JP2000295254A - Data transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a data transmission system from which a constant polling period is obtained even if a transmission channel is operated at a low transfer rate and employs half duplex communication. SOLUTION: The data transmission system comprises a monitor controller 10 and a plurality of controllers 30a-30n to be monitored that are interconnected by a channel 20. The monitor controller 10 sequentially polls a plurality of the controllers 30a-30n to be monitored, and collects data denoting a state change separately from data for polling processing when the state of the controllers 30a-30n to be monitored has been changed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmission apparatus, and more particularly, to a data transmission apparatus having a low transmission line speed and transmitting data using a half-duplex communication line.

[0002]

2. Description of the Related Art In order to effectively use a communication line, a host computer which is accessed from a plurality of terminal devices periodically inquires each terminal as to whether or not there is communication content. In some cases, a polling process for starting communication is performed. In addition, an apparatus has been devised in which each terminal detects whether or not the host computer periodically performs polling processing on each terminal so that each terminal detects an abnormality in the host computer. As the latter, for example, Japanese Patent Publication No. Hei 4-186944 discloses that
High-level data link control (HDLC)
A technique has been disclosed in which each terminal detects an abnormality in a host computer using a protocol with a timeout as short as possible.

[0003]

By the way, in the conventional data transmission system, especially in the case of a line in which the transmission line speed is low and half-duplex communication is performed, the transmission speed is low.
There has been a problem in that the response monitoring timer becomes long and the polling cycle cannot be made constant when a failure occurs. Further, since the polling and the request for state change collection are usually performed at once, the response monitoring timer value is set in consideration of the maximum message length, and there is a problem that the polling cycle cannot be shortened.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a data transmission apparatus capable of providing a constant polling cycle even on a line having a slow transmission path and performing half-duplex communication. The purpose is to provide.

[0005]

In order to solve the above-mentioned problems, the present invention relates to a data transmission apparatus in which a monitoring control device and a plurality of monitored control devices are connected via a line, The control device sequentially polls the plurality of monitored control devices, and collects state change data separately from the polling process only when there is a state change of the monitored control device. I do. Further, the present invention is characterized in that, when there is no response to the polling polling request, the monitoring control device polls another monitored control device after the lapse of the polling cycle. Further, the present invention is characterized in that the monitored control device divides the data of the state change and transmits the divided data to the monitoring control device when the data amount is large. Further, the present invention provides the monitored control device,
When the amount of data of the state change is large, the amount of data transmitted to the monitoring control device at a time is the amount transmitted within the polling cycle. Further, the present invention is characterized in that the line is a line for performing half-duplex communication.

According to the present invention having the above configuration, the monitoring control device monitors the presence or absence of a status change from the monitored control device, and collects the status change data only from the monitored control device having the status change. Even if there is a monitored control device that does not return a response during polling, polling can be performed without changing the cycle.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a data transmission device according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration of a data transmission device according to an embodiment of the present invention. As shown in FIG. 1, the present embodiment roughly includes a monitoring control device 10 that monitors the status of each monitored control device 30 a to 30 n connected to the line 20. The monitoring control device 10 includes a state change detection processing unit 12, a transmission / reception memory 14, a difference reception processing unit 1,
6 and a communication processing unit 18. Line 20 above
Is a low-speed line and a line on which half-duplex communication is performed.

[0008] The state change detection processing unit 12 detects a state change from the monitored and controlled devices 30a to 30n, and performs processing for the transmission / reception memory 14 and the transmission / reception processing unit 16. The transmission / reception processing unit 16 communicates with the monitored control devices 30a to 30n via the communication processing unit 18, and collects state change data. The communication processing unit 18 makes a polling request to the monitored and controlled devices 30a to 30n according to the request of the transmission and reception processing unit 16, and transmits a response from the monitored and controlled devices 30a to 30n to the transmission and reception processing unit 16. The transmission / reception memory 14 is a data storage memory used by the monitoring control device 10 to perform transmission / reception. Further, the monitored and controlled devices 30a to 30n have the above-described communication processing unit and have the same configuration as the above-described monitoring and control device 10, and thus the detailed configuration is omitted.

