Epson GT-6500 EN - Manual (Page 153)

Parameter i determines the number of image lines that are included in
the data block. The value specified must be greater than 0 and less
than or equal to 255. (If 0 is specified, the scanner returns NAK in
response to this command.)
When the block data transfer mode is enabled with this command, the
receiving host computer must check the line counter and byte counter
in the data block to ensure the image data is received correctly. If the
color line sequence mode is selected, the host computer should count
the number of image data lines separately for green, red, and blue data.
Note that since the number of sub scan lines can vary, the value of the
line counter for the last data block will usually not be the same as i.
Therefore, the line counter must be checked in order to ensure correct
image data reception. For a given sub scan read length (SSRL), the
number of lines in the last data block can be determined as follows.
MOD (SSRL/i)
Note:
❏ MOD is a function that produces the remainder of a division
operation.
❏ The ESC d command is effective for increasing scanning speed,
especially when using the SCSI interface.
Command Reference 3-59