6.2.1 Machine engine

The machine engine is the device able to create or deliver or collect a given product. It interacts with the UI, the payment service, and the audit collect. It interacts with the customer by physically providing the product to the customer. It provides information to monitor the Vending Machine. A Vending Machine according to this specification needs to support at least one machine engine, but may have several machine engines as components. A machine engine cannot be assigned to more than one Vending Machine, i.e., it can only be used by one payment service.

The machine engine provides its interface by implementing an instance of the MachineEngineType (shown in Figure 10, defined in 7.1). The machine engine does not require OPC UA Client functionality to access other components of the Vending Machine.

The MachineEngineType provides the identification of the machine engine in the Identification Object, defined in OPC 10000-100. The configuration of the machine engine is provided by the Configuration Object of BaseConfigurationType defined in 7.3. The configuration may be writable via the OPC UA interface to change the configuration of the machine engine. The machine engine provides the configuration for the UI in the Capabilities Object of MachineEngineCapabilitiesType defined in 7.5. The configuration is accessed by the UI and parts may be writable to change the configuration of the UI. The Delivery Object of MachineEngineDeliveryType defined in 7.6 provides functionality to request a delivery (by the payment service) as well as expose the status of the delivery (displayed by the UI). The Status Object of MachineEngineStatusType defined in 7.7 provides the overall status of the machine engine, to be displayed in the UI and consumed by the payment service. The optional Components Object of BaseComponentsType defined in 7.4 can provide information about subcomponents of the machine engine. The machine engine generates Events of VendingBaseAuditEventType to provide audit data.