JP2003087259A - Information transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an information transmission system capable of transmitting a change of data without missing it even when the capacity of a transmission resource is small. SOLUTION: In a control device 10, a scanning function 13 monitors a tag of monitored information in a prescribed scanning period, and at detecting a status change, a transmission function 17 transmits a status change message to the other device through a transmission line 30. A transmission resource inspection function 18 monitors the transmission resource, and when the remaining capacity of transmission resource is reduced below a prescribed value, the start of a busy transmission period is judged, the scanning period of the function 13 is extended and the generation frequency of status change messages is reduced. Consequently, a change of data can be transmitted without omitting it even when the capacity of the transmission resource is small.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information transmission system in which a control device and an operation monitoring device are connected by a transmission line.

[0002]

2. Description of the Related Art Conventionally, there is an input / output as an interface with the outside, a tag that is direct or indirect information regarding the input / output, and a scan function for managing the input / output and the tag is provided. There is a transmission function for transmission, and the scanning function has a control device that creates and interprets messages, and an operation monitoring device that monitors or operates the tags of the control device through the messages flowing through the transmission path. In an information transmission system in which the operation and monitoring devices are connected by a transmission line, in order to notify the change of the tag to the operation and monitoring device at high speed from the control device, a status change (abbreviated to a status change for short) using tag change information as a message ) A message is used to convey the change.

FIG. 12 shows an example of this conventional information transmission system. As shown in the figure, the control device 10 and the operation monitoring device 20 are connected one-to-one by a transmission line 30 or 1
A plurality of operation monitoring devices 20 and other control devices 10 are related to one control device 10. When a plurality of devices are connected, a LAN is used as the transmission line 30.

FIG. 13 is a block diagram of the inside of the control device.
FIG. 14 shows the flow of processing and data in the device.

As shown in FIG. 14A, the controller 10
In, the input information is taken in by the input function 11 and processed by the scan function 13. The processed result is tag 1
4 and the tag 14 is changed, a state change message as a notification message is created. The created message is stored in the transmission queue 15,
It is sequentially sent out to the transmission path 30 by the transmission function 17.

As shown in FIG. 14B, the read request from the operation monitoring device 20 is sent as a read message to the control device 1.
It is received by the transmission function 17 of 0, stored in the reception queue 16, and sequentially processed by the scan function 13. In the read request, the data in the tag 14 is read, and the read data is returned as a response message.

As shown in FIG. 14C, the write request (change request) from the operation monitoring device 20 is received by the transmission function 17 of the control device 10 as a write message (change message) and is received by the reception queue 16. Stored and scan function 13
Are processed in sequence. The write request is normally written to the tag 14 in synchronization with the scan processing cycle, and the data is passed to the output function 12 and output to the final end. The writing result is returned as a writing response message.

FIG. 15 shows the flow of the scan function.
The scan function is repeatedly executed at a certain interval (scan cycle). In the flow of a general scan function, input (step S101) is performed at the beginning of the loop, output (step S105) is performed at the end, and this is repeated for all tags (step S106) to delay (step S107). enter. Between the input (step S101) and the output (step S106), message processing (step S102) and state change detection processing (step S10).
3), other tag processing (step S104) is performed.

[0009]

By the way, the controller 1
0, when a large number of input changes, which are reflections of changes in the external environment, or requests from the outside of the operation monitoring device 20 or output changes or tag internal information due to internal time factors. When a large number of changes occur, a change message proportional to their sum occurs.

Conventionally, a sufficiently large transmission resource is used so as to guarantee that the maximum possible amount of these large amount of generated messages is transmitted from the control device 10 to the operation monitoring device 20 without omission within the designated time. Needed. Transmission resources include transmission buffer (memory), transmission queue size,
It is a transmission line band, CPU resources, and the like.

The present invention has been made in view of such a conventional point, and a system having a property that a large amount of data change occurs but it does not continue, a high-speed operation when the data change is small. In a system in which it is necessary to convey state changes to the data transmission, but when there are many changes, it is not necessary to send all state changes at high speed, and information transmission that can transmit data changes without missing even if transmission resources are low The purpose is to provide a system.

[0012]

SUMMARY OF THE INVENTION The present invention is a state change detection processing means for detecting a state change of information by monitoring a tag of monitored information at a predetermined scan cycle and comparing previous information with latest information. And an information transmission system having a control device including a transmission means for transmitting information indicating the state change to another device via a transmission line when the state change is detected by the state change detection processing means, The control device monitors the transmission resources, and when the remaining transmission resources fall below a prescribed value, it is judged that the busy transmission period has entered, and when the remaining transmission resources rise above the prescribed value, exit from the busy transmission period. If the transmission resource investigation means determines that the transmission busy period has entered, the scan cycle of the state change detection processing means is lengthened to leave the transmission busy period. When disconnection is characterized in that a means for controlling so as to return to the original scan cycle.

