Time KPI’s may depend on external parameters that are not available in the machine tool controls. For this reason, relevant statuses are presented rather than absolute time values. To determine the time KPI’s, the status duration must be measured. For complex time KPI’s, the value results from measuring the combined duration of multiple relevant statuses.
General: Determination with the use of status variables
This specification provides two StateMachines in the MachineOperationMonitoringType:
- MachineryItemState (MachineryItemState_StateMachineType) to represent the machine status in terms of production and technical availability (error status).
- MachineryOperationMode (MachineryOperationModeStateMachineType) to represent the operation mode (production, order-related setup, general maintenance).
Both the above data types are defined in OPC 40001-1 (from version 1.02 onwards). Both objects each contain a CurrentState variable that represents the current state.
General: Determination by means of Events
Production jobs are modelled as objects of the type ProductionJobType. The objects are stored as a list in the ProductionPlan variable of the type ProductionType.
The current status of the production job is represented in the State variable of the ProductionJobType. State is of the type ProductionJobStateMachineType and sends an event of the type ProductionJobTransitionEventType with every state change. When processing these events, the variable State can be used to determine the current state by evaluating the respective value ToState.
In case of an interruption, an event of the type InterruptionConditionType can be sent. The type of interruption can be classified using the variables ConditionClassId and ConditionClassName.