Setting Up Outsourcing Ports / Function Modules 
Prerequisites
Make sure that you have configured the port area on the server so that the third-party payroll service provider is able to access the file easily. Also ensure that both the user and the outsourcer know the name of the port before they need to create and export the payroll file or import the payroll results file.
Make sure that you create both an Outbound file and an Inbound file port on the server, if you are both exporting and importing information. These directories must be separate.
You can also assign a function module for an Inbound or Outbound file at the same time you are setting up the ports. Depending on your business requirements, you can use an existing function module or you can create your own.

This procedure assumes that you are using an existing function module.
If you are starting this process from the SAP Reference IMG screen, begin with step 3.

The IMG path varies by release.
Procedure
Setting up the Outbound file port
The Customizing Edit Project screen appears.
The Display IMG screen appears.
The Ports in IDoc Processing screen appears.

The detailed information appears on the right hand side of the screen.

If you want to set up a function module, continue with step 14.
If you do not want to set up a function module, continue with step 15.
If you do not need to set up an inbound file port, choose Save.
Setting up the Inbound file port
The detailed information appears on the right hand side of the screen.

If you want to set up a function module, continue with step 18.
If you do not want to set up a function module, choose Save.
Result
You have successfully set up your file ports. Continue with
Setting Up the Partner Definition.