According to the present invention having such a configuration, even if the transmission resource is small, the change in data can be transmitted without omission.

Further, according to the present invention, as described above, instead of changing the scan cycle depending on whether the transmission is in the busy period or not, the acquisition of the original data to the tag may be controlled. Alternatively, the transmission interval of the information indicating the state change may be changed.

Then, a plurality of existing tags are given priorities, and a judgment reference value for judging that a busy transmission period has been entered, or for exiting from a busy transmission period, is determined according to the priority of the tags. May be.

Further, when the transmission busy period is entered, the input data is stored in the new input data area provided in the tag, and when the transmission busy period is over, when there is input data in the new input data area. It is also possible to take out the input data.

[0017]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. In the following drawings, the same reference numerals indicate the same or corresponding parts including the drawings showing the conventional example.

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
The internal configuration of the control device in the information transmission system according to the embodiment is shown. The transmission resource investigation function 18 is added to the internal configuration of FIG. 13 showing a conventional example.

The transmission resource checking function 18 constantly monitors the transmission resources, judges that the remaining transmission resources become a certain value or less, determines that the transmission is busy, and notifies the scan function 13 of the state.
The scan function 13 changes the loop delay time of the scan function based on the information of the busy transmission period as shown in the flow of FIG. During busy periods of transmission (Yes in step S121)
By increasing the delay time (step S122), decreasing the frequency of occurrence of the status change message, and reducing the processing itself of the scan function 13, the free time of the CPU is increased and the load is increased so as to get out of the busy transmission state. Lower.

When the remaining transmission resources exceed a certain value,
It is determined that the transmission has come out of the busy period (step S121).
No), the scan cycle is returned to the original one (step S10).
7).

By providing a difference in the judgment conditions when entering the busy transmission period and when exiting (hysteresis), it is possible to reduce the state transition between the busy transmission period and the normal period and to stabilize the control device.

The transmission resources include a transmission buffer (memory), a transmission queue size, a transmission line band, CPU resources, etc., but the transmission buffer capacity, transmission queue size, CPU
Normally, the resource inquires from the OS, and the transmission path bandwidth is directly estimated by collecting the transmission message amount of the transmission path 30 and directly measuring the bandwidth, or by how many seconds it takes for the transmitted frame to be completed.

(Second Embodiment) Next, an information transmission system according to a second embodiment of the present invention will be described.

The same internal control device configuration as in the first embodiment is used, and the flow of the scanning function uses FIG.

In the second embodiment, unlike the case of the first embodiment, during the busy transmission period (step S
Yes in step 121) without inputting (step S101),
The scan function 13 is operated using the old input data.
During the busy period of transmission, new input data is not fetched, so that the tag data does not change and the status change message is not transmitted. If the transmission is not busy (step S1)
21: No) New input is taken in (step S10)
1).

Since the input is not taken in during the busy period of transmission, the operation output is output and the output delay and the like are operated as usual. With respect to the input, when there is no new input, the time-related functions such as input filtering use the old input and operate as in the normal period.

This creates the same state as if the input had not changed. By this method, the load of the status change message can be reduced without affecting functions other than input.

In this method, when the busy transmission period and the normal period are frequently repeated, in the worst case, some tags may be frequently input and some tags may be hardly input. is there. To prevent this, one of the two methods shown in FIGS. 4 and 5 is used.

In the flow of FIG. 4, it is judged at the beginning of the scan loop whether or not it is busy at the same time (step S121), and it is selected whether or not the input is taken in every scan cycle (steps S141 to S143).

According to this method, even if it is judged that the transmission is busy in the middle of the scan loop, a change message is generated for the tag whose input is changed until the end of the scan loop.

The flow of FIG. 5 improves this.
Although the process becomes complicated, the creation of the status change message is stopped immediately if it is determined that the transmission is in a busy period. Resuming the creation of the status change message starts from the place where the tag order was determined to be the busy transmission last time in the scan loop.

That is, in the flow of FIG. 5, it is determined whether or not the transmission is busy during the scan loop (step S12).
1), in the normal period (No in step S121), IX =
The state change message is created (step S101) as -1 (step S152), but if it is determined that the transmission is busy even during the scan loop (Yes in step S121).
s) Since IX = tag order (step S153),
The tag order does not become IX until one cycle is completed, and step S1
The flow branches to No at 51, and the state change message is not created.
When the tag turn is judged to be the busy transmission last time, that is, when the tag turn = IX, the step S151 is completed.
If Yes, the normal time is reached (No in Step S121), the creation of the status change message is restarted from this tag order (Step S152, Step S152).
101).

(Third Embodiment) Next, an information transmission system according to a third embodiment of the present invention will be described.