Next, the operation of the data transmission apparatus having the above configuration according to an embodiment of the present invention will be described. Before describing the operation of the present embodiment, the operation of the conventional device will be described. 2 and 3 are diagrams showing an operation sequence of the conventional device. First, the monitoring control device 10 performs a polling process on each of the monitored control devices 30a to 30n, and when a polling request is output to the monitored control devices 30a to 30n, the monitored control devices 30a to 30n are transmitted. The polling request is processed, the presence or absence of a status change is confirmed, and if there is a status change, all data of the status change is added to the response to the polling request and returned to the monitoring control device 10.

That is, in FIG. 2, the monitoring control device 10 first performs polling processing on the monitored control device 30a (procedure P1), and the monitored control device 30a processes the transmitted polling request and Confirm the presence / absence of a change and return the data "No state change" (procedure P
2). Next, the monitoring control device 10 is controlled by the monitored control device 30b.
(Step P3), the monitored controller 30b processes the sent polling request,
Return data indicating that "state change has occurred" (procedure P
4). When there is a state change, data indicating the state change is also transmitted. Thereafter, the same processing as that described above is performed up to the monitored control device 30n, and when the processing for the monitored control device 30n ends, the monitored control device 3
Returning to 0a, the same processing is repeated.

As shown in FIG. 3, while the polling request is being made to the monitored control devices 30a to 30n, the monitored control device 30
When a response to the polling request is not returned to the monitoring control device 10 from a to 30n (in the example shown in FIG.
After 5), the monitoring control device 10 performs a waiting process using the response monitoring timer for a time period in consideration of returning all the state change data. That is, if a failure occurs during the polling process, the process waits for a predetermined time and performs the process for the next monitored control device 30c (procedure P6). In the subsequent processing, the same processing as the processing shown in FIG. 2 is performed.

When the processing shown in FIG. 2 and FIG. 3 is performed, the monitoring control device 10 is changed when any of the monitored control devices 30a to 30n changes in state or when a fault occurs.
Becomes longer, and as a result, the polling cycle changes, and the processing cannot be performed efficiently.

Next, the operation of the data transmission apparatus according to one embodiment of the present invention will be described. 4 and 5 are diagrams showing an operation sequence of the data transmission device according to one embodiment of the present invention. First, the monitoring control device 10 performs polling processing on each of the monitored control devices 30a to 30n, and when the polling request is output to the monitored control devices 30a to 30n, the monitored control devices 30a to 30n Is processed, and the presence or absence of a state change is confirmed. If there is a state change, the presence / absence of the state change is added to the response to the polling request and returned to the monitoring control device 10. When receiving a status change from the monitored control devices 30a to 30n, the monitoring control device 10 performs status change data collection separately from normal polling.

That is, in FIG. 4, first, the monitoring control device 10 performs a polling process on the monitored control device 30a (procedure P10), and the monitored control device 30a processes the transmitted polling request, and Confirm the presence / absence of a change and return the data "No state change" (procedure P
11). Next, the monitoring control device 10
b (step P12), the monitored control device 30b processes the sent polling request, and returns data indicating "state change" (step P12).
13). As shown in FIG. 4, the monitored control device 30b
Even if there is a status change, the monitoring control device 10 does not collect the status change data at that time. That is, the monitoring control device 10 performs the status change data collection separately from the polling process.

In other words, the status change data is not collected for the monitored control device 30b having no status change. The data indicating the state change is transmitted from the monitored control device 30b after the monitoring control device 10 makes a data collection request to the monitored control device 30b (procedure P14). The request for data collection is almost the same as the polling cycle.
Therefore, in the present embodiment, the polling interval does not become long when there is a state change as shown in FIG. Thereafter, the same processing as that described above is performed up to the monitored control device 30n. When the processing for the monitored control device 30n is completed, the process returns to the monitored control device 30a and the same processing is repeated.

As shown in FIG. 5, while the polling request is being made to the monitored control devices 30a to 30n, the monitored control device 30
When a response to the polling request is not returned to the monitoring control device 10 from a to 30n (in the example shown in FIG.
15), since the monitoring control device 10 performs the polling process and the data collection of the state change separately, the waiting time is the time measured by the response monitoring timer for the same time as the normal polling. This is good, and even if there is a failure in any of the monitored control devices 30a to 30n, the influence of polling on other monitored control stations is reduced. Subsequent processing is similar to the processing shown in FIG.

