Yamaha USB-MIDI INTERFACE UX16 Owner's Manual page 22

Changing the device number
If you are using multiple UX16s, you can change the device number.
Click "Device Name." The System displays the drop-down list. Select the device
for which you wish to change the setting.
If you are using a Macintosh computer, the device number is assigned sequentially,
NOTE
such as "USB1," "USB2," etc., as the Device Name.
Checking the signal path
To see if the MIDI device is connected correctly, you can try transmitting MIDI
signals.
Note Off Message
When you click [Send All Note OFF], a MIDI All Note Off message will be sent
to the UX16.
Note On Message
When you click [Send All Note On], a MIDI All Note On message will be sent
to the UX16.
Changing connections during playback (PC OUT MIDI OUT)
The left column shows the computer's output port (OUT 1), and the top column
shows the UX16's output port (1). If you remove the check box, a MIDI signal
from the computer to a MIDI device does not flow.
Changing connections during recording (MIDI IN PC IN)
The left column shows the computer's input port (IN 1), and the top column
shows the UX16's input port (1). If you remove the check box, a MIDI signal from
a MIDI device to the computer does not flow.
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