Page 631 - ExtendSim User Guide
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Model Execution 605
Time units
Global time units are set by going to the Run > Simulation
Setup > Setup tab and selecting and defining the unit of
time. Once you select a global time unit, all blocks with
time-based parameters, including those subsequently added to the model, use it by default as their local time unit.
Using the generic global time unit
By default, the non-specified “Generic” time is a new model’s global time unit. Generic is a conceptual unit of time and has whatever meaning you give it. Generic time is the same for the whole model and for each block that has time-based parameters.
This option is used by most modelers to quickly create a model without having to select a spe- cific time unit. It is also commonly used when the model’s blocks use the same time units as the model.
Global time unit
The global time unit is the base unit for the entire model, defining the units for the start and end times of the simula- tion.
There are two ways to specify a global time unit:
• Use the Generic time unit to be the default for the whole model.
• Select a specific global time unit, such as hours or sec- onds, to be the default for the whole model.
With the Generic global time unit, time-based blocks do not have a local time unit. Instead, all blocks that include a time- based parameter will specify generic “time units.”
Block’s time-based parameter when Generic selected as global time unit
Global time units popup with Seconds selected
You must be sure to maintain all time-based parameters
throughout the model in that same unit of conceptual time.
For example, if you have a model that simulates a factory over the course of three hours and your conceptual time unit is minutes, set the end time of the simulation to be 180 in the Simu- lation Setup dialog and enter parameters based on minutes in block dialogs. The Comments tab in the Simulation Setup dialog is a convenient place for noting what unit of time Generic rep- resents in your model.
☞ Models cannot use Calendar dates or specify a local time unit if the global time unit is set to Generic.
Using a specific global time unit
In the Run > Simulation Setup > Setup tab you can change the default global time unit to be something specific, such as hours or seconds. Using a specific global time unit can add to the understanding of the model, since it allows you to specify parameters based on different time units throughout the model.
When a specific global time unit is selected, that setting becomes the default global time unit for the model as well as the default local time unit within time-based blocks. There will be an asterisk (*) next to the name of the time unit in the dialog of each block.
Asterisk indicates time unit in block is the same as global time unit
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