The Lighting Controller

Hello,
I am setting up a large club lighting rig that will need 5-6universes depending on what we end up going with DMX channel wise. My question, what hardware configuration would be needed. I am using show xpress, currently have used the 512 and 1024 hardware universes in the past, but since they use eithernet to send the info to the computer, what would be the process for having 3 DMX 1024 devices to give me 6 universes?

Not sure we really understood your question.
In the meantime, please note that the interface D1024 has 2 DMX outputs (2 universes), which means 2*512 DMX channels.
So with 3 of these DMX interfaces, you will cover 6 DMX universes.

How do 3 of these work with one computer?

The PC has to have 3 USB ports.
Then just plug the DMX interfaces to these USB ports and our software will find them.