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FS-8700-47 DNP 3.0 Driver Manual Page 24 of 51
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5.3.9. Map Descriptor Example 5 – Serving Objects which have a time field
Some Data Objects have a time field associated with them, e.g. Frozen Analog Input with Time of Freeze (Object = 31, Variation 3). When this
object is served the Server must provide the value of the frozen input as well as the time of the freeze. The driver extracts the object’s value from
the Primary Data Array. The object’s time is extracted from a secondary Data Array. If a secondary Data Array is not specified, the driver serves
the current FieldServer time in UTC (Universal Coordinated Time). If a secondary Data Array is specified, the driver extracts the value and
multiplies it by 1000 before serving it. Thus the Secondary Data Array is assumed to contain the number of seconds since Jan 1 1970 and not the
number of milliseconds.
// Server Side Map Descriptors
Map_Descriptors
Map_Descriptor_Name ,Data_Array_Name ,Data_Array_Offset ,Function ,Node_Name ,Address ,Length ,dnpDataType ,dnpDataVari ,DA_Byte_Name
Serve_FrozenAI_vari3 ,DA_AI ,0 ,Server ,Node_A ,0 ,100 ,31 ,
3
,DA_AI_TIMES
5.3.10. Map Descriptor Example 6 – Unsolicited Messages
A driver configured as an active Server can send unsolicited messages (not responses to a poll) to a remote Client when data changes.
In this example, 100 elements of the Data Array called DA_AI are monitored. If the data in any one of these elements is updated (even if the value
doesn’t change) then the driver generates a once off write message to the remote node called Node_A.
Subscriptions
Data_Array_Name ,Data_Array_Offset ,Node_Name ,COV_Deadband
DA_Class0_bin ,1 ,Node_A ,1
DA_Class0_bin ,3 ,Node_A ,1
DA_Class0_ana ,0 ,Node_A ,2.0
// Client Side Map Descriptors
Map_Descriptors
Map_Descriptor_Name ,Data_Array_Name ,Data_Array_Offset ,Function ,Node_Name ,Address ,Length ,dnpDataType ,dnpDataVari ,DnpFunction
EventMsg1 ,DA_AI ,0 ,Wrbx ,Node_A ,0 ,100 ,30 ,
0
,130
This is how you specify the Data Array that will contain the time (in seconds). The driver uses the value found at the offset specified by
Data_Array_Offset. You should use a Data Array whose format is UINT32 as only that format provides sufficient precision to store the big
numbers required to specify the number of seconds since Jan 1, 1970.
Example: 1095135207 == Aprox Sept 14th 2004
The function 30 tells the driver to send the message as
an unsolicited message.