Page 826 - ExtendSim User Guide
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800 Miscellaneous
Sharing model files
• The most common method is to use the connector that corresponds to the dialog parameter field. Connect this to a block that calculates the desired value, such as a Random Number or Lookup Table block (Value library). This approach visually shows the connection between the parameter value and where the value comes from. In general, this is also computationally efficient since only the blocks connected to the parameter are recalculated.
• AsecondapproachistolinktheparameterfieldwitharecordinanExtendSimdatabase.To do this, right-click the parameter and select create/edit dynamic link. (You can also create this link programmatically by creating a custom block that links the parameters of other blocks with an ExtendSim database or global array.) Whenever the linked value in the data- base changes, the parameter will change as well. This method hides the relationship between the parameter and where it is calculated, however it is very useful for centralizing the loca- tion of certain parameters in the database or for broadcasting the same value at the same time to a number of blocks throughout the model.
• Inadiscreteeventmodel,someblocks(suchastheActivityorEquation(I)block)allowyou to specify a property value for a parameter. Using an item’s property is an easy way to make the parameter value a function of the item in the block.
• Sensitivity analysis allows you to change a parameter from one simulation run to the next. Sensitized parameters change values at the start of each new run. They can change randomly, based on a value in a file, or by a fixed increment. Changing parameters is useful for sensi- tivity analysis and Monte Carlo simulation. To utilize sensitized parameters, the number of simulation runs must be greater than one. For a complete discussion, see “Sensitivity analy- sis” on page 646.
• Some blocks allow you to specify that a parameter is random. While this is not directly changing the parameter dynamically, this feature allows you to simulate a parameter that changes randomly each time the block is recalculated.
• Thereareothermethods,suchascallingtheSetDialogVariablefunctioninanequationblock or custom block, but these are generally just used for specific situations.
Sharing model files
You may want to provide access to models you have built, without giving users the ability to change the models. ExtendSim provides two methods for preventing changes being made to models:
• Lockingamodeltopreventanythingotherthanparameterchangeswhenthemodelisrunin the full version of ExtendSim.
• Using the LT-RunTime version of ExtendSim to open and run models.
Locking the model
Locking a model is especially useful when giving the model to others who may accidentally move or delete blocks or anytime you want to prevent changes to a model’s layout. The Model > Lock Model command prevents any modification of a model other than changing dia- log values. Since this command hides many of the tools in the toolbar, the user also cannot add or change connection lines, drawing elements, and so forth.
This command does allow the user to save the model and any dialog value changes. If they give the command File > Save Model As, the new model will also be locked.
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