In FlexSim, ports are used to connect objects together logically. Each object can have an unlimited number of ports. There are three types of ports: input, output, and central.
For Fixed Resources, input and output ports are used in the routing of flowitems. For example, a mail sorter places packages in one of several queues depending on the destination of the package. To simulate this in FlexSim, you would connect the output ports of a Processor object to the input ports of several Queue objects, meaning once the Processor (or mail sorter) has finished processing the flowitem (or package), it sends it to a specific queue through one of its output ports.
Central ports are used to create references from one object to another. A common use for central ports is for referencing mobile objects such as operators, fork lifts, and cranes from fixed resources such as machines, queues, or conveyors.
See Fixed Resource Concepts for more information on how Fixed Resource input/output port hand-shaking works.
For Task Executers and Dispatchers, input/output ports are used to define task sequence dispatching. See the Dispatcher topic for more information on how this works.
Creating Ports
Ports are created and connected in one of two ways:
1) By clicking on one object and dragging to a second object while holding down different letters on the keyboard. If the letter 'A' is held down while clicking-and-dragging, an output port will be created on the first object and an input port will be created on the second object. These two new ports will then be automatically connected. Holding down the 'S' key will create a central port on both objects and connect the two new ports. Connections are broken and ports deleted by holding down the 'Q' for input and output ports and the 'W' key for central ports. The following table shows the keyboard letters used to make and break the two types of port connections. The First Model from the Getting Started section demonstrates how to properly make port connections.
| Output - Input | Center | |
| Connect | A | S |
| Disconnect | Q | W |
2) By entering the connection mode via clicking the 
button. Once in the connection mode, there are a couple of ways to make a connection between two objects. You can either click on one object, then click on another object; you may also click and drag from one object to the next as with method one. Either way, keep in mind that the flow direction of a connection is dependent on the order in which you make the connection. Flow goes from the first object to the second object. Incidentally, connections can be broken by clicking the 
button then clicking or dragging from one object to another in the same manner as when you connected them. Center port connections are not affected by the order in which the objects are connected.
