Epson GT-30000 - Manual (Page 25)

Setting Up Your Scanner
19
If the scanner is in the middle of a chain, turn the switch OFF .
Setting the Select Switch
The scanner has two SCSI connectors: one for a 68-pin SCSI cable and the other for a
50-pin SCSI cable. You may need to change the select switch setting depending on
the SCSI card and cable you are using in your computer.
If you are using a 50-pin host adapter and SCSI cable connection anywhere on the
bus between the host adapter and the scanner, use the
N setting. Use the W setting for
68-pin SCSI ultra-wide host adapter and cable connections.