JPH0442633A - Line control system - Google Patents

Abstract

PURPOSE:To make the line control efficient by allowing a host station to collate a reply decision table deciding a frequency of reply of each subordinate station, and omitting the transmission of a polling signal to a subordinate station with a low frequency of reply tentatively so as to reduce the polling period in response to the number of subordinate stations whose transmission of the polling signal is omitted. CONSTITUTION:The system is provided with a reply decision table 12 in which a data representing the frequency of reply to save the number of times of no reply and the transmission of a polling signal to subordinate stations 3A - 3C whose frequency of reply is low is tentatively omitted. Thus, the subordinate stations 3A - 3C whose frequency of reply is high receive the polling signal in a short period substantially and the subordinate stations 3A - 3C whose frequency of reply is low receive the polling signal in a long period substantially. Thus, when the transmission of the polling signal is omitted, the polling period is reduced in response to the number of subordinate stations to which the transmission of the polling signal is omitted to make the line control efficient.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is characterized by polling signal control when a plurality of terminals, which are lower stations, are connected to a central processing unit, etc., which is an upper station. Regarding line control systems.

(Prior Art) In a system in which a large number of lower stations are connected and operated around an upper station, various methods are employed to perform line control in response to processing requests from each lower station. The global polling method is one such method, in which an upper station sends a polling signal to all lower stations, waits for a response, and checks whether there is a processing request.

FIG. 2 shows an operation sequence chart of a conventional line control system that employs such a global polling method.

In the figure, an upper station 1 communicates with a plurality of lower stations via a communication line 2, for example, three lower stations 3A, 3B, 3 in this example.
Connected to C. The upper station 1 sends out a polling signal at appropriate intervals in order to check whether there is a processing request from each lower station (step 2 in FIG. 2). Each lower station 3A.

Upon receiving this polling signal, 3B and 3C send a response to the upper station 1 if there is a processing request. The timing of this response is, for example, one hour after receiving the polling signal for lower station 3A, two hours after receiving the polling signal for lower station 3B, and three hours after receiving the polling signal for lower station 3C. It is preset to respond later.

In this way, for each subordinate station, a unique response waiting time tl,
t2. The reason why t3 is set is to prevent the responses of the lower stations 3A, 3B, and 3C from colliding on the communication line 2.

The upper station 1 waits for responses from the lower stations 3A, 3B, and 3C to be input.

In the example shown in the figure, as shown in steps ■, ■, and ■, there is no response from any lower station. The upper station 1 waits for the response waiting time t set for the lower stations 3A, 3B, and 3C.
l, t2. Waits for time T, which is longer than the maximum time of t3, and outputs the polling signal again (step
).

Here, for example, if there is no response from the lower station 3A (step ■) but there is a response from the lower station 3B (step ■), the upper station 1 outputs data transfer permission to the lower station 3B. ), the lower station 3B transfers the data to the upper station 1 accordingly (step ■). When the upper station 1 receives the data, it sends a reception completion notification to the lower station 3B (step 0).

(Problem to be Solved by the Invention) In the conventional line control system as described above, the upper station 1 repeatedly sends out a polling signal at a polling cycle T that is always longer than a preset maximum response waiting time. There is a need.

Furthermore, in the above method, the response waiting time t1 to t3
Lower stations that have been set for a shorter time can receive data transfer permission preferentially. Therefore, it is wasteful to set a short response waiting time for lower-level stations that respond less frequently.

Therefore, in the past, a priority comparison was performed according to the response frequency of the lower station, and the response waiting time was changed.

FIG. 3 shows a frame format of a polling signal used in such a case.

The frame in the figure is, in order from the beginning, flag 21, address 22, control unit 23, station address #124, station address #225, station address #
326, FCS 27, and flag 28.

The flag 21 consists of an identification code or the like indicating that this frame is a polling signal. The address 22 indicates the destination address, but in the case of a polling signal, it is sent to all lower stations, so a so-called global address is set. The control unit 23 is a part that stores instructions (commands) from the sending side to the receiving side.

Station addresses 24, 25, and 26 are addresses for identifying each lower station. For example, if the address of lower station 3A is stored in station address #1, the response waiting time t1 for lower station 3A is Set.

Similarly, if the address of lower station 3B is stored in station address #2, the response waiting time of lower station 3B is t2, and if the address of lower station 3C is stored in station address #3, the response waiting time is t2. It becomes t3.

This order is changed depending on the response frequency of the lower station.

FC527 is an area for inspection in which parity pits and the like are stored. The flag 28 is an area in which a stop bit and the like indicating the end of a frame are stored.

