Item To Flow

Overview and Key Concepts

The Item To Flow is designed to interface between FloWorks objects and FlexSim's discrete objects. It receives discrete flow items from a fixed resource and converts it into flow. An example of a real-life process represented by a Item To Flow could be an unpacking machine that converts discrete packs into continuous bulk material.

The input side of the item to flow is similar to a fixed resource sink, while the output side looks like a regular FloWorks object. You can specify an outflow rule, maximum outflow rate and a fluid amount per entering item. This amount is specified as an expression, which can yield a different result for each flow item.

The visual representation of the item to flow includes a progress bar and in the statistics of the object the progress of the emptying process of the current flow item is shown. The bar is a level indicator that fills to 100% when a flow item enters and gradually reduces, representing the amount of flow still to be sent before the next flow item is allowed to enter.


The item to flow provides the On Rate Change event that fires whenever a change in the output flow rate occurs. In addition it has the following object specific events.

On Entering

This function is called when an item enters the item to flow object, regardless of whether it can start flowing or has items queued before it.

It has the following parameters:

Event Parameter Explanation
item A reference to the flow item that is entering the item to flow.
port The input port that the item is entering through.

On Entered

This function is called as soon as all the items queued before the current item have finished and the outflow corresponding to this item starts.

It has the following parameters:

Event Parameter Explanation
item A reference to the flow item that is entering the item to flow.
amount The outflow amount that has been determined for this item by the "Flowamount per item" expression.

On Item Empty

This function is called as soon as the outflow corresponding to an item has finished, immediately before the item will be removed.

It has the following parameters:

Event Parameter Explanation
item A reference to the flow item that will be destroyed immediately after this event.


For statistical purposes, the item to flow's FloWorks state profile will be in one of the following states at various points during a simulation run:


No flow is collected because there is no flow item, or because the output side is blocked, for example because the item to flow is waiting for downstream availability or an operator.


Flow is being released until the required amount to release an item has exited.


The item to flow tracks the following statistics. These can be viewed by clicking on the object and then viewing the Statistics panel in Properties.


The total number of discrete flow items that have entered the object.


The total number amount of flow, measured in fluid units, that has exited the object.

Outflow rate

The current output, measured in fluid units per time unit. The input rate will always be zero.


The ratio of the output volume (total amount of outflow) to the maximal possible value for that statistic.

For example, if you run the model for two hours and the maximum flow rate was 10 for one hour and 20 for the second hour, while the actual flow rate was 10 per hour during the whole run, the utilization will be (20 (total flow)) / (10 + 20 (maximal flow)) × 100% ≈ 67%.


The item to flow uses the following properties panels:


The object specific triggers are described above under Events.

For more information about the remaining events see Fixed Resource - Events.

Custom coding

You may control the behavior of the item to flow dynamically by writing FlexScript, for example in a Script window or by changing the code behind one of the options in an object trigger.

The item to flow is an instance of the FlowObject class, see the class reference for information about its properties.

FloWorks also provides a specific ItemToFlow class that may be needed in some special cases.