Epson GT-6500 EN - Manual (Page 127)

Reading area
The figure below illustrates the scanning area definition.
c
Caution:
If the reading area param eters are w rong, a com m and error
occurs in the scanner. The m ost likely m istake is that the value
used for the m ain scan is not a m ultiple of 8. The m axim um
value of n
3
is different for each scanner. The offset length can
be set in units of one.
Command Reference 3-33