Server maintains current state only – OPC Unified Architecture

B.1.2 Server maintains current state only

This example is for Servers that do not support previous states and therefore do not create and maintain Branches of a single Condition.

Figure B.1 shows an Alarm as it becomes active and then inactive and also the acknowledgement and confirmation cycles. Table B.1 lists the values of the state Variables. All Events are coming from the same Condition instance and therefore have the same ConditionId.

Table B.1 – Example of a Condition that only keeps the latest state

EventId	BranchId	Active	Acked	Confirmed	Retain	Description
-*)	NULL	False	True	True	False	Initial state of Condition.
1	NULL	True	False	True	True	Alarm goes active.
2	NULL	True	True	False	True	Condition acknowledged Confirm required
3	NULL	False	True	False	True	Alarm goes inactive.
4	NULL	False	True	True	False	Condition confirmed
5	NULL	True	False	True	True	Alarm goes active.
6	NULL	False	False	True	True	Alarm goes inactive.
7	NULL	False	True	False	True	Condition acknowledged, Confirm required.
8	NULL	False	True	True	False	Condition confirmed.
) The first row is included to illustrate the initial state of the Condition. This state will not be reported by an Event*.