Some Midi controllers, such as a Novation Launchpad, or an Akai APC, send Midi messages that look just like a note being played. These can still be assigned as triggers in Box Of Stops, but if you find them behaving strangely (e.g. stopping a [[Bank]] from being played by another keyboard input), it may be worth [[Bank#Explicitly assigning an input|directly assigning]] any keyboards to their Banks.
The difference here is the type of Midi message being used. Most Midi controllers either send a Control Change message (like the Sustain Pedal), or a Program Change message (e.g. to select Grand Piano), or even can be configured to whichever is preferred. A grid based controller like the Launchpad will often instead choose to use Note messages, where a separate note is assigned to each button.