Epson GT-6500 EN - Manual (Page 75)

The main scan reading length (n
3
) must always be set in exact
multiples of eight (8-dot units equal units of 1 byte). The main scan
skip length (n
1
), sub scan skip length (n
2
), and sub scan reading length
(n
4
) can be set in 1-dot increments.
Use the above values to set the scanning area with the ESC R, ESC H,
and ESC A commands.
Note:
The ESC A command sets the length (number of lines) of the sub scan
reading length. However, you should always check the area end flag
in the status byte to confirm whether the current data block is the final
block. Do not rely solely on your calculations from the ESC A
command.
Command Usage 2-37