Oki PT390 Manuel D'utilisation page 13

For a unit with Dual interface
Insert
Power connector
Drawer kick connector
Connector cover
Insert
Interface Connector
(USB Interface Type-B)
* Connect the printer to a PC
through this connector.
11
USB Interface Cable
Type-B
* Connect the printer to a PC
through this connector.
Serial interface cable
* Secure the connector with
screws after making the
connection.
Interface connector
(Serial interface)