication control rights (called tokens or batons) on a transmission line are transmitted one after another using command frames (token pass frames) in a predetermined order. This relates to the communication control method of the system.

(Prior Art) When a plurality of distributed stages are connected by a common transmission line and communicated with each other, control is required to maintain the order of one communication.

One of the conventional communication control methods is the talk/pass method. In this token pass type communication system,
Stage 1: receiving the token and acquiring communication control rights
While the station holds the communication control authority, the station performs one communication and passes the token to the zero-order station.

(Problem to be solved by the invention) Like this lkv! In the conventional token pass communication control method, when multiple communication requests occur at a certain station, even if there are no communication requests at other stages,
Communication control must be handed over to the next station every time one communication is completed, and the time required for a token to complete a round is exceeded for each communication, resulting in depletion and reducing the transmission capacity of the transmission line. There was a problem that it could not be improved. Note that if multiple communications are allowed to occur while retaining the communication control authority, the time it takes for a token to go through one cycle may significantly increase, causing the problem that line access time cannot be guaranteed.

The present invention was made in view of these problems, and
The purpose of this is to suppress the time it takes for a token to go around within a certain value in a token pass type communication system, and to allow multiple communications under certain conditions while retaining communication control rights (master rights). The goal is to increase communication capacity by making effective use of transmission lines.

(Means for Solving the Problems) The present invention solves the above-mentioned problems in a communication system in which communication control rights are rotated among a plurality of stages connected to a common transmission line. The STacylon counts the total number of communications while the communication control authority goes around the communication system, and if this number of communications is less than a predetermined value and there are multiple communication requests for the own station, the number of communications in one round is counted. The present invention is characterized in that communication is performed a plurality of times while maintaining control of the communication within a range in which the value does not exceed a predetermined value.

(Example) FIG. 1 is a conceptual diagram of a communication system to which the present invention is applied.

In the figure, 81=82... are all stationaries having a communication control function, and these are connected via a common path-type transmission line Ln.

Each station S1.82... has various interfaces with a computer, and performs various data processing, including communication processing such as controlling 0 communication and passing communication control rights, and also has 0 communication control rights. (There is only one station with 0 communication control rights on the communication system) 6
Manage communications for the entire communications system.

FIG. 2 is a 70-chart of the operations performed by each stage. In the following explanation, one communication control right is called a token, the stage that acquires this token and performs communication is called the master station, and the stations other than the one are called the slave stations.

In FIG. 2, the left side shows the operation of the master stage 1, and the right side shows the operation of the slave station.

First, the master stage compares the number of communications M in the entire communication system during one cycle of the previous token with the number N of stations connected to the transmission line Ln (step l).
. Here, if N is larger than M (N-M)O), the difference (=N-M) is the number of allowed communications for this time (step,
2). Also, if N is smaller than M (N-M<O),
Let 1 be the number of communications allowed (Step 3). Next, initialize the value M of the counter that counts the number of communications in one cycle of the 0th cycle to 0 (step 4), then determine whether there is a communication request for the local station.Step 5) 1 communication request If there is, it is processed by communication (Step 6), and then 1 is added to a counter that counts the number of communications (Step 7). Next, it is determined whether the count value M of the counter that counts the number of communications has reached the permissible number of communications (step 8).
(If L, return to step 5 and repeat steps 5 to 8 until there is no more communication request. When there is no more communication request.

Or, if it is no longer M (L), move on to Step 9.

Here, send one token to the next stage recommendation and hand over the mask rights.

Slave stage 1] receives communication from the master station (Step 10).

It is determined whether the token is addressed to the own station (Step 11). If it is a token addressed to the own station, the master is acquired and the process moves to Step 1. Further, if the communication is directed to the own station other than the token, a predetermined slave operation is performed and 1 is added to the count value of the counter that counts the number of communications. Also, when a communication other than a token addressed to another station is received, 1 is added to the count value of the counter (step 12).

With the above-described operation flow, this communication system has relatively few communication requests for each station, and when multiple communication requests occur at a certain station,
It is possible to process all communication requests by acquiring master rights once. Normally, the number of communications during one round of the token is kept within the maximum number of communication stations N, and even in the maximum case, the maximum number of communications The number of stations will not exceed twice the number N.

Figure 3 is. FIG. 3 is an explanatory diagram for explaining the above relationship.

Here, if 2m0' is the number of communications from the previous station, mI is the number of communications from other stations, 1mo is the number of communications from the current station, and N is the maximum number of communications, then the relationship between them is expressed by a linear equation.

mo≦N −CIno'+ 2m 1) i=1 However, when (right side)≦0, m0≦1 (Effects of the Invention) As explained above, according to the present invention, a token goes around the communication system once. The total number of communications during this period can be kept within the maximum number of communication stations at one time, and within twice the maximum number of communication stations at most. In addition, the number of communications per communication system as a whole is relatively small,
If multiple communication requests occur at a certain communication station, all communication requests can be processed by acquiring master rights once, increasing the communication capacity of 6 channels and increasing the communication capacity of 1 communication line. can be used effectively.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram of a communication system to which the present invention is applied. FIG. 2 is a flowchart of operations performed by each station, and FIG. 3 is an explanatory diagram for explaining the number of communications in the communication system. ! 91.82.83...Stage depression, Ln...Transmission line.

Claims (1)

[Claims] In a communication system in which communication control rights are passed around among a plurality of stations connected to a common transmission line, the plurality of stations count the total number of communications while the communication control rights go around the communication system. , if the number of communications is less than a predetermined value and the local station has multiple communication requests, the communication may be performed multiple times while maintaining control of the communication within the range where the number of communications in one round does not exceed the predetermined value. A communication control method characterized by performing the following.