Epson GT-6500 EN - Manual (Page 161)

ACK Normal response (acknowledge)
Format: B1 B2 B3 B4 B5 A5
ASCII: ACK
Decimal: 6
Hexadecimal: 06
Explanation:
This code is used by both the scanner and computer for handshaking.
This code indicates that a command, a set of parameters, or a data
block was legal and accepted by the receiving device.
The computer should always send an ACK code in response to a data
block sent from the scanner, except after the last data block of a page
of image data. If the computer fails to send an ACK code within 30
seconds, an interface error occurs in the scanner.
Note:
The ACK code shown here is the ASCII code for 06
H
. The ACK code
does not refer to the ACKNLG signal line of the interface.
Command Reference 3-67