The LifetimeVariableType defines Variables representing the remaining lifetime. It provides generically the remaining lifetime and can be used on anything; for example, on machines, actuators or sensors, but also on immaterial things like software. It is formally defined in Table 107.

Table 107 – LifetimeVariableType definition

Attribute	Value
BrowseName	LifetimeVariableType
IsAbstract	False
ValueRank	−1 (−1 = Scalar)
DataType	Number
Description	Remaining lifetime
References	Node Class	BrowseName	DataType	TypeDefinition	Other
Subtype of the 0:AnalogUnitType
0:HasProperty	Variable	StartValue	0:Number	0:PropertyType	M
0:HasProperty	Variable	LimitValue	0:Number	0:PropertyType	M
0:HasProperty	Variable	Indication	0:NodeId	0:PropertyType	O
0:HasProperty	Variable	WarningValues	0:Number{ScalarOrOneDimension}	0:PropertyType	O
Conformance Units
DI LT Lifetime Base

The mandatory StartValue indicates the initial value, when there is still the full lifetime left. The engineering unit is the same as for the Value of the Variable, provided by the LifetimeVariableType's mandatory 0:EngineeringUnits, derived from the 0:AnalogUnitType. The DataType shall be the same as for the Value of the Variable.

The mandatory LimitValue indicates when the end of lifetime has been reached. The engineering unit is the same as for the Value of the Variable, provided by the LifetimeVariableType's mandatory 0:EngineeringUnits, derived from the 0:AnalogUnitType. The DataType shall be the same as for the Value of the Variable.

If the StartValue is larger than the LimitValue, the Value of the Variable is expected to move over the time downwards to the LimitValue, otherwise upwards to the LimitValue.

The optional Indication gives an indication of what is actually measured / represented by the Value of the Variable and the StartValue and LimitValue. The mandatory 0:EngineeringUnits, derived from the 0:AnalogUnitType already does this, to a certain degree. But for example, a length unit does not indicate what length is provided, like the cutting distance, the feed distance or the abraded length of a tool. The Indication contains a NodeId of the BaseLifetimeIndicationType or a subtype of it, providing a more detailed indication.

Note: It is expected that companion specifications or vendors may define additional subtypes of BaseLifetimeIndicationType.

The optional WarningValues defines one or more limits when the end of lifetime is reached soon and may be used to inform the user. Servers may also generate Events when such a limit is reached. If provided, the WarningValues shall be between the StartValue and the LimitValue. If it contains more than one entry, the first array entry defines a warning level with lowest severity. The following entries increase the severity so that the highest entry defines the most serious level.

The engineering unit is the same as for the Value of the Variable, provided by the LifetimeVariableType's mandatory 0:EngineeringUnits, derived from the 0:AnalogUnitType. The DataType shall be the same as for the Value of the Variable.

This VariableType can be used in various cases. Examples include

• The Variable may just indicate the remaining lifetime as a percentage value. In that case, the 0:EngineeringUnits is percentage, the StartValue is 100 and the LimitValue is 0 (or vice versa if counted upwards).
• The Variable may represent the number of parts produced. In this case, the 0:EngineeringUnits is One, the StartValue is 0 and the LimitValue the maximum producible parts (e.g. 100 000); or vice versa if the number of remaining parts that still can be produced is provided.
• The Variable may represent the remaining time, for example until a software license becomes invalid. The 0:EngineeringUnits could be “Day”, “Month”, “Year”, etc., the StartValue 0 and the LimitValue the overall duration, or vice versa if the remaining time is provided.

The child Nodes of the LifetimeVariableType have additional Attribute values defined in Table 108.

Table 108 – LifetimeVariableType Attribute values for child Nodes

BrowsePath	Description Attribute
StartValue	StartValue indicates the initial value, when there is still the full lifetime left.
LimitValue	LimitValue indicates when the end of lifetime has been reached.
Indication	Indication gives an indication of what is actually measured / represented by the Value of the Variable and the StartValue and LimitValue.
WarningValues	WarningValues indicates one or more levels when the end of lifetime is reached soon and may be used to inform the user when reached.