Each plugin in a rack (both instruments and insert effects) has a MIDI routing filter.
|•||All MIDI routing is per-scene and can change for each scen|
Open the Plugin Console to show the MIDI Filter
Press the arrow next to the instrument name and select the MIDI Routing tab:
Enable or Disable an Input Port
The "From" column has entries for each MIDI input port. Right click on the "To" column to present a menu with choices for how to enable or disable MIDI from a specific input port.
Select an Input Port and Channel
Select an Input Port and Channel to display the MIDI routing and filtering for that input port/channel combination. Right click in the "To" column of a channel for a menu of options for enabling or disabling MIDI input from a specific channel, remap a channel, add a layer, etc.
Select a Key Range Tab
A Key Range blocks MIDI notes outside a selected range of notes and also enables you to transpose the selected range up or down in half-steps. Four key ranges can be configure to do advanced ranges and splits. Uncheck "Enable MIDI Notes" to disable MIDI Note events from this input port/channel.
Select the Controllers Tab
The controllers table enables, disables, remaps and layers MIDI CC messages. Press "Unity Map" to restore the default no remap. You can also do things like rescale between a minimum and maximum value, set a value to send when the scene is used (Init value), and set up advanced modes like Toggle and Snap.
Full discussion of MIDI Filtering and Automation