JPS627242A - Polling control system - Google Patents

Abstract

PURPOSE:To upgrade the efficiency of use of a data bus and to perform an efficient data transmission by so constituting the titled system that a communication controller executes polling even during the time when a communication equipment is transmitting. CONSTITUTION:A transmission right endowment control circuit 10 outputs a polling address signal through a line 2 and changes it sequentially. When the communication equipment 52 has the transmission right and is transmitting the data and a bus-busy signal is issued in a line 1, if a request-to-communicate is issued by another communication equipment 5n, the polling is stopped, and the polling address is fixed at the equipment 5n, and retains it until the equipment 52 ends the data transmission. On ending the data transmission, the equipment 52 abandons the transmission right, and a line 62 is made '1'. Accordingly, the circuit 10 makes the line 1 to be '1', and informs each communication equipment that a data bus 4 is vacant. The equipment 5n starts a data transmission operating similarly to the equipment 52, and abandons the communication right when ending, making a line 6n to be '1'. Accordingly, the circuit 10 makes the line 1 to be '1' and informs each equipment of the vacancy of the bus 4.

Description

[Detailed Description of the Invention] [Summary] In a data communication system that uses a polling method, even after an arbitrary communication device secures a transmission right, polling is continued to search for other communication devices that have a new transmission request. However, after the communication device that already has the transmission right to this searched communication device finishes data transmission, the transmission right is assigned preferentially.

[Industrial application field]

The present invention relates to a data communication device, and particularly to a polling control method for controlling communication between a plurality of communication devices.In a conventional polling control method, a communication control device transmits a polling signal, and a communication device having a transmission request sends a polling signal. If so, polling is stopped at that point and the communication device uses the data bus to transmit data, and after the communication device finishes transmitting data, it starts polling again, so the data bus cannot be used effectively. There are some shortcomings, and improvements to these are strongly desired.

[Conventional technology]

Conventionally, a data bus shared by multiple communication devices, etc.
and a data communication device comprising a communication control device that manages transmission rights of each communication device, wherein the communication control device sequentially changes the polling address at fixed time intervals when there is no transmission request from each communication device. do.

When each communication device receives the polling address assigned to it, it turns on a transmission request if there is data to be transmitted.

When the communication control device learns that an arbitrary communication device has turned on a transmission request, it fixes the polling address of that communication device. As a result of this, the communication device that issued the transmission request acquires the transmission right, transmits information regarding the data destination and the data on the data bus, and continues transmitting the data.

When the data transmission is finished, the communication device turns off the transmission request, and in response to this off signal, the communication control device resumes polling and sequentially changes the polling address at regular time intervals.

Polling and data communication are performed according to the procedure described above.

[Problem that the invention seeks to solve]

However, in the conventional method described above, polling and data transmission/reception operations are not performed at the same time, and the data bus remains unused while polling is being performed, so although it is an effective method in terms of data bus usage efficiency, There was a drawback that there was no such thing.

SUMMARY OF THE INVENTION An object of the present invention is to provide a polling control method that allows efficient data transmission by increasing data bus usage efficiency by simultaneously polling a communication control device even when a communication device is transmitting. .

[Means for solving problems]

The above problem involves a plurality of communication devices equipped with data transmission and reception functions, a data bus that coexists in order for the communication devices to communicate with each other, and a function that controls the allocation of transmission rights to the data bus using a polling method. In a data communication system consisting of a communication control device, the communication control device is provided with a transmission right granting control circuit 10, and the transmission right granting control circuit 10 allows any communication device to secure the transmission right and control the data bus. Polling continues even while data is being transmitted, and if another communication device has a transmission request, the communication device that has already secured the transmission right can secure the transmission right preferentially after completing data transmission. This is solved by

[Effect]

According to the present invention, the communication control device performs polling, and the communication device consists of (!) the transmission right! After obtaining the right and starting data transmission, the communication control device continues to poll, and fixes the polling address with the address for other communication devices with transmission requests, so the communication device that has already obtained the transmission right ends data transmission. Then, the communication device to which the polling address is fixed can immediately start data transmission, resulting in the effect that the data bus usage efficiency can be increased.

〔Example〕

FIG. 1 is a diagram showing an embodiment of a polling control method according to the present invention.

In the figure, 1 is a line that a bus busy signal passes, 2 is a line that a polling address signal passes, 3 is a line that a polling address strobe signal passes, 4 is a data bus, and 51.5□
...5n is a communication device, 6I, 6□ ...6nn
A transmission request amount passes through a line, 7 is a communication control device, and 10 is a transmission right granting control circuit. The same symbols represent the same objects throughout the following discussion.

The present invention will be described in detail below with reference to the drawings.

A transmission right grant control circuit 10 is provided in the communication control device 7 to perform polling control. The transmission right grant control circuit 10 uses the line 2 to send a polling address signal, and the addresses of the polling address signal are sequentially changed and output.

Further, the transmission right grant control circuit 10 outputs a polling address strobe signal to the line 3, which is a timing signal indicating whether or not this polling address signal indicates a valid value.

