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5.5 Condition Model ToC Previous Next

5.5.3 Condition and branch instances ToC Previous Next

Conditions are Objects which have a state which changes over time. Each Condition instance has the ConditionId as identifier which uniquely identifies it within the Server.

A Condition instance may be an Object that appears in the Server Address Space. If this is the case the ConditionId is the NodeId for the Object.

The state of a Condition instance at any given time is the set values for the Variables that belong to the Condition instance. If one or more Variable values change the Server generates an Event with a unique EventId.

If a Client calls Refresh the Server will report the current state of a Condition instance by re-sending the last Event (i.e. the same EventId and Time is sent).

A ConditionBranch is a copy of the Condition instance state that can change independently of the current Condition instance state. Each Branch has an identifier called a BranchId which is unique among all active Branches for a Condition instance. Branches are typically not visible in the Address Space and this standard does not define a standard way to make them visible.

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