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8.57 AccessLevelType ToC Previous Next index

This is a subtype of the Byte DataType with the OptionSetValues Property defined. It is used to indicate how the Value of a Variable can be accessed (read/write) and if it contains current and/or historic data. The AccessLevelType is formally defined in Table 40.

Table 40 – AccessLevelType Definition

Name Bit Description
CurrentRead 0 Indicates if the current value is readable. It also indicates if the current value of the Variable is available. (0 means not readable, 1 means readable).
CurrentWrite 1 Indicates if the current value is writable. It also indicates if the current value of the Variable is available (0 means not writable, 1 means writable).
HistoryRead 2 Indicates if the history of the value is readable. It also indicates if the history of the Variable is available via the OPC UA Server. (0 means not readable, 1 means readable).
HistoryWrite 3 Indicates if the history of the value is writable It also indicates if the history of the Variable is available via the OPC UA Server.
(0 means not writable, 1 means writable).
SemanticChange 4 This flag is set for Properties that define semantic aspects of the parent Node of the Property and where the Property Value, and thus the semantic, may change during operation.
(0 means is not a semantic, 1 means is a semantic).
StatusWrite 5 Indicates if the current StatusCode of the value is writable
(0 means only StatusCode Good is writable, 1 means any StatusCode is writable).
TimestampWrite 6 Indicates if the current SourceTimestamp is writable
(0 means only null timestamps are writable, 1 means any timestamp value is writeable).
Reserved 7 Reserved for future use. Shall always be zero.

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