Hi,
I have done this successfully often following this procedure:
- Stop BE services
- Unplug the device
- Go to device manager and rescan, it should detect the drive as gone and remove it
- Do your offline work
- Reconnect the device
- Right click on your SCSI interface card, and disable it
- Wait a minute
- Reenable the SCSI interface card in the device manager
- Windows rescans the SCSI ids and reinstall the tape drive
- Start BE services
This is not an official procedure of course, so do so at your own risk.