The DataChangeTrigger is an enumeration that specifies the conditions under which a data change notification should be reported. The possible values are described in Table 134.
Table 134 – DataChangeTrigger values
|
Name |
Value |
Description |
|
STATUS |
0 |
Report a notification ONLY if the StatusCode associated with the value changes. See Table 183 for StatusCodes defined in this document. OPC 10000-8 specifies additional StatusCodes that are valid in particular for device data. |
|
STATUS_VALUE |
1 |
Report a notification if either the StatusCode or the value change. The Deadband filter can be used in addition for filtering value changes. For floating point values a Server shall check for NaN and only report a single notification with NaN when the value enters the NaN state. When testing for changes, a Server shall treat null and empty arrays of the same DataType as equal. This also applies to Strings and ByteStrings. This is the default setting if no filter is set. |
|
STATUS_VALUE_TIMESTAMP |
2 |
Report a notification if either StatusCode, value or the SourceTimestamp change. If a Deadband filter is specified, this trigger has the same behaviour as STATUS_VALUE. |