JPH0319449A - Polling system - Google Patents

Abstract

PURPOSE:To prevent the delay time from being prolonged to a communication in which the prolongation in the delay time is a problem by providing priority on a communication request applied by a slave station. CONSTITUTION:A priority polling means 5 is provided with plural storage means 21, 22 storing the communication request of a slave station 4 in response to the priority of each communication request. When the communication with the slave station 4 is finished by the 1st kind of polling, a master station 1 applies the 1st kind polling to the slave station 4 applying communication request with the highest priority among the communication requests stored in the plural storage means respectively. Thus, at every end of the communication by the 1st kind polling, the transmission right by the 1st kind rolling is shifted to a slave station having the communication request with the highest priority at all times. Then the prolongation in the delay time to the communication in which the prolongation in the delay time is the problem is prevented.

Description

[Detailed Description of the Invention] [Summary] Regarding the polling method in the multiple access method, by setting priorities for communication requests made by slave stations, an increase in delay time is prevented for communications where an increase in delay time is a problem. For this purpose, the slave station that receives the first type of polling from the master station performs the necessary communication with the master station,
Other slave stations that have received the second type of balling from the master station notify the master station of the presence or absence of a communication request, and the master station then memorizes the slave station that sent the communication request. In a system for determining a slave station that performs polling, priority levels are set for communication requests made by slave stations, and the master station selects slave stations that should perform the above-mentioned 10) type of polling in accordance with the priority of the communication request. A priority polling means for determining the priority polling means is provided, and the master station then performs the first type of polling on the other slave stations determined by the priority polling means.

(Industrial Application Field) The present invention relates to a polling method in a multiple access method.

In the multiple access method, communication between the master station and slave stations is performed by sequentially polling and calling multiple slave stations from the master station, and the called slave stations return data in response. .

In the case of such a polling method, it is desired to improve the communication characteristics by starting the communication earlier for communications whose characteristics are affected by communication delays.

[Prior Art] In a polling type communication system, in a method in which transmission rights are fairly assigned to each slave station and polling is performed in a predetermined order, polling is performed even for slave stations that do not have a communication request. It takes a wasted time until the transmission right is handed over to the requesting slave station, which inevitably reduces communication efficiency.

So, are there two types of bowling from the master station to the slave station? The slave station that received the first type of polling performs the necessary length of communication. On the other hand, the master station performs a second type of polling in parallel with the first type of polling, and the slave station that has received the second type of polling notifies the master station of the presence or absence of a communication request. The master station memorizes the slave station that made the communication request through the second type of polling, and when the slave station with which it was communicating ends, it performs the first type of polling on the memorized slave station. A method for starting communication has been proposed.

Figure 5 shows the overall structure of the conventional polling method 2 communication system, which includes a main station 1, a downlink 2
, a plurality of slave stations 41 to 4N connected via the uplink 3
A system consisting of is shown.

In the main station 1, the multiplexer 11 receives the number TB of the slave station that performs the first type of polling read from the buffer 12.
Data DA to be sent to NO■ and its slave station
TA and the number of the slave station that performs the second type of polling output from polling counter l2 T E N O r
z and is multiplexed and sent to the downlink 2.

On the other hand, the slave station that received the first type of polling,
Own station number TE NOT. and a first type of communication request R indicating a request to continue communication, and data DATA to be transmitted to the main station are sent to the uplink 3. Further, when the slave station that has received the second type of polling has data to be transmitted, its own station number TENO7. Similarly, a second type of communication request R2 indicating a transmission start request is sent to the uplink 3. These signals are multiplexed on the uplink 3 and sent to the main station 1.

6A and 6B are diagrams explaining the operation of the main station l in the conventional system using flowcharts, in which FIG. 6A shows the processing of the communication request R, and FIG. 6B shows the communication request R. It shows the processing of R2.

The main station 1 separates multiplexed signals on the uplink 3.
Separate at 4. Initially, the first type of communication request R1 is waiting to be received (step Sl)'. When the communication request R is received? Check whether or not is "Engine" (step S2), and if it is "1'", the slave station number T' E N stored in buffer l2 is checked.
O■ continues to be sent from the main station. When the data sent from the slave station is finished, a communication request R is sent.
, is no longer "1°", the slave station number written in the FIFO memory 15 is read out and written to the buffer 12 (step S3).This slave station number will be used at the next transmission.
It is sent to the downlink 2 as the slave station number TENOP+.

