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5.3.8.Map Descriptor Example 5 - Class_Data_Serving_Ctrl
To configure the Server to serve changed data only, specify this parameter for the node of interest. If the parameter value = Classx and Classx data is requested by the remote client, the driver will use the subscriptions configured for the data objects that constitute the class to determine which data objects should be served and will only serve them if they have been changed and the change meets the subscription requirements.
If the parameter is not specified or the value is specified as static then all data objects are served, irrespective of whether they have changed or not.
In this example Class 0 has been configured to serve changed data only. The parameter ‘Class_Data_Serving_Ctrl’ has been allocated a value of ‘Class0’. All other classes will serve the complete set of data objects that define the class. When Class 0 data is requested the driver will do the following:
•Check each data object that forms the class to see whether it has been updated by the downstream protocol.
•If it has been updated since it was last served then its value is checked against the data objects subscription ‘COV_DeadBand’.
•If the value has changed by at least that much then the data object is served. If a subscription has not been defined for the point then it will not be served.
When the data is served the objects may be
// Server Side Nodes |
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Node_Name | ,Node_ID | ,Protocol | ,Class_Data_Serving_Ctrl | Port |
Node_DNP3 | ,1 | ,DNP | ,Class0 | ,R1 |
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The Class Map Descriptor is a dummy, used only to match an incoming request and find “Associated” Map Descriptor's which define the composite data set that must be served in the response
Map_Descriptors |
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Map_Descriptor_Name | ,Data_Array_Name | ,Data_Array_Offset | ,Function | ,Node_Name | ,Address | ,Length | ,dnpDataType | ,dnpDataVari | ,dnpAssociate |
Class_0 | ,Class_DA0 | ,0 | ,Server | ,Node_DNP3 | ,0 | ,1 | ,60 | ,1 | ,1 |
Class_0_Bin | ,Bin_Inputs | ,0 | ,Server | ,Node_DNP3 | ,0 | ,20 | ,2 | ,2 | ,1 |
Class_0_Ana | ,Ana_Inputs | ,0 | ,Server | ,Node_DNP3 | ,0 | ,7 | ,32 | ,4 | ,1 |
Class_1 | ,Class_DA1 | ,0 | ,Server | ,Node_DNP3 | ,0 | ,1 | ,60 | ,2 | ,2 |
Class_1_Bin | ,Bin_Inputs | ,0 | ,Server | ,Node_DNP3 | ,0 | ,20 | ,1 | ,1 | ,2 |
Class_1_Ana | ,Ana_Inputs | ,0 | ,Server | ,Node_DNP3 | ,0 | ,7 | ,30 | ,1 | ,2 |
Class_2 | ,Class_DA2 | ,0 | ,Server | ,Node_DNP3 | ,0 | ,1 | ,60 | ,3 | ,3 |
Class_2_Bin | ,Bin_Inputs | ,0 | ,Server | ,Node_DNP3 | ,0 | ,20 | ,1 | ,1 | ,3 |
Class_3 | ,Class_DA3 | ,0 | ,Server | ,Node_DNP3 | ,0 | ,1 | ,60 | ,4 | ,4 |
Class_3_Ana | ,Ana_Inputs | ,0 | ,Server | ,Node_DNP3 | ,0 | ,7 | ,30 | ,1 | ,4 |
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