JPH08204756A - Cyclic data transfer system - Google Patents

Abstract

PURPOSE: To prevent the stagnation of old cyclic data after restoration of a fault of a network by adding an identifier to cyclic data, giving the resulting data to a queue management means, and abolish the cyclic data having been linked when the cyclic data having the same identifier are in existence in a queue. CONSTITUTION: An ID adding means 21A is provided in a transmission period management device 21 and a means 31A for deleting the same ID data having been liked is provided in a transmission queue management device 31. Then an identifier representing a kind is added to cyclic data by the device 21, which gives the result to the device 31. When data having the same identifier as cyclic data newly linked are in existence in data 6 making linking request, the device 31 uses the means 31A to abolish the cyclic data having been linked. Thus, when a fault in the network is restored, the undesired data is prevented from being transmitted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cyclic data transfer system for transmitting data generated in a fixed cycle (cyclic) in a control device for controlling communication, a computer or the like. In the drawings, the same reference numerals indicate the same or corresponding parts.

[0002]

2. Description of the Related Art FIG. 5 shows an example of the structure of a transmission processing unit of this type of cyclic data transfer system. In the figure,
5 is a network leading to the data transfer destination of this system, 20 (20-1 to 20-3) is cyclic data as data for each type to be transmitted from this system at a fixed cycle, 2 is this cyclic data 20-1
20-3 manages the respective transmission cycles and sends the transmission request data 6 at the time when the respective cyclic data should be transmitted. The transmission cycle management unit 1 irregularly sends general messages to be transmitted from this system. A general message processing unit that is created at any time, and that is the transmission request data 6 at the time of its creation, 3
Detects the state of the network 5 and links the transmission request data 6 to the end of the queue (queue) 33 in the order of request, and when the network 5 is normal, the transmission control is performed sequentially from the head data of the queue 33 to the network 5. It is a department.

As described above, in the cyclic transmission control system in which the transmission cycle management source and the transmission control unit, which are the subject of the present invention, are separate mechanisms, the transmission cycle management unit 2 as the transmission cycle management source uses the transmission cycle management mechanism 21. A periodical measurement is performed through the transmission, and a transmission request (request) for the cyclic data 20-1 to 20-3 is made to the transmission control unit 3 at a fixed period.
Makes a transmission request to the transmission control unit 3 via the message mechanism 11 whenever a message to be transmitted is generated. The transmission control unit 3 sends the transmission request data 6 requested for transmission onto the network 5 in the order of request.

However, the transmission control unit 3 is provided with a transmission queue management mechanism 31 and a transmission control mechanism 32, and the transmission queue management mechanism 31 sends the transmission request data 6 from the higher-order means 1 and 2 so as not to cause transmission omissions. Are linked to the end of the queue 33 in the order of request, and are sent to the transmission control mechanism 32 in the order of request, that is, from the head data of the queue 33. Further, the transmission control mechanism 32 sequentially transmits the transmission request data transmitted from the transmission queue management mechanism 31 to the network 5, and
When an error occurs on the network, it waits for its recovery before sending.

[0005]

In the control method of transmitting data in a fixed cycle (cyclic), the cyclic data of the old cycle is unnecessary and the latest data is required.
It is desirable to send the latest data. But,
In the prior art, when an abnormality occurs on the network, the data requested to be transmitted from the transmission cycle management source to the transmission control unit stays in the transmission management queue of the transmission control unit and stays in the queue when the network is restored. Unnecessary (old)
It had the drawback that cyclic data would flow over the network all at once.

It is an object of the present invention to solve the above problems and to provide a cyclic data transfer system capable of eliminating unnecessary cyclic data transmission at the time of abnormal recovery and transmitting only the latest cyclic data. .