Further, the main station is always waiting to receive the second type of communication request R2 (step Sit). Communication request R! When received, it is checked whether it is ゜"I I+ (step 312), and if it is not 11 1 11, it continues waiting for reception.

On the other hand, communication request R! becomes ``1'', the number TENO. of the slave station that made the communication request. ．． has already been written to the FIFO memory 15 (step S13).
), if it has been written, returns to the state of waiting for reception of communication request R. If it has not been written yet, the slave station number T
ENOT! is written into the FIFO memory 15 (step S14). As described above, this slave station number T E N O t t is sent out from the master station by the first type of polling when the previous communication by the first type of polling ends.

In this way, FIGS. 5 and 6A. According to the system shown in FIG. 6B, slave stations that do not have a communication request are skipped and polled, so that unnecessary polling can be omitted and efficient communication can be performed.

Furthermore, such a communication method was proposed in a patent application filed in 1982 by the present applicant.
-326118.

(Problems to be Solved by the Invention) In the conventional communication system shown in FIG. 5, FIG. 6A, and FIG. 6B, when communication between a master station and a certain slave station ends,
Another slave station can start communicating immediately.

However, if there is a slave station that performs a large amount of communication at once, other slave stations cannot start communication, which increases the communication delay time of that slave station.

An increase in delay time can be a serious problem in communications performed by slave stations. For example, in the case of a voice terminal using the wideband IsDN system, although the amount of communication is small, an increase in delay causes deterioration of sound quality and must be avoided.

The present invention is an attempt to solve the problems of the prior art as described above, and by setting priorities for communication requests made by slave stations in polling-based communication, it is possible to solve the problem of communication in which increased delay time becomes a problem. However, the present invention aims to provide a polling method that can prevent an increase in delay time.

(Means for Solving the Problem) As shown in FIG. 1, the present invention has a main station 1.
The slave station 4 that received the first type of polling from the main station 1 performs the necessary communication with the master station 1, and the other slave stations 4 that received the second type of polling from the master station 1 determine whether or not there is a communication request. In a system in which the master station 1 determines the next slave station to perform the first type of polling by memorizing the slave station 4 that sent the communication request, the master station 1 assigns a priority level to the communication request made by the slave station 4. In addition, the main station l is provided with priority polling means 5.

Here, the priority polling means 5 determines the slave station to which the first type of polling is to be performed in accordance with the priority of the communication request.

As a result, the master station next performs the first type of polling on the other slave stations determined by the priority polling means 5.

In this case, the priority polling means 5 has a plurality of storage means for storing the communication requests of the slave stations according to the priority of each communication request, and the master station 1 has completed communication with the slave stations by the first type of polling. At this time, the slave station that made the communication request with the highest priority among the stored communication requests is
This type of polling should be performed.

The priority polling means 5 also has means for comparing the priority of the received communication request with the priority of the communication request of the slave station currently communicating, and the master station 1 is determined that the received communication request has a high priority. When this occurs, the first type of polling is immediately performed for other slave stations with higher priority.

[Effect]

In the system to which the present invention is applied, the slave station 4 that has received the first type of polling from the master station l sends the first type of communication request R, indicating a request to continue communication to the master station together with its own station number. By transmitting the data, communication of the necessary length is performed with the live station 1. Other slave stations 4 that have received the second type of polling performed by the master station 1 in parallel send a second type of communication request Rt to the master station 1 indicating the presence or absence of a communication start request.

The master station 1 determines the slave station to perform the first type of polling next by storing the slave station 4 that sent the communication request Rt. At this time, priority levels are set for the communication requests made by the slave station 4, and priority polling means 5 is provided in the master station 1 to select the slave station that should perform the first type of polling in accordance with the priority of the communication request. The master station 1 then performs the first type of polling on the slave station 4 determined by the priority polling stage 5.

The present invention has a first embodiment and a second embodiment, depending on the method of determining the slave station to be polled preferentially by the priority polling means 5.

