Allen-Bradley 2755-HDG-4 User Manual page 84

4-28 Communication Setup (Cable Configuration)
AdaptaScan Pass Through Cable Options (Continued)
Software Handshaking
Software handshaking controls the transmission of data. Use software
handshaking instead of (but not with) hardware handshaking.
There are four options:
•
None (default)
•
ACK/NAK Only
•
ENQ Only
•
ACK/NAK with ENQ
•
XON/XOFF
ACK/NAK Only checks the result of a transmission. The scanner waits
for one of two responses from the host: ACK which means a successful
transmission or NAK which means there was a problem. Whenever the
scanner receives a NAK, it retransmits the data up to three times. If an
ACK is still not received after three attempts, the transmission is aborted
and the scanner provides four short beeps.
ENQ ONLY requires that the scanner receive an an enquire character
(ENQ) from the host before sending data. With ENQ enabled, the
scanner must receive an ENQ from the host within a two second period
after the last scan or a transmission error occurs. The scanner provides
four short beeps to indicate an error (ENQ not received).
ACK/NAK with ENQ combines both ACK/NAK and ENQ options.
With XON/ XOFF enabled, the scanner assumes an XON for the first
transmission. The scanner transmits data until an XOFF is received from
the host device. If an XON is not received within 30 seconds after an
XOFF, a transmission error occurs.
Publication 2755-6.2