[0007]

In order to solve the above-mentioned problems, the cyclic data transfer system according to claim 1 comprises:
At least (via the transmission cycle management mechanism 21, etc.), a plurality of types of data to be transmitted (20-1
~ 20-3, etc.)
Has queue management means (such as the transmission queue management mechanism 31) linked to the end of the queue (such as the queue 33) of data to be transmitted in the order of reception (in the form of the transmission request data 6 or the like),
In a cyclic data transfer system in which, when the outside of this system is ready for transmission (via the transmission control mechanism 32, etc.), the link is sequentially removed from the data to be transmitted at the head of the queue and the data is transmitted to the outside. The queue management means includes means (ID addition means 21A, etc.) for adding an identifier (ID) indicating the type of the cyclic data generated in a fixed cycle and passing the identifier to the queue management means. Completed identical ID data deleting means 31
When linking this passed cyclic data to the queue (via A etc.), if there is cyclic data with the same identifier as the newly linked cyclic data in the queue immediately before this link, , Make sure to discard this linked cyclic data.

Further, in the cyclic data transfer system of claim 2, in the cyclic data transfer system of claim 1, the outside is a network (5 or the like). Further, in the cyclic data transfer system according to claim 3, in the cyclic data transfer system according to claim 1 or 2, the queue management means also sends a message to be transmitted (passed through the message mechanism 11 or the like). The queues are linked to the end of the queue in the order of reception that is indistinguishable from the cyclic data.

[0009]

In order to distinguish the type of cyclic data from the general message, the transmission request side first defines an identifier (ID) for the transmission data. The identifier identifies the type of cyclic data block, and the same identifier is added to each data block of the same type. When cyclic data with an old cycle is accumulated in the queue 33 of the transmission queue management mechanism 31 due to an abnormality on the network, old unnecessary data is recognized by the identifier and discarded.

[0010]

Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 shows the structure of a cyclic data transfer processing unit according to the present invention, and this figure corresponds to FIG. In FIG. 1, in contrast to FIG. 5, an ID (identifier) adding means 21A as a main functional unit related to the present invention is provided in the transmission cycle management mechanism 21, and a linked same ID data deleting means is similarly provided in the transmission queue management mechanism 31. 31A is provided.

That is, when an abnormality occurs on the network 5, the transmission control section 3 stops the transmission. Therefore, the transmission request data 6 is retained in the queue (queue) 33 of the transmission queue management mechanism 31. In the present invention, unnecessary cyclic data having an old cycle is identified (determined) by the ID (identifier) added to the transmission request data 6. Therefore, the ID adding means 21A in the transmission cycle management mechanism 21
When the cyclic data 20-1 to 20-3 classified by type is used as new transmission request data 6, the cyclic data to be the transmission request data is added with an ID indicating the type of the cyclic data.

FIG. 2 is a flow chart showing the procedure of the queue link processing of the transmission request data 6 based on the present invention by the transmission queue management mechanism 31, and S1 to S5 show the steps. That is, the transmission queue management mechanism 31 first determines whether the ID (identifier) of the data 6 for which the link request (transmission request) is made is other than 0 (S1). This is because the general message needs to be transmitted without missing all data and is not deleted from the queue 33. Therefore, in this embodiment, the ID of the transmission request data 6 of the general message is set to 0 and is excluded from the search target. .

When the ID is not 0, the transmission request data 6 is the cyclic data 20, and the transmission queue management mechanism 31 sends the transmission request data 6 before linking the transmission request data 6 to the queue 33. It is searched whether or not the data having the same ID as the ID added to is already linked to the queue 33 (S2), and if it is linked (S3, branch “Yes”), the linked data is unnecessary. The data is determined to be deleted from the queue 33 (S4), and the new transmission request data 6 is newly linked to the queue 33 (S5). The function of the linked same ID data deleting means 31A in FIG. 1 corresponds to step S4 in FIG.

FIG. 3 shows a concrete example of the state transition of the queue of transmission request data when the network is normal according to the present invention.
Here, FIG. 3A shows the temporal transition of the queue 33 of the transmission request data 6 linked by the transmission queue management mechanism 31 in the order of, and FIG. 3B shows the transmission cycle management mechanism corresponding to the transition of. 21, transmission queue management mechanism 31,
Each operation of the transmission control mechanism 32 is shown. Note that FIG.
ID1 to ID5 attached to each data in (A) indicate IDs for each type of cyclic data. In FIG. 3, the transmission request data 6 is sent out on the network in the order of request without staying. That is, it is assumed that the cyclic data to be transmitted has already been requested to be transmitted in the order of ID1, ID5, and ID2 (FIG. 3,). Since the state of the network 5 is normal, the transmission control mechanism 32 sends the ID1 data at the head of the queue 33, and the ID5 and ID2 data are linked to the queue (FIG. 3,). A new ID in that state
No. 1 data is requested to be transmitted, and the transmission queue management mechanism 31 confirms that the ID 1 data is not linked to the queue, and links the ID 1 data to the queue (FIG. 3, FIG.
). The transmission control mechanism 32 transmits the ID5 data at the head of the queue, and the queue becomes the state shown in FIG. When the network 5 is normal, the above states are repeated.