Next, another embodiment of the present invention will be described. FIG. 6 is a diagram illustrating an operation sequence of a data transmission device according to another embodiment of the present invention. The operation of the data transmission apparatus according to another embodiment of the present invention is different from the operation of the data transmission apparatus according to the embodiment of the present invention shown in FIGS. 4 and 5 in that the efficiency of collecting data indicating a state change is improved. It is a point. That is, when polling is performed from the monitoring control device 10 to the monitored control devices 30a to 30n, the monitored control devices 30a to 30n process the polling request,
The presence / absence of a state change is confirmed. If there is a state change, the presence / absence of the state change is added to the response to the polling request and returned to the monitoring control device 10. When receiving a status change from the monitored control devices 30a to 30n, the monitoring control device 10 collects data indicating the status change separately from the normal polling. The monitored control devices 30a to 30n transmit data indicating a state change. However, when the amount of data indicating the state change becomes very large, the data indicating the state change is transmitted after being divided into the number of data indicating the state change that does not affect the response monitoring timer.

The above operation will be described in more detail. In FIG.
a (step P20), the monitored controller 30a processes the sent polling request, confirms whether or not there is a state change, and returns data indicating "no state change" (step P21). ). Next, the monitoring control device 10 performs a polling process on the monitored control device 30b (procedure P22), and the monitored control device 30b processes the transmitted polling request and returns data indicating "state change". (Step P23). Now, it is assumed that the amount of data indicating a state change is very large.

If the data returned from the monitored control device 30b is "state change" and the amount of data indicating the state change is very large, the monitor control device 10 A data collection request is transmitted (procedure P24). Upon receiving this request, the monitored control device 30b divides the data indicating the state change and transmits the data to the monitoring control device 10 (procedure P25). If all data indicating the state change has not been transmitted, the monitoring control device 10 transmits a request for information collection to the monitored control device 30b again (procedure P26). Upon receiving the request, the monitored control device 30b transmits the remaining data (procedure P27).
It should be noted that the data amount divided and transmitted is the amount that can be transmitted within the polling period, and the time interval for requesting information collection is almost the same as the polling period.

When the above processing is completed, the monitoring control device 3
Normal processing is performed on 0c to 30n, and when the processing on the monitored control device 30n ends, the process returns to the monitored control device 30a again, and the same processing is repeated. As described above, in the present embodiment, it is not necessary to extend the response monitoring timer even when the data indicating the state change becomes very large by dividing and transmitting the data indicating the state change.

The embodiments of the present invention and other embodiments have been described above. In these embodiments, data transmission is performed without using the HDLC protocol as in the conventional device. Therefore, processing such as connect processing and disconnection processing is unnecessary, and the processing time can be reduced as a whole. Further, in these embodiments, by collecting data on the state change only from the monitored control device, it is possible to make the response monitoring timer extremely short, and there is a monitored control device that does not return a response during polling. Also, the polling cycle does not change.

[0022]

As described above, according to the present invention, the normal polling and the request for collecting data indicating a state change are separated, so that the polling cycle can be extremely shortened. . Further, by shortening the polling period, even if a failure occurs in the monitored control device during polling, the effect of polling other monitored control devices can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a data transmission device according to an embodiment of the present invention.

FIG. 2 is a diagram showing an operation sequence of a conventional device.

FIG. 3 is a diagram showing an operation sequence of a conventional device.

FIG. 4 is a diagram showing an operation sequence of the data transmission device according to one embodiment of the present invention.

FIG. 5 is a diagram showing an operation sequence of the data transmission device according to one embodiment of the present invention.

FIG. 6 is a diagram illustrating an operation sequence of a data transmission device according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF REFERENCE NUMERALS 10 monitoring control devices 30a to 30n monitored control devices 20 lines

Claims (5)

[Claims] 1. A data transmission device comprising a monitoring control device and a plurality of monitored control devices connected via a line, wherein the monitoring control device sequentially polls the plurality of monitored control devices, A data transmission apparatus characterized in that data of a state change is collected separately from the polling process only when there is a state change of the monitored control device. 2. The monitoring control device according to claim 1, wherein if there is no response to the polling polling request, the monitoring control device polls another monitored control device after the lapse of the polling cycle. A data transmission device according to claim 1. 3. The data transmission apparatus according to claim 2, wherein the monitored control device divides the state change data when the amount of the state change data is large, and transmits the divided data to the monitor control device. 4. The monitored control device, when the amount of data of the state change is large, the amount of data transmitted to the monitoring control device at a time is the amount transmitted within the polling cycle. 4. The data transmission device according to claim 3, wherein: 5. The data transmission apparatus according to claim 1, wherein the line is a line for performing half-duplex communication.