JPH04249445A - Cyclic polling system - Google Patents

Abstract

PURPOSE:To level the throughput between stations by discriminating the traffic in the present network from a calculated data length and an observed cycle, and discriminating the number of successive transmittable frames. CONSTITUTION:Transmitting data from stations 1-4 is accumulated in a transmitting data queue 10. Every time receiving a polling frame from a transmission line 5, a transmission control circuit 7 uses the leading data of queue 10 as a queue to send it out to the transmission line 5. Then, control circuit 7 of central processing circuit 8 carries out control, whereby a frame sent out to transmission line 5 is fetched by receiving control circuit 6 at an addressed station and is accumulated in receiving data queue 9. Further, from a data length calculated at each station 1-4 and an observed cycle, a traffic in the present network is discriminated. Furthermore, in accordance with the discriminated traffic, how many frames can be transmitted for next polling is discriminated to level the throughputs between stations.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cyclic polling system for transmitting data by sequentially polling stations.

0002

2. Description of the Related Art Conventionally, in this type of cyclic polling system, it has not been possible to dynamically change the amount of data that can be transmitted in one polling.

0003

[Problems to be Solved by the Invention] As mentioned above, in the conventional cyclic polling system, the number of transmitted frames during polling is dynamically changed according to the system throughput of the entire network, and the throughput between each station is leveled. The disadvantage is that it cannot be done.

An object of the present invention is to provide a cyclic polling system that can equalize the throughput between stations.

[0005]

[Means for Solving the Problems] A cyclic polling system according to the present invention is a cyclic polling system in which data is transmitted between a plurality of stations by sequentially passing transmission rights between the stations. means for calculating the data length of a frame waiting to be transmitted; means for observing, at each station, the cycle of polling indicating transmission rights; and means for calculating the data length of a frame waiting for transmission; and means for determining how many frames can be transmitted the next time polling is performed according to the determined traffic.

[0006]

Embodiments Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1A shows a cyclic polling system to which the present invention is applied. The illustrated cyclic polling system includes stations 1, 2, 3, and 4, and a transmission path 5 connecting each station.

FIG. 1B shows the configuration of each station for realizing the throughput leveling method according to the present invention. The illustrated station includes a reception control circuit 6, a transmission control circuit 7, a central processing circuit 8, a reception data queue 9,
It has a transmission data queue 10.

Next, FIG. 1(A) shows the operation of this embodiment.
This will be explained with reference to and (B). Transmission data from a station is accumulated in a transmission data queue 10. Every time a polling frame is received from the transmission path 5, the transmission control circuit 7 converts the data at the head of the queue into a frame and sends it to the transmission path 5. Control at this time is performed by the transmission control circuit 7 under the control of the central processing circuit 8, as will be described later. The frames sent out on the transmission path 5 are taken into the station by the reception control circuit 6 at the destination station and stored in the reception data queue 9.

FIG. 2 shows a flowchart for explaining the operation of the central processing circuit 8 shown in FIG. 1(B). A specific example of a sequence will be explained in detail below. In a network as shown in FIG. 1A, when each station mutually transmits data of arbitrary length, the amount of data that one station can transmit per unit time is defined as the throughput for each station. In the present invention, this variation in throughput between stations is leveled out.

First, let the data length of the Xth frame be “M”.
(X)''.Each station has the right to frame data and send it out to the transmission path 5 by receiving polling.Each station can set the number of stations in the network and the line speed as parameters in advance, and each station The polling cycle time when transmitting the frame is given to each station as management information.Each station measures the actual polling cycle from time to time.
From the measured value, the network calculates how much data each station is currently transmitting as a whole, and this calculated value is set as "N". In this example, the calculated values are averaged several times, and the average value is N.
The value of is being updated. Thereafter, after the value of N is determined, that value of N is used until the next time N is updated.

When polling arrives, as shown in FIG. 2, packet lengths M(X) are added up from the head of the transmission data queue 10, and packets are transmitted until N is reached in total.

0012

As explained above, the present invention provides means for calculating the data length of a frame waiting to be transmitted at each station, means for observing at each station the cycle of polling indicating transmission rights, and Equalizes the throughput between each station by having a means of determining the current traffic on the network from the information and, accordingly, determining how many frames can be sent the next time it is polled. The effect is that it can be done.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a cyclic polling system to which the present invention is applied and the configuration of each station for realizing a throughput leveling method according to the present invention.

FIG. 2 is a flowchart for explaining the operation of the central processing circuit in FIG. 1(B).

[Explanation of symbols]

1 station 2 Station 3 Station 4 Station 5 Transmission line 6 Reception control circuit 7 Transmission control circuit 8 Central processing circuit 9 Receive data queue 10 Transmission data queue

Claims (1)

[Claims] 1. In a cyclic polling system in which data is transmitted between a plurality of stations by sequentially passing transmission rights between the stations, means for calculating the data length of a frame waiting to be transmitted at each station; means for observing, at each station, the cycle of polling indicating transmission rights; means for determining current traffic within the network from the calculated data length and the observed cycle; 1. A cyclic polling system comprising means for determining how many frames can be transmitted the next time polling is performed according to traffic.