question

So if you want to track the number of flow items in the whole model/system, there is a default WorkInProgress tracked variable already set in place in FlexSim. To view this variable WorkInProgress vs Time in the model, go to the Dashboard or create a new one. Drag out the Tracked Variable vs Time widget. Open its preferences and in the TrackedVariables tab, click on the green '+' button to add a new TrackedVariable to the chart. Then just select WorkInProgress from the drop-down menu.

If you want to only track the WIP or content of a particular section of your model, you can do this by creating your own Tracked Variable. (Go to the Toolbox tab, click on the green '+', select Statistics > Tracked Variable from the dropdown menu). IN the Tracked Variable preferences you can name your Tracked variable, and be sure to set the type to Level (Content).

Then you just go to the first object (queue, processor, etc) in the section you want to track, and in the object's OnEntry trigger. Create a new trigger, select Data > Set Tracked Variable. Change the operation from 'Set' to 'Increment' and the value by 1. (This will increment your tracked variable everytime a flow item enters the object.) Then in your LAST item in the segment, do the same thing on the object's OnExit trigger. (Only set the operation to 'Decrement' instead) (This will remove 1 from the tracked variable when the item leaves that object.)

Finally you can see this tracked variable the same way you do for the WorkInProgress, in the Dashboard. (Just select your newly created TrackedVariable from the drop down instead of WorkInProgress.)