Canon BJC-3000 - Manual (Page 19)

19 Connecting and Switching On the Printer
Notes on Handling the USB Interface
Wait for at least 5 seconds before connecting the USB interface cable
again.
When you disconnect the USB interface cable while the printer and
computer are turned on and connect it again, wait for at least 5 seconds.
If you connect the USB interface cable immediately after disconnecting,
the printer and computer may not operate properly.
When you connect multiple printers using the USB interface, use the
external USB hub.
When you connect multiple printers using the USB interface, use the
external USB hub and then install the printer driver each time you connect
the printer. For more details on the procedures for installing the printer
driver, please refer to the Driver and Utility Guide for Windows Users in the
Reference Guide (CD-ROM) or the Driver and Utility Guide for Macintosh
Users (book), depending on the computer system you are using.
Disconnect the USB interface cable on the side of the computer or USB
hub.
When you disconnect the USB interface cable while the printer and
computer are turned on, always disconnect on the side of the computer or
USB hub.