Using the Steel Connections: Tube Truss Node extension, you can generate a tube connection (a node of the truss from tubular sections).
At the top of the dialog are 2 selection lists:
You can select a connection name and / or number from these lists or specify a new number or name.
At the bottom are 3 buttons:
Details concerning the calculation algorithms for steel connections can be found in the main Autodesk® Robot™ Structural Analysis help file (see Steel Connection Design).