In this embodiment, in order to suppress the frequency of state change transmission regardless of the type of tag, if the shortest state change notification interval is provided, this interval is lengthened during the busy transmission period to reduce the number of transmissions. . FIG. 6 shows the situation at a timing. Increase the timer value during the busy transmission period from the normal period. The feature of this embodiment is that the shortest state change alert interval is made variable and its value is changed according to the degree of state change busyness.

Further, when the monitored information has a weight on the information such as analog data, regarding the information with a low weight,
It may change all the time. Frequent changes of such unweighted information are not very useful, but rather adversely affect the load. To remove this adverse effect,
There are a method of filtering the input data in the state change detection and a method of weighting and comparing the data in the change detection.

As a general method of realizing the latter, the data value at the time of the previous notification of the condition change is set as the central value, the limit value (range value of ±) of the condition change is designated, and the subsequent input data is +
If it exceeds either side, it is judged that there has been a change,
Send a change message.

In the case of applying the former input filter in these two methods, the time constant is made variable and the time constant is lengthened during a busy transmission period. When the latter state change alarm limit value is used, this value is made variable, and as shown in FIG. 7, this range is widened during a busy transmission period. In this way, the number of times the status change is issued is controlled.

(Fourth Embodiment) Next, an information transmission system according to a fourth embodiment of the present invention will be described.

In this embodiment, in the first to third embodiments described above, a plurality of existing tags are divided into a plurality of groups based on the importance of the status change message, and priority is given to each group. Here, for the sake of explanation, it is divided into two groups and important tags, that is, tags that want to send a change message as much as possible even during a busy transmission period (called a priority tag).
In order to give priority to the priority tag, during the busy period of transmission,
It is divided into a normal tag that immediately stops the transmission of state change messages.

In the transmission resource investigation function 18 of FIG. 1, when the busy transmission period is determined based on the level of the transmission resource, the reference level for entering the busy period (busy entry level)
According to the number of the above-mentioned tag groups, a set of levels (busy cancellation level), which is a standard for exiting the busy season, is provided. In each level group, the busy entry level and the busy release level are differentiated from each other so that the busy period and the normal period do not frequently fluctuate.

The level set is selected in accordance with the priority of the tag so that the priority tag can change the state of transmission more than the normal tag.

FIG. 8 shows an example of determination levels during a busy transmission period. The lower the value of the transmission resource, the higher the transmission load and the more difficult it is to transmit. The priority tag level set is set to a lower value than that of the normal tag, and the priority tag makes it possible to transmit the state change message as much as possible, and the more important the tag, the more state change message can be transmitted. To do so.

As shown in FIG. 9, it is judged whether the tag is a priority tag (step S191), and the priority tag scanning function 1
3 performs processing, the transmission busy period is determined using the level set for the priority tag (step S192), and the normal tag is determined using the level set for the normal tag (step S192).
193).

As a special example, a prioritized tampering of tags can be sent without the effects of transmission busy.

(Fifth Embodiment) Next, an information transmission system according to a fifth embodiment of the present invention will be described.

In this embodiment, when the change of the monitored information is detected, the transmission is not performed during the busy period, and
If a tag change occurs without sending a status change, add one or more sets to the tag to store only the changed input information, the changed input information and the time when it changed, or only the changed time. Then, when the transmission resource becomes available, a state change message is created from the newly stored information and the contents of the conventional tag, and even if the state change message is delayed,
This is to prevent the state change message from being omitted and the state change time to be incorrect.

In this embodiment, the tag data structure has a new input FIFO. FIG. 10 shows the tag structure in this embodiment, and FIG. 11 shows the processing flow.

As shown in FIG. 10, the basic unit of the new input FIFO is the input data and the time when the input data is fetched.

As shown in FIG. 11, during the busy transmission period (Yes in step S121), the input data at that time and the time at that time are put in the new input FIFO (step S121).
201, step S202).

When the transmission is not in a busy period (step S121
No), if there is data in the new input FIFO (Yes in step S203), the data and time are extracted from the new input FIFO without inputting at that time (step S203).
204, step S205). When the new input FIFO becomes empty (No in step S203), data is fetched from the input (step S101), and the time at that time is used (step S206) to perform the scanning process.

In the system which does not use the change time, only the input data need be added without adding the time to the tag structure.

According to this method, even if an input is not made so as not to send the status change message during the busy period of transmission, the input is saved with the time, so that the change can be reproduced later.

[0053]

According to the present invention, in a system using a low-speed LAN or a control device with a small number of transmission resources, a state change message may be missed or resources may be consumed by the state change message even when the state change occurs frequently. It is possible to prevent the transmission from becoming impossible.

Further, even in the case where the above-mentioned state changes frequently, the response to the operation can be performed at high speed.

