10 Lifetime model

10.1 General

The lifetime model provides information about the lifetime, related limits and semantic of the lifetime of things like tools, material or machines.

Table 143 illustrates the model with two examples, showing the information that can be provided with the model defined in this clause. The Value of the LifetimeVariable provides the current value. The EngineeringUnits Property and the relation of the Indication to a classification ObjectType provide the semantic. The StartValue and LimitValue Properties indicate the range of the Value.

For the CertificateValidity example, the instance of the LifetimeVariableType defines the remaining validity of a certificate with a unit of days and a classification of TimeIndication. The Value specifies 200 days – the remaining validity of a certificate. The initial value is 365 days with a warning level of 10 days. The certificate is invalid when the Value is zero.

For the PartsProduced example, the instance of the LifetimeVariableType defines the produced parts in the lifetime with a classification of NumberOfPartsIndication. The Value specifies 553 parts. The starting value is 0 parts and it is possible to produce up to 1000 parts with a warning indication if the number reaches 950.

10.2 LifetimeVariableType definition

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 144.

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 define additional subtypes of BaseLifetimeIndicationType.

The optional WarningValues defines one or more limits when the end of lifetime is reached soon and can be used to inform the user. Servers can 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 just indicates 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 represents 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 represents 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 145.

10.3 BaseLifetimeIndicationType definition

The BaseLifetimeIndicationType ObjectType defines the base indication of a Variable of LifetimeVariableType, without defining any specific semantic. Servers should use a more specific subtype, if possible. It is formally defined in Table 146.

10.4 TimeIndicationType definition

The TimeIndicationType ObjectType indicates the time the entity has been in use or can still be used. It is formally defined in Table 147.

10.5 NumberOfPartsIndicationType definition

The NumberOfPartsIndicationType ObjectType indicates total number of parts that have been produced or can still be produced. It is formally defined in Table 148.

10.6 NumberOfUsagesIndicationType definition

The NumberOfUsagesIndicationType ObjectType indicates counting the process steps the entity has been used or can still be used for (for example usages of a punching tool). It is formally defined in Table 149.

10.7 LengthIndicationType definition

The LengthIndicationType ObjectType indicates the abraded length, for example of a drill. It is formally defined in Table 150.

10.8 DiameterIndicationType definition

The DiameterIndicationType ObjectType indicates the abraded diameter, for example of a drill. It is formally defined in Table 151.

10.9 SubstanceVolumeIndicationType definition

The SubstanceVolumeIndicationType ObjectType indicates the volume of a substance, for example of a liquid. It is formally defined in Table 152.