Page 31 - Continuous Process Modeling Quick Start Guide
P. 31

Tutorial 27
Enter dialog parameters and settings
Lookup Table block that represents rainfall
The assumptions state that there is a table of data for the expected rainfall for each month. In a real-life situation, for example, these numbers may have been deter- mined by annual recorded averages.
To open the dialog of the Lookup Table block, double-click its icon or right-click on the icon and choose Open Dialog.
By default, the 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.
Enter settings in the Table tab
Customize the dialog’s Table tab by setting the behavior of the block to look up simulation time each month:
Lookup the: time. This setting means the block will compare current simulation time to a time in the table and output the corresponding value.
Output is: stepped. This means that ExtendSim will use the exact values you enter in the table, not an interpolated amount.
Time units: months (the model default as set in the Simulation Setup command)
Enter data in the data table
Increase the number of rows so the table has room for twelve months of data:
Click the +/- resize button - the green square at the bot- tom 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.
Or copy the data from the Rainfall.txt or Rainfall.xlsx files
located at ExtendSim/Examples/Tutorials/Continuous and paste it into the data table. Note that since the starting time is 0, the first month’s index is 0.
☞ After entering a value, tab or use the keyboard’s arrow keys to move to the next cell.
At the bottom of the Table tab, check the checkbox labeled Repeat table every and enter 12 in the months box. This causes the determination of monthly rainfall to restart every 12 months.
With this information, the table’s left column will specify the month and the right column will specify the amount of expected rainfall in inches. At each step, ExtendSim will check the block’s table for a time in the left column that is less than or equal to the current simulation time and output the corresponding value (inches of rainfall) from the right column.

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