Simplify repetitive logic with sub flows

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In FlexSim, a sub process flow, or sub flow, is a specific segment of a process that can be reused at multiple points within the process.

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This eliminates the need to recreate repetitive logic.

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Using a sub flow allows for modular process flow designs and enhances the flexibility, efficiency, and scalability of your simulation model.

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In this example, a previously created model shows items moving from conveyors into a warehousing system.

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The ProcessFlow is set up to control the flow and loading of items through the ASRS system to the racks.

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Here, you can see that each ASRS process is set up individually, making for a complicated design that uses repetitive logic.

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While this setup works, you can simplify it by using a sub flow, resulting in a more manageable and efficient design.

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First, Stop the simulation.

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In the SouthSide of the model, begin by grouping the ASRS decision points.

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Right-click a decision point and select Object Groups > Add to a New Group.

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In the Group Properties dialog, enter a name for the Group, such as “SouthDP”.

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Then, use the Sampler to add the rest of the decision points to the group—here, DP1 through DP10.

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Close the Group Properties.

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Select one of the decision points in the model.

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In Properties, under Triggers, click Add, and select On Arrival.

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Then, click Add and select Data > Set Label.

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In the Set Label dialog, change the Label to “ASRS” and the Value to “1”.

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Repeat these steps for the remaining decision points, increasing the Value by one.

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For example, the second decision point will have a Value of 2, the third a Value of 3, and so on.

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The trigger is now set up to add a corresponding label to each item when it arrives at the decision point.

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Next, in the SouthSide ProcessFlow,

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move the ASRS activities down to make space, and then copy and paste one of the repetitive process flows to use as a starting point.

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Open the Source Quick Properties and then click the Object Sampler.

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In the Model, select one of the decision points, then select Group: SouthDP > On Arrival.

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This sets the Source up for the group instead of an individual decision point.

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Back in the Source Quick Properties, under Label Assignment, add a Label Name of “pallet”, and for the Operation, select assign.

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Open the Quick Library and add an Assign Labels activity to the Source.

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In the Assign Labels Quick Properties, set the Name to “ASRS”, and the Value to “token.pallet.ASRS”

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to apply a label to each token that corresponds to its pallet.

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Next, open the Pull from ASRS_1 list Quick Properties, and change the setup from an individual list to a uniform list.

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Click the List Reference Sampler and select a blank spot in the ProcessFlow.

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In Quick Properties, rename the list to “Pull from South ASRS List”.

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Then, in the Toolbox, select ASRS_1, then right-click and select Duplicate.

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Rename the list to “South ASRS List”, then click OK.

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Back in the ProcessFlow, in the List Quick Properties, expand the List drop-down-and select Global List > South ASRS List.

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Next, create a sub flow for the process that finds and assigns slots, and then loads and unloads each item.

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Select this part of the process and move it to the side.

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Open the Quick Library and add a Run Sub Flow, placing it below the Acquire activity.

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Disconnect the Pull from South ASRS List activity from its current activity block, and then add it below Assign Labels.

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When you add a Run Sub Flow activity, you must link it to a sub flow.

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Click the exclamation mark icon next to Run Sub Flow to select the Sampler.

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Click in the ProcessFlow to create a Start activity, then make it the first activity in your sub flow.

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In this example, some of the connections and the adjacent flow are deleted to make room for the sub flow.

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Next, the Decide is separated from its block and the sub flow activities are moved up.

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Then, in the Quick Library, a Finish Sub Flow is selected and placed as the last activity in the sub flow.

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The Decide and connector are removed, and the Move Object block is added below Run Sub Flow.

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The List is moved up closer to the rest of the newly created flow.

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In List Quick Properties, the List is renamed to “South ASRS List”.

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Then, the remaining individual ASRS process flows are deleted, and the Process Flow container is resized to fit the new sub flow.

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In the Run Sub Flow Quick Properties, the Quantity is set to “token.pallet.subnodes.length.”

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In the Acquire Quick Properties, the Query is adjusted to “WHERE ASRSvehicle = puller.ASRS”.

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When the model is Reset and Run, you can see that it accomplishes the same outcome as the previous model.

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However, the ProcessFlow logic has been significantly simplified by adding decision points to a group,

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and by adding labels for the process flow and sub flow to recognize.

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In this example, you can further simplify the design by performing the same steps on the North Side Operations.

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With both processes using sub flows, the overall ProcessFlow design is far more efficient.