RS-232 Interface 6 - 17

ACK/NAK with ENQ

This combines the two previous options. For re-transmissions o f data due to a NAK from the host, an additional
ENQ is not required.
ACK/NAK with ENQ

XON/XOFF

An XOFF character turns the scanner transmission off until the scanner recei ves an XON character. There are two
situations for XON/XOFF:
•
The scanner receives an XOFF before it has data to send. When the scann er has data to send, it waits up to
Host Serial Response Time-out for an XON character before transmission. If it d oes not receive an XON
within this time, it issues an error indication and disc ards the data.
•
The scanner receives an XOFF during a transmission. Data transmission then stops after sendi ng the current
byte. When the scanner receives an XON character, it sends the rest of the data message. The scanner
waits up to 30 seconds for the XON.
XON/XOFF