Page 56 - ExtendSim User Guide
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Building a Model
Working with block dialogs
Working with block dialogs
Now that all the blocks have been placed and connected in the model, you can enter data and select options in block dialogs. The data for this model comes from a table of values and from a random sample. The sections below will describe the settings used in each block’s dialog.
Rainfall source
The amount of rainfall entering the reservoir is determined by a Lookup Table block that con- tains each month’s expected rainfall. In a real-life situation, for example, these numbers may have been determined by annual recorded averages.
Double-click the Lookup Table block to open its dialog.
By default, the Lookup Table block is set to Lookup the: input value. In that mode, the block outputs a value that corresponds to the value it receives at its input. However, you want the Lookup Table block to output a value--the amount of rainfall for the month--that corresponds to the current simulation time.
Customize the dialog’s Table tab by setting the behavior of the block to look up simulation time each month:
Lookup the: time
Output is: stepped (Default) Time units: months (Model Default)
Time means the block will compare current simulation time to a time in the table and output the corresponding value. Stepped means that ExtendSim will use the exact values you enter in the table, not an interpolated amount.
Increase the number of rows so the table has room for twelve months of data:
Click the +/- resize button - the green square at the bottom right of the table.
Enter 12 for the number of rows and 2 (the default) for the number of columns.
Click OK
Enter data into the table as shown in the screenshot
at right.
☞ If you click Enter after each value, the cursor will auto- matically move to the next cell.
Check the Repeat table every checkbox and enter 12 in the months box.
Table settings for Lookup Table
This causes the determination of monthly rainfall to start over every 12 months.

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