Note that in order to determine the priority, the following data is generated.

FIG. 5 shows an example of a priority comparison table. This table is stored in a memory (not shown) of the upper station 1.

The priority comparison table 40 in FIG. 5 stores the number of times of transmission and reception with the lower station 3A 41, the number of times of transmission and reception with the lower station 3B 42, the number of times of transmission and reception with the lower station 3C 43, and the number of times of transmission and reception clear value 44.

FIG. 5 shows an operation flowchart of the conventional system.

As shown in the figure, first, the upper station 1 is the lower station 3A.

A polling signal is sent to 3B and 3C (step Sl). After that, the upper station 1 receives 4m5ec by the timer.
Wait for a while (step S2). In this example, the response waiting time of each lower station is 1 m5ec for time t1, t
2 is set to 2 m5ec, and t3 is set to 3 m5ec.

Here, it is determined whether there is a response from the lower station (
Step S3). If there is no response from the lower station, the polling signal is sent again (step Sl).

On the other hand, if there is a response from the lower station, a predetermined communication process is executed (step S4), and the corresponding number of times of transmission and reception is incremented (step S5). That is, for example, when there is a response from the lower station 3B, the number of times of transmission and reception with the lower station 3B in the priority comparison table 40 shown in FIG. 5 is incremented.

Here, priority comparison is performed in step S6 in FIG. That is, the number of transmissions and receptions 41 with the lower station 3A in the priority comparison table 40, the number of transmissions and receptions with the lower station 3B 42,
The number of transmissions and receptions 43 with the lower station 3C is compared with each other, and the one showing the maximum value is selected as station address #l, the second one is set as station address #2, and the third one is set as station address #3. Select. As a result, responses are processed preferentially for lower-level stations that respond most frequently.

Note that if you integrate the number of transmissions and receptions unconditionally, even if it is a lower station with a very high response frequency, if the startup of the device itself is delayed by a considerable amount of time than other lower stations, the cumulative value of the number of transmissions and receptions will be calculated. If you compare and determine the priority, it is difficult to get the highest priority processing. Therefore, if the number of transmissions and receptions exceeds a certain value, all the number of transmissions and receptions are cleared to zero, and then the cumulative number of transmissions and receptions is compared again. It is preferable to do this.

For this purpose, the priority comparison table 40 of FIG.
A transmission/reception count clear value 44 is set in advance.

Then, as shown in the flowchart of FIG. 5, in step S7 it is determined whether or not to clear the number of transmissions and receptions, and if any number of transmissions and receptions exceeds the number of transmissions and receptions clear value, in step S8 all transmissions and receptions are cleared. I am trying to clear the number of times to zero.

However, even in the above method, the upper station 1
0, a polling signal is always sent at a predetermined period T, which results in wasted time when there are lower stations that are not used at all.

The present invention has been made with attention to the above points, and provides a line control system that improves the efficiency of polling by temporarily omitting the sending of polling signals to lower-order stations that respond less frequently. The purpose is to

(Means for Solving the Problems) In the line control system of the present invention, an upper station simultaneously sends polling signals to multiple lower stations, and each lower station waits for a preset unique response waiting time. After waiting,
The upper station responds to the upper station, and the upper station repeatedly sends the polling signal at a polling cycle longer than the maximum response waiting time set, and the upper station determines the response frequency of each of the lower stations. and the response determination table to temporarily omit sending polling signals to lower-order stations with low response frequency, and according to the number of lower-order stations for which sending of polling signals is omitted, The present invention is characterized by comprising a response control section that performs control to shorten the polling period.

(Function) The system of the present invention provides a response determination table that stores data indicating response frequency including the number of non-responses, and temporarily omits sending polling signals to lower-order stations with low response frequency. Therefore, a lower station with a high response frequency receives a polling signal in a substantially short cycle, and a lower station with a low response frequency receives a polling signal in a long cycle. As a result, when the sending of polling signals is omitted, it is possible to shorten the polling cycle and improve efficiency according to the number of omitted lower-order stations.

(Example) Hereinafter, the present invention will be explained in detail using embodiments shown in the drawings.

FIG. 1 is a sequence chart showing an embodiment of the line control system of the present invention.

In the system of the present invention, the upper station includes a response control section 11 and a response determination table 12, as shown in FIG.

Before explaining the operation of FIG. 1, first, the specific contents of the response determination table 12 of the upper station 10 will be explained.

FIG. 6 is an explanatory diagram of the contents of the response determination table in the system of the present invention.

This response determination table 50 is stored in a memory (not shown) provided in the upper station 10.