Each communication device 51.5□...5n receives this polling address signal and polling address strobe signal, and when the number assigned to itself and the polling address match, if there is a transmission request, it sends the signal to line 6I. , 6□
...Set 6n to "0" to indicate that there is a transmission request. If there is none, set it to “1”.

Below, a communication control device 7 and a communication device 53 according to the present invention.
5□...The operation of 5n will be explained.

(2) The transmission right grant control circuit 10 outputs a polling address signal via the line 2, and sequentially changes the polling address.

■There is a transmission request from a communication device (for example, 5□) with a device number corresponding to the polling address consisting of ('f
rfA line 6□ is "O"), and if there is no transmission request from another device, the transmission right is given to the communication device 5□ and line 1
is set to "0" to issue a hasty busy signal, and then polling is continued by sequentially changing the polling address.

Note that since the communication device 5□ has acquired the transmission right, it starts data transmission as in the conventional method.

■When communication device 5□ acquires the transmission right and transmits data, and a bus busy signal is output on track 1, a communication request is received from another communication device (for example, 5n) that has the device number corresponding to its polling address. If , the polling is stopped and the polling address is fixed to the communication device 5n. This fixing of the polling address continues until the communication device 5□ finishes transmitting data.

- When the communication device 5□ completes data transmission, it relinquishes the communication right and sets the line 6□ to "1". Based on this signal, the transmission right granting control circuit 10 sets the line 1 to "1" to notify each communication device that the data bus 4 has become vacant.

At this point, the communication device 5n performs the operation described in (2) and starts data transmission. When the communication device 5n finishes transmitting data, it relinquishes the communication right and sets the line 6n to 1''.

This signal causes the transmission right granting control circuit 10 to set the line 1 to "1".
” to notify each communication device that the data bus 4 has become vacant.

In the figure, 10a is a polling address generation circuit, 10b is an encoder, IOC is a latch signal generation circuit, 10d is a polling address launch circuit, 10e is an encoder, 1
0f is a stop signal generation circuit.

The polling address generation circuit 10a generates a polling address signal and outputs it to the line 2. The address of this polling address signal changes sequentially. Also, a polling address strobe signal, which is a timing signal indicating whether or not this polling address signal indicates a valid value, is output to the line 3.

The polling address latch circuit 10d is a latch circuit for storing the polling address of a communication device that has acquired the transmission right and is transmitting.

The launch signal generation circuit 10c is bus busy (encoder t
oe output), polling address launch circuit 1
A latch signal is not output at 0d, but a latch signal is generated based on the output of encoder 10b when the bus is no longer busy.

The conditions for generating a stop signal by the stop signal generating circuit 10f are: (1) the bus is busy and (2) the transmission request signal encoded by the encoder tab indicates that there is a transmission request. However, when the polling address is the same as the address for which the transmission right is currently reserved and is currently transmitting (when the output of the polling address launch circuit 10d and the polling address match), the stop signal is not generated.

The encoder 10b includes a polling address generation circuit 10.
When the polling address signal of the a output is applied, for example, the polling address signal of the communication device 52 is being output, and the transmission request signal is input, the latch signal generating circuit 10
The communication device 5□ starts communication by driving the line L and sending a bus busy signal to the line L, but the polling address generation circuit 10a continues its operation and sequentially changes the address of the polling address signal.

When the transmission request signal is further input, the latch signal generation circuit 1
0c, the polling address launch circuit 10 sets the polling address of the communication device 5n that has received the transmission request signal.
d, the stop signal generation circuit 10f is operated to stop the operation of the polling address generation circuit lOa at that point, and when the communication of the communication device 5□ ends, the communication device 5n starts communication. The polling address generation circuit 10a resumes operation with the signal flowing.

〔Effect of the invention〕

As explained in detail above, according to the present invention, - When a communication device is transmitting data, it can poll other communication devices at the same time, so the efficiency of data bus usage can be improved. effective.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of a polling control method according to the present invention. In the figure, 1 is a line that a bus busy signal passes, 2 is a line that a polling address signal passes, 3 is a line that a polling address strobe signal passes, 4 is a data bus, 53.5□
...5n are communication devices, 6I, 6□ ...6n lines through which transmission request signals pass, 7 is a communication control device, 10 is a transmission right granting control circuit, 10a is a polling address generation circuit, 10b is an encoder, 10c is a latch signal generation circuit,
10d is a polling address latch circuit, 10e is an encoder, and 10f is a stop signal generation circuit.

Claims (1)

[Scope of Claims] A plurality of communication devices each having a data transmission/reception function, a data bus shared by the communication devices to communicate with each other, and a function of controlling allocation of transmission rights to the data bus using a polling method. In a data communication system including a communication control device, the communication control device is provided with a transmission right granting control circuit (10), and the transmission right granting control circuit (10) allows any of the communication devices to Even when the transmission right is secured and data is being transmitted to the data bus, the polling continues, and if another communication device has a transmission request, the communication device that has secured the transmission right transmits the data. The polling control method is characterized in that the transmission right can be secured preferentially after the completion of the polling control method.