All OPC UA DataEncodings are based on rules that are defined for a standard set of built-in types. These built-in types are then used to construct structures, arrays and Messages. The built-in types are described in Table 1.
|
ID |
Name |
Nullable |
Default |
Description |
|
1 |
Boolean |
No |
false |
A two-state logical value (true or false). |
|
2 |
SByte |
No |
0 |
An integer value between −128 and 127 inclusive. |
|
3 |
Byte |
No |
0 |
An integer value between 0 and 255 inclusive. |
|
4 |
Int16 |
No |
0 |
An integer value between −32 768 and 32 767 inclusive. |
|
5 |
UInt16 |
No |
0 |
An integer value between 0 and 65 535 inclusive. |
|
6 |
Int32 |
No |
0 |
An integer value between −2 147 483 648 and 2 147 483 647 inclusive. |
|
7 |
UInt32 |
No |
0 |
An integer value between 0 and 4 294 967 295 inclusive. |
|
8 |
Int64 |
No |
0 |
An integer value between −9 223 372 036 854 775 808 and 9 223 372 036 854 775 807 inclusive. |
|
9 |
UInt64 |
No |
0 |
An integer value between 0 and 18 446 744 073 709 551 615 inclusive. |
|
10 |
Float |
No |
0 |
An IEEE single precision (32 bit) floating point value. |
|
11 |
Double |
No |
0 |
An IEEE double precision (64 bit) floating point value. |
|
12 |
String |
Yes |
null |
A sequence of Unicode characters. |
|
13 |
DateTime |
Yes |
DateTime.MinValue (see 5.1.4) |
An instance in time. |
|
14 |
Guid |
Yes |
All zeros |
A 16-byte value that can be used as a globally unique identifier. |
|
15 |
ByteString |
Yes |
null |
A sequence of octets. |
|
16 |
XmlElement |
Yes |
null |
A sequence of Unicode characters that is an XML element. |
|
17 |
NodeId |
Yes |
All fields set to default. |
An identifier for a node in the address space of an OPC UA Server. |
|
18 |
ExpandedNodeId |
Yes |
All fields set to default. |
A NodeId that allows the namespace URI to be specified instead of an index. |
|
19 |
StatusCode |
No |
Good |
A numeric identifier for an error or condition that is associated with a value or an operation. |
|
20 |
QualifiedName |
Yes |
All fields set to default. |
A name qualified by a namespace. |
|
21 |
LocalizedText |
Yes |
All fields set to default. |
Human readable text with an optional locale identifier. |
|
22 |
ExtensionObject |
Yes |
All fields set to default. |
A structure that contains an application specific data type that may not be recognized by the receiver. |
|
23 |
DataValue |
Yes |
All fields set to default. |
A data value with an associated status code and timestamps. |
|
24 |
Variant |
Yes |
Null |
A union of all of the types specified above. |
|
25 |
DiagnosticInfo |
Yes |
No fields specified. |
A structure that contains detailed error and diagnostic information associated with a StatusCode. |
Most of these data types are the same as the abstract types defined in OPC 10000-3 and OPC 10000-4. However, the ExtensionObject and Variant types are defined in this document. In addition, this document defines a representation for the Guid type defined in OPC 10000-3.
The Nullable column indicates whether a ‘null’ value exists for the DataType in all DataEncodings. A ‘null’ value is a value that is equavalent ‘no value specified’. A nullable type with a default value means the default value shall be interpreted equivalent to a null.
The Default column specifies the default value for the type if a default value is needed. The default value for all arrays is ‘null’.