question

Hello Sandrine,

There are multiple solutions to implement what you are looking for. As you are a beginner, I will try to share with you what I think is the easiest solution, without using advanced tools.

You can add a new tracked variable in your model:

Rename this variable for example TotalWeight and select the type of variable: Level.

Then pin this new tracked variable to a dashboard (in a new dashboard or an existing dashboard if you already have one) as a Line Chart:

Currently you just have an empty graph:

The next step is to update your tracked variable.

I assume that you defined a label on your flowitems for the weight.

In this example, let's assume that you created a label named Weight on all boxes:

And that when the source creates boxes, you update this value to whatever weight you want (using a schedule, or an On Creation trigger).

We need to update our tracked variable TotalWeight:

• when a box enters the queue, we want to increment the tracked variable TotalWeight
• when a box exits the queue, we want to decrement the tracked variable TotalWeight

So in the properties of the Queue, add 2 triggers: On Entry and OnExit:

For both triggers, add the pickoption Set Tracked Variable:

In the On Entry trigger, select Increment, then pick your tracked variable and by how much it will be incremented:

The expression item.Weight means that it will read the value of the label Weight of the flowitem.

In the On Exit trigger, select Decrement, then pick your tracked variable and by how much it will be decremented:

Reset and Run your model, your chart will be updated:

I advice you to set a custom title, a Y axis title and you can also hide the legend if you want:

Please find attached a small example: 2021-05-03 Weight in queue versus time.fsm

Hope this helps.