Asynchronous ReadProcessed.
This method computes aggregate values, qualities, and timestamps from data in the history database for the specified time domain for one or more items. The time domain is divided into subintervals of duration resampleInterval. The specified aggregate is calculated for each subinterval beginning with startTime by using the data within the next resampleInterval. This method is intended to provide values calculated with respect to the resample interval. For example, This method can provide hourly statistics such as Maximum, Minimum, Average, et. al. for each item during the specified time domain when resampleInterval is 1 hour.
The results are returned via the client's IOPCHDA_DataCallback::OnReadComplete method.
'Usage
Dim instance As AppPlugin
Dim transactionID As Integer
Dim startTime As Date
Dim endTime As Date
Dim interval As TimeSpan
Dim serverHandles() As Integer
Dim aggregates() As Integer
Dim cancelID As Integer
Dim errors As Integer()
Dim value As Integer
value = instance.ReadProcessed(transactionID, startTime, endTime, interval, serverHandles, aggregates, cancelID, errors)
public int ReadProcessed(
int ,
DateTime ,
DateTime ,
TimeSpan ,
int[] serverHandles,
int[] ,
out int ,
out int[]
)
Parameters
- transactionID
- An identifier created by the client and passed to the server in this call. The server shall return this identifier along with the results of this call.
- startTime
- The beginning of the history period to be read.
- endTime
- The end of the history period to be read.
- interval
- Interval between returned values.
- serverHandles
- The list item handles for the items to be read from the server.
- aggregates
- The list of aggregate values to be returned.
- cancelID
- Place to return a Server generated ID to be used in case the operation needs to be canceled.
- errors
- Array of HRESULTs indicating whether the corresponding server handle was valid.
Return Value
HRESULTS success/error code.
Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2