History Data Groups

The History data groups are used to read historical data from a field device. A device can have several types of historical data, such as hourly, daily, weekly, and monthly. The DNP3 Emerson History data groups can poll for station, general, and user data. The record end time is used as the timestamp when processing historical point values.

See DNP3 Emerson Data Groups for more information.

Get latest data: There are three different parameters associated with a Get latest data request, each of which may be combined with the others for different effects:

• Max records to read: Specifies the maximum number of historical records to retrieve.
• Start date: Specifies the oldest date limit. If there is no cached "last record," reading will begin at the indicated start date. If the "last record" has been cached, the start time will be used only if it is later than the cached record time.
• End date: Specifies the most recent date limit.

Get data by index: There are two parameters associated with this selection:

• Starting record index: The number of the record index to start polling from.
• Max records to read: Specifies the maximum number of historical records to retrieve.

Get data by date range: There are two parameters associated with this selection:

• Start date: Specifies the oldest date limit.
• End date: Specifies the most recent date limit.

Example

Click here to see an example of a History data group   <HistGenD niceName="Hist - General Daily" baseOrd="1" maxCnt="1"> <dgElements secLev="4" type="vrnt"/> <uccRecvParms required="false"> <Cnt desc="Max records to read" type="ui4"/> <GetLatest desc="Get latest?" type="boolean"/> <Seq desc="Sequence #" type="ui4"/> <SDate desc="Start date" type="string"/> <EDate desc="End date" type="string"/> </uccRecvParms> </HistGenD>