This is a subtype of the UInt32 DataType with the OptionSetValues Property defined. It is used to indicate how the Value of a Variable can be accessed (read/write), if it contains current and/or historic data and its atomicity.
The AccessLevelExType DataType is an extended version of the AccessLevelType DataType and as such contains the 8 bits of the AccessLevelType as the first 8 bits.
The NonatomicRead, and NonatomicWrite Fields represent the atomicity of a Variable. In general Atomicity is expected of OPC UA read and write operations. These Fields are used by systems, in particular hard-realtime controllers, which can not ensure atomicity.
The AccessLevelExType is formally defined in Table 41.
Table 41 – AccessLevelExType Definition
|0:7||Formally defined by the AccessLevelType in Table 40.|
|NonatomicRead||8||Indicates non-atomicity for Read access (0 means that atomicity is assured).|
|NonatomicWrite||9||Indicates non-atomicity for Write access (0 means that atomicity is assured).|
|WriteFullArrayOnly||10||Indicates if Write of IndexRange is supported.
(0 means Write of IndexRange is supported)
|11:31||Reserved for future use. Shall always be zero.|