HUI control surface devices don’t support automatic scanning. You need to manually add these devices to your setup. When you add a device in this way, you need to assign the MIDI In and Out port parameters.
Make sure that your HUI devices are connected bidirectionally with the computer, using a MIDI interface.
Choose Logic Pro > Preferences > Control Surfaces > Setup.
Choose New > Install in the Setup window.
Select HUI in the Install window.
Click the Add button.
Select the added device in the Setup window, then set the MIDI In and MIDI Out parameters as appropriate.