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DAIS uses the DAF SimpleValue type for data transferred over the API instead of the OPC type VARIANT. The data types used
in OPC are Microsoft COM types and as DAIS is a CORBA API a mapping of the data types is needed. The translation of OPC/COM
data types to DAF/CORBA data types is listed below.
Table 2-2 Mappings between OPC and DAF data types
| OPC/COM basic types | DAF Simple Value types | ||||
| - | ResourceID (RESOURCE_TYPE) | ||||
| - | URI (URI_TYPE) | ||||
| LPWSTR (VT_BSTR) | string (STRING_TYPE) | ||||
| BOOL (VT_BOOL) | boolean (BOOLEAN_TYPE) | ||||
| LONG (VT_R4) | long (INT_TYPE) | ||||
| DWORD (VT_I4) | unsigned long (UNSIGNED_TYPE) | ||||
| double (VT_R8) | double (DOUBLE_TYPE) | ||||
| - | Complex (COMPLEX_TYPE) | ||||
| FILETIME (VT_Date) | DateTime (DATE_TIME_TYPE) | ||||
| - | ULongLong (ULONG_LONG_TYPE) | ||||
| WORD (VT_I2) | unsigned long (UNSIGNED_TYPE) | ||||
| FLOAT (VT_R4) | double (DOUBLE_TYPE) | ||||
| BYTE (VT_UI1) | - | ||||
| HRESULT (VT_ERROR) | - | ||||
| VARIANT (VARTYPE) | SimpleValue (SimpleValueType) |