As shown in the figure, the response determination table 50 includes the number of times of transmission and reception with the lower station 3A 51, the number of times of transmission and reception with the lower station 3B 52, the number of times of transmission and reception with the lower station 3C 53, and the number of unresponses from the lower station 3A 5
4. Number of times The number of unresponses from the lower station 3B 55, the number of unresponses from the lower station 3C 56, the number of transmission/reception times clear value 57, the through ball transition value 58, the number of times of through ball transmission 59, and the through ball counter 60.

Number of transmissions and receptions of lower stations 3A, 3B, 3C 51゜52.53
is a part that accumulates and stores the number of responses sent and received in the past for each lower station. Lower stations 3A, 3B, 3C
The number of non-responses 54.55.56 is a part that accumulates and stores the number of times when there is no response despite sending a polling signal for each lower station. The transmission/reception count clear value 57 is a value that serves as an index for clearing all the transmission/reception counts when any of the transmission/reception counts 51, 52, and 53 exceeds a certain value.

The through ball transition value 58 is the number of non-responses mentioned above, 54.55.
．． 56 exceeds a certain value, this is an area in which a limit value is stored so that a determination is made to omit polling. The through ball transmission count 59 is an area that stores the maximum number of times polling is omitted for one lower station. The through ball counter 60 is a counter that is incremented each time polling is omitted.

The operating principle of the line control system of the present invention will be explained below with reference to FIG.

First, the upper station 10 communicates with the lower stations 3A and 3A via the communication line 2.
3B and 3C, and is set to output a polling signal using the conventional method (step ■), wait for a response from each lower station (steps ■■, ■), and perform polling at a predetermined cycle T1. ing. The response control unit 11 of the upper station is a circuit for setting such a polling cycle TI, and is composed of a processor and the like.

Here, as shown in FIG. 1, it is assumed that, for example, the lower station 3B does not respond for a predetermined period of time due to power being turned off or the like.

In this case, the number of unresponses 55 of the lower station 3B shown in FIG.
is accumulated each time.

If the value exceeds the through-ball transition value 58 shown in FIG. 6, polling is performed only to the lower station 3A and the lower station 3C, as shown in step ■ in FIG.
Polling to the lower station 3B is omitted. In this case, even if the lower station 3C has a lower priority than the lower station 3A, its response time is shorter than the previous response time, and the time the upper station 10 has to wait is shortened.

That is, the response control unit 11 of the upper station 10 newly sets the polling period T2, and after waiting for T2 time, performs the next polling (step 2). If polling is omitted only once, all lower stations 3A will be omitted in the next polling.

Polling will be performed for 3B and 3C. Regarding the subsequent response step (2) and [phase]2 (2), there is no difference from the initial operation.

In this way, in the line control system of the present invention, the transmission of polling signals is temporarily omitted for lower stations with a small number of unresponses, and the polling period is shortened by the amount of omitting the transmission of polling signals. ing.

If polling is to be omitted in this way, all station addresses should be written in the frame format shown in Figure 3 in the section 24° 2526 for storing station addresses, as in the past. does not require

That is, for example, when polling for the lower station 3B is omitted, the address of the lower station 3A is stored in station address #l, the address of lower station 3C is stored in station address #2, and the remaining station address writing area is Do not write address. Such a method eliminates polling for any subordinate stations.

A more specific operation of the system of the present invention will be explained using FIG. 7.

FIG. 7 is a system operation flowchart of the present invention.

In the figure, first, the upper station 10 and each lower station 3A
, 3B, and 3C (step S1), and waits for an initially set polling cycle T1 (step S2).

Then, in step S3, it is determined whether there is a response from the lower station. If there is a response, predetermined communication processing is performed as already explained using FIG. 2 (step S4).

Further, in step S5, the number of transmissions and receptions in the response determination table 50 shown in FIG. 6 is incremented to 0.
For example, when there is a response from the lower stations 3A and 3C, the number of times of transmission and reception, 51.53, is incremented. Furthermore, for the lower stations that have responded in this way, the number of non-responses in the response determination table 50 shown in FIG. 6 is immediately cleared to zero (step S6), that is, the lower stations 3A, 3
The number of unresponses for C, 54.56, is cleared to zero.

Then, in step S7, priority comparison is performed. That is, as previously explained using FIG. 5, the transmission/reception frequencies 51, 52, and 53 of the lower stations 3A, 3B, and 3C in the response determination table 50 of FIG. 6 are compared, and priority is given in descending order of the values. Set the ranking. Then, the frame for the polling signal shown in FIG. 3 is rewritten.

If polling is not omitted and only the priority order is changed, lower stations 3A, 3B, 3 to station addresses #1, #2, #3, as shown in the conventional example earlier,
Change the address storage order of C.

