OPC UA defines a value rank that differs from the common understanding of array rank. Scalars have OPC UA value rank of -1 (not 0), and there are other special value ranks defined.
Value rank specifies if the Value Attribute of an OPC-UA Variable is an array, and if so, the number of dimensions it has. This class provides constants representing different value ranks as defined by OPC-UA, facilitating the interpretation and handling of variable value ranks within OPC-UA applications.
The OPC UA value rank values are summarized in the following table. The "Array ranks" column contains the corresponding value or values of the array rank in its traditional meaning.
| OPC UA value rank | Symbolic name | Description | Array rank |
|---|---|---|---|
| -3 | ScalarOrOneDimension | The variable may be a scalar or a one dimensional array. | 0 or 1 |
| -2 | Any | The variable may be a scalar or an array of any dimension. | 0, 1, 2, ... |
| -1 | Scalar | The variable is always a scalar. | 0 |
| 0 | OneOrMoreDimensions | The variable is always an array with one or more dimensions. | 1, 2, 3, ... |
| 1 | OneDimension | The variable is always one dimensional array. | 1 |
| 2 | TwoDimensions | The variable is always an array with two dimensions. | 2 |
| 3, 4, 5, ... | The variable is always an array with the specified number of dimensions. | 3, 4, 5, ... |
OPC UA value ranks 3 and higher do not have symbolic names in this class, but they are still valid.
System.Object
OpcLabs.EasyOpc.UA.UAValueRanks