AGFA DuoScan Owner's Manual page 25

If SCSI ID number 2 is free, go to instruction 5.
If SCSI ID number 2 is already assigned, you need to set the scanner to a free SCSI ID number.
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Make sure your scanner is switched off and is disconnected from your computer.
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Decide on an unassigned SCSI ID number.
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Use the SCSI ID switch (see figure) at the rear of the scanner to set the desired SCSI ID.
Push above the SCSI ID number to decrease the number, push underneath the SCSI ID
number to increase the number.
5. Click OK to close the SCSI ID Checker.
Chapter 2 — Installing the scanner 25