In the first embodiment, the priority polling stage 5 is provided with a plurality of storage means 21 and 22 for storing communication requests of the slave stations 4 according to the priority of each communication request. When the master station 1 completes communication with the slave station 4 through the first type of polling, the master station 1 returns to the slave station 4 that has made the communication request with the highest priority among the communication requests stored in the plurality of storage means. The first type of polling is performed for the first type of polling.

As a result, each time the communication by the first type of polling ends, the transmission right by the first type of polling is always transferred to the slave station that has made the communication request with the highest priority.

In the second embodiment, the priority polling means 5 is provided with means 25 for comparing the priority of the received communication request with the priority of the communication request of the slave station 4 currently communicating. When the master station 1 determines that the priority of the received communication request is higher, the master station 1 immediately sends the received communication request to another slave station 4 that has been determined to have a higher priority.
A first type of polling is performed on the .

As a result, communication is always performed with the slave station 4 having the highest priority every time a communication request occurs.

〔Example〕

FIG. 2 is a diagram showing the configuration of an embodiment of the present invention, and only the configuration of the main station I is shown, but the other parts are the same as in FIG. 5. In Fig. 2, the same parts as in Fig. 4 are indicated by the same numbers, and 21 is a high priority FIF○;
22 is low priority FIFO, 23 is l→2 selector, 24
is a 2→1 selector.

In this embodiment, a high-priority FIFO for high-priority communication is used as a FIFO memory for storing the number T E N O t + of a slave station that performs the first type of polling.
21 and a low priority FIFO 22 for low priority communications.
and The l→2 selector 23 is a communication request R! The slave station number T E N O t t received by the second type of polling is switched according to the priority level of T E N O t t
, high priority FIFO21 or low priority FIFO22
Distinguish and memorize. Then, when the communication of the currently communicating slave station ends and the communication request R becomes "O", if the slave station number is stored in the high priority FIFO 21, it is transferred to the buffer l2 via the 2→l selector 24. write to. When the slave station number is not stored in the high priority FIFO○21, the slave station number stored in the low priority FIFO22 is
The data is written to the buffer 12 via the 2→1 selector 24.

Figure 3 A. FIG. 3B is a flowchart explaining the operation of the main station 1 in this embodiment, and FIG.
3B shows the processing of communication request R1, and FIG. 3B shows the processing of communication request R1.
This shows the processing of t. The main station 1 separates the multiplexed signal on the uplink 3 in the demultiplexing device 14, and is initially waiting to receive the first type of communication request R+ (step S1). When the communication request R is received, it is checked whether it is "l" (step S2), and if it is "l", the slave station number T stored in the buffer l2 is
ENO ■ continues to be sent from the main station l.

When the data sent from the slave station is finished, a communication request R is sent.
1 is no longer ゛1'゜, check whether the slave station number is stored in the high priority FIFO 21 (step S4
), if it is stored, it is read out via the 2→l selector 24 and written into the buffer l2 (step S5).

If the slave station number of the high priority I''I F 02I is not stored, the slave station number stored in the low priority FIFO 22 is read out via the 2→1 selector 24 and written into the buffer 12 (step S6).

At the next transmission, this slave station number is sent to the downlink 2 as slave station numbers TEN0 and TEN1 by the t-th type of polling.

Further, the main station is always waiting to receive the second type of communication request R2 (step Sll). When the communication request R is received, it is checked whether it is "°1" (step S12), and if it is "O"° indicating that there is no communication request, it continues waiting for reception.

? When communication request R2 is no longer "0", the number TENO. of the slave station that made the communication request is returned. Check whether ■ has already been written to the FIFO memory (step S
13) If the writing has been completed, the state returns to the state of waiting for reception of communication request R2. If it has not been written yet, communication request R
Check the priority of t, and if it is ``2゛, indicating a high priority, write the slave station number TENOT■ into the high priority FIF○21 (step S16). Also, ``゜1'' indicating a low priority.
If it is 1, the slave station number TF,NOT■ is written into the low priority FIFO 22 (step 317).

As mentioned above, these slave station numbers TEN0 and 2 are
When the communication using the first type of polling ends, the local station sends the first type of polling.

In the embodiments shown in FIG. 2, FIG. 3A, and FIG. 3B, it is also possible to set the priority to three or more levels.

In the above embodiment, instead of writing the slave station numbers TEN0 and TEN2 to the FIFO memory according to the priority, ? Station number T
ENO,! It is also possible to write the information and the priority in parallel in one word of the FIFO memory.

