Doepfer d3c Midi/USB Organ Controller - Manual (Page 15)

d3c Page 15 User's Guide V1.0
Power on sequence / USB connection sequence
The USB connection between the computer and d3c must not be established or interrupted
while a program is running that uses the USB Midi port (e.g. B4) ! Otherwise the program can
block the connection or the Midi ports will not work any longer. In this case it is
recommended to reboot the computer.
If the USB connection has been already established earlier (or if the USB Midi port was
already in use) and the USB connection has been interrupted and established again it may
last several minutes until the USB Midi port is recognized again. In this case it is not allowed
to start a Midi program (e.g. B4) as otherwise the Midi port cannot be opened again. Even in
this case it is recommended to reboot the computer.
We have to point out that is not a problem of the d3c but of the operation system of the
computer and the USB drivers.