Synchronous ReadModified.
This method reads the values, qualities, timestamps, user ID, and timestamp of the modification from the history database for the specified time domain for one or more items. The purpose of This method is to read values from history that have been modified/replaced. If ReadRaw, ReadProcessed, or ReadAtTime has returned a quality of OPCHDA_EXTRADATA, indicating that there are values which have been superseded, This method reads those values which were superseded. Only values that have been modified/replaced or deleted are read by this method.

The domain of the request is defined by startTime, endTime, and numValues; at least two of these must be specified. If endTime is less than startTime, or endTime and numValues alone are specified, the data shall be returned in reverse order, with later data coming first. If all three are specified, the call shall return up to numValues results going from startTime to endTime, in either ascending or descending order depending on the relative values of startTime and endTime. If more than numValues results exist within that time range, the errors entry for that ItemID shall be OPC_S_MOREDATA. If numValues is 0, then all the values in the range are returned. If a value has been modified multiple times, all values for the time are returned. This means that a timestamp can appear in the array more than once. The order of the returned values with the same timestamp should be from most recent to oldest modified value. It is server dependent whether multiple modifications are kept or only the most recent.

'Usage
 
Dim instance As AppPlugin
Dim startTime As Date
Dim endTime As Date
Dim numValues As Integer
Dim serverHandles() As Integer
Dim itemValues As OPCHDAModifiedItem()
Dim errors As Integer()
Dim value As Integer
 
value = instance.ReadModified(startTime, endTime, numValues, serverHandles, itemValues, errors)

public int ReadModified( 
   DateTime startTime,
   DateTime endTime,
   int numValues,
   int[] serverHandles,
   out OPCHDAModifiedItem[] itemValues,
   out int[] errors
)