Oki PT390 Manuel D'utilisation page 48

Notes on using the printer through the USB interface
(1) The printer must be connected directly to the host computer.
(2) Before starting printing, turn on the power to the printer.
(3) If a printer error occurs during printing, recover the printer from the error,
and then retry printing.
(4) The host computer should not be set to any of the following modes: standby,
sleep, suspend, and pause.
If the host computer or printer does not work normally after the host
computer returns to normal operation mode from one of the above modes,
disconnect the USB cable once and then reconnect it, or turn off the printer
power switch once and then turn on the switch again. If the host computer
or printer cannot be restored to normal operation after the cable is
reconnected or power switch is turned on again, restart the host computer.
(5) The USB hub function cannot be used when the power to the printer is off.
(6) If a peripheral device connected to the USB hub is not recognized, perform
one of the following operations:
- Disconnect the USB cable from the peripheral device once, and then
reconnect it.
- Connect the peripheral device to the other port of the USB hub.
(7) The operation of connected USB devices is not guaranteed. Before using a
USB device, verify its operation yourself.
Note: Do not turn off the power to the printer during printing.
If you inadvertently turn off the power to the printer during printing and
the printer then fails to work normally, restart the host computer.
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