12.2.7.2.2 Datatype mapping
The datatype mapping for parameter data is described in Table 70.
| OPC | FDT | |
|---|---|---|
| Data type | Data type | Description |
| Float | Float | |
| Double | Double | |
| Byte | Byte | |
| Int32 | Int | |
| Int64 | Long | |
| UInt32 | UInt | |
| UInt64 | ULong | |
| DateTime | DateTime | |
| DateTime | Date | Date is represented as date at 0:00 a clock. |
| Duration | Time | Time is expressed as duration since midnight. |
| Duration | TimeSpan | Duration is expressed in milliseconds, TimeSpan is expressed in terms of days, hours, minutes. For the conversion of large TimeSpan a loss of precision may occur. |
| String | String | |
| Array of Byte | BinaryByteArray | |
| Array of Bit | BinaryBitArray | |
| Enumeration | Enumerator | |
| Boolean | Boolean | |
| SByte | SByte | |
In OPC UA array datatypes are represented by a combination of the properties datatype, value-rank and array-dimensions (see OPC OPC UA 10000-5, section 5.6.2).
In FDT array datatypes are represented with a dedicated ArrayDatatypeInfo datatype. This datatype has a member ArrayDatatypeInfo.ArrayDimensions, which specifies the length of each dimension of the array.
The mapping for array data types is defined as follows.
OPC datatype value is mapped according to Table 70.
OPC value rank is:
-1 for a simple datatype, or
Number of fields in FDT ArrayDatatypeInfo.ArrayDimensions (always > 0)
OPC array-dimensions property is:
NULL for a simple datatype, or
has the same value as ArrayDatatypeInfo.ArrayDimensions.
value of 0 means that the array has a variable length,
values > 0 indicate a defined length.