AcknowledgeableConditions are sub-types of the base ConditionType. AcknowledgeableConditions expose states to indicate whether a Condition has to be acknowledged or confirmed.
An AckedState and a ConfirmedState extend the EnabledState defined by the Condition. The state model is illustrated in Figure 2. The enabled state is extended by adding the AckedState and (optionally) the ConfirmedState.
Figure 2 – AcknowledgeableConditions state model
Acknowledgment of the transition may come from the Client or may be due to some logic internal to the Server. For example, acknowledgment of a related Condition may result in this Condition becoming acknowledged, or the Condition may be set up to automatically Acknowledge itself when the acknowledgeable situation disappears.
Two Acknowledge state models are supported by this standard. Either of these state models can be extended to support more complex acknowledgement situations.
The basic Acknowledge state model is illustrated in Figure 3. This model defines an AckedState. The specific state changes that result in a change to the state depend on a Server’s implementation. For example, in typical Alarm models the change is limited to a transition to the Active state or transitions within the Active state. More complex models however can also allow for changes to the AckedState when the Condition transitions to an inactive state.
Figure 3 - Acknowledge State Model
A more complex state model which adds a confirmation to the basic Acknowledge is illustrated in Figure 4. The Confirmed Acknowledge model is typically used to differentiate between acknowledging the presence of a Condition and having done something to address the Condition. For example, an Operator receiving a motor high temperature Notification calls the Acknowledge Method to inform the Server that the high temperature has been observed. The Operator then takes some action such as lowering the load on the motor in order to reduce the temperature. The Operator then calls the Confirm Method to inform the Server that a corrective action has been taken.
Figure 4 - Confirm acknowledge State model
The AcknowledgeableConditions model can also be used for a simple Condition that requires a confirmation. For example, a motor start event might need to be acknowledged by an operator, this event is not an alarm, just an action that needs to be acknowledged by the operator. It could also be an event that is generated for an operator change of a process input (grade of paper being made) that needs to be acknowledged. It is not something that requires an anwser like a question, for this there are DialogCondition. It is just an acknowledge that the operator observed the change.