The HistoryRead Service defined in OPC 10000-4 can perform several different functions. The HistoryReadDetails parameter is an Extensible Parameter that specifies which function to perform and the details that are specific to that function. See OPC 10000-4 for the definition of Extensible Parameter. Table 19 lists the symbolic names of the valid Extensible Parameter structures. Some structures will perform different functions based on the setting of its associated parameters. For simplicity a functionality of each structure is listed. For example, text such as ‘using the Read modified functionality’ refers to the function the HistoryRead Service performs using the Extensible Parameter structure ReadRawModifiedDetails with the isReadModified Boolean parameter set to TRUE.
Table 19 – HistoryReadDetails parameterTypeIds
|
Symbolic Name |
Functionality |
Description |
|
ReadEventDetails |
Read event |
This structure selects a set of Events from the history database by specifying a filter and a time domain for one or more Objects or Views. See 6.4.2.1. When this parameter is specified the Server returns a HistoryEvent structure for each operation (see 6.5.4). |
|
ReadRawModifiedDetails |
Read raw |
This structure selects a set of values from the history database by specifying a time domain for one or more Variables. See 6.4.3.1. When this parameter is specified the Server returns a HistoryData structure for each operation (see 6.5.2). |
|
ReadRawModifiedDetails |
Read modified |
This parameter selects a set of modified values from the history database by specifying a time domain for one or more Variables. See 6.4.3.1. When this parameter is specified the Server returns a HistoryModifiedData structure for each operation (see 6.5.3). |
|
ReadProcessedDetails |
Read processed |
This structure selects a set of Aggregate values from the history database by specifying a time domain for one or more Variables. See 6.4.4.1. When this parameter is specified the Server returns a HistoryData structure for each operation (see 6.5.2) |
|
ReadAtTimeDetails |
Read at time |
This structure selects a set of raw or interpolated values from the history database by specifying a series of timestamps for one or more Variables. See 6.4.5.1. When this parameter is specified the Server returns a HistoryData structure for each operation (see Clause 6.5.2). |
|
ReadAnnotationDataDetails |
Read Annotation Data |
This structure selects a set of Annotation Data from the history database by specifying a series of timestamps for one or more Variables. See 6.4.6.1. When this parameter is specified the Server returns a HistoryAnnotationData structure for each operation (see Clause 6.5.5). |