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Process Simulation in the iGrafx Platform

Description

This page discusses the discrete event simulation engine feature.

You can now create a simulation model for a process using the web diagrammer. You can get the results of running it and/or watch the simulation running live.

To get started, you can either use an existing diagram as a starting point, or start with a blank diagram. The simulation will be stored in a Simulation Project object which will contain all things relating to the simulation.

Starting with a new diagram

Go to the location you want to store the Simulation Project in, and create a Simulation Project object.

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Starting with an existing diagram

Go to the existing diagram. Click Apps in the top right, and click Create Simulation Project.

Note that the diagram should be checked in. Any changes made since the last check in won’t show up on the new diagram.

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Getting started with simulation

Click Apps in the top right, and click Simulation. A toolbar will appear. Click Properties to open the Simulation Properties dialog. To hide this dialog, click Properties again.

If a shape is selected, the Simulation Properties dialog will show the properties for that shape. If no shape is selected, the dialog will show properties for the whole simulation. You can also select a connector line to add a duration for it. The dialog can be resized to the size you like.

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For help building more complex expressions, change the type of the input box using the dropdown. Selecting “Expression” will enable autocomplete with suggestions for variables present in the model and built-in functions.

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Running the simulation

Clicking Run will run the simulation and then display results.

Clicking Trace opens up a more interactive view. You can:

  • Watch cases move through the simulation

  • Adjust the speed

    • Note that the speed slider is on an exponential scale. Every 5 units represents about a 2x increase in speed. For example, moving the slider from 40 to 60 will cause much more than a small increase: the simulation will go 16x faster.

  • Play/pause

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Fixing problems

If the simulation model has invalid parameters, then a dialog will be displayed showing where the problems are. Problems that prevent the simulation from running are displayed with a red error icon, while problems that potentially produce unexpected results are displayed with a yellow warning icon.

Most warnings will have a navigation icon on the right and/or clickable links that take you to where the problem is. Some warnings (for example, if the model has no active generators) do not have navigation links.

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Results

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Once the simulation finishes, results will be displayed. You can choose to save the results to a Simulation Results object, or export them. All the results are saved, regardless of which ones are selected to be visible from the Columns option.

If you choose to save to a Simulation Results object, the object will be saved to the Simulation Project folder, and you can view them later by going to the object.

Comparing results

You can compare multiple sets of results to see which one best produces your desired outcome. Click on the Simulation Project object to compare all the results saved in the project.

To see what changed in the diagram from the baseline to produce the different results, click on the “Compare with baseline run” button.

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Troubleshooting

  • My simulation does not run and I get a dialog titled “Problems (Last Simulation)”

    • See the section “Fixing Problems” above.

  • My simulation does not make any progress

    • It is possible your simulation contains an infinite loop. If a case moves in an infinite loop of activities that take no time to complete, the simulation clock will not advance. This can be seen if you run the simulation in Trace mode.

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