Furthermore, in the above embodiment, when the communication of the slave station currently in communication ends and the communication request R becomes "0", the buffer that stores the slave station number for which the first type of polling is to be performed is rewritten. However, when receiving communication request R2, which has a higher priority than the currently communicating slave station, the slave station number TEPO■ is immediately rewritten, so that the high priority communication can be performed immediately. You can also start.

FIG. 4 shows another embodiment of the present invention, in which the same parts as in FIG. 2 are designated by the same numbers, 25 is a priority comparison section, and 26 is a rewriting section.

In FIG. 2, the priority comparison unit 25 compares the received communication request R! and the communication request of the currently communicating slave station stored in buffer {2, and the received communication request R. When the priority of the slave station is higher than the communication request of the currently communicating slave station, the rewriting unit 26 is controlled to rewrite the data in the buffer l2. As a result, the data in the buffer 12 is rewritten with the received slave station number TEN○a2, and
This type of polling is based on this slave number T E N O y
Done by z.

In this way, when the communication request R2, which has a higher priority than the slave station currently communicating, is received, slave station number TEPOP. Since the information is rewritten immediately, high-priority communication can be started immediately.

[Effects of the Invention] As explained above, according to the present invention, the first type of polling in which the slave station sends a communication continuation request to the master station and performs communication of the necessary length, and the first type of polling in which the slave station sends a communication continuation request to the master station, In a polling type communication system in which a second type of polling is transmitted from a master station to a slave station, multiple priorities are given to communication requests of slave stations in the second type of polling, and the master station transmits a second type of polling to a slave station. The first type of polling is performed on the slave station with the highest priority among the slave stations that are issuing Deterioration of characteristics can be prevented.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the principle structure of the present invention, Fig. 2 is a diagram showing the practicality of the first embodiment of the invention, and Figs. 3A and 3B are diagrams showing the practicality of the first embodiment. The operation of the main station is explained using a flowchart, and FIG. 3A shows the communication request R.
, FIG. 3B is a diagram showing the processing of communication request R2, FIG. 4 is a diagram showing the structure of the second embodiment of the present invention,
FIG. 5 is a diagram showing the overall structure of a conventional polling type communication system, and FIGS. 6A and 6B are flowcharts explaining the operation of the main station in conventional method 2. A is a diagram showing the processing of communication request R, No. 6
FIG. B is a diagram showing the processing of communication request R2. 1 is the main station, 2 is the downlink, 3 is the uplink, 4 is the slave station, 5
is the preferred polling method. Po. 1α @! Fig. 1 shows the basic structure of the defense of the book; Fig. 3 shows the processing of the sending request R1 in the first embodiment
Figure A: Figure 3 shows the processing of transmission request R2 in the first embodiment.
Figure B Diagram showing the processing of transmission request R1 in the conventional method Figure 6A

Claims (3)

[Claims] (1) The slave station (4) receives the first type of polling from the master station (1), performs the necessary communication with the master station (1), and then receives the second type of polling from the master station (1). The other slave station (4) that received the request notifies the master station (1) of the presence or absence of a communication request, and the master station (
1) is a system that determines the first type of slave station to perform polling by storing the slave station (4) that sent the communication request, and sets priority levels for the communication requests made by the slave station (4). In addition, the main station (1) is provided with a priority polling means (5) for determining the slave station to which the first type of polling is to be performed in accordance with the priority of the communication request, and the main station (1) performs the priority polling. A polling method characterized in that a first type of polling is then performed on the slave station (4) determined by the means (5). (2) In the polling method according to claim 1, the priority polling means (5) has a plurality of storage means (21, 22) for storing the communication requests of the slave stations (4) according to the priority of each communication request. ), and when the master station (1) completes communication with the slave station (4) through the first type of polling, the master station (1) selects the slave station (4) that has made the communication request with the highest priority among the stored communication requests. ). (3) In the polling method according to claim 1, means for comparing the priority of the communication request received by the priority polling means (5) with the priority of the communication request of the slave station (4) currently communicating. 25), and when the master station (1) determines that the priority of the received communication request is high, it immediately performs the first type of polling on another slave station (4) with a high priority. A polling method featuring