Background technology:
In the typical supervisory control system network, the communication structure between two communication equipments as shown in Figure 1.Each node in the system (control desk or monitored equipment) all exists application controls layer and two part of Control on Communication layer.Wherein the application controls layer is realized the function of application, as user interface, and the transmission of monitor command and reception or the like.Carry out information interaction and collaborative by the control message between the application controls layer between the different nodes, thereby realize that control is with controlled.
Control message between the different nodes can not directly be transmitted on the application controls layer, and must be by the Control on Communication layer.The Control on Communication layer is responsible for the transmission of specific implementation control message between different nodes, and particularly, the control message that this node is produced is packaged into communication message, is delivered to the Control on Communication layer of peer node; Perhaps the Control on Communication layer from equity receives and the parsing communication message, and therefrom recovers the control message, passes to the application controls layer of this node.Undertaken alternately by communication message between the Control on Communication layer, it consists of the communication frame head and adds the control message.
In existing Control on Communication layer protocol design, generally adopt the mode of the corresponding control message of a communication message, the mode of this encapsulation has control simple, the advantage that is easy to realize.But can there be the low problem of communication efficiency.Especially in the supervisory control system network, the message of various control usefulness all shorter and smaller (1~100Bytes), comparatively speaking, the proportion that the communication frame head occupies in communication message is big (as using ICP/IP protocol as communication protocol, then the frame head expense of each communication message is more than the 54Bytes), thereby a large amount of network bandwidths all is used on the non-effective information of transmission, has a strong impact on the transfer rate of control message.
Summary of the invention:
Purpose of the present invention is exactly in order to overcome the above problems, and the transmission method of control message in the supervisory control system is provided, and improves the load-carrying efficiency of communication message.
For achieving the above object, the present invention proposes the transmission method of control message in a kind of supervisory control system, it is characterized in that comprising the steps: that the control message with this node produces is packaged into communication message, the communication frame head that consists of of communication message adds the control message, a plurality of control messages of encapsulation in the communication message; Communication message is delivered to the Control on Communication layer of peer node; The Control on Communication layer of peer node receives and resolves communication message, and therefrom recovers the control message, passes to the application controls layer of this node.
Owing to adopted above scheme, a plurality of control messages have been encapsulated in the communication message, thereby reduced the relative proportion of communication frame head in communication message, improve the load-carrying efficiency of communication message, solved the low problem of propagation efficiency of in monitor network, controlling message between a plurality of equipment.
Embodiment:
Also the present invention is described in further detail in conjunction with the accompanying drawings below by specific embodiment.
See Fig. 2, as we can see from the figure, improve in the later Control on Communication layer protocol, encapsulated a plurality of control messages in the communication message, thereby reduced the relative proportion of communication frame head in communication message, improved the load-carrying efficiency of communication message.
For a plurality of control messages are encapsulated in the communication message, designed following communication control processor, its structure is as shown in Figure 3.
Wherein " underlying protocol frame head " territory is different because of different basic communication protocols, as the Ethernet protocol frame head, and ICP/IP protocol frame head or the like.
" control message number " territory has indicated the number of the control message that comprises altogether in this communication message.The length in this territory will determine the maximum number of the control message that comprises in the communication message.
In order from communication message, accurately to locate and recover a plurality of control messages, in each control message, boundary and locating information have been increased.
Wherein " start of heading sign " indicated the beginning of each control message.Specific value of general agreement is filled this information field between the communication equipment.
The total length (containing two information fields of " start of heading sign " and " control message length ") of this control message has been indicated in " control message length " territory, and the bit wide in this territory selects to want can enough represent to control the maximum length that message may occur.
What carry in " control message content " territory will be the control message content of actual needs transmission.
Because the randomness of control content of message wherein may occur and " start of heading sign " identical field of thresholding.Therefore it is not enough only relying on " start of heading sign " to locate each control message.To accurately locate and respectively control message, also need to utilize " control message length " territory, use " chain type positioning mode " to finish.
The process that " chain type positioning mode " carries out is: at first find first control start of heading sign in the communication message, because each communication message frame head length is certain, first position of controlling start of heading also should be fixed; By the starting position of first control message and the length of this message, we can locate the starting position of second control message.Whether the content of checking this position is " start of heading sign " value of agreement.If then expression is resolved correctly, can use the same method and continue to resolve follow-up control message.If not, then represent parse error, need to stop resolving.Under the right-on situation of message transmissions,, can decomposite all control message structures in the communication message fully with this kind " chain type positioning mode ".
As seen, the present invention has realized a plurality of control messages are encapsulated in the communication message, and can recover a plurality of control messages exactly at receiving terminal by the communication frame head and the sub-message locating information of appropriate design.This kind method is compared with general method, and communication efficiency improves greatly.In the supervisory control system network, when the Content of Communication of a plurality of nodes when being main with short message, when perhaps the Network Transmission bandwidth became system bottleneck, this kind method improvement effect was very obvious.
In certain experimental system, we utilize a control desk that the equipment of a plurality of test usefulness is managed and monitors, control message between control desk and the controlled device has adopted method of the present invention to encapsulate, the result has improved communication efficiency greatly, and the configuration management speed of control desk and the response speed of control command are obviously improved.