RS-232 Interface
281
Software Handshaking
This parameter offers control of data transmission in addition to, or instead of, that offered by hardware
handshaking. If software handshaking and hardware handshaking are both enabled, hardware handshaking takes
precedence.
Options:
• None - This transmits data immediately. The scanner expects no response from the host.
• ACK/NAK - After transmitting data, the scanner waits for an ACK or NAK response from the host. If it
receives a NAK, the scanner transmits the data again and waits for an ACK or NAK. After three
unsuccessful attempts to send data after receiving NAKs, the scanner sounds a transmit error and
discards the data.
The scanner waits up to the programmable Host Serial Response Timeout to receive an ACK or NAK. If
the scanner does not get a response in this time, it sounds a transmit error and discards the data. There
are no reattempts.
• ENQ - The scanner waits for an ENQ character from the host before transmitting data. If it does not receive
an ENQ within the Host Serial Response Timeout, the scanner sounds a transmit error and discards the
data. The host must transmit an ENQ character at least every Host Serial Response Timeout to prevent
transmission errors.
• ACK/NAK with ENQ - This combines the two previous options. An additional ENQ is not required to
re-transmit data due to a NAK from the host.
• XON/XOFF - An XOFF character stops data transmission until the scanner receives an XON character.
There are two situations for XON/XOFF:
• The scanner receives an XOFF before it has data to send. When the scanner has data, it waits up to
the Host Serial Response Timeout for an XON character before transmitting. If it does not receive the
XON within this time, the scanner sounds a transmit error and discards the data.
• The scanner receives an XOFF during data transmission and stops transmission after sending the
current byte. When the scanner receives an XON character, it sends the rest of the data. The scanner
waits indefinitely for the XON.
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