[Brief description of drawings]

FIG. 1 is a diagram showing an internal configuration of a control device in an information transmission system according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a flow of a scan function according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a flow of a scan function according to the second embodiment of the present invention.

FIG. 4 is a diagram showing another example of the flow of the scan function according to the second embodiment of the present invention.

FIG. 5 is a diagram showing still another example of the flow of the scan function according to the second embodiment of the present invention.

FIG. 6 is a diagram for explaining a state change transmission interval extension during a busy transmission period of general data according to a third embodiment of the present invention.

FIG. 7 is a diagram for explaining a state change transmission interval extension during a busy transmission period of analog data according to the third embodiment of the present invention.

FIG. 8 is a diagram for explaining a determination level during a busy transmission period according to the third embodiment of the present invention.

FIG. 9 is a diagram showing a flow of a scan function according to the fourth embodiment of the present invention.

FIG. 10 is a diagram showing a tag structure according to a fifth embodiment of the present invention.

FIG. 11 is a diagram showing a flow of a scan function in the fifth embodiment of the invention.

FIG. 12 is a diagram showing an example of a conventional information transmission system.

FIG. 13 is a diagram showing an internal configuration of a control device in a conventional information transmission system.

FIG. 14 is a diagram showing a message flow in a conventional example.

FIG. 15 is a diagram showing a flow of a scan function in a conventional example.

[Explanation of symbols]

10 ... Control device 11 ... Input function 12 ... Output function 13 ... Scan function 14 ... Tag 15 ... Send queue 16 ... Receive queue 17 ... Transmission function 18 ... Transmission resource investigation function 20 ... Operation monitoring device 30 ... Transmission line

Claims (5)

[Claims] 1. A state change detection processing means for detecting a state change of information by monitoring a tag of monitored information at a predetermined scan cycle and comparing previous information with latest information, and this state change detection processing means. When a state change is detected by
In an information transmission system having a control device having a transmission means for transmitting information indicating a state change to another device via a transmission line, the control device monitors the transmission resource, and the remaining transmission resource has a predetermined value. Transmission resource check means determines when the busy transmission period has entered, and transmission resource check means determines when the remaining transmission resources have exceeded the specified value when the transmission busy period has passed. And a means for controlling so that the scan cycle of the state change detection processing means is lengthened when it is determined that the busy period has entered, and that the scan cycle is returned to the original state when it is determined that the transmission busy period is exited. Information transmission system characterized by. 2. A state change detection processing means for detecting a state change of information by monitoring a tag of monitored information at a predetermined scan cycle and comparing previous information with latest information, and this state change detection processing means. When a state change is detected by
In an information transmission system having a control device having a transmission means for transmitting information indicating a state change to another device via a transmission line, the control device monitors the transmission resource, and the remaining transmission resource has a predetermined value. Transmission resource check means determines when the busy transmission period has entered, and transmission resource check means determines when the remaining transmission resources have exceeded the specified value when the transmission busy period has passed. When it is determined that the busy period has been entered, the original data is not captured in the tag, and when it is determined that the transmission is out of the busy period, the original data is captured. Information transmission system. 3. A state change detection processing means for detecting a state change of information by monitoring a tag of monitored information at a predetermined scan cycle and comparing previous information with latest information, and this state change detection processing means. When a state change is detected by
In an information transmission system having a control device having a transmission means for transmitting information indicating a state change to another device via a transmission line, the control device monitors the transmission resource, and the remaining transmission resource has a predetermined value. Transmission resource check means determines when the busy transmission period has entered, and transmission resource check means determines when the remaining transmission resources have exceeded the specified value when the transmission busy period has passed. When it is determined that the busy period has entered, the transmission interval of the information indicating the state change is lengthened, and when it is determined that the transmission busy period is over, the transmission interval is restored to the original state. Information transmission system characterized by. 4. The information transmission system according to any one of claims 1 to 3, wherein a plurality of existing tags are prioritized, and the transmission resource checking means judges that the transmission busy period has been entered, or the transmission busy period is busy. An information transmission system characterized in that the predetermined value, which is a judgment reference value for judging that the time has passed, is decided according to the priority of the tag. 5. A state change detection processing means for detecting a state change of information by monitoring a tag of monitored information at a predetermined scan cycle and comparing previous information with latest information, and this state change detection processing means. When a state change is detected by
In an information transmission system having a control device having a transmission means for transmitting information indicating a state change to another device via a transmission line, the control device monitors the transmission resource, and the remaining transmission resource has a predetermined value. When the following occurs, it is judged that the transmission busy period has been entered, and when the remaining transmission resources exceed a predetermined value, it is judged that the transmission resource has exited from the busy transmission period. When it is determined that the busy period is entered, the input data is stored in the new input data area provided in the tag, and when it is determined that the transmission busy period is over, there is input data in the new input data area. At this time, the information transmission system is provided with means for controlling to take out the input data.