4. Develop and Test Models

The LIFTER_MVL system configuration implements the layered Model+View testing architecture for the pallet handling example.

The HMI device encapsulates the functionality of the HMI layer of the architecture - specifically the HMI elements needed to read sensor values and write actuator values - while the MODEL device encapsulates both the Model and the View layers.

As in the VIEW device of the LIFTER_VIEWL configuration, the MODEL device contains an instance of the specialized VIEW_PANEL resource type to provide the necessary layout of View elements for the pallet handling example. In addition, an instance of the PANEL_RESOURCE type contains the User Interface (UI) elements necessary for operation of the model, specifically:

• Two pushbuttons to load a pallet onto the feed conveyor and unload it from the takeoff conveyor, respectively
• A FAULT output to indicate the existence of a fatal condition (which stops the simulation clock), and a RESET button to recover from the fault condition

The MODEL device also contains five instances of the EMB_RES type, which in turn contain the Model elements for the corresponding Views, as well as logic to simulate the physics of the interactions among Model elements including their sensors and actuators; transfer of workpieces; and simulation of fatal and non-fatal fault conditions:

1. The CLK resource contains the simulation clock, whose events are distributed using the local multicast pattern.
2. The FEED_MDL resource contains an instance of the CNVG_MDLL type, corresponding to the feed conveyor in the VIEW panel, along with local multicast elements, logic and instances of the LOADLE type to handle pallet transfer to the lifter element as well as display of fault conditions.
3. The LIFTER_MDL resource contains an instance of the XBAR_MDLL type, corresponding to the lifter element in the VIEW panel, as well as elements to handle pallet transfer and display of fault conditions in a manner similar to the FEED_MDL resource.
4. The TAKEOFF_MDL resource contains an instance of the CNV_MDLL type, corresponding to the takeoff conveyor in the VIEW panel, as well as elements to handle pallet transfer and display of fault conditions in a manner similar to the FEED_MDL and TAKEOFF_MDL resources.
5. The XFER_MDL resource contains an instance of the LIFTER_XFER type to model the normal loading and unloading of pallets from the lifter as well as fatal and non-fatal fault conditions.

Inter- and intra-layer communication is implemented with the local multicast pattern, in particular for the distribution of the simulation clock and the simulation of workpiece transfer with instances of the LOADLE type.