Next, in step S8 of FIG. 7, it is determined whether the number of transmissions and receptions is to be cleared. This is to judge whether the number of transmissions and receptions 51°52.53 of any of the lower stations 3A, 3B, and 3C in the response determination table 50 shown in FIG. 6 does not exceed the number of transmissions and receptions clear value 57. This is done by The number of sending/receiving times is the number of sending/receiving times clear value 5
If the number exceeds 7, all transmission/reception counts are cleared to zero. Otherwise, proceed to step S.
Move to IO. The reason is as explained above.

Then, the response control unit 11 of the upper station 10 shown in FIG. 1 sets the polling period. If there are no lower stations that omit sending polling signals, the polling cycle will not be changed.

On the other hand, in step S3, if there is no response from the lower station, the number of non-responses in the response determination table 50 shown in FIG. 6 is incremented. For example, lower station 3B
If there is no response, the number of non-responses 55 of the lower station 3B is incremented.

Then, in step S12, it is determined whether the number of non-responses exceeds the through ball transition value 58 or not.

If the number of non-responses exceeds the through-ball transition value 58, a setting is made to omit polling for that lower station, that is, in step S13, the priority comparison described earlier in step S7 is performed. , configure the lower station to omit polling.

Then, in step S14, the through ball counter 60 and the number of through balls sent out 59 are compared, and the value of the through ball counter 60 is 5.
If it is lower than 9, the sending of the boring signal is omitted again for the corresponding lower station. Therefore, step S
At step 15, the through ball counter 60 is incremented, and if the polling cycle is set at step SIO, the polling cycle is made shorter than normal. Further, if the value of the through ball counter 60 is larger than the number of times 59 of sending out through balls, the value of the through ball counter is cleared to zero in step 51.
6) In this case, the boring signal is sent out even if the number of unresponses is small.Therefore, by setting the value of the through ball sending number 59, the sending cycle of the boring signal to the lower station with very few responses can be adjusted. It will be decided.

In this way, for example, the response waiting time of the highest priority lower station is 1 m5ec, and the response waiting time of the next lower station is 2 m5ec.
m5ec, if the response waiting time of the next lower station is 3 m5ec, and if the T1 of the boring signal device initially set in the upper station 10 is 4 m5ec, then if the sending of the boring signal for one station is omitted. , the polling period T2 can be shortened to 3 m5ec.

Also, for lower-level stations with particularly few responses, for example, 1
To send a boring signal once every 0 times or once every 20 times, and send the boring signal in a short cycle to lower stations that respond more frequently to efficiently control the line. I can do it.

The present invention is not limited to the above embodiments.

In the above embodiment, it has been explained that the response control unit 11 is substantially controlled by a software timer, but in reality, a hardware configuration in which a plurality of timer circuits etc. are provided and the output signal is selected is also possible. It is. Furthermore, the number of lower stations connected to the upper station 10 may be selected to any desired number.

(Effects of the Invention) The line control system of the present invention described above creates a response judgment table that represents the response frequency of lower-level stations to boring signals using data including the number of unresponses, and refers to this response judgment table. Therefore, the sending of boring signals to lower-order stations that are used less frequently is temporarily omitted, so that the polling period for other lower-order stations is shortened by the amount of skipping the sending of boring signals, which improves the efficiency of line control. It is possible to aim for

[Brief explanation of drawings]

Fig. 1 is a sequence chart showing an embodiment of the line control system of the present invention, Fig. 2 is a conventional line control system operation sequence chart, Fig. 3 is a frame format of a boring signal, Fig. 4 is an explanatory diagram of a priority comparison table, Fifth
This figure is a conventional system operation flowchart, FIG. 6 is an explanatory diagram of a response determination table related to the present invention, and FIG. 7 is a system operation flowchart of the present invention. 2...Communication line, 3A, 3B, 3C-...Lower station, 1
0...Upper station, 11...Response control unit, 12...Response determination table. Conventional line control system Figure 2

Claims (1)

[Scope of Claims] An upper station simultaneously sends a polling signal to a plurality of lower stations, each lower station waits for a preset unique response waiting time, and then responds to the upper station,
The upper station repeatedly sends out the polling signal at a polling cycle longer than the set maximum response waiting time, and the upper station includes: a response determination table for determining the response frequency of each lower station; Referring to the determination table, temporarily omit sending a polling signal to a lower station with a low response frequency, and
1. A line control system comprising: a response control unit that controls the polling cycle to be shortened in accordance with the number of lower-order stations for which transmission of polling signals is omitted.