Computers And Handshaking - Epson ES-1000C Reference Manual

Computers and Handshaking

Scanners are connected to their host computers by some kind of
interface. Since a scanner sends data to the computer, the interface
must carry data not only from the computer to the scanner, but also
from the scanner to the computer. For this reason, the interface must
be capable of bi-directional communication.
A method of interaction between the computer and scanners is
necessary to prevent the computer from sending data at the same time
the scanner is sending data. This interaction method is the basis for
governing scanner operation.
EPSON scanner and computer interaction is controlled by a method
called handshaking. After the computer sends data to the scanner, it
must wait for the proper reply from the scanner before sending more
data. Also, when the scanner sends data to the computer, it must wait
for the correct response from the computer before sending additional
data. Handshaking dictates the method of sending data and how the
data is acknowledged by both the computer and scanner.
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