4 to 4 indicate that the network 5 has an abnormality and cannot be transmitted, and the transmission request data 6 is stored in the queue 3.
3 shows a concrete example of the state transition of the queue when the data having the same ID is repeatedly requested to be transmitted in a constant cycle. The meanings of ID1 to ID5 in FIG. 4 are the same as in FIG. That is, the data is already ID1, ID5, ID
It is assumed that the transmission is requested in the order of 2 (Fig. 4,). The transmission control mechanism 32 is not transmitting the data in the queue 33 because an abnormality has occurred in the network. When a transmission request for the data of ID1 is generated in this state, the transmission queue management mechanism 31 retrieves the data of ID1 from the queue and deletes it, and links the newly requested data of ID1 (FIG. 4). Also, when a transmission request for the data of ID2 occurs in that state, the transmission queue management mechanism 3 similarly.
1 retrieves the data of ID2 from the queue and deletes it, and links the data of ID2 newly requested to be transmitted (FIG. 4, FIG.
). In this embodiment, since the link is always performed at the end of the queue 33, the data arrangement of the queue 33 changes every time a transmission request occurs, but the queue 33 always contains only the latest cyclic data. It will be linked.

[0016]

According to the present invention, an ID is added to cyclic transmission data so that the type and the general message can be distinguished from each other, and the transmission queue management mechanism 31 can identify new cyclic transmission request data. If the data with the same ID is already linked to the queue, the linked data is deleted and new transmission request data is linked, so an error occurs in the network and the data cannot be sent. Even if it happens, only the latest data cyclically transmitted at regular intervals is stored in the transmission management queue, and when the network error is restored, unnecessary data is not sent and the latest data is not sent. Only data is sent.

[Brief description of drawings]

FIG. 1 is a structural diagram of a cyclic data transmission processing unit as an embodiment of the present invention.

FIG. 2 is a flowchart showing a procedure of link processing of the transmission queue management mechanism of FIG.

FIG. 3 is a diagram showing an example of state transition of a queue of cyclic transmission request data when the network is normal according to the present invention.

FIG. 4 is a diagram showing an example of state transition of a queue of cyclic transmission request data when the network is abnormal.

FIG. 5 is a conventional structural diagram corresponding to FIG.

[Explanation of symbols]

 1 General Message Processing Unit 2 Transmission Cycle Management Unit 3 Transmission Control Unit 5 Network 6 Transmission Request Data 11 Message Mechanism 20 (20-1 to 20-3) Cyclic Data 21 Transmission Cycle Management Mechanism 21A ID Adding Means 31 Transmission Queue Management Mechanism 31A Linked same ID data deleting means 32 Transmission control mechanism 33 Queue

Claims (3)

[Claims] 1. A plurality of types of data to be transmitted (hereinafter referred to as cyclic data) that are generated at least in fixed cycles.
Has a queue management means for linking to the end of the queue of the data to be transmitted in the order of reception, and when the outside of this system is ready for transmission, the link is sequentially removed from the data to be transmitted at the head of the queue. In the cyclic data transfer system for transmitting to the outside, the cyclic data transfer system further comprises means for adding to the queue management means an identifier indicating the type of the cyclic data generated in a fixed cycle, and the queue management means, When linking the passed cyclic data to the queue, if there is cyclic data having the same identifier as the newly linked cyclic data in the queue immediately before the link,
A cyclic data transfer system characterized by discarding this linked cyclic data. 2. The cyclic data transfer system according to claim 1, wherein the outside is a network. 3. The cyclic data transfer system according to claim 1 or 2, wherein the queue management means links the messages to be transmitted to the end of the queue in a reception order indistinguishable from the cyclic data. A cyclic data transfer system characterized by the fact that there is.