First the networks must to be created by right clicking on Networks under Communication.
From the Unity I/O map double clicking on the Ethernet port will bring up a window asking the user to link a configured network to the card.
Often user will try to choose a network and there are no network options available to choose.
Right click on the particular network from the project tree shown in figure #1 and select Configure; the screen below will open. The Model Family must be chosen for the network. When the mouse is moved over the Model Family list a pop-up window will show the user which Family to choose for which type of network card.
Going back into the I/O map and double clicking on the port will now show available networks for that port.