The DiscrepancyAlarmTypeis commonly used to report an action that did not occur within an expected time range.

The DiscrepancyAlarmTypeis based on the AlarmConditionType. It is formally defined in Table 78.

Table 78– DiscrepancyAlarmType definition

Attribute

Value

BrowseName

DiscrepancyAlarmType

IsAbstract

False

References

Node Class

BrowseName

DataType

TypeDefinition

ModellingRule

Subtype of the AlarmConditionTypedefined in 5.8.2.

HasProperty

Variable

TargetValueNode

NodeId

PropertyType

Mandatory

HasProperty

Variable

ExpectedTime

Duration

PropertyType

Mandatory

HasProperty

Variable

Tolerance

Double

PropertyType

Optional

The TargetValueNode Propertyprovides the NodeIdof the Variablethat is used for the target value.

The ExpectedTime Propertyprovides the Durationwithin which the value pointed to by the InputNode shall equal the value specified by the TargetValueNode(or be within the Tolerancerange, if specified).

The Tolerance Propertyis a value that can be added to or subtracted from the TargetValueNode’svalue, providing a range that the value can be in without generating the Alarm.

A DiscrepancyAlarmType can be used to indicate a motor has not responded to a start request within a given time, or that a process value has not reached a given value after a setpoint change within a given time interval.

The DiscrepancyAlarmTypeshall return to normal when the value has reached the target value.