8 Standard DataTypes ToC Previous Next

8.58 AccessLevelExType ToC Previous Next index

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

Name Bit Description
  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.

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