Read modified data from an OPC HDA server
DObj = readModified(HdaClient,
ItmList, StartTime, EndTime)
DObj = readModified(HdaClient, ItmList, StartTime, EndTime) reads modified data from the items defined by ItmList, stored on the OPC HDA server connected to OPC HDA Client HdaClient, between StartTime (inclusive) and EndTime (exclusive). The StartTime and EndTime arguments must be date numbers, or strings that can be converted to a MATLAB date number. DObj is returned as an opc.hda.Data array, with one element per item specified in ItmList.
DObj contains only data items that have been modified, replaced or deleted on the OPC HDA server. That is, only data values that return a quality of 'Extra Data' during a readRaw operation. If a value has been modified multiple times, all values for that time are returned.
